Wide-ranging consequences of priority effects governed by an overarching factor

Priority effects, where arrival order and initial relative abundance modulate local species interactions, can exert taxonomic, functional, and evolutionary influences on ecological communities by driving them to alternative states. It remains unclear if these wide-ranging consequences of priority effects can be explained systematically by a common underlying factor. Here, we identify such a factor in an empirical system. In a series of field and laboratory studies, we focus on how pH affects nectar-colonizing microbes and their interactions with plants and pollinators. In a field survey, we found that nectar microbial communities in a hummingbird-pollinated shrub, Diplacus (formerly Mimulus) aurantiacus, exhibited abundance patterns indicative of alternative stable states that emerge through domination by either bacteria or yeasts within individual flowers. In addition, nectar pH varied among D. aurantiacus flowers in a manner that is consistent with the existence of these alternative stable states. In laboratory experiments, Acinetobacter nectaris, the bacterium most commonly found in D. aurantiacus nectar, exerted a strongly negative priority effect against Metschnikowia reukaufii, the most common nectar-specialist yeast, by reducing nectar pH. This priority effect likely explains the mutually exclusive pattern of dominance found in the field survey. Furthermore, experimental evolution simulating hummingbird-assisted dispersal between flowers revealed that M. reukaufii could evolve rapidly to improve resistance against the priority effect if constantly exposed to A. nectaris-induced pH reduction. Finally, in a field experiment, we found that low nectar pH could reduce nectar consumption by hummingbirds, suggesting functional consequences of the pH-driven priority effect for plant reproduction. Taken together, these results show that it is possible to identify an overarching factor that governs the eco-evolutionary dynamics of priority effects across multiple levels of biological organization.

Niche expansion via acquired metabolism facilitates competitive dominance in planktonic communities

Acquired phototrophs, organisms that obtain their photosynthetic abilities by hosting endosymbionts or stealing plastids from their prey, are omnipresent in aquatic ecosystems. This acquisition of photosynthetic metabolism allows for niche expansion, and can therefore influence competition outcomes by alleviating competition for shared resources. Here, we test how acquired metabolism alters competitive outcomes by manipulating light availability to control the energetic contribution of photosynthesis to acquired phototrophs. Using freshwater protists that compete for bacterial prey, we demonstrate light-dependent competition outcomes of acquired phototrophs (Paramecium bursaria) and strict heterotrophs (Colpidium sp.) in laboratory model experiments. We then synthesize these findings using a series of mathematical models, and show that explicitly accounting for resource competition improves model fits. Both empirical and mathematical models predict that the acquired phototroph should increase in competitive dominance with increasing light availability. Our results highlight the importance of acquired metabolism to community dynamics, highlighting the need for more empirical and theoretical studies of this mechanism for niche expansion.

Prey type constrains growth and photosynthetic capacity of the kleptoplastidic ciliate Mesodinium chamaeleon (Ciliophora)

Kleptoplastidic, or chloroplast-stealing, lineages offer insight into the process of acquiring photosynthesis. By quantifying the ability of these organisms to retain and use photosynthetic machinery from their prey, we can understand how intermediaries on the endosymbiosis pathway might have evolved regulatory and maintenance mechanisms. Here, we focus on a mixotrophic kleptoplastidic ciliate, Mesodinium chamaeleon, noteworthy for its ability to retain functional chloroplasts from at least half a dozen cryptophyte algal genera. We contrasted the performance of kleptoplastids from blue-green and red cryptophyte prey as a function of light level and feeding history. Our experiments showed that starved M. chamaeleon cells are able to maintain photosynthetic function for at least 2 weeks and that M. chamaeleon containing red plastids lost chlorophyll and electron transport capacity faster than those containing blue-green plastids. However, likely due to increased pigment content and photosynthetic rates in red plastids, M. chamaeleon had higher growth rates and more prolonged growth when feeding on red cryptophytes. For example, M. chamaeleon grew rapidly and extensively when fed the blue-green cryptophyte Chroomonas mesostigmatica, but this growth appeared to hinge on high levels of feeding supporting photosynthetic activity. In contrast, even starved M. chamaeleon containing red plastids from Rhodomonas salina could achieve high photosynthetic rates and extensive growth. Our findings show that plastid origin impacts the maintenance and magnitude of photosynthetic activity, though whether this is due to variation in ciliate control or gradual loss of plastid function in ingested prey cells remains unknown.

POS0855 PATIENT PREFERENCES, TRADE-OFFS AND ACCEPTABLE RISKS IN THE TREATMENT OF SYSTEMIC SCLEROSIS-ASSOCIATED INTERSTITIAL LUNG DISEASE: A STEP TOWARDS SHARED DECISION-MAKING

Background:

Current treatments for systemic sclerosis-associated interstitial lung disease (SSc-ILD) are characterised by different attributes such as mode of administration, adverse events (AE) and efficacy. Physicians and patients often have different perspectives on treatments, thus shared decision-making between patients and physicians is essential. An understanding of patients’ decision processes when weighing treatment attributes and the trade-offs they are willing to make is important for shared decision-making.

Objectives:

The study aimed to 1) identify relevant treatment attributes, 2) elicit patient preferences for these attributes and 3) quantify preference as relative attribute importance (RAI; a higher RAI indicates that more of the variability in patients’ responses may be explained by changes in the attribute); and maximum acceptable risk (MAR) of diarrhoea, nausea and/or vomiting (MAR is a trade-off measure that evaluates attributes in risk-equivalences as a unit of measurement).

Methods:

A discrete choice experiment (DCE) was created, based on a literature review, a patient advisory board, qualitative patient interviews, and a workshop involving SSc-ILD expert physicians. Seven SSc-ILD treatment attributes were identified: 1) mode of administration; 2) shortness of breath; 3) skin tightness; 4) cough; 5) tiredness; 6) risk of gastrointestinal tract (GIT) AEs; and 7) risk of serious and non-serious infections. The levels of AE risk were informed by frequencies observed in clinical trials and patient input during the interviews. The DCE was integrated into an online survey, which asked patients to make repeated choices between two alternatives described by varying levels of included attributes. Patients with SSc-ILD were recruited by physician referral from Switzerland, Norway, France, Germany and the USA. DCE data were analysed using a logit model, and RAI and MAR measures were calculated.

Results:

A total of 231 patients with physician-confirmed SSc-ILD (mean age 52.6±13.2 years; 54% diagnosed for >5 years) completed the survey. Patients with SSc-ILD mostly preferred twice-daily oral treatments (p<0.001) and infusion every 6–12 months (p<0.001) over monthly infusions. Patients’ choices were mostly affected by the risk of GIT AEs (RAI=25%; 95% CI 22–28%) and risk of infections (RAI=20%; 95% CI 16–24%). Improvements in shortness of breath and type and severity of cough were jointly more important than improvement in skin tightness (p<0.001).

Patients accepted an additional 21% risk (95% CI 13–29%) of GIT AEs if they could reduce the frequency of infusions from monthly to 6–12 monthly, or accepted an extra 15% (95% CI 7–23%) increase in risk if changing to an oral treatment twice daily. Among symptoms, an additional 28% (95% CI 20–36%) risk of GIT AEs was considered acceptable if the severity of patients’ persistent cough was reduced to a level that was easier to tolerate, even if it remained persistent. Similarly, a 37% (95% CI 28–46%) increase in the risk of GIT AEs was acceptable if it resulted in breathlessness during routine activities rather than breathlessness at rest. Finally, patients were willing to accept an additional 36% risk (95% CI 27–45%) of GIT AEs if it reduced their risk of non-serious infections from 30% to 15% and of serious infections from 10% to 5%.

Conclusion:

This is the first study to quantitatively elicit patients’ preferences for attributes of SSc-ILD treatments. Preferences were driven by safety, efficacy and technical considerations. Patients showed willingness to make trade-offs, providing a firm basis for shared decision-making in routine clinical practice.

Disclosure of Interests:

Cosimo Bruni Speakers bureau: Actelion, Consultant of: Eli Lilly, Grant/research support from: Gruppo Italiano Lotta alla Scleroderma (GILS), Fondazione Italiana per la Ricerca sull’Artrite (FIRA), New Horizon Fellowship, European Scleroderma Trial and Research (EUSTAR), Foundation for Research in Rheumatology (FOREUM)., Sebastian Heidenreich Consultant of: Sebastian Heidenreich, PhD is employed by Evidera Inc, a business unit of PPD. Evidera is a CRO that offers paid research services to pharmaceutical companies., Ashley Duenas Consultant of: Yes. I am an employee of Evidera which received funding from Boehringer Ingelheim for work related to this study., Anna-Maria Hoffmann-Vold Speakers bureau: Boehringer Ingelheim, Actelion, Roche, Merck Sharp & Dohme, Lilly, Consultant of: Actelion, Boehringer Ingelheim, Roche, Bayer, Merck Sharp & Dohme, ARXX, Lilly and Medscape, Grant/research support from: Boehringer Ingelheim, Armando Gabrielli Grant/research support from: Pfizer Bhering, Yannick Allanore Consultant of: Honorarium received from Boehringer, Medsenic,

Sanofi, Menarini, Grant/research support from: Grants received from Alpine, Ose Immunogenetics, Emmanuel Chatelus: None declared, Jörg H.W. Distler Shareholder of: JHWD is stock owner of 4D Science, Consultant of: JHWD has consultancy relationships with Actelion, Active Biotech, Anamar, ARXX, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, JB Therapeutics, Medac, Pfizer, RuiYi and UCB, Grant/research support from: JHWD has received research funding from Anamar, Active Biotech, Array Biopharma, ARXX, aTyr, BMS, Bayer Pharma, Boehringer Ingelheim, Celgene, Galapagos, GSK, Inventiva, Novartis, Sanofi-Aventis, RedX, UCB, Eric Hachulla: None declared, Vivian Hsu Speakers bureau: I am a speaker for Boehringer Ingelheim Pharmaceuticals, Consultant of: with Boehringer Ingelheim Pharmaceuticals, Grant/research support from: Principal Investigator for several clinical trials, currently with Genentech, Corbus Pharmaceutical, and EICOS, Nicolas Hunzelmann Speakers bureau: Boehringer, Roche, Sanofi, Dinesh Khanna Shareholder of: Eicos Sciences, Inc (less than 5%), Consultant of: Paid Consultant for: Acceleron, Actelion, Abbvie, Amgen, Bayer, Boehringer Ingelheim, CSL Behring, Corbus, Gilead, Galapagos, Genentech/Roche, GSK, Horizon, Merck, Mitsubishi Tanabe Pharma, Sanofi-Aventis, and United Therapeutics, Grant/research support from: Research Grant support from: Immune Tolerance Network, Bayer, BMS, Horizon, Pfizer, Employee of: Leadership/Equity position – Chief Medical Officer, CiviBioPharma/Eicos Sciences, Inc – recieves a stipend for role as Chief Medical Officer, which would technically qualify as emplyoment., Marie-Elise Truchetet Speakers bureau: Abbvie, Lilly, Sobi, Boehringer, Paid instructor for: Lilly, Consultant of: UCB, Sobi, Abbvie, Grant/research support from: UCB, Gilead, Ulrich Walker Shareholder of: Bayer, NASDAQ, MSCI-World ETF’s, Speakers bureau: All companies producing pharmaceuticals used in AIDS, Paid instructor for: Roche, Abbvie, Novartis, Consultant of: All companies producing pharmaceuticals used in AIDS, Grant/research support from: Gilead, Abbvie, (in the last two years). Other companies in previous years., Margarida Alves Employee of: Boehringer Ingelheim, Nils Schoof Employee of: Employee of Boehringer Ingelheim International GmbH, Lesley Ann Saketkoo Speakers bureau: Boehringer Ingelheim, Actelion, Janssen, Mallinckrodt, United Therapeutics, Consultant of: Actelion, Boehringer Ingelheim, Bayer, Bristol Meyer Squibb, Corbus, EICOS, Janssen, Horizon, United Therapeutics, Inc, Grant/research support from: Mallinckrodt, United Therapeutics, Oliver Distler Speakers bureau: Boehringer Ingelheim, Medscape, IQone, Roche, Consultant of: OD has/had consultancy relationship and/or has received research funding in the area of potential treatments for systemic sclerosis and its complications from (last three years):

Abbvie, Acceleron Pharma, Amgen, AnaMar, Arxx Therapeutics, Baecon Discovery, Blade Therapeutics, Bayer, Boehringer Ingelheim, ChemomAb, Corbus Pharmaceuticals, CSL Behring, Galapagos NV, Glenmark Pharmaceuticals, GSK, Horizon (Curzion) Pharmaceuticals, Inventiva, iQvia, Italfarmaco, iQone, Kymera Therapeutics, Lilly, Medac, Medscape, Mitsubishi Tanabe Pharma, MSD, Novartis, Pfizer, Roche, Sanofi, Serodapharm, Topadur, Target Bioscience and UCB. Patent issued “mir-29 for the treatment of systemic sclerosis” (US8247389, EP2331143)., Grant/research support from: Kymera Therapeutics, Mitsubishi Tanabe

Metabolic Symbiosis Facilitates Species Coexistence and Generates Light-Dependent Priority Effects

Metabolic symbiosis is a form of symbiosis in which organisms exchange metabolites, typically for mutual benefit. For example, acquired phototrophs like Paramecium bursaria obtain photosynthate from endosymbiotic green algae called Chlorella. In addition to facilitating the persistence of P. bursaria by providing a carbon source that supplements P. bursaria’s heterotrophic digestion of bacteria, symbiotic Chlorella may impact competitive interactions between P. bursaria and other bacterivores, with cascading effects on community composition and overall diversity. Here, we tested the effects of metabolic symbiosis on coexistence by assessing the impacts of acquired phototrophy on priority effects, or the effect of species arrival order on species interactions, between P. bursaria and its competitor Colpidium. Our results suggest light-dependent priority effects. The acquired phototroph benefited from metabolic symbiosis during sequential arrival of each organism in competition, and led to increased growth of late-arriving Colpidium. These findings demonstrate that understanding the consequences of priority effects for species coexistence requires consideration of metabolic symbiosis.

Physical Activity and Exercise Interventions in the Workplace Impacting Work Outcomes: A Stakeholder-Centered Best Evidence Synthesis of Systematic Reviews

Background:

The prevention of work disability is beneficial to employees and employers, and mitigates unnecessary societal costs associated with social welfare. Many service providers and employers have initiated workplace interventions designed to reduce unnecessary work disability.

Objective:

To conduct a best-evidence synthesis of systematic reviews on workplace interventions that address physical activities or exercise and their impact on workplace absence, work productivity or financial outcomes.

Methods:

Using a participatory research approach, academics and stakeholders identified inclusion and exclusion criteria, built an abstraction table, evaluated systematic review quality and relevance, and interpreted the combined findings. A minimum of two scientists participated in a methodological review of the literature followed by a consensus process.

Results:

Stakeholders and researchers participated as a collaborative team. 3363 unique records were identified, 115 full text articles and 46 systematic reviews were included, 18 assessed the impact of physical fitness or exercise interventions. 11 focused on general workers rather than workers who were absent from work at baseline; 16 of the reviews assessed work absence, 4 assessed productivity and 6 assessed financial impacts.

Conclusion:

The strongest evidence supports the use of short, simple exercise or fitness programs for both workers at work and those absent from work at baseline. For workers at work, simple exercise programs (1–2 modal components) appear to provide similar benefits to those using more complex multimodal interventions. For workers off-work with subacute low back pain, there is evidence that some complex exercise programs may be more effective than simple exercise interventions, especially if they involve workplace stakeholder engagement, communication and coordination with employers and other stakeholders. The development and utilization of standardized definitions, methods and measures and blinded evaluation would improve research quality and strengthen stakeholder-centered guidance.

Mental Health Interventions in the Workplace and Work Outcomes: A Best-Evidence Synthesis of Systematic Reviews

Background:

Mental health issues in the workplace are a growing concern among organizations and policymakers, but it remains unclear what interventions are effective in preventing mental health problems and their associated organizational consequences. This synthesis reports on workplace mental health interventions that impact absenteeism, productivity and financial outcomes.

Objective:

To determine the level of evidence supporting mental health interventions as valuable to work outcomes.

Methods:

Databases were searched for systematic reviews between 2000 and 2012: Medline, EMBASE, the Cochrane Database of Systematic Reviews, DARE, CINAHL, PsycINFO and TRIP. Grey literature searches included health-evidence.ca, Rehab+, National Rehabilitation Information Center (NARIC), and Institute for Work and Health. The assessment of articles for inclusion criteria and methodological quality was conducted independently by two or more researchers, with differences resolved through consensus.

Results:

The search resulted in 3363 titles, of which 3248 were excluded following title/abstract review, with 115 articles retrieved for full-text review. 14 articles finally met the inclusion criteria and are summarized in this synthesis.

Conclusion:

There is moderate evidence for the effectiveness of workplace mental health interventions on improved workplace outcomes. Certain types of programs, such as those incorporating both mental and physical health interventions, multicomponent mental health and/or psychosocial interventions, and exposure in vivo containing interventions for particular anxiety disorders had a greater level of research evidence to support their effectiveness.

Social Support and Supervisory Quality Interventions in the Workplace: A Stakeholder-Centered Best-Evidence Synthesis of Systematic Reviews on Work Outcomes

Background:

There is controversy surrounding the impact of workplace interventions aimed at improving social support and supervisory quality on absenteeism, productivity and financial outcomes.

Objective:

To determine the value of social support interventions for work outcomes.

Methods:

Databases were searched for systematic reviews between 2000 and 2012 to complete a synthesis of systematic reviews guided by the PRISMA statement and the IOM guidelines for systematic reviews. Assessment of articles for inclusion and methodological quality was conducted independently by at least two researchers, with differences resolved by consensus.

Results:

The search resulted in 3363 titles of which 3248 were excluded following title/ abstract review, leaving 115 articles that were retrieved and underwent full article review. 10 articles met the set inclusion criteria, with 7 focusing on social support, 2 on supervisory quality and 1 on both. We found moderate and limited evidence, respectively, that social support and supervisory quality interventions positively impact workplace outcomes.

Conclusion:

There is moderate evidence that social support and limited evidence that supervisory quality interventions have a positive effect on work outcomes.

Application of Physiologically Based Pharmacokinetic (PBPK) Modeling to Support Dose Selection: Report of an FDA Public Workshop on PBPK

The US Food and Drug Administration (FDA) public workshop, entitled "Application of Physiologically-based Pharmacokinetic (PBPK) Modeling to Support Dose Selection focused on the role of PBPK in drug development and regulation. Representatives from industry, academia, and regulatory agencies discussed the issues within plenary and panel discussions. This report summarizes the discussions and provides current perspectives on the application of PBPK in different areas, including its utility, predictive performance, and reporting for regulatory submissions.

Job demand and control interventions: a stakeholder-centered best-evidence synthesis of systematic reviews on workplace disability

BACKGROUND

Physical and psychological job demands in combination with the degree of control a worker has over task completion, play an important role in reducing stress. Occupational stress is an important, modifiable factor affecting work disability. However, the effectiveness of reducing job demands or increasing job control remains unclear, particularly for outcomes of interest to employers, such as absenteeism or productivity.

OBJECTIVE

This systematic review reports on job demand and control interventions that impact absenteeism, productivity and financial outcomes.

METHODS

A stakeholder-centered best-evidence synthesis was conducted with researcher and stakeholder collaboration throughout. Databases and grey literature were searched for systematic reviews between 2000 and 2012: Medline, EMBASE, the Cochrane Database of Systematic Reviews, DARE, CINAHL, PsycINFO, TRIP, health-evidence.ca, Rehab+, National Rehabilitation Information Center (NARIC), and Institute for Work and Health. Articles were assessed independently by two researchers for inclusion criteria and methodological quality. Differences were resolved through consensus.

RESULTS

The search resulted in 3363 unique titles. After review of abstracts, 115 articles were retained for full-text review. 11 articles finally met the inclusion criteria and are summarized in this synthesis. The best level of evidence we found indicates that multimodal job demand reductions for either at-work or off-work workers will reduce disability-related absenteeism.

CONCLUSION

In general, the impacts of interventions that aim to reduce job demands or increase job control can be positive for the organization in terms of reducing absenteeism, increasing productivity and cost-effectiveness. However, more high quality research is needed to further assess the relationships and quantify effect sizes for the interventions and outcomes reviewed in this study.

Pulmonary hypertension and interstitial lung disease within PHAROS: impact of extent of fibrosis and pulmonary physiology on cardiac haemodynamic parameters

OBJECTIVES

We sought to examine the relationship between measures of ILD severity and PH in patients with SSc.

METHODS

We identified 55 subjects from 12 PHAROS sites with RHC-proven PH and HRCT evidence of ILD. Subjects with PH due to left heart disease were excluded. Baseline HRCT scans were scored by a standardised system that graded severity of ILD. Summary statistics were generated for baseline characteristics. Spearman correlation and linear regression were used to examine relationships between ILD and PH severity variables.

RESULTS

The majority of subjects were white women; nearly half had limited cutaneous SSc. Most subjects were New York Heart Association functional class II or III. Pulmonary function testing revealed moderate restriction (mean FVC 64.3 ± 17.2% predicted) with severe reduction in diffusing capacity (mean DLco 34.2 ± 13.3% predicted). RHC demonstrated mild to moderate PH (mean PAP 35 ± 9 mmHg, mean PVR 5.1 ± 3.7 WU). There was no correlation between severity of ILD (by either HRCT or PFT) and cardiac haemodynamic parameters of PH.

CONCLUSIONS

No association between severity of ILD and cardiac haemodynamic profiles were identified in this cohort. We believe this underscores the complex nature of PH and ILD in individuals with SSc. We do suspect that some individuals with SSc-ILD will also have concomitant pulmonary vascular disease but simple assessments to grade severity of ILD - by PFT or HRCT estimates of ILD extent - are likely not enough to reliably distinguish between PAH versus PH-ILD. Further research into how to distinguish and manage these subsets is warranted.

Creatine phosphate administration preserves myocardial function in a model of off-pump coronary revascularization

AIM

Off pump coronary artery bypass grafting (OPCAB) involves, and is occasionally impaired by obligatory regional myocardial ischemia, particularly with the use of proximal coronary in-flow occlusion techniques. Intracoronary shunts do not guarantee absence of distal ischemia given their small inner diameter and the presence of proximal coronary stenosis. Additional adjunctive measures to provide short-term myocardial protection may facilitate OPCAB. High-energy phosphate supplementation with creatine phosphate prior to ischemia may attenuate ischemic dysfunction.

METHODS

In a rodent model of a transient coronary occlusion and myocardial ischemia, 36 animals underwent preischemic intravenous infusion of either creatine phosphate or saline, 10 minutes of proximal left anterior descending (LAD) occlusion, and 10 minutes of reperfusion. Rats underwent continuous intracavitary pressure monitoring and cellular ATP levels were quantified using a luciferin/luciferase bioluminescence assay.

RESULTS

Within 2 minutes of ischemia onset, creatine phosphate animals exhibited statistically significant greater preservation of myocardial function compared to controls, an augmentation which persisted throughout the duration of ischemia and subsequent reperfusion. Furthermore, significantly greater cellular ATP levels were observed among creatine phosphate treated animals (344+/-55 nMol/g tissue, n=5) compared to control animals (160+/-9 nMol/g tissue, n=5)(p=0.014).

CONCLUSIONS

A strategy of intravenous high-energy phosphate administration successfully prevented ischemic ventricular dysfunction in a rodent model of OPCAB.

Digital ulcers in systemic sclerosis: Prevention by treatment with bosentan, an oral endothelin receptor antagonist

OBJECTIVE

Recurrent digital ulcers are a manifestation of vascular disease in patients with systemic sclerosis (SSc; scleroderma) and lead to pain, impaired function, and tissue loss. We investigated whether treatment with the endothelin receptor antagonist, bosentan, decreased the development of new digital ulcers in patients with SSc.

METHODS

This was a randomized, prospective, placebo-controlled, double-blind study of 122 patients at 17 centers in Europe and North America, evaluating the effect of treatment on prevention of digital ulcers. The primary outcome variable was the number of new digital ulcers developing during the 16-week study period. Secondary assessments included healing of existing digital ulcers and evaluation of hand function using the Scleroderma Health Assessment Questionnaire.

RESULTS

Patients receiving bosentan had a 48% reduction in the mean number of new ulcers during the treatment period (1.4 versus 2.7 new ulcers; P = 0.0083). Patients who had digital ulcers at the time of entry in the study were at higher risk for the development of new ulcers; in this subgroup the mean number of new ulcers was reduced from 3.6 to 1.8 (P = 0.0075). In patients receiving bosentan, a statistically significant improvement in hand function was observed. There was no difference between treatment groups in the healing of existing ulcers. Serum transaminase levels were elevated to >3-fold the upper limit of normal in bosentan-treated patients; this elevation is comparable with that observed in previous studies of this agent. Other side effects were similar in the 2 treatment groups.

CONCLUSION

Endothelins may play an important role in the pathogenesis of vascular disease in patients with SSc. Treatment with the endothelin receptor antagonist bosentan may be effective in preventing new digital ulcers and improving hand function in patients with SSc.

A comparison of microbiologic flora of the sinuses and airway among cystic fibrosis patients with maxillary antrostomies

The placement of maxillary antrostomies among cystic fibrosis (CF) patients has been used as a treatment to allow localized antibiotic lavage of infected sinus passages. This procedure is increasingly recommended by lung transplantation centers as a prerequisite prior to accepting a CF patient as a candidate for transplantation. Our study attempts to define the degree of identity between sinus, endotracheal and sputum cultures from 35 patients. The samples (n = 137) were collected within two weeks of each other. An analysis of the microbiologic type, strain, and antibiotic resistance patterns was undertaken. Randomization analysis was performed and a p-value of < 0.05 was considered significant. The results indicated a high degree of correlation between sinus-sputum pairs (n = 55) and endotracheal samples (p < 0.008). This study provides evidence that there is a potential for cross-infection between sinus passages and the lower airway. The localized irrigation of CF sinus cavities post-transplantation may be warranted in an attempt to reduce bacterial counts and potential direct infection of the allograft. However, it is unlikely that this will eliminate this risk because bacterial colonization continues and the CF trachea is another source of infection.

Recombinant human relaxin in the treatment of scleroderma. A randomized, double-blind, placebo-controlled trial

BACKGROUND

Relaxin is a pregnancy-related hormone that has tissue remodeling and antifibrotic effects. Systemic sclerosis (scleroderma) is characterized by fibrosis of the skin, vasculature, and internal organs.

OBJECTIVE

To assess the efficacy, safety, and dose-response effect of recombinant human relaxin in patients with scleroderma.

DESIGN

Multicenter, parallel-group, randomized, double-blind, placebo-controlled trial.

SETTING

Academic referral centers.

PATIENTS

68 patients who had had stable, diffuse scleroderma (moderate to severe) for less than 5 years.

INTERVENTION

Recombinant human relaxin, 25 or 100 microg/kg of body weight per day, or placebo administered by continuous subcutaneous infusion over 24 weeks.

MEASUREMENTS

Modified Rodnan skin score was the primary efficacy measure. Secondary measurements were pulmonary function, the Health Assessment Questionnaire, and other measures of scleroderma that reflected fibrosis.

RESULTS

Patients who received 25 microg/kg of recombinant human relaxin per day had significantly lower skin scores than those who received placebo (mean change, -3.6 at 4 weeks [P = 0.021], -7.5 at 12 weeks [P < 0.001], and -8.7 at 24 weeks [P = 0.040]). Similar trends were noted in other outcome measures, including forced vital capacity, measures of oral aperture and hand extension, functional status, and global assessment. Patients who received 100 microg/kg of relaxin per day did not differ from those who received placebo. Drug-related adverse events included menometrorrhagia, reversible anemia, and complications of the subcutaneous drug administration system (site irritation and local infection).

CONCLUSIONS

Twenty-four weeks of recombinant human relaxin, 25 microg/kg per day, is associated with reduced skin thickening, improved mobility, and improved function in patients with moderate to severe diffuse scleroderma.

The prevalence of major depressive disorder and low self-esteem in medical inpatients

OBJECTIVE

To determine the prevalence of major depressive disorder in acutely ill medical inpatients, and the relationship of this to low self-esteem.

METHOD

A total of 186 patients were interviewed 6 or 7 days following admission to detect the presence of DSM-IV major depressive disorder (MDD). Patients were assessed using a new brief psychiatric interview, the Silverstone Concise Assessment for Depression (SCAD), which has previously been validated for use in the physically ill. The cognitive function of the patients was measured, using the Mini-Mental State Examination (MMSE), with patients scoring less than 22 on the MMSE being excluded from the study. The patients' self-esteem was also assessed, using the Rosenberg self-esteem rating scale. The severity and type of the patients' medical illness, and the recognition of psychiatric illness by both nurses and physicians were also noted.

RESULTS

The results showed that 18 patients (9.7%) were depressed. The depressed patients were significantly younger than the nondepressed patients (mean age 46.3 +/- 3.9 years versus 57.1 +/- 1.5 years, respectively) and were significantly more likely to be female (61% versus 44%, respectively). The depressed patients had a significantly lower self-esteem than the nondepressed patients, whose self-esteem was no different from the general population. However, the depressed patients were not more severely ill than the nondepressed patients. The results also demonstrated that both nurses and physicians were poor at recognizing the presence of major depression, with nurses recognizing 33% of cases compared to 22% for medical staff.

CONCLUSIONS

The results from this study demonstrate that while there is an increase in the incidence of depression in medically ill patients, this is not as great as has been previously reported, and is not related to severity of illness. The results from this study, therefore, are in keeping with other recent findings which show that the prevalence rates for MDD in medical patients is between 5% to 10% rather than the previously accepted range of 20% to 40%.

Transcriptional regulation of the murine TCR zeta gene

The TCR zeta chain plays a significant role in the assembly of the receptor complex and in coupling antigen recognition to the intracellular signal transduction apparatus. Since the zeta protein level is considered the limiting factor for receptor assembly in mature T cells, aberrant expression of the zeta chain affects both receptor structure and function. To understand the regulatory mechanisms controlling zeta gene expression, we characterized the 5' flanking region of the gene. Our analysis reveals the existence of at least three regions within the -784 to +121 fragment involved in the transcription of the zeta gene in T cells: (i) the fragment from -216 to +121 contains the basal promoter; (ii) the sequence between -561 and -216 includes positive elements which confer strong transcriptional activity; and (iii) the region between -784 and -561 which contains negative element(s) that down-regulate zeta gene transcription. The entire 5' flanking region of the zeta gene is functional in both T and fibroblast cell lines, although the transcriptional levels and the specific regions required for maximal activity differ between the two cell types. Maximal transcriptional activity is achieved when T cells are stimulated simultaneously via the TCR and with PMA. The transcriptional activity of the zeta gene can be induced by PMA alone in T cells but not in fibroblasts, suggesting that this effect is mediated by T cell-specific factors. We also demonstrate that upregulation of the transcriptional activity induced by the different stimuli is consistent with increased expression of zeta mRNAm, pointing to the possibility that signal transduction events initiated during T cell activation may be involved in controlling zeta gene expression.

40Ar/39Ar Dating of the Brunhes-Matuyama Geomagnetic Field Reversal

Magnetostratigraphic studies are widely used in conjunction with the geomagnetic polarity time scale (GPTS) to date events in the range 0 to 5 million years ago. A critical tie point on the GPTS is the potassium-argon age of the most recent (Brunhes-Matuyama) geomagnetic field reversal. Astronomical values for the forcing frequencies observed in the oxygen isotope record in Ocean Drilling Project site 677 suggest that the age of this last reversal is 780 ka (thousand years ago), whereas the potassium-argon-based estimate is 730 ka. Results from 4039; Ar incremental heating studies on a series of lavas from Maui that straddle the Brunhes-Matuyama reversal give an age of 783 + 11 ka, in agreement with the astronomically derived value. The astronomically based technique appears to be a viable tool for dating young sedimentary sequences.

Energy-rich glyceric acid oxygen esters: implications for the origin of glycolysis

The apparent Gibbs free energy change of hydrolysis (delta G degrees', pH 7) of the 2- and 3-O-glyceroyl esters of 2- and 3-O-L-glyceroyl-L-glyceric acid methyl ester were measured at 25 degrees C. The 2- and 3-glyceroyl esters were found to be 'energy-rich' with delta G degrees' values of -9.1 kcal mol-1 and -7.8 kcal mol, respectively. This result indicates that the analogous 2- and 3-glyceroyl esters of polyglyceric acid are also 'energy-rich' and, therefore, could have acted as an energy source for primitive phosphoanhydride synthesis.

Fluorescence studies of a single tyrosine in a type II DNA binding protein

We studied the fluorescence properties of a single tyrosine (Tyr94) located in the C-terminal tail of transcription factor 1 (TF1), a type II procaryotic DNA binding protein encoded by the Bacillus subtilis phage SPO1. The time-resolved fluorescence intensity of Tyr94 in free TF1 dimers decays as a single exponential, and this is consistent with a twofold symmetrical structure. The fluorescence is readily quenched by acrylamide, but it is less accessible to anionic quenchers (iodide and citrate), suggesting that the tyrosine is located on the protein surface in a negatively charged environment provided by neighboring Glu95 and Asp96 residues. TF1 dimers associate at moderate concentrations (greater than 0.02 mg/mL) as judged from concentration dependencies in the molar fluorescence intensity, the steady-state fluorescence polarization, and the bimolecular quenching constants. Nonspecific binding of TF1 to SPO1 and calf thymus (CT) DNA and various double-stranded polynucleotides quenches the Tyr94 fluorescence to varying extent. Fluorescence lifetimes of TF1 in the bound state correlate with spectral overlaps between TF1 emission and DNA absorption, demonstrating that excitation energy transfer to DNA bases contributes significantly to the observed quenching. From analysis of the observed quenching in the DNA complexes we conclude that Tyr94 is located within 10-14 A of the DNA helix axis and not in direct contact with the DNA bases. Equilibrium analyses based on fluorescence titrations show that the maximum binding density on DNA extrapolates to ca. 1 TF1 dimer/5 DNA base pairs. We find several differences in TF1 binding to SPO1 DNA, which contains hydroxymethyluracil instead of thymine, and CT DNA: (i) The tyrosine residue is less exposed to the solvent in the SPO1 DNA complex than in the CT DNA complex. (ii) D2O addition enhances the Tyr94 fluorescence when TF1 binds to SPO1 DNA but not when it binds to CT DNA. (iii) The TF1-SPO1 DNA complex is stable at higher NaC1 concentrations than is the TF1-CT DNA complex, and its formation involves the dissociation of more Na+ ions than does the TF1-CT DNA complex. On the basis of these observations and the fact that the Tyr94-containing tail of TF1 is essential for binding to SPO1 DNA, we discuss various models for the TF1-DNA complex.

Mixed clinicopathologic behavior of a solitary mesothelioma

A large solitary mesothelioma was found to exhibit malignant features microscopically, but benign characteristics grossly, including a surgically curative resection. The mixed behavior of this tumor supports the evolving understanding of mesotheliomas as progeny of multipotential subserosal cells with capabilities of differentiating into several tissue types with varying degrees of anaplasia.