The Ploidy State as a Determinant of Hepatocyte Proliferation

The liver's unique chromosomal variations, including polyploidy and aneuploidy, influence hepatocyte identity and function. Among the most well-studied mammalian polyploid cells, hepatocytes exhibit a dynamic interplay between diploid and polyploid states. The ploidy state is dynamic as hepatocytes move through the "ploidy conveyor," undergoing ploidy reversal and re-polyploidization during proliferation. Both diploid and polyploid hepatocytes actively contribute to proliferation, with diploids demonstrating an enhanced proliferative capacity. This enhanced potential positions diploid hepatocytes as primary drivers of liver proliferation in multiple contexts, including homeostasis, regeneration and repopulation, compensatory proliferation following injury, and oncogenic proliferation. This review discusses the influence of ploidy variations on cellular activity. It presents a model for ploidy-associated hepatocyte proliferation, offering a deeper understanding of liver health and disease with the potential to uncover novel treatment approaches.

Association of oxidized ApoB and oxidized ApoA-I with high-risk coronary plaque features in cardiovascular disease

BACKGROUND

Oxidized apolipoprotein B (oxLDL) and oxidized ApoA-I (oxHDL) are proatherogenic. Their prognostic value for assessing high-risk plaques by coronary computed tomography angiography (CCTA) is missing.

METHODS

In a prospective, observational study, 306 participants with cardiovascular disease (CVD) had extensive lipoprotein profiling. Proteomics analysis was performed on isolated oxHDL, and atherosclerotic plaque assessment was accomplished by quantitative CCTA.

RESULTS

Patients were predominantly White, overweight men (58.5%) on statin therapy (43.5%). Increase in LDL-C, ApoB, small dense LDL-C (P < 0.001 for all), triglycerides (P = 0.03), and lower HDL function were observed in the high oxLDL group. High oxLDL associated with necrotic burden (NB; β = 0.20; P < 0.0001) and fibrofatty burden (FFB; β = 0.15; P = 0.001) after multivariate adjustment. Low oxHDL had a significant reverse association with these plaque characteristics. Plasma oxHDL levels better predicted NB and FFB after adjustment (OR, 2.22; 95% CI, 1.27-3.88, and OR, 2.80; 95% CI, 1.71-4.58) compared with oxLDL and HDL-C. Interestingly, oxHDL associated with fibrous burden (FB) change over 3.3 years (β = 0.535; P = 0.033) when compared with oxLDL. Combined Met136 mono-oxidation and Trp132 dioxidation of HDL showed evident association with coronary artery calcium score (r = 0.786; P < 0.001) and FB (r = 0.539; P = 0.012) in high oxHDL, whereas Met136 mono-oxidation significantly associated with vulnerable plaque in low oxHDL.

CONCLUSION

Our findings suggest that the investigated oxidized lipids are associated with high-risk coronary plaque features and progression over time in patients with CVD.

TRIAL REGISTRATION

CLINICALTRIALS

gov NCT01621594.

FUNDING

National Heart, Lung, and Blood Institute at the NIH Intramural Research Program.

Changes in tropospheric air quality related to the protection of stratospheric ozone in a changing climate

Ultraviolet (UV) radiation drives the net production of tropospheric ozone (O3) and a large fraction of particulate matter (PM) including sulfate, nitrate, and secondary organic aerosols. Ground-level O3 and PM are detrimental to human health, leading to several million premature deaths per year globally, and have adverse effects on plants and the yields of crops. The Montreal Protocol has prevented large increases in UV radiation that would have had major impacts on air quality. Future scenarios in which stratospheric O3 returns to 1980 values or even exceeds them (the so-called super-recovery) will tend to ameliorate urban ground-level O3 slightly but worsen it in rural areas. Furthermore, recovery of stratospheric O3 is expected to increase the amount of O3 transported into the troposphere by meteorological processes that are sensitive to climate change. UV radiation also generates hydroxyl radicals (OH) that control the amounts of many environmentally important chemicals in the atmosphere including some greenhouse gases, e.g., methane (CH4), and some short-lived ozone-depleting substances (ODSs). Recent modeling studies have shown that the increases in UV radiation associated with the depletion of stratospheric ozone over 1980-2020 have contributed a small increase (~ 3%) to the globally averaged concentrations of OH. Replacements for ODSs include chemicals that react with OH radicals, hence preventing the transport of these chemicals to the stratosphere. Some of these chemicals, e.g., hydrofluorocarbons that are currently being phased out, and hydrofluoroolefins now used increasingly, decompose into products whose fate in the environment warrants further investigation. One such product, trifluoroacetic acid (TFA), has no obvious pathway of degradation and might accumulate in some water bodies, but is unlikely to cause adverse effects out to 2100.

Dysregulation of Lipid and Glucose Homeostasis in Hepatocyte-Specific SLC25A34 Knockout Mice

Nonalcoholic fatty liver disease (NAFLD) is an epidemic affecting 30% of the US population. It is characterized by insulin resistance, and by defective lipid metabolism and mitochondrial dysfunction in the liver. SLC25A34 is a major repressive target of miR-122, a miR that has a central role in NAFLD and liver cancer. However, little is known about the function of SLC25A34. To investigate SLC25A34 in vitro, mitochondrial respiration and bioenergetics were examined using hepatocytes depleted of Slc25a34 or overexpressing Slc25a34. To test the function of SLC25A34 in vivo, a hepatocyte-specific knockout mouse was generated, and loss of SLC25A34 was assessed in mice maintained on a chow diet and a fast-food diet (FFD), a model for NAFLD. Hepatocytes depleted of Slc25a34 displayed increased mitochondrial biogenesis, lipid synthesis, and ADP/ATP ratio; Slc25a34 overexpression had the opposite effect. In the knockout model on chow diet, SLC25A34 loss modestly affected liver function (altered glucose metabolism was the most pronounced defect). RNA-sequencing revealed changes in metabolic processes, especially fatty acid metabolism. After 2 months on FFD, knockouts had a more severe phenotype, with increased lipid content and impaired glucose tolerance, which was attenuated after longer FFD feeding (6 months). This work thus presents a novel model for studying SLC25A34 in vivo in which SLC25A34 plays a role in mitochondrial respiration and bioenergetics during NAFLD.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2021

The Environmental Effects Assessment Panel of the Montreal Protocol under the United Nations Environment Programme evaluates effects on the environment and human health that arise from changes in the stratospheric ozone layer and concomitant variations in ultraviolet (UV) radiation at the Earth’s surface. The current update is based on scientific advances that have accumulated since our last assessment (Photochem and Photobiol Sci 20(1):1–67, 2021). We also discuss how climate change affects stratospheric ozone depletion and ultraviolet radiation, and how stratospheric ozone depletion affects climate change. The resulting interlinking effects of stratospheric ozone depletion, UV radiation, and climate change are assessed in terms of air quality, carbon sinks, ecosystems, human health, and natural and synthetic materials. We further highlight potential impacts on the biosphere from extreme climate events that are occurring with increasing frequency as a consequence of climate change. These and other interactive effects are examined with respect to the benefits that the Montreal Protocol and its Amendments are providing to life on Earth by controlling the production of various substances that contribute to both stratospheric ozone depletion and climate change.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

This assessment by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) provides the latest scientific update since our most recent comprehensive assessment (Photochemical and Photobiological Sciences, 2019, 18, 595-828). The interactive effects between the stratospheric ozone layer, solar ultraviolet (UV) radiation, and climate change are presented within the framework of the Montreal Protocol and the United Nations Sustainable Development Goals. We address how these global environmental changes affect the atmosphere and air quality; human health; terrestrial and aquatic ecosystems; biogeochemical cycles; and materials used in outdoor construction, solar energy technologies, and fabrics. In many cases, there is a growing influence from changes in seasonality and extreme events due to climate change. Additionally, we assess the transmission and environmental effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, in the context of linkages with solar UV radiation and the Montreal Protocol.

Environmental effects of stratospheric ozone depletion, UV radiation and interactions with climate change: UNEP Environmental Effects Assessment Panel, update 2019

This assessment, by the United Nations Environment Programme (UNEP) Environmental Effects Assessment Panel (EEAP), one of three Panels informing the Parties to the Montreal Protocol, provides an update, since our previous extensive assessment (Photochem. Photobiol. Sci., 2019, 18, 595-828), of recent findings of current and projected interactive environmental effects of ultraviolet (UV) radiation, stratospheric ozone, and climate change. These effects include those on human health, air quality, terrestrial and aquatic ecosystems, biogeochemical cycles, and materials used in construction and other services. The present update evaluates further evidence of the consequences of human activity on climate change that are altering the exposure of organisms and ecosystems to UV radiation. This in turn reveals the interactive effects of many climate change factors with UV radiation that have implications for the atmosphere, feedbacks, contaminant fate and transport, organismal responses, and many outdoor materials including plastics, wood, and fabrics. The universal ratification of the Montreal Protocol, signed by 197 countries, has led to the regulation and phase-out of chemicals that deplete the stratospheric ozone layer. Although this treaty has had unprecedented success in protecting the ozone layer, and hence all life on Earth from damaging UV radiation, it is also making a substantial contribution to reducing climate warming because many of the chemicals under this treaty are greenhouse gases.

Colchicine's effects on lipoprotein particle concentrations in adults with metabolic syndrome: A secondary analysis of a randomized controlled trial

BACKGROUND

Colchicine has received renewed interest for its potential beneficial effects in secondary prevention of cardiovascular disease. This was presumed to be primarily because of its anti-inflammatory effects; however, limited data exist regarding colchicine's impact on other cardiovascular risk factors.

OBJECTIVE

The aim of this study was to examine if colchicine's anti-inflammatory actions would lead to reduced circulating concentrations of oxidized low-density lipoprotein (oxLDL) in metabolically unhealthy individuals. We also examined if colchicine would improve concentrations of other atherogenic lipoprotein subfractions.

METHODS

This is a secondary analysis of a double-blind, randomized, placebo-controlled pilot study in which 40 adults with metabolic syndrome were randomized to colchicine 0.6 mg or placebo twice daily for 3 months. Blood samples were collected in the fasted state. OxLDL was measured using enzyme-linked immunosorbent assay. Nuclear magnetic resonance spectroscopy was used to measure other lipoprotein particle subfraction concentrations.

RESULTS

Compared with placebo, colchicine reduced markers of inflammation, including C-reactive protein, erythrocyte sedimentation rate, and GlycA (P < .01). Concentrations of oxLDL (P = .019) and small LDL (P = .022) appeared significantly increased in the colchicine arm. Colchicine had no significant effect on other lipoprotein subfractions or lipoprotein particle sizes (all P > .05).

CONCLUSION

Although colchicine may have benefit in secondary prevention of cardiovascular disease in at-risk individuals, we found no evidence that these effects are because of improvements in circulating atherogenic lipoprotein particle concentrations. Further studies are needed to confirm whether colchicine increases circulating oxLDL and small LDL levels in adults with metabolic syndrome. If true, additional research is warranted to elucidate the mechanisms underlying these associations.

Interactive effects of changing stratospheric ozone and climate on tropospheric composition and air quality, and the consequences for human and ecosystem health

The composition of the air we breathe is determined by emissions, weather, and photochemical transformations induced by solar UV radiation. Photochemical reactions of many emitted chemical compounds can generate important (secondary) pollutants including ground-level ozone (O₃) and some particulate matter, known to be detrimental to human health and ecosystems. Poor air quality is the major environmental cause of premature deaths globally, and even a small decrease in air quality can translate into a large increase in the number of deaths. In many regions of the globe, changes in emissions of pollutants have caused significant changes in air quality. Short-term variability in the weather as well as long-term climatic trends can affect ground-level pollution through several mechanisms. These include large-scale changes in the transport of O₃ from the stratosphere to the troposphere, winds, clouds, and patterns of precipitation. Long-term trends in UV radiation, particularly related to the depletion and recovery of stratospheric ozone, are also expected to result in changes in air quality as well as the self-cleaning capacity of the global atmosphere. The increased use of substitutes for ozone-depleting substances, in response to the Montreal Protocol, does not currently pose a significant risk to the environment. This includes both the direct emissions of substitutes during use and their atmospheric degradation products (e.g. trifluoroacetic acid, TFA).

Versatile, sensitive liquid chromatography mass spectrometry - Implementation of 10 μm OT columns suitable for small molecules, peptides and proteins

We have designed a versatile and sensitive liquid chromatographic (LC) system, featuring a monolithic trap column and a very narrow (10 μm ID) fused silica open tubular liquid chromatography (OTLC) separation column functionalized with C₁₈-groups, for separating a wide range of molecules (from small metabolites to intact proteins). Compared to today’s capillary/nanoLC approaches, our system provides significantly enhanced sensitivity (up to several orders) with matching or improved separation efficiency, and highly repeatable chromatographic performance. The chemical properties of the trap column and the analytical column were fine-tuned to obtain practical sample loading capacities (above 2 μg), an earlier bottleneck of OTLC. Using the OTLC system (combined with Orbitrap mass spectrometry), we could perform targeted metabolomics of sub-μg amounts of exosomes with 25 attogram detection limit of a breast cancer-related hydroxylated cholesterol. With the same set-up, sensitive bottom-up proteomics (targeted and untargeted) was possible, and high-resolving intact protein analysis. In contrast to state-of-the-art packed columns, our platform performs chromatography with very little dilution and is “fit-for-all”, well suited for comprehensive analysis of limited samples, and has potential as a tool for challenges in diagnostics.

Appearance of metastable B2 phase during solidification of Ni50Zr50 alloy: electrostatic levitation and molecular dynamics simulation studies

High-energy x-ray diffraction measurements of undercooled, electrostatically levitated Ni50Zr50 liquid droplets were performed. The observed solidification pathway proceeded through the nucleation and growth of the metastable B2 phase, which persisted for several seconds before the rapid appearance of the stable B33 phase. This sequence is shown to be consistent with predictions from classical nucleation theory using data obtained from molecular dynamics (MD) simulations. A plausible mechanism for the B2-B33 transformation is proposed and investigated through further MD simulations.

Theoretical calculation of the melting curve of Cu-Zr binary alloys

Helmholtz free energies of the dominant binary crystalline solids found in the Cu-Zr system at high temperatures close to the melting curve are calculated. Our theoretical approach combines fundamental measure density functional theory (applied to the hard-sphere reference system) and a perturbative approach to include the attractive interactions. The studied crystalline solids are Cu(fcc), Cu_{51}Zr_{14}(β), CuZr(B2), CuZr_{2}(C11b), Zr(hcp), and Zr(bcc). The calculated Helmholtz free energies of crystalline solids are in good agreement with results from molecular-dynamics (MD) simulations. Using the same perturbation approach, the liquid phase free energies are calculated as a function of composition and temperature, from which the melting curve of the entire composition range of this system can be obtained. Phase diagrams are determined in this way for two leading embedded atom method potentials, and the results are compared with experimental data. Theoretical melting temperatures are compared both with experimental values and with values obtained directly from MD simulations at several compositions.

Two-year weight-loss maintenance in primary care-based Diabetes Prevention Program lifestyle interventions

Objective:

To investigate whether the effects on weight loss and cardiometabolic risk factor reduction of two technology-mediated lifestyle interventions for 15 months in a primary care-based translation trial sustained at 24 months (that is, 9 months after the end of intervention).

Design:

This study analyzed data from an extended follow-up of participants in the original ‘E-LITE' (Evaluation of Lifestyle Interventions to Treat Elevated Cardiometabolic Risk in Primary Care)-randomized controlled trial, which demonstrated the effectiveness of two adapted Diabetes Prevention Program (DPP) lifestyle interventions compared with usual primary care.

Subjects:

E-LITE randomized 241 overweight or obese participants with pre-diabetes and/or metabolic syndrome to receive usual care alone (n=81) or usual care plus a coach-led (n=79) or self-directed intervention (n=81). The interventions provided coach-led group behavioral weight-loss treatment or a take-home, self-directed DVD using the same 12-week curriculum, followed by 12 additional months of technology-mediated coach contact and self-monitoring support. Participants received no further intervention after month 15. A blinded assessor conducted 24-month visits by following the measurement protocols of the original trial. Measurements include weight and cardiometabolic risk factors (waist circumference, fasting plasma glucose, resting blood pressure, triglycerides, high- and low-density lipoprotein cholesterol, total cholesterol and triglyceride to high-density lipoprotein cholesterol ratio).

Results:

At month 24, mean±s.e. changes in body mass index (trial primary outcome) and weight (kg) from baseline were –1.9±0.3 (P=0.001) and –5.4±0.9 (P<0.001) in the coach-led intervention, and –1.6±0.3 (P=0.03) and –4.5±0.9 (P=0.001) in the self-directed intervention, compared with –0.9±0.3 and 2.4±0.9 in the usual care group. In addition, both interventions led to a greater percentage of participants maintaining ⩾7% weight loss and sustained improvements in waist circumference and fasting plasma glucose levels than usual care.

Conclusion:

This study shows sustained benefits of the two primary care-based, technology-mediated DPP lifestyle interventions. The findings warrant replication in long-term studies involving diverse populations.

Guidelines and good clinical practice recommendations for contrast enhanced ultrasound (CEUS) in the liver--update 2012: a WFUMB-EFSUMB initiative in cooperation with representatives of AFSUMB, AIUM, ASUM, FLAUS and ICUS

Initially, a set of guidelines for the use of ultrasound contrast agents was published in 2004 dealing only with liver applications. A second edition of the guidelines in 2008 reflected changes in the available contrast agents and updated the guidelines for the liver, as well as implementing some non-liver applications. Time has moved on, and the need for international guidelines on the use of CEUS in the liver has become apparent. The present document describes the third iteration of recommendations for the hepatic use of contrast enhanced ultrasound (CEUS) using contrast specific imaging techniques. This joint WFUMB-EFSUMB initiative has implicated experts from major leading ultrasound societies worldwide. These liver CEUS guidelines are simultaneously published in the official journals of both organizing federations (i.e., Ultrasound in Medicine and Biology for WFUMB and Ultraschall in der Medizin/European Journal of Ultrasound for EFSUMB). These guidelines and recommendations provide general advice on the use of all currently clinically available ultrasound contrast agents (UCA). They are intended to create standard protocols for the use and administration of UCA in liver applications on an international basis and improve the management of patients worldwide.

Safety in magnetic resonance units: an update

The number of anaesthetists who are involved in magnetic resonance (MR) units is increasing. Magnetic resonance systems are becoming more powerful and interventional procedures are now possible. This paper updates information relating to safety terminology, occupational exposure, reactions to gadolinium-based contrast agents and the risk of nephrogenic systemic fibrosis. Magnetic resonance examinations of patients with pacemakers are still generally contra-indicated but have been carried out in specialist centres under strictly controlled conditions. As availability of MR increases, so the education of anaesthetists, who are occasionally required to provide a service, must be considered.

Anaesthesia in MR units was first described in the 1980s. Guidelines on the provision of anaesthetic services in MR units were published by the Association of Anaesthetists of Great Britain and Ireland (AAGBI) in 2002 [1]. Since then, the number of hospitals with MR units, and hence the number of patients requiring anaesthesia for MR, has increased. While the issues relating to setting up anaesthetic services in MR have not changed, there have been a number of developments that warrant this update:

Safety terminology and guidelines have changed.

MR systems utilise higher magnetic-field strengths and more open designs are available.

Interventional and intra-operative MR are now routine in some centres.

Mobile MR scanners are increasingly used to reduce waiting lists.

Although still generally contra-indicated, some patients with pacemakers have been scanned under strictly controlled conditions in specialist centres.

‘MR safe’ medical implants are now being produced.

New equipment is now available for use in MR.

Out-of-hours availability of MR investigations has increased.

Reports of allergic reactions to MR contrast media have increased.

Gadolinium based contrast agents (Gd-CAs) are associated with a varying degree of risk of nephrogenic systemic fibrosis in patients with impaired renal function.

Chemical Scent Constituents in the Urine of the Red Fox (Vulpes vulpes L.) During the Winter Season

Four volatile chemical compounds have been identified as apparently unique constituents in urines of red foxes (both sexes) during the winter season when mating occurs. Quinaldine was found only in male fox urine. Several other compounds identified are found in other species also. Some or all of these compounds may function in olfactory communication in the red fox.

Changes in tropospheric composition and air quality due to stratospheric ozone depletion and climate change

It is well-understood that reductions in air quality play a significant role in both environmental and human health. Interactions between ozone depletion and global climate change will significantly alter atmospheric chemistry which, in turn, will cause changes in concentrations of natural and human-made gases and aerosols. Models predict that tropospheric ozone near the surface will increase globally by up to 10 to 30 ppbv (33 to 100% increase) during the period 2000 to 2100. With the increase in the amount of the stratospheric ozone, increased transport from the stratosphere to the troposphere will result in different responses in polluted and unpolluted areas. In contrast, global changes in tropospheric hydroxyl radical (OH) are not predicted to be large, except where influenced by the presence of oxidizable organic matter, such as from large-scale forest fires. Recent measurements in a relatively clean location over 5 years showed that OH concentrations can be predicted by the intensity of solar ultraviolet radiation. If this relationship is confirmed by further observations, this approach could be used to simplify assessments of air quality. Analysis of surface-level ozone observations in Antarctica suggests that there has been a significant change in the chemistry of the boundary layer of the atmosphere in this region as a result of stratospheric ozone depletion. The oxidation potential of the Antarctic boundary layer is estimated to be greater now than before the development of the ozone hole. Recent modeling studies have suggested that iodine and iodine-containing substances from natural sources, such as the ocean, may increase stratospheric ozone depletion significantly in polar regions during spring. Given the uncertainty of the fate of iodine in the stratosphere, the results may also be relevant for stratospheric ozone depletion and measurements of the influence of these substances on ozone depletion should be considered in the future. In agreement with known usage and atmospheric loss processes, tropospheric concentrations of HFC-134a, the main human-made source of trifluoroacetic acid (TFA), is increasing rapidly. As HFC-134a is a potent greenhouse gas, this increasing concentration has implications for climate change. However, the risks to humans and the environment from substances, such as TFA, produced by atmospheric degradation of hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) are considered minimal. Perfluoropolyethers, commonly used as industrial heat transfer fluids and proposed as chlorohydrofluorocarbon (CHFC) substitutes, show great stability to chemical degradation in the atmosphere. These substances have been suggested as substitutes for CHFCs but, as they are very persistent in the atmosphere, they may be important contributors to global warming. It is not known whether these substances will contribute significantly to global warming and its interaction with ozone depletion but they should be considered for further evaluation.

Health-related quality of life in patients with idiopathic pulmonary fibrosis: a systematic review

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) profoundly affects the quality of patients' lives. A systematic review was performed to evaluate critically the published literature and to examine what is known about health-related quality of life (HRQL) in patients with IPF.

METHODS

The MEDLINE, EMBASE, Health and Psychosocial Instruments, and Cochrane Library databases were searched to 1 April 2004. Abstracts and bibliographies of published articles were scanned and contact was made with investigators. Included studies analysed HRQL (or quality of life) in at least 10 patients with IPF. Two reviewers independently selected studies, evaluated their quality according to predetermined criteria, and abstracted data on study design, patients' demographic and clinical characteristics, and quality of life outcome measures.

RESULTS

Seven studies met the inclusion criteria. The studies enrolled 512 patients with IPF and used three different instruments to measure HRQL. All studies had important limitations in methodological quality; none measured longitudinal changes in HRQL over time. Patients reported substantially impaired HRQL, especially in domains that measured physical health and level of independence. Patients with IPF appear to have similar impairments in HRQL to those with chronic obstructive pulmonary disease. Measures of dyspnoea were moderately correlated with scores from domains that measured physical health (R2 = 0.03-0.66) and energy/fatigue/pep (R2 = 0.19-0.55), but measures of pulmonary function and gas exchange did not correlate as strongly with these and other domains.

CONCLUSION

Studies of HRQL in patients with IPF suggest that, in addition to the obvious effect on physical health, general health, energy level, respiratory symptoms, and level of independence are also impaired. Variability in HRQL among patients is not fully explained by measures of dyspnoea or pulmonary function, suggesting that HRQL measures provide unique information. More research is needed to identify or design appropriate measurement instruments for patients with IPF and to examine changes in HRQL over time or in response to specific treatments.

Squamous cell carcinoma of the anal sac in five dogs

Tumors of the perianal area of dogs are common and include multiple tumor types. Whereas perianal adenomas occur often, adenocarcinomas of the apocrine glands of the anal sac occur less frequently. A review of the literature revealed no reports of squamous cell carcinomas arising from the epithelial lining of the anal sac. Squamous cell carcinomas originating from the lining of the anal sac were diagnosed in five dogs. Microscopically, the tumors consisted of variably sized invasive nests and cords of epithelial cells displaying squamous differentiation. Four of the five dogs were euthanatized because of problems associated with local infiltration by the tumors. In the fifth dog, there was no evidence of tumor 7 months after surgical removal, but further follow up was not available.

CARD15/NOD2 risk alleles in the development of Crohn's disease in the Australian population

We have previously reported strong evidence for linkage between IBD1 and Crohn's disease (CD) in Australian Crohn's disease families. Three risk alleles for Crohn's disease, (Arg702Trp (C/T), Gly908Arg (G/C) and 980fs981 (-/C), were recently identified in the CARD15/NOD2 gene on chromosome 16, implicating this as the IBD1 locus. Using a novel diagnostic PCR-RFLP, we have examined the frequency of these alleles in 205 multiplex IBD families, 107 sporadic Crohn's disease cases and 409 normal individuals. We demonstrate that the three risk alleles are more frequent in Crohn's disease, than in controls, with allelic frequencies of 0.11, 0.02 and 0.07 respectively. Heterozygosity for individual variants conferred a three-fold increase in risk for Crohn's disease while substantially higher risks were associated with being homozygous or compound heterozygous. Despite a significantly lower population allele frequency for the frameshift mutation than reported by other groups, we see a similar contribution by this allele to the risk of developing Crohn's disease. While the three risk alleles influence susceptibility to Crohn's disease in Australia, we show that these alleles do not fully explain the linkage evidence and suggest that there are very likely additional IBD1 susceptibility alleles yet to be described in Australian CD at the NOD2 locus. We also show a second linkage peak in Australian CD that provides some support for a second disease susceptibility locus on chromosome 16.

The effect of pasture species on parasitism and performance of lambs grazing one of three grass-white clover pasture swards

Lamb parasitism and performance were compared on three pasture treatments: browntop/white clover, Yorkshire fog/white clover, and ryegrass/white clover swards maintained at a sward height of 5cm in each of two years by using continuous variable stocking management. In year 1, lamb performance (both suppressively drenched (SD) and trigger drenched (TD)) was similar on ryegrass and browntop swards but was poorer (P<0.05) on Yorkshire fog swards. In year 2, lamb performance (both SD and TD) was markedly better on ryegrass than on Yorkshire fog or browntop swards. This coincided with an increase in white clover content in the ryegrass/white clover swards and a decrease in white clover content in the browntop/white clover swards. Lamb performance was related to the white clover content of the swards (R2=85.4, P<0.001 and R2=77.5, P<0.001 for SD lambs and TD lambs, respectively). Differences among pasture treatments in faecal egg count (FEC) of TD lambs were greater in year 2 than in year 1 when no significant pasture effects were observed. In year 2, FEC was lowest in lambs which grazed ryegrass/white clover, intermediate in those which grazed Yorkshire fog/white clover and highest in lambs which grazed browntop/white clover, despite herbage allowance (kg herbage mass/kg lamb mass) being greater on the browntop/white clover and Yorkshire fog/white clover swards than the ryegrass/white clover swards. Circulating antibodies to gastrointestinal parasites were measured at the end of year 2. Antibody titres were highest (P<0.05) in the plasma of lambs which grazed ryegrass/white clover swards, and lowest in lambs which grazed browntop/white clover swards due to differences in levels of antibody to (P<0.05) Haemonchus contortus, Ostertagia circumcincta larvae and adults, but not Trichostrongylus colubriformis larvae or adults. These findings indicate that pasture composition, especially, the proportion of white clover, can help alleviate the production losses due to gastrointestinal parasitism. This information can provide a quick and readily adoptable practice for farmers who aim to reduce drench reliance and could become a key component of any integrated parasite control programme.

Synthetic and structural studies on [Fe2(SR)2(CN)x(CO)6-x](x-) as active site models for Fe-only hydrogenases

A series of models for the active site (H-cluster) of the iron-only hydrogenase enzymes (Fe-only H2-ases) were prepared. Treatment of MeCN solutions of Fe2(SR)2(CO)6 with 2 equiv of Et4NCN gave [Fe2(SR)2(CN)2(CO)4](2-) compounds. IR spectra of the dicyanides feature four nu(CO) bands between 1965 and 1870 cm(-1) and two nu(CN) bands at 2077 and 2033 cm(-1). For alkyl derivatives, both diequatorial and axial-equatorial isomers were observed by NMR analysis. Also prepared were a series of dithiolate derivatives (Et4N)2[Fe2(SR)2(CN)2(CO)4], where (SR)2 = S(CH2)2S, S(CH2)3S. Reaction of Et4NCN with Fe2(S-t-Bu)2(CO)6 gave initially [Fe2(S-t-Bu)2(CN)2(CO)4](2-), which comproportionated to give [Fe2(S-t-Bu)2(CN)(CO)5](-). The mechanism of the CN(-)-for-CO substitution was probed as follows: (i) excess CN(-) with a 1:1 mixture of Fe2(SMe)2(CO)6 and Fe2(SC6H4Me)2(CO)6 gave no mixed thiolates, (ii) treatment of Fe2(S2C3H6)(CO)6 with Me3NO followed by Et4NCN gave (Et4N)[Fe2(S2C3H6)(CN)(CO)5], which is a well-behaved salt, (iii) treatment of Fe2(S2C3H6)(CO)6 with Et4NCN in the presence of excess PMe3 gave (Et4N)[Fe2(S2C3H6)(CN)(CO)4(PMe3)] much more rapidly than the reaction of PMe3 with (Et4N)[Fe2(S2C3H6)(CN)(CO)5], and (iv) a competition experiment showed that Et4NCN reacts with Fe2(S2C3H6)(CO)6 more rapidly than with (Et4N)[Fe2(S2C3H6)(CN)(CO)5]. Salts of [Fe2(SR)2(CN)2(CO)4](2-) (for (SR)2 = (SMe)2 and S2C2H4) and the monocyanides [Fe2(S2C3H6)(CN)(CO)5](-) and [Fe2(S-t-Bu)2(CN)(CO)5](-) were characterized crystallographically; in each case, the Fe-CO distances were approximately 10% shorter than the Fe-CN distances. The oxidation potentials for Fe2(S2C3H6)(CO)4L2 become milder for L = CO, followed by MeNC, PMe3, and CN(-); the range is approximately 1.3 V. In water,oxidation of [Fe2(S2C3H6)(CN)2(CO)4](2-) occurs irreversibly at -0.12 V (Ag/AgCl) and is coupled to a second oxidation.

A controlled trial of an environmental tobacco smoke reduction intervention in low-income children with asthma

STUDY OBJECTIVES

To determine the effectiveness of a cotinine-feedback, behaviorally based education intervention in reducing environmental tobacco smoke (ETS) exposure and health-care utilization of children with asthma.

DESIGN

Randomized controlled trial of educational intervention vs usual care.

SETTING

The pediatric pulmonary service of a regional pediatric hospital.

PARTICIPANTS

ETS-exposed, Medicaid/Medi-Cal-eligible, predominantly minority children who were 3 to 12 years old and who were seen for asthma in the hospital's emergency, inpatient, and outpatient services departments (n = 87).

INTERVENTION

Three nurse-led sessions employing behavior-changing strategies and basic asthma education and that incorporated repeated feedback on the child's urinary cotinine level.

MEASUREMENTS

The primary measurements were the urinary cotinine/creatinine ratio (CCR) and the number of acute asthma medical visits. The secondary measurements were number of hospitalizations, smoking restrictions in home, amount smoked, reported exposures of children, and asthma control.

RESULTS

The intervention was associated with a significantly lower odds ratio (OR) for more than one acute asthma medical visit in the follow-up year, after adjusting for baseline visits (total visits, 87; OR, 0.32; p = 0.03), and a comparably sized but nonsignificant OR for one or more hospitalization (OR, 0.34; p = 0.14). The follow-up CCR measurement and the determination of whether smoking was prohibited inside the home strongly favored the intervention group (n = 51) (mean difference in CCR adjusted for baseline, -0.38; p = 0.26; n = 51) (60; OR [for proportion of subjects prohibiting smoking], 0.24; p = 0.11; n = 60).

CONCLUSIONS

This intervention significantly reduced asthma health-care utilization in ETS-exposed, low-income, minority children. Effects sizes for urine cotinine and proportion prohibiting smoking were moderate to large but not statistically significant, possibly the result of reduced precision due to the loss of patients to active follow-up. Improving ETS reduction interventions and understanding their mechanism of action on asthma outcomes requires further controlled trials that measure ETS exposure and behavioral and disease outcomes concurrently.

Epistasis and its possible effects on transmission disequilibrium tests

Most approaches to analysing complex genetic disorders are based on an underlying model that assumes that the probability of being affected is mainly due to the effect of a major, single disease locus. Where the penetrance (the conditional probability of being affected) is hypothesised to be influenced by known covariates, methods have been developed to accommodate these covariates appropriately in the analysis. Unexplained variation in the incomplete penetrance is then attributed to either unspecified environmental effects or to other genes of small effect that might act epistatically with the 'disease gene'. Recently, there have been some proposals to incorporate two (or more) possibly epistatic identified loci as major effects in the analysis. However, the effect of two (or more) major epistatic disease genes on the analysis of data that assumes a single 'disease gene', and so ignores any other major gene, does not seem to have been explored. This investigation is undertaken here for triad data consisting of affected singletons and their parents. Following development of a quite general underlying genetic model, a global approach to analysing two marker loci for triad data is developed. This approach is the appropriate one for such data where two, possibly epistatic, loci have been identified a priori. The motivation for the development of this methodology is to evaluate the possible effect a second epistatic disease locus might be having on the results for triad data collected and analysed in different population studies, where the underlying analysis is based on an underlying major, single disease locus model. It is shown that, dependent on the population parameters associated with the other unidentified major disease gene, results concerning the single 'disease gene' can vary markedly. So, finding that conclusions differ from study to study may be indicative of the 'disease gene' under investigation acting epistatically with other major disease genes.

Transperineal and transvaginal sonography of perianal inflammatory disease

OBJECTIVE

Perianal infection arises in small intersphincteric anal glands predominantly located at the dentate line. Documentation of fluid collections and the relationship of inflammatory tracts to the sphincter mechanism is important for surgical treatment. Transanal sonography for assessment of perianal inflammatory disease is limited because placement of the rigid probe into the anal canal does not allow assessment of disease in the perineal region. The purpose of this study was to validate the use of transperineal sonography in men and both transvaginal and transperineal sonography in women for evaluation of perianal inflammatory disease.

SUBJECTS AND METHODS

Fifty-four patients, 28 men and 26 women, were imaged with transperineal and a combination of transperineal and transvaginal sonography, respectively. All patients were examined in the supine lithotomy and left lateral position with a transvaginal 8-to 4-MHz probe or a linear 12- to 7-MHz transducer. All fluid collections, sinus tracts, and fistulas were described by their location in relation to the sphincter mechanism and perineum.

RESULTS

Forty-six of 54 patients had perianal fistulas or sinus tracts: 33 transphincteric, seven intersphincteric, and six extrasphincteric. Fifteen patients had an associated abscess. In the eight remaining patients, there were two anovaginal fistulas, one rectovaginal fistula, one prolapsed internal hemorrhoid, two perianal complex masses, and two vascular perianal or perirectal inflammatory masses. Twenty-six patients underwent surgical procedures involving the anorectal canal or perirectal region, and of these, preoperative sonographic findings were confirmed in 22 (85%) of 26 patients. Three patients refused surgery, and six are awaiting surgery at this writing. Fifteen patients were treated conservatively.

CONCLUSION

Transperineal and transvaginal sonography are accurate, painless, and cost-effective methods for documenting perianal fluid collections and fistulas or sinus tracts or both.

On cloning and clone libraries for finite and infinite length genomes

This paper develops mathematical theory to determine the representativeness of clone libraries for various models, defined below in the text. In particular, the means and variances of fragment lengths and the mean of the length of a randomly selected fragment are determined, as well as the probability of the event that a particular base pair of a given double-stranded DNA sequence is clonable. Further, some results are given for partial digestion where the digest is stopped before all cuts are made. A summary is given comparing the main biological conclusions from assuming that the length of the genome is (effectively) infinite with the corresponding conclusions from the more realistic assumption that the genome is of finite length.

Synthetic approaches to a variety of covalently linked porphyrin--fullerene hybrids

There is substantial interest in dyads in which C(60) is covalently linked to electron donors, such as porphyrins, which absorb light strongly in the visible region. We present here the details of the syntheses of such compounds, which can be broadly organized into categories depending upon the nature of the linker joining the two chromophores. The structural aspects of intramolecular electronic interaction that we have sought to explore have dictated the synthetic strategies employed to generate these classes of molecules. Flexible glycol linkers were used to allow close approach between the fullerene and porphyrin, facilitating through-space interactions. These linkers also allowed studies of the effects of metal cation complexation. Naphthalene and alkyne linkers were used to examine the possible effects a conjugated or aromatic linker might have on photophysical properties. Finally, steroids were used as linkers in dyads expected to possess a large distance between the two chromophores, in which only through-bond interactions between the fullerene and porphyrin should be possible.

Synthesis and evaluation of hexahydrochrysene and tetrahydrobenzofluorene ligands for the estrogen receptor

To prepare novel estrogen receptor (ER) ligands, we have developed a facile approach to substituted hexahydrochrysene and tetrahydrobenzo[a]fluorene systems. Substituents, including basic side chains, were added to these systems, and their binding affinity to ERalpha and ERbeta, and in some cases their transcriptional activity were evaluated.

Liver mass evaluation with ultrasound: the impact of microbubble contrast agents and pulse inversion imaging

Liver mass evaluation includes two essential elements--lesion detection and lesion characterization. Both of these are greatly improved on sonography with the addition of contrast agents and the use of specialized imaging techniques, particularly pulse inversion imaging. Ultrasound contrast agents are comprised of tiny microbubbles of gas that interact with the ultrasound beam producing an enhancement of the Doppler signal from blood. Pulse inversion imaging allows preferential detection of the signal from the microbubble agents with suppression of the signal from background tissue. Two imaging techniques include a low mechanical index (MI) nondestructive method to show lesional vascularity and a high MI destructive mode that produces disruption of the bubbles in a single frame. The latter allows for quantitative assessment of the relative enhancement of a lesion as compared with the adjacent liver parenchyma, which is a reflection of the relative vascular volumes. Vascular imaging has shown characteristic and reproducible features of common liver masses, including hemangioma, focal nodular hyperplasia, hepatocellular carcinoma, and liver metastases. Delayed postvascular enhancement of the normal liver, a phenomenon that is unique to certain classes of microbubble contrast agents, allows detection of more and smaller malignant lesions than on baseline.

Ultrasound for the visualization and quantification of tumor microcirculation

Advances in ultrasound based methods for the non-invasive assessment of the tumor microcirculation are described. Two new ultrasound approaches are highlighted. The first method relies on commercially available ultrasound contrast agents in combination with specialized nonlinear imaging sequences. Nonlinear scattering by microbubble contrast agents provides a unique intravascular signature that can be distinguished from the echoes caused by surrounding tissues. Through destruction-reperfusion experiments it is possible to use microbubble contrast agents as a tracer revealing the kinetics of tumor blood flow. The second ultrasound method for examining the microcirculation involves the use of much higher frequencies. At frequencies on the order of 50 MHz, Doppler processing allows the direct assessment of flow dynamics in realtime in arterioles as small as 15 microm. Three dimensional Doppler maps of flow patterning are presented. The strengths and weaknesses of these new methods are discussed and the potential for their use in preclinical animal drug studies, clinical drug trials, and prognostic studies is described.

Redox properties of C6S8(n-) and C3S5(n-) (n = 0, 1, 2): stable radicals and unusual structural properties for C-S-S-C bonds

The new anionic carbon sulfides C6S10(2-) and C12S16(2-) are described and crystallographically characterized. The C12S16(2-) anion consists of two C6S8 units connected by an exceptionally long (2.157(12) A) S-S bond. In solution, C12S16(2-) exists in equilibrium with the radical C6S8(-*). The equilibrium constant for radical formation (293 K, THF) is 1.2 x 10(-4) M, as determined by optical spectroscopy at varying concentrations. Radical formation occurs through scission of the S-S bond. On the basis of variable temperature EPR spectra, the thermodynamic parameters of this process are DeltaH = +51.5 +/- 0.5 kJ x mol(-1) and DeltaS = +110 +/- 3 J x mol(-1) x K(-1). C6S10(2-) is an oxidation product of C3S5(2-) and consists of two C3S5 units connected by an S-S bond. The S-S bond length (2.135(4) A) is long, and the CS-SC torsion angle is unusually acute (52.1 degrees ), which is attributed to an attractive interaction between C3S2 rings. The oxidation of (Me4N)2C3S5 occurs at -0.90 V vs Fc+/Fc in MeCN, being further oxidized at -0.22 V. The similarity of the cyclic voltammogram of (Me4N)2C6S10 to that of (Me4N)2C3S5 indicates that C6S10(2-) is the initial oxidation product of C3S5(2-).

Subcutaneous heparin versus low-molecular-weight heparin as thromboprophylaxis in patients undergoing colorectal surgery: results of the canadian colorectal DVT prophylaxis trial: a randomized, double-blind trial

OBJECTIVE

To compare the effectiveness and safety of low-dose unfractionated heparin and a low-molecular-weight heparin as prophylaxis against venous thromboembolism after colorectal surgery.

METHODS

In a multicenter, double-blind trial, patients undergoing resection of part or all of the colon or rectum were randomized to receive, by subcutaneous injection, either calcium heparin 5,000 units every 8 hours or enoxaparin 40 mg once daily (plus two additional saline injections). Deep vein thrombosis was assessed by routine bilateral contrast venography performed between postoperative day 5 and 9, or earlier if clinically suspected.

RESULTS

Nine hundred thirty-six randomized patients completed the protocol and had an adequate outcome assessment. The venous thromboembolism rates were the same in both groups. There were no deaths from pulmonary embolism or bleeding complications. Although the proportion of all bleeding events in the enoxaparin group was significantly greater than in the low-dose heparin group, the rates of major bleeding and reoperation for bleeding were not significantly different.

CONCLUSIONS

Both heparin 5,000 units subcutaneously every 8 hours and enoxaparin 40 mg subcutaneously once daily provide highly effective and safe prophylaxis for patients undergoing colorectal surgery. However, given the current differences in cost, prophylaxis with low-dose heparin remains the preferred method at present.

Radiology reports: examining radiologist and clinician preferences regarding style and content

OBJECTIVE

The introduction of picture archiving and communication systems (PACS) frequently includes the option of computer-generated itemized reports. This motivated us to reassess the merits of traditional prose dictated reports. This study examines radiologist and clinician preferences regarding report style and content.

MATERIALS AND METHODS

The study was conducted in two parts. The first part was a retrospective audit of existing medical imaging prose reports to determine their content. The second part comprised a questionnaire containing three mock clinical scenarios. Three pairs of reports were provided for each scenario, with only essential information in the first pair, some optional information in the second, and the most complete report in the third. Each pair consisted of a prose and itemized report with identical content. Participants ranked reports by preference and were asked specific questions regarding report content. The questionnaires were mailed to referring clinicians and administered during an interactive forum to staff radiologists, radiology fellows, and radiology residents.

RESULTS

The audit of existing reports showed a wide variation in all fields with consistency limited to a given radiologist. Responses to the questionnaire showed that, in general, a majority of radiologists and referring clinicians preferred itemized reports. The itemized report with the most detailed content was ranked highest of all three scenarios.

CONCLUSION

Prose reports foster a lack of standardization of content among different radiologists. Itemized reports facilitate complete documentation of information and measurements and are more popular with both radiologists and referring clinicians.

Tissue harmonic imaging: is it a benefit for bile duct sonography?

OBJECTIVE

Our purpose was to compare tissue harmonic imaging with conventional sonography of the biliary tract.

SUBJECTS AND METHODS

Eighty patients with suspect biliary disease had conventional sonography and tissue harmonic imaging with an ATL 3000 or 5000 scanner in a 6-month interval. Final diagnoses included malignant biliary obstruction (n = 30), choledocholithiasis (n = 16), sclerosing cholangitis (n = 4), normal or nonobstructed ducts (n = 16), and miscellaneous conditions (n = 14). Similar images were taken with each technique in terms of projection, field of view, focal zone selection, and evidence of disease. Two separate observers blinded to patient data and technique reviewed and graded images individually for the appearance of the lumen of the bile ducts, the length of the visible duct, the appearance of the duct wall, the presence of any intraluminal masses, and the appearance of associated acoustic shadows. Images were graded from zero to 3, with 3 being the best.

RESULTS

The median of the 546 tissue harmonic images was one grade higher than the median for the corresponding conventional images (p < 0.0001). Improvements with tissue harmonic imaging included better sharpness of the duct walls (p < 0.01), a clearer lumen (p < 0.0001), identification of a longer length of the common bile duct (p < 0.0001), and improved detection of intraluminal masses (p < 0.006). Acoustic shadows were better defined and blacker with tissue harmonic imaging (p < 0.007).

CONCLUSION

Improvement in contrast and reduction of side lobe artifacts with tissue harmonic imaging enhance visualization of the biliary ducts. Tissue harmonic imaging is now our routine technique for bile duct examination.

The impact of practice setting on physician perceptions of the quality of practice and patient care in the managed care era

BACKGROUND

Managed care is practiced in both traditional institutional health maintenance organization (HMO) settings and in a variety of complex and decentralized office-based arrangements. This study examines how practice setting affects physician perceptions of the quality of professional practice and patient care in a managed care environment.

PARTICIPANTS AND METHODS

A survey was conducted in 1998 of 1081 physicians in San Mateo County, California, who practice in either a traditional staff group model HMO (SGM-HMO) (n = 113) or office-based independent practice (OBIP) (n = 250). Respondents were surveyed about current and past practice characteristics, income changes, current satisfaction with professional and patient care matters, utility of treatment guidelines and formularies, and general perceptions of managed care. Responses were compared between practice settings using bivariate comparisons and logistic regression analyses.

RESULTS

Physicians in the SGM-HMO and those in OBIP reported similar hours worked per week, time spent with patients during office visits, and total patient encounters per week. Declining income was more frequent in OBIP (61% vs 47%) and relatively more substantial (27% with income declines >25% vs 4% in SGM-HMO). Adjusting for income changes, practice setting, years in practice, and sex, SGM-HMO physicians were significantly more satisfied with a variety of professional and quality of care issues (P<.001), viewed more favorably the utility of treatment guidelines and drug formularies (P<.001), and held more positive general perceptions of managed care (P<.001) than OBIP physicians.

CONCLUSIONS

In a managed care environment, SGM-HMO physicians are significantly more satisfied with the quality of practice and patient care than physicians in OBIP. This study suggests that the myriad managed care contracts, formularies, and guidelines received by physicians in OBIPs may lead to more negative perceptions of the quality of professional practice and patient care.

C60-Fullerene monomalonate adducts selectively inactivate neuronal nitric oxide synthase by uncoupling the formation of reactive oxygen intermediates from nitric oxide production

C(60)-Fullerene monomalonate adducts inactivate selectively the neuronal nitric oxide synthase isoform in a manner completely preventable by the concurrent presence of superoxide dismutase and catalase. This inactivation is time-, fullerene concentration-, and turnover-dependent and is not reversible by dilution. The di(carboxypropan-3-ol)methano-[60]-fullerene (diol adduct) has no effect on NADPH consumption by nNOS as measured in the absence of arginine substrate, but dramatically increases NADPH consumption in the presence of arginine. This fullerene-enhanced NADPH consumption is linked to oxygen as electron acceptor and is accompanied by the increased production of hydrogen peroxide. These effects of fullerene monomalonate adducts are unique to the nNOS isoform and are not observed using either the iNOS or the eNOS isoform. The inhibitory effects of fullerene monomalonate adducts are unaltered and insurmountable by increased concentrations of arginine, tetrahydrobiopterin, or calmodulin. These observations indicate that fullerene monomalonate adducts uncouple in the presence of arginine the formation of reactive oxygen intermediates from NO production by nNOS. These reactive oxygen intermediates dissociate from the enzyme and, acting from solution, inactivate NOS NO forming activity.

Testing for concordant equilibria between population samples

A substantial body of theory has been developed to assess the effect of evolutionary forces on the distribution of genotypes, both single and multilocus, within populations. One area where the potential for application of this theory has not been fully appreciated concerns the extent to which population samples differ. Within populations, the divergence of genotype or haplotype frequencies from that expected under Hardy-Weinberg (HW) or linkage equilibrium can be measured as disequilibria coefficients. To assess population samples for concordant equilibria, an analytical framework for comparing disequilibria coefficients between populations is necessary. Here we present log-linear models to evaluate such hypotheses. These models have broad utility ranging from conventional population genetics to genetic epidemiology. We demonstrate the use of these log-linear models (1) as a test for genetic association with disease and (2) as a test for different levels of linkage disequilibria between human populations.

Influence of H2S and thiols on the binding of alkenes and alkynes to ReS4-: the spectator sulfido effect

The three-component reaction of ReS4- (1), H2S, and unsaturated substrates (un = alkene, alkyne) affords the ReV derivatives Re(S)(S2un)(SH)2-. These adducts arise via the addition of H2S to intermediate dithiolates ReS2(S2C2R4)- and dithiolenes ReS2(S2C2R2)-. The species [ReS[S2C2(tms)2](SH)2]-, [ReS(S2C7H10)(SH)2]- (3), and [ReS(S2C2H4)(SH)2]- are prepared according to this route. Similarly, the selenolate-thiolate complex [ReS(S2C7H10)(SeH)(SH)]- (5) is produced by the reaction of [ReS2(S2C7H10)]- with H2Se. The corresponding reactions using benzenethiol in place of H2S afford the more thermally robust adducts [ReS[S2C2(tms)2](SH)(SPh)]-, [ReS(S2C7H10)(SH)(SPh)]- (7), and [ReS(S2C2H4)(SH)(SPh)]-. Norbornanedithiolato compounds 3, 5, and 7 are obtained as pairs of isomers that differ in terms of the relative orientation of the norbornane bridgehead relative to the Re=S unit. The reaction of [ReS(S2C7H10)(SD)2]- (3-d2) with H2S to give 3 is proposed to proceed via elimination of D2S and subsequent addition of H2S. Variable-temperature 1H NMR measurements on the equilibrium of [ReS(S2C6H12)(SPh)(SH)]- with 1,1-hexene, and PhSH gave the following results: deltaH = -7 (+/- 1) kJ x mol(-1); deltaS = 23 (+/- 4) J x mol(-1) x K(-1). Solutions of ethanedithiol and 1 react with C2(tms)2 and C2H4 to give [ReS[S2C2(tms)2](S2C2H4)]- and [ReS(S2C2H4)2]-, respectively, concomitant with loss of H2S. The pathway for the ethanedithiol reaction is examined using 2-mercaptoethanol, affording [ReS[S2C2(tms)2](SC2H4OH)]-, which does not cyclize. Treatment of a solution of diphenylbutadiyne and 1 with PhSH gives two isomers of the dithiolene [ReS(SH)(SPh)[S2C2Ph(C2Ph)]]-. The corresponding reaction of ethanedithiol, diphenylbutadiyne, and 1 affords the 1,4-diphenylbutadiene-1,2,3,4-tetrathiolate complex [[ReS(S2C2H4)]2(S4C4Ph2)]2-.

X-ray crystal structure of an anti-Buckminsterfullerene antibody fab fragment: biomolecular recognition of C(60)

We have prepared a monoclonal Buckminsterfullerene specific antibody and report the sequences of its light and heavy chains. We also show, by x-ray crystallographic analysis of the Fab fragment and by model building, that the fullerene binding site is formed by the interface of the antibody light and heavy chains. Shape-complementary clustering of hydrophobic amino acids, several of which participate in putative stacking interactions with fullerene, form the binding site. Moreover, an induced fit mechanism appears to participate in the fullerene binding process. Affinity of the antibody-fullerene complex is 22 nM as measured by competitive binding. These findings should be applicable not only to the use of antibodies to assay and direct potential fullerene-based drug design but could also lead to new methodologies for the production of fullerene derivatives and nanotubes as well.

Ethical decision making and patient autonomy: a comparison of physicians and patients in Japan and the United States

BACKGROUND

Patient-centered decision making, which in the United States is typically considered to be appropriate, may not be universally endorsed, thereby harboring the potential to complicate the care of patients from other cultural backgrounds in potentially unrecognized ways. This study compares the attitudes toward ethical decision making and autonomy issues among academic and community physicians and patients of medical center outpatient clinics in Japan and the United States.

METHODS

A questionnaire requesting judgments about seven clinical vignettes was distributed (in English or Japanese) to sample groups of Japanese physicians (n = 400) and patients (n = 65) as well as US physicians (n = 120) and patients (n = 60) that were selected randomly from academic institutions and community settings in Japan (Tokyo and the surrounding area) and the United States (the Stanford/Palo Alto, CA, area). Responses were obtained from 273 Japanese physicians (68%), 58 Japanese patients (89%), 98 US physicians (82%), and 55 US patients (92%). Physician and patient sample groups were compared on individual items, and composite scores were derived from subsets of items relevant to patient autonomy, family authority, and physician authority.

RESULTS

A majority of both US physicians and patients, but only a minority of Japanese physicians and patients, agreed that a patient should be informed of an incurable cancer diagnosis before their family is informed and that a terminally ill patient wishing to die immediately should not be ventilated, even if both the doctor and the patient's family want the patient ventilated (Japanese physicians and patients vs US physicians and patients, p < 0.001). A majority of respondents in both Japanese sample groups, but only a minority in both US sample groups, agreed that a patient's family should be informed of an incurable cancer diagnosis before the patient is informed and that the family of an HIV-positive patient should be informed of this disease status despite the patient's opposition to such disclosure (Japanese physicians and patients vs US physicians and patients, p < 0.001). Physicians in both Japan and the United States were less likely than patients in their respective countries to agree with physician assistance in the suicide of a terminally ill patient (Japanese physicians and patients vs US physicians and patients, p < 0.05). Across various clinical scenarios, all four respondent groups accorded greatest authority to the patient, less to the family, and still less to the physician when the views of these persons conflicted. Japanese physicians and patients, however, relied more on family and physician authority and placed less emphasis on patient autonomy than the US physicians and patients sampled. Younger respondents placed less emphasis on family and physician authority.

CONCLUSIONS

Family and physician opinions are accorded a larger role in clinical decision making by the Japanese physicians and patients sampled than by those in the United States, although both cultures place a greater emphasis on patient preferences than on the preferences of the family or physician. Our results are consistent with the view that cultural context shapes the relationship of the patient, the physician, and the patient's family in medical decision making. The results emphasize the need for clinicians to be aware of these issues that may affect patient and family responses in different clinical situations, potentially affecting patient satisfaction and compliance with therapy.

Trauma ultrasound feasibility during helicopter transport

OBJECTIVE

To evaluate the feasibility of performing a standard four-view focused abdominal sonography for trauma (FAST) examination during helicopter transport using a hand-carried ultrasound machine.

METHODS

In this prospective observational study, actual and simulated trauma patients were evaluated using the SonoSite 180 ultrasound machine by two air transport programs serving Level I trauma centers. FAST examinations were performed in flight by emergency medicine faculty, residents, flight nurses, and ultrasound technologists, who rated the difficulty posed by various factors using Likert scales (0 = not difficult to 5 = impossible). BK 117, Bell 230, and BO 105 medical helicopters flew in all aviating modes. Pilots were queried regarding avionics variations throughout the flights.

RESULTS

Ten flight sonographers performed 21 FAST examinations on 14 patients (five actual, nine simulated). The median Likert value for each parameter was 0 except for patient position, which was 1 (somewhat difficult). Interquartile ranges were 0-0 for vibration, bedding, IV catheters, monitor cables, and ventilator; 0-0.5 for backboard straps; and 0-1 for sunlight, patient position, spider straps, gurney straps, and clothing. Mean examination duration, was 3.0 minutes (range 1.5 to 5.5 minutes, SD 1.3). Pilots reported no effects on avionics in any flight mode.

CONCLUSION

The FAST examination using the SonoSite 180 in flight was rated by 10 evaluators to be performed easily. Examinations were conducted quickly and did not interfere with helicopter avionics. This digital ultrasound machine is the first one small enough to be used in most medical helicopters.

Evaluating linkage and linkage disequilibrium: use of excess sharing and transmission disequilibrium methods in affected sib pairs

Two popular and robust approaches to analysing affected sib pair (ASP) data for linkage are the traditional excess sharing methods and the transmission/disequilibrium test (TDT). Here we derive an overall test of linkage for multi-allelic ASP marker data which comprises two component tests: one for excess sharing and one for transmission disequilibrium. This method has several advantages. Firstly the overall test of linkage is often more powerful than either of the two component tests. Secondly the method makes it possible to determine the contribution of linkage disequilibrium (LD), in addition to linkage, to an overall positive linkage result. This is useful because the presence of LD in addition to linkage may suggest that the marker locus is in very close proximity to a disease susceptibility gene. Thirdly the method provides estimates of the risk associated with transmission of the different marker alleles.