Trading off accuracy and explainability in AI decision-making: findings from 2 citizens' juries

Objective

To investigate how the general public trades off explainability versus accuracy of artificial intelligence (AI) systems and whether this differs between healthcare and non-healthcare scenarios.

Materials and Methods

Citizens’ juries are a form of deliberative democracy eliciting informed judgment from a representative sample of the general public around policy questions. We organized two 5-day citizens’ juries in the UK with 18 jurors each. Jurors considered 3 AI systems with different levels of accuracy and explainability in 2 healthcare and 2 non-healthcare scenarios. Per scenario, jurors voted for their preferred system; votes were analyzed descriptively. Qualitative data on considerations behind their preferences included transcribed audio-recordings of plenary sessions, observational field notes, outputs from small group work and free-text comments accompanying jurors’ votes; qualitative data were analyzed thematically by scenario, per and across AI systems.

Results

In healthcare scenarios, jurors favored accuracy over explainability, whereas in non-healthcare contexts they either valued explainability equally to, or more than, accuracy. Jurors’ considerations in favor of accuracy regarded the impact of decisions on individuals and society, and the potential to increase efficiency of services. Reasons for emphasizing explainability included increased opportunities for individuals and society to learn and improve future prospects and enhanced ability for humans to identify and resolve system biases.

Conclusion

Citizens may value explainability of AI systems in healthcare less than in non-healthcare domains and less than often assumed by professionals, especially when weighed against system accuracy. The public should therefore be actively consulted when developing policy on AI explainability.

Should free-text data in electronic medical records be shared for research? A citizens' jury study in the UK

BACKGROUND

Use of routinely collected patient data for research and service planning is an explicit policy of the UK National Health Service and UK government. Much clinical information is recorded in free-text letters, reports and notes. These text data are generally lost to research, due to the increased privacy risk compared with structured data. We conducted a citizens' jury which asked members of the public whether their medical free-text data should be shared for research for public benefit, to inform an ethical policy.

METHODS

Eighteen citizens took part over 3 days. Jurors heard a range of expert presentations as well as arguments for and against sharing free text, and then questioned presenters and deliberated together. They answered a questionnaire on whether and how free text should be shared for research, gave reasons for and against sharing and suggestions for alleviating their concerns.

RESULTS

Jurors were in favour of sharing medical data and agreed this would benefit health research, but were more cautious about sharing free-text than structured data. They preferred processing of free text where a computer extracted information at scale. Their concerns were lack of transparency in uses of data, and privacy risks. They suggested keeping patients informed about uses of their data, and giving clear pathways to opt out of data sharing.

CONCLUSIONS

Informed citizens suggested a transparent culture of research for the public benefit, and continuous improvement of technology to protect patient privacy, to mitigate their concerns regarding privacy risks of using patient text data.

Commercial use of health data-A public "trial" by citizens' jury

INTRODUCTION

Surveys suggest a dichotomy in how citizens view research for public benefit and research for commercial gain. Therefore, a research initiative, such as a learning health system, which works for both public and commercial benefit, may be controversial and lower public trust.

METHODS

This study aimed to investigate what informed citizens considered to be appropriate uses of health data in a learning health system and why they made those decisions. Two-paired 4-day juries were run, with different jurors but the same purpose, expert witnesses, and facilitators. Overall, 694 people applied; 36 jurors were selected to match criteria based on demographics and privacy views. Jurors considered whether and why eight exemplars of anonymised patient data were acceptable. The exemplars were either planned initiatives to improve care pathways (Planned Examples) or possible commercial data uses (Potential Examples).

RESULTS

These citizens' juries found that all Planned and two of the Potential Examples were considered appropriate by most, but not all, jurors because they could deliver public benefit. In general, positive health outcomes for patients were more acceptable than improved efficiency of services for the NHS, although they recognised that the latter also improved health. Jurors had concerns about whether improving efficiency would lead to inequitable distribution or closure of services, based on their existing understanding from media reports. Commercial gain that accrued secondary to this benefit was acceptable, with some jurors becoming more accepting of commercial uses as they understood them better. Prioritising profit, however, was unacceptable, regardless of any governance arrangements.

CONCLUSIONS

Jurors tended to be more accepting of data sharing to both private and public sectors after the jury process. Many jurors accept commercial gain if public benefit is achieved. Some were suspicious of data sharing for efficiency gains. Juries elicited more informed and nuanced judgement from citizens than surveys.

Consensus Statement on Public Involvement and Engagement with Data Intensive Health Research

This consensus statement reflects the deliberations of an international group of stakeholders with a range of expertise in public involvement and engagement (PI&E) relating to data-intensive health research. It sets out eight key principles to establish a secure role for PI&E in and with the research community internationally and ensure best practice in its execution. Our aim is to promote culture change and societal benefits through ensuring a socially responsible trajectory for innovations in this field. Our key premise is that the public should not be characterised as a problem to be overcome but a key part of the solution to establish socially beneficial data-intensive health research for all.

Commercial use of health data in the dock – results of a public “trial”

IntroductionSurveys suggest that there is a dichotomy in how citizens view research for public good and research for commercial gain. As a consequence, the idea that a research initiative, such as a learning health system, for both public and commercial benefit may be controversial and reduce public trust. Objectives and ApproachThis study aims to investigate what informed citizens considered to be appropriate uses of health data in a learning health system. Two paired four-day juries were run, with different jurors but the same purpose, expert witnesses and facilitators. Overall, 694 people applied to be jurors; 36 were selected to match criteria based on national demographics and their prior privacy views. Jurors considered whether and why eight exemplar data uses of depersonalised patient data were acceptable. The exemplars were data uses planned by the learning health system initiative to improve care pathways (planned uses), and possible unplanned data uses. ResultsAll planned uses were considered appropriate by most, but not all, jurors, as they had the potential of benefitting the public through improving care. Positive health outcomes were more acceptable than improved efficiency of services, given jurors prior beliefs about how the NHS operates raising concerns about whether improving efficiency would lead to inequitable distribution or closure of services. The potential uses were considered appropriate where there were improvements in drugs, treatments, or lower NHS costs. Some jurors became more accepting of commercial uses as they understood them better. Commercial uses that prioritised generating profit and did not produce health benefits for the public were unacceptable, regardless of any safeguards for the data. Commercial gain that occurred secondary to achieving public benefit were generally accepted. Conclusion/ImplicationsJuries elicit more informed and nuanced judgement from citizens than surveys. Jurors tended to be more accepting of data sharing to both private and public sector after the jury process. Many jurors accept commercial gain if public benefit is achieved. Some were suspicious of data sharing for efficiency gains.

Investigating the Extent to Which Patients Should Control Access to Patient Records for Research: A Deliberative Process Using Citizens' Juries

BACKGROUND

The secondary use of health data for research raises complex questions of privacy and governance. Such questions are ill-suited to opinion polling where citizens must choose quickly between multiple-choice answers based on little information.

OBJECTIVE

The aim of this project was to extend knowledge about what control informed citizens would seek over the use of health records for research after participating in a deliberative process using citizens' juries.

METHODS

Two 3-day citizens' juries, of 17 citizens each, were convened to reflect UK national demographics from 355 eligible applicants. Each jury addressed the mission "To what extent should patients control access to patient records for secondary use?" Jurors heard from and questioned 5 expert witnesses (chosen either to inform the jury, or to argue for and against the secondary use of data), interspersed with structured opportunities to deliberate among themselves, including discussion and role-play. Jurors voted on a series of questions associated with the jury mission, giving their rationale. Individual views were polled using questionnaires at the beginning and at end of the process.

RESULTS

At the end of the process, 33 out of 34 jurors voted in support of the secondary use of data for research, with 24 wanting individuals to be able to opt out, 6 favoring opt in, and 3 voting that all records should be available without any consent process. When considering who should get access to data, both juries had very similar rationales. Both thought that public benefit was a key justification for access. Jury 1 was more strongly supportive of sharing patient records for public benefit, whereas jury 2 was more cautious and sought to give patients more control. Many jurors changed their opinion about who should get access to health records: 17 people became more willing to support wider information sharing of health data for public benefit, whereas 2 moved toward more patient control over patient records.

CONCLUSIONS

The findings highlight that, when informed of both risks and opportunities associated with data sharing, citizens believe an individual's right to privacy should not prevent research that can benefit the general public. The juries also concluded that patients should be notified of any such scheme and have the right to opt out if they so choose. Many jurors changed their minds about this complex policy question when they became more informed. Many, but not all, jurors became less skeptical about health data sharing, as they became better informed of its benefits and risks.

Should policy ethics come in two colours: green or white?

When writing about policy, do you think in green or white? If not, I recommend that you do. I suggest that writers and journal editors should explicitly label every policy ethics paper either 'green' or 'white'. A green paper is an unconstrained exploration of a policy question. The controversial 'After-birth abortion' paper is an example. Had it been labelled as 'green', readers could have understood what Giubilini and Minerva explained later: that it was a discussion of philosophical ideas, and not a policy proposal advocating infanticide. A serious policy proposal should be labelled by writer(s) and editor(s) as 'white'. Its purpose should be to influence policy. In order to influence policy, I suggest three essential, and two desirable, characteristics of any white paper. Most importantly, a white paper should be set in the context in which the policy is to be made and applied.

How can one be both a philosophical ethicist and a democrat?

How can one be both a philosophical ethicist and a democrat? In this article I conclude that it can be difficult to reconcile the two roles. One involves understanding, and reconciling, the conflicting views of citizens, and the other requires the pursuit of truth through reason. Nevertheless, an important function of philosophy and ethics is to inform and improve policy. If done effectively, we could expect better, and more just, laws and policies, thereby benefiting many lives. So applying philosophical thinking to policy is an important job. However, it comes with substantial difficulties, not least in reconciling, or choosing between, competing philosophical theories. Despite the importance of the task, and the apparent obstacles, there is relatively little literature on how to apply ethics to real-world policy-making. Democracies need ethicists who can engage in democratic debate and bridge the gap between philosophy and public policy. I offer some tactics here.

Abstract P5-10-13: Pre-surgical plasma microRNA pattern defines a biologically distinct triple negative breast cancer (TNBC) occuring in black (B) compared to white (W) women

Background: Black women with triple negative breast cancer have 46% lower survival rates; this may be due to differences in tumor biology. We analyzed presurgical plasma microRNA of white (W) and black (B) women with TNBC enrolled in the breast ovarian tissue bank to detect if differences in the pre-surgical plasma microRNA could be detected in B patients relative to W patients relative to healthy controls.

Aims: MicroRNA in pre-surgical plasma of TNBC W or B was compared to plasma from controls race and age matched controls to assess if differences in plasma and tumor microRNA may explain the survival disparity observed in B. We addressed 2 questions 1) are the patterns in the pre-surgical miRNA profiles different between W and B patients, differences that could explain outcomes discrepancy? 2) What are the miRs changes in patients W or B relative to healthy controls?

Methods: Between 2004 and 2011 plasma miRNAs was measured before, after surgery, during and after chemotherapy in 73 surgical breast cancer patients and 11 age and race matched controls. We also analized miRs in the tumor and benign adjacent breast in 5 specimes. Samples were analyzed using qRT-PCR in the ABI's TaqMan OpenArray Panel for 750 miRs. Samples were spiked with ath-miR-159a and hsa-miR-320 most strongly correlated in its expression to ath-miR-159a through the Pearson correlation coefficient. 2-sample t-test was used for comparisons between means and ANOVA followed by post-hoc test to compare the mean response between subject factors of interest. All tests were 2-tailed; statistical significance was set at p < 0.05.

Results: 44 W and 23 B, mean age at surgery 48 years (range 35–78) and 11 controls – mean age 44 years (range 35–67). Black TNBC patients did not express over 70 % of pre-surgical plasma miRs present in the W pre-surgical plasma. B over-expressed high levels of miR-1244, -190 and -638, which were not detected in any of the W patients (p < 0.005). W patients and controls expressed miRs10a, -190, -502-3p, -548, and -9* not detected in B TNBC patients. White patients over-expressed over 80% of plasma miRs present in controls, while black patients over-expressed only 30% of miRs present in controls (P < 0.005).

Conclusions: Patterns of pre-surgical miR expression are different in B versus W patients with TNBC. In B the presence of TNBC leads to silence in circulating plasma miRs in comparison to W and controls. In W the presence of the tumor increases the miR “chatter”. Black patients have a different “communication” style between host-TNBC when analyzed by the response of plasma microRNA. This difference may call for different treatment protocols for patients. Specific treatment interventions, such as administration of chemotherapy before surgery, in an attempt to increase the microRNA levels in plasma may improve the outcomes of black patients with TNBC.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-10-13.

Inhibition of tumor angiogenesis by antibodies, synthetic small molecules and natural products

Cancer remains one of the major causes of death worldwide. The switch to pathological angiogenesis is a key process in the promotion of cancer and consequently provides several new and promising targets to anticancer therapy. Thus, antagonizing angiogenesis cuts off the tumor's oxygen and nutrition supply. This review focuses on angiogenesis inhibitors as option for cancer treatment. Modes of action, adverse effects, mechanisms of resistance as well as new developments are highlighted. One approach in angiogenesis inhibition is intermitting the further VEGF (vascular endothelial growth factor) signal pathway with monoclonal antibodies. Bevacizumab is a highly specific recombinant humanized monoclonal IgG antibody targeting VEGF-A. An efficient antitumor therapy demands more specific antibodies that affect other signal molecules besides VEGF-A, which is in the focus of current research. In addition to antagonizing VEGF, there are also small molecules that inhibit receptor tyrosine kinases (RTKs). Many RTK inhibitors have been described, which exhibit different specificity profiles. The question, whether highly specific antagonists are necessary remains open, because other affected RTKs may also represent growth factor receptors that are essential for tumor growth. Therefore their inhibition may also contribute to anticancer activity. Secondary plant metabolites represent templates for the development of new small molecules. The identification of new drugs from plants has a long and successful history. There is convincing evidence for the beneficial effect of phytochemicals on cancer-related pathways, particularly with regard to anti-angiogenesis. Plant phenolics are the most important category of phytochemicals, including flavanoids. Prominent phytochemicals affecting different pathways of angiogenesis are green tea polyphenols (epigallocatechin gallate) and soy bean isoflavones (genistein).

Strain-specific alteration of zebrafish feeding behavior in response to aversive stimuli

Behavioral management of risk, in which organisms must balance the requirements of obtaining food resources with the risk of predation, has been of considerable interest to ethologists for many years. Although numerous experiments have shown that animals alter their foraging behavior depending on the levels of perceived risk and demand for nutrients, few have considered the role of genetic variation in the trade-off between these variables. We performed a study of four zebrafish (Danio rerio (Hamilton, 1822)) strains to test for genetic variation in foraging behavior and whether this variation affected their response to both aversive stimuli and nutrient restriction. Zebrafish strains differed significantly in their latency to begin foraging from the surface of the water under standard laboratory conditions. Fish fed sooner when nutrients were restricted, although this was only significant in the absence of aversive stimuli. Aversive stimuli caused fish to delay feeding in a strain-specific manner. Strains varied in food intake and specific growth rate, and feeding latency was significantly correlated with food intake. Our results indicate significant genetic variation in foraging behavior and the perception of risk in zebrafish, with a pattern of strain variation consistent with behavioral adaptation to captivity.

Intravaskuläre optische Kohärenztomographie: Unterscheidung verschiedener Plaquetypen und Vermessung von Gefäßdimensionen in atherosklerotischen Unterschenkelarterienex vivo

PURPOSE

Intravascular optical coherence tomography (OCT) is a new technique based on infrared light that visualizes the arteries with a resolution of 10-20 microm. Intravascular ultrasound (IVUS) is the current in vivo reference standard and provides a resolution of 100-150 microm. This study compared OCT to IVUS and histopathology with respect to the ability to differentiate atherosclerotic plaques and quantify vascular dimensions in peripheral crural arteries ex vivo.

MATERIALS AND METHODS

50 segments of atherosclerotic arteries derived from five amputated human lower extremities were examined. The different plaque types (fibrous, high-lipid content, calcified) were assigned by two independent examiners, and the sensitivity and specificity of OCT in comparison with histopathology as well as intra- and interobserver consensus were calculated. A comparison of OCT with IVUS addressed the parameters: luminal area (LA), vascular wall area (VA) and plaque area (PA).

RESULTS

When comparing OCT and histopathology with respect to the differentiation of various plaque types, sensitivities of 81 % and specificities of 89 % for fibrous plaques, of 100 % and 93 % for lipid-rich plaques and of 80 % and 89 % for calcified plaques were achieved (overall correlation 83 %). Intra- and interobserver consensus was very high (kappa = 0.86 and kappa = 0.89, p < 0.001, respectively). There was also a high correlation between quantitative measurements (Bland-Altman plot [LA]: mean bias, 0.1 mm(2) accuracy +/- 1.8 mm(2), r = 0.95 [p < 0.001] Bland-Altman plot [VA]: mean bias, 0.3 mm(2) accuracy +/- 2.3 mm(2), r = 0.94 [p < 0.001] Bland-Altman plot [PA]: mean bias, 0.4 mm(2) accuracy +/- 2.3 mm(2), r = 0.80 [p < 0.01].

CONCLUSION

OCT allows the differentiation of atherosclerotic plaque types in crural arteries with high accuracy compared to histopathology. Quantitative measurements show a high correlation with IVUS, the current reference standard.

Expression of hepatic transporters OATP-C and MRP2 in primary sclerosing cholangitis

BACKGROUND/AIMS

In chronic cholestatic liver diseases, biliary excretion of organic anions from blood into bile is impaired. The aim of this study was to identify the underlying mechanism.

METHODS

Expression of the basolateral organic anion transporting polypeptide OATP-C (SLC21A6) and the canalicular multidrug resistance protein 2 (MRP2) was studied in patients with primary sclerosing cholangitis (PSC) (n=4), a chronic cholestatic liver disease, and in non-cholestatic controls (n=4) (two with chronic hepatitis C, one with idiopathic liver cirrhosis and one with fatty liver). Total RNA was isolated from liver tissue, reverse transcribed and subjected to polymerase chain reaction (PCR) amplification using primers specific for OATP-C, MRP2 and beta-actin. PCR products were quantified densitometrically.

RESULTS

When normalized for beta-actin expression, the level of OATP-C mRNA in liver tissue of patients with PSC was 49% of controls (OATP-C/beta-actin 1.60+/-0.25 vs. 3.24+/-0.69; p<0.05) and the level of MRP2 mRNA was 27% of controls (MRP2/beta-actin 0.70+/-0.36 vs. 2.54+/-0.56; p<0.01).

CONCLUSIONS

Both OATP-C and MRP2 are decreased as measured by mRNA level in PSC. Downregulation of OATP-C might be the consequence of impaired canalicular secretion of organic anions and could serve to reduce the organic anion load of cholestatic hepatocytes.

Mtr1, a novel biallelically expressed gene in the center of the mouse distal chromosome 7 imprinting cluster, is a member of the Trp gene family

We recently described a novel putative Ca(2+) channel gene, MTR1, which shows a high level of homology to the human TRPC7 gene and the melastatin 1 (MLSN1) gene, another Trp (transient receptor potential protein)-related gene whose transcript was found to be downregulated in metastatic melanomas. It maps to human chromosome band 11p15.5, which is associated with the Beckwith-Wiedemann syndrome and predisposition to a variety of neoplasias. Here we report the isolation and characterization of the murine orthologue Mtr1. The chromosomal localization on distal chromosome 7 places it in a cluster of imprinted genes, flanked by the previously described Tapa1 and Kcnq1 genes. The Mtr1 gene encodes a 4.4-kb transcript, present in a variety of fetal and adult tissues. The putative open reading frame consists of 24 exons, encoding 1158 amino acids. Transmembrane prediction algorithms indicate the presence of six membrane-spanning domains in the proposed protein. Imprinting analysis, using RT-PCR on RNA from reciprocal mouse crosses harboring a sequence polymorphism, revealed biallelic expression of Mtr1 transcripts at all stages and tissues examined.

Effect of cholestyramine on bile acid pattern and synthesis during administration of ursodeoxycholic acid in man

BACKGROUND

Cholestyramine is the first-line treatment for cholestasis-induced pruritus and is prescribed along with ursodeoxycholic acid (UDCA) in patients with cholestatic liver diseases. Impairment of the intestinal absorption of endogenous hydrophobic bile acids by cholestyramine is well known. It is unclear, however, whether cholestyramine also impairs the absorption of the hydrophilic bile acid, UDCA, in man.

AIMS

To study serum levels of UDCA and endogenous bile acids as well as endogenous bile acid synthesis during simultaneous or separate administration of UDCA and cholestyramine in vivo; and absorption of UDCA both in the presence and absence of its hydrophobic epimer, chenodeoxycholic acid (CDCA), by cholestyramine in vitro.

PATIENTS AND METHODS

Five healthy subjects received UDCA (12.5 +/- 0.5 mg kg-1 daily) as a single dose for periods of 14 days with or without cholestyramine (4 g daily). Fasting serum levels of bile acids and of 7alpha-hydroxy-4-cholesten-3-one (alpha-HC), a measure of endogenous bile acid synthesis, were determined by gas chromatography and high pressure liquid chromatography, respectively. In vitro, bile acid solutions were incubated for 24 h in the presence or absence of cholestyramine, and bile acid concentrations were determined in the supernatant.

RESULTS

Simultaneous administration of UDCA and cholestyramine in man led to a decrease of fasting serum levels of UDCA by 60% when compared to UDCA serum levels during administration of UDCA alone. In contrast, serum levels of endogenous bile acids were not affected and alpha-HC serum levels were found increased 2. 7-fold indicating stimulation of endogenous bile acid synthesis by cholestyramine. Administration of cholestyramine and UDCA at an interval of 5 h tended to diminish the effect of cholestyramine on UDCA serum levels. In vitro, conjugated and unconjugated UDCA were effectively bound by cholestyramine both in the presence and absence of hydrophobic bile acids.

CONCLUSIONS

The results strongly support the recommendation to administer UDCA and cholestyramine at different times of day.

Prognostic value of lung function and pulmonary haemodynamics in OSA patients treated with CPAP

The aim of the present study was to determine survival rates of obstructive sleep apnoea patients treated with continuous positive airway pressure (CPAP) and to investigate the prognostic value of pretreatment lung function and pulmonary haemodynamics. Two hundred and ninety-six patients, exhibiting > or = 20 apnoeas plus hypopnoeas per hour of sleep, were included. Patients were treated with nasal CPAP and regularly followed up. The cumulative survival rates were 0.96 (95% confidence interval (CI): 0.94-0.99) at 3 yrs and 0.93 (95% CI: 0.91-0.97) at 5 yrs. Most patients died from cardiovascular disease. Apart from age, covariates associated with a lower survival were the presence of a heavy smoking history, a low vital capacity, a low forced expiratory volume in one second (FEV1) and a high mean pulmonary artery pressure. Only three covariates were included by forward stepwise selection in the multivariate analysis, smoking habit (>30 pack-yrs), age and FEV1. The observed survival rates of the group as a whole were similar to those of the general population matched in terms of age, sex and smoking habit, except for patients between 50 and 60 yrs old who had reduced survival. This difference disappeared when patients of the present study with an associated chronic obstructive pulmonary disease were excluded from the comparison. In conclusion, survival of obstructive sleep apnoea patients treated with nasal continuous positive airway pressure is near to that of the general population. The prognosis is worse in subgroups of patients with a history of heavy smoking and with an associated chronic obstructive pulmonary disease.

Daytime hypoventilation in obstructive sleep apnoea syndrome

Chronic alveolar hypoventilation is a classic feature of the "pickwickian syndrome" (i.e. obesity-hypoventilation syndrome) but in fact hypercapnia is observed in a minority of obstructive sleep apnoea syndrome (OSAS) patients. Most recent studies having included large numbers of unselected, consecutive OSAS patients agree on a prevalence of 10-20% of alveolar hypoventilation. The mechanisms of hypercapnia in OSAS are not fully understood but the determining factors of daytime respiratory insufficiency are probably the presence of a marked obesity, leading to the obesity hypoventilation syndrome and, principally, the association of OSAS with chronic obstructive pulmonary disease. This association (the so-called "overlap syndrome") is observed in >10% of OSAS patients. Bronchial obstruction is generally mild to moderate and may be asymptomatic. The severity of the nocturnal events (apnoeas, hypopnoeas) and a (possible) diminished chemosensitivity to hypercapnic and hypoxic stimuli do not appear to be determining factors of hypercapnia. The most important consequence of chronic alveolar hypoventilation is pulmonary hypertension which is only observed in patients with daytime arterial blood gases disturbances, and which can lead to right heart failure. When nasal continuous positive airway pressure fails to correct sleep-related hypoxaemia, supplementary O, must be given or another way of assisted ventilation (BIPAP) must be considered. In the most severe patients (diurnal PaO(2) <55 mmHg) conventional O(2) therapy (>or=16h/24h) is required in addition to nocturnal ventilation.

Lung membrane diffusing capacity, heart failure, and heart transplantation

The pulmonary diffusing capacity for carbon monoxide (DLCO) is reduced in chronic heart failure and remains decreased after heart transplantation. This decrease in DLCO may depend on a permanent alteration after transplantation of one or the other of its components: diffusion of the alveolar capillary membrane or the pulmonary capillary blood volume (Vc). Therefore, we measured DLCO, the membrane conductance, and Vc before and after heart transplantation. At the time of hemodynamic measurements, the Roughton and Forster method of measuring DLCO at varying alveolar oxygen concentrations was used to determine the membrane conductance, Vc, DLCO/alveolar volume (VA), the membrane conductance/VA and thetaVc/VA (theta = carbon monoxide conductance of blood, VA = alveolar volume) in 21 patients with class III to IV heart failure before and after transplantation, and in 21 healthy controls. Transplantation normalized pulmonary capillary pressure and increased cardiac index. DLCO was decreased before transplantation (7.11 vs 10.0 mmol/min/kPa in controls), but DLCO/VA was normal (1.67+/-0.44 vs 1.71+/-0.26 mmol/min/kPa/L in controls). DLCO/VA remained unchanged after transplantation, because the decrease in Vc (82+/-30 vs 65+/-18 ml before and after transplantation) and thetaVc/VA was not compensated by the changes in membrane conductance (11+/-4 vs 12+/-5 mmol/min/kPa before and after transplantation, respectively) and membrane conductance/VA. We conclude that the decrease in DLCO in patients with chronic heart failure is due to a restrictive ventilatory pattern because their DLCO/VA remains normal; the decrease in the membrane conductance is compensated by the increase in Vc. After transplantation, the decrease in Vc due to normalization of pulmonary hemodynamics is not completely compensated for by an increase in membrane conductance. Because the membrane conductances, measured before and after transplantation, are negatively correlated with duration of heart failure, its abnormal pulmonary hemodynamics may have irreversibly altered the alveolar capillary membrane.

[Short-duration nocturnal hypoxemia and persistent pulmonary hypertension]

Can daily short-duration hypoxemia (4-8 hours) induce pulmonary hypertension and right ventricular hypertrophy? A clinical model of this type of hypoxemia does exist: isolated nocturnal hypoxemia in patients with obstructive sleep apnea syndrome (OSAS) or chronic obstructive pulmonary disease (COPD). By investigating the pulmonary hemodynamics of these patients, it should be possible to determine whether nocturnal hypoxemia alone can induce pulmonary hypertension. Although nocturnal hypoxemia (in OSAS as well as in COPD) can induce acute episodes of pulmonary hypertension, it would not appear that nocturnal hypoxemia alone would be sufficient to provoke permanent diurnal pulmonary hypertension. This is the conclusion of recent studies concerning diurnal pulmonary hemodynamics in OSAS and COPD patients exhibiting minimal hypoxemia during the day but significant nocturnal desaturation. The therapeutic consequences of these data, particularly in COPD are important: current evidence is insufficient to treat with nocturnal oxygen therapy COPD patients who have minimal diurnal hypoxemia but significant nocturnal desaturation.

Dehydroepiandrosterone sulfate (DHEAS): identification of a carrier protein in human liver and brain

Dehydroepiandrosterone sulfate (DHEAS) is the major circulating steroid in man. Pharmacologically, it exerts marked neuropsychiatric effects. Since no target receptor has been identified, we investigated whether the organic anion transporting polypeptide (OATP), a multispecific steroid carrier, transports DHEAS. Expression of the human liver OATP in Xenopus laevis oocytes resulted in high-affinity, partially Na+-dependent uptake of [3H]DHEAS (Km: 6.6 micromol/l). DHEAS transport was inhibited by bromosulfophthalein, bile acids, sulfated estrogens and dexamethasone. Northern blot analysis showed widespread expression of OATP in human brain. These data identify OATP as the first known target protein of DHEAS in human liver and brain.

[Cholestasis: therapeutic options]

Ursodeoxycholic acid (UDCA) has been shown to be both an effective and well-tolerated treatment of primary biliary cirrhosis, a model chronic cholestatic liver disease. Beneficial effects of UDCA have also been observed in other cholestatic disorders such as primary sclerosing cholangitis, cystic fibrosis, or intrahepatic cholestasis of pregnancy. Liver transplantation is the treatment of choice in end stage chronic cholestatic liver disease. Symptomatic therapeutic concepts include the treatment of cholestasis-associated problems such as pruritus, osteopathy and vitamin deficiency.

Five-year effects of nasal continuous positive airway pressure in obstructive sleep apnoea syndrome

There have been very few studies assessing the long-term physiological effects of nasal continuous positive airway pressure (CPAP) for the obstructive sleep apnoea syndrome. We therefore investigated prospectively the evolution of lung function, arterial blood gases and pulmonary haemodynamics in patients with this syndrome treated with CPAP. Sixty five patients were included. The mean duration of home treatment with nasal CPAP was 64+/-6 months. Most of the patients (77%) were smokers at the baseline assessment. We observed a small, but significant, decrease in forced expiratory volume in one second (FEV1) from 80+/-21% at baseline (t0) to 76+/-21% of the predicted value at the follow-up evaluation (t5) (p<0.01). Arterial oxygen tension (P[a,O2]) for the group as a whole remained stable (9.4+/-1.5 kPa (71+/-11 mmHg) versus 9.4+/-1.2 kPa (71+/-9 mmHg)). However, P(a,O2) increased in the subgroup of patients with hypoxaemia at t0 (n=23), from 7.8+/-0.7 kPa (59+/-5 mmHg) to 8.9+/-1.2 kPa (67+/-9 mmHg). Arterial carbon dioxide tension (P[a,CO2]) for the group as a whole increased slightly, but significantly, from 5.2+/-0.7 kPa (39+/-5 mmHg) to 5.4+/-0.5 kPa (41+/-4 mmHg) (p<0.05). Mean pulmonary artery pressure (Ppa) at rest did not change (16+/-5 mmHg versus 17+/-5 mmHg; NS) nor did exercising Ppa. In the 11 patients with pulmonary hypertension at t0, Ppa was 24+/-5 mmHg at t0 versus 20+/-7 mmHg at t5 (NS). We conclude that the significant decrease of forced expiratory volume in one second after 5 yr follow-up was related to a high percentage of smokers and exsmokers in the study population. Daytime arterial oxygen tension and pulmonary artery pressure remained stable in an unselected series of 65 obstructive sleep apnoea syndrome patients treated for 5 yrs with nasal continuous positive airway pressure, unlike arterial carbon dioxide tension, which increased by a small, but significant, amount.

[The status of urodynamic examination in urologic evaluation]

Urodynamics encompass a number of functional tests of the lower and occasionally the upper urinary tract. These tests comprise uroflowmetry, cystometry or measurement of bladder pression during bladder filling and voiding, urethral pressure profile, electromyography (EMG) of the external urethral sphincter, pressure-flow studies and video-urodynamics. Alone or in combination these examinations have become essential elements of urological clinical work-up, since they do not only allow to precisely classify a functional disorder but also to establish an adequate therapy. Urodynamics are nowadays standard in any urological department.

Chlorambucil-taurocholate is transported by bile acid carriers expressed in human hepatocellular carcinomas

BACKGROUND & AIMS

Chemotherapy of hepatocellular carcinomas is hampered by the insufficient accumulation of cytostatic drugs within the tumor cells. The aim of this study was to evaluate the feasibility of therapeutic strategies using antineoplastic agents coupled to bile acids.

METHODS

Expression of the Na(+)-taurocholate-cotransporting polypeptide (NTCP) was analyzed in six hepatocellular carcinomas and in nonmalignant liver tissue. Uptake of the cytostatic drug [3H]-chlorambucil-taurocholate (S2676) was measured in Xenopus laevis oocytes injected with total messenger RNA (mRNA) from the carcinomas or peritumor tissue or with complementary RNA encoding the NTCP or the organic anion-transporting polypeptide (OATP) of human liver.

RESULTS

Expression of hepatocellular carcinoma mRNA in oocytes resulted in mainly Na(+)-dependent uptake of chlorambucil-taurocholate. The level of NTCP mRNA in carcinomas amounted to 56% +/- 27% compared with peritumor tissue. Immunofluorescence studies confirmed the expression of NTCP on the surface of hepatocellular carcinoma cells. OATP expression, determined by immunoblotting, was similar in hepatocellular carcinomas and surrounding liver tissue (n = 3). NTCP mediated Na(+)-dependent uptake of chlorambucil-taurocholate (Michaelis constant, 11 mumol/L), whereas OATP mediated Na(+)-independent uptake.

CONCLUSIONS

Hepatocellular carcinomas express the Na(+)-dependent bile acid transporter NTCP. Because NTCP mediates high-affinity uptake of chlorambucil-taurocholate, targeting of cytostatic bile acids to hepatocellular carcinomas could become a feasible therapeutic strategy.

Clinical assessment of fluorescence cytoscopy during transurethral bladder resection in superficial bladder cancer

The prognosis of superficial bladder cancer in terms of recurrence and disease progression is related to bladder tumor multiplicity and the presence of concomitant "plane" tumors such as high-grade dysplasia and carcinoma in situ. This study in 33 patients aimed to demonstrate the role of fluorescence cystoscopy in transurethral resection of superficial bladder cancer. The method is based on the detection of protoporphyrin-IX-induced fluorescence in urothelial cancer cells by topical administration of 5-aminolevulinic acid. The sensitivity and the specificity of this procedure on apparently normal mucosa in superficial bladder cancer are estimated to be 82.9% and 81.3%, respectively. Thus, fluorescence cytoscopy is a simple and reliable method for mapping the bladder mucosa, especially in the case of multifocal bladder disease, and it facilitates the screening of occult dysplasia.

[Vaporization of urethral stenosis using the KTP 532 laser]

The authors treated 16 patients presenting with a total of 20 anterior urethral strictures using the KTP 16 Laser. The aetiology was iatrogenic in 50% of cases, infectious in 20% of cases, traumatic in 20% of cases and unknown in 10% of cases. The stricture was situated in the bulbous urethra (80%), membranous urethra (10%) or penil urethra (10%). Laser vaporization of the urethral stricture was performed over the entire circumference of the urethra when necessary, followed by bladder drainage by urethral catheter for 24 hours. All patients were prospectively reviewed at 3 weeks, 3 months and 6 months (clinical symptoms, uroflowmetry, cystourethrography). A complete symptom and urodynamic success was obtained in 13 patients (81%) at 3 and 6 months. The stricture recurred in 4 patients, but only three of them (19%) required treatment (reoperation of repeat dilatations). The mean maximum flow rate increased from 6 mL/s to 20 mL/s at 3 months and was maintained at 19 mL/s at 6 months. No intraoperative or postoperative complications were observed. In conclusion, our results confirm that KTP 532 laser urethral strictures is a reliable and effective method in the medium term. These good results also suggest an advantage in terms of the recurrence rate in comparison with internal urethrotomy. However, our series needs to be evaluated with a longer follow-up and prospective, randomized trials comparing the two methods need to be conducted.

Pulmonary hypertension in the obstructive sleep apnoea syndrome: prevalence, causes and therapeutic consequences

"Cor pulmonale" is a classic feature of the "Pickwickian syndrome". Earlier studies have reported a high prevalence of pulmonary hypertension (PH) in obstructive sleep apnoea (OSA) patients, but this has not been confirmed by recent studies with a more adequate methodology, including larger groups of patients. The first part of this review is devoted to the prevalence of PH in OSA; most recent studies agree on prevalence of 15-20%. The second (and major) part of the study deals with the causes and mechanisms of PH in OSA. Pulmonary hypertension is rarely observed in the absence of day-time hypoxaemia, and the severity of nocturnal events (apnoea index (AI), apnoea+ hypopnoea index (AHI) does not appear to be the determining factor of PH. Diurnal arterial blood gas disturbances and PH are most often explained by the presence of severe obesity (obesity-hypoventilation syndrome) and, principally, by association of OSA with chronic obstructive pulmonary disease (the so called "overlap syndrome"). Bronchial obstruction is generally of mild-to-moderate degree and may be asymptomatic. The final part of the review analyses the therapeutic consequences of the presence of PH in OSA patients. Pulmonary hypertension, which is generally mild-to-moderate, does not need a specific treatment. When nasal continuous positive airway pressure (CPAP) fails to correct sleep-related hypoxaemia, supplementary oxygen must be administered. In patients with marked daytime hypoxaemia (arterial oxygen tension (Pa,O2), < or = 7.3 kPa (55 mmHg) conventional O2 therapy (nocturnal + diurnal) is required.

Pulmonary hemodynamics in the obstructive sleep apnea syndrome. Results in 220 consecutive patients

We have investigated pulmonary hemodynamics in a large series of consecutive, unselected patients with obstructive sleep apnea syndrome (OSAS). The aims of this study were to evaluate the frequency of pulmonary artery hypertension (PH) in OSAS and to analyze, as far as possible, its mechanisms. Two hundred twenty patients were included on the basis of a polysomnographic diagnosis of OSAS (apnea+hypopnea index > 20). PH, defined by a resting mean pulmonary artery mean pressure (PAP) of at least 20 mm Hg, was observed in 37 of 220 patients (17%). Patients with PH differed from the others with regard to pulmonary volumes (vital capacity [VC], FEV1) and the FEV1/VC ratio that were significantly lower (p < 0.001); PaO2 (64.4 +/- 9.3 vs 74.7 +/- 10.1 mm Hg; p < 0.001); PaCO2 (43.8 +/- 5.4 vs 37.6 +/- 3.9 mm Hg; p < 0.001), apnea+hypopnea index (100 +/- 33 vs 74 +/- 32; p < 0.001), and mean nocturnal arterial oxygen saturation (SaO2) (88 +/- 6% vs 94 +/- 2%; p < 0.001). Patients with PH were also more overweight (p < 0.001). Multiple regression analysis showed that 50% of the variance of PAP could be predicted by an equation including PaCO2 (accounting for 32% of the variance), FEV1 (12%), airway resistance (4%), and mean nocturnal SaO2 (2%). In conclusion, PH is observed, in agreement with previous studies, in less than 20% of OSAS patients. PH is strongly linked to the presence of an obstructive (rather than restrictive) ventilatory pattern, hypoxemia, and hypercapnia, and is generally accounted for by an associated obstructive airways disease. In this regard, the severity of OSAS plays only a minor role.

Association of HLA class I antigen deficiency related to a TAP2 gene mutation with familial bronchiectasis

Two siblings with pansinusitis, nasal polyps, and bronchiectasis were found to have histocompatibility lymphocyte antigen (HLA) class I antigen deficiency ("bare lymphocyte syndrome") and dysfunction of natural killer cells. Reduced class I cell surface expression resulted from a single mutation in the TAP2 gene, which is located in the class II region of the major histocompatibility complex and encodes subunit 2 of the class I peptide transporter. The defect was transmitted in an autosomal recessive manner. This deficiency did not lead to severe viral infections but was apparently associated with susceptibility to bacterial infections of the respiratory mucosae. We suggest that class I HLA typing should be systematically performed in children with unexplained bronchiectasis.

[Possibilities of surgical therapy in prostatic carcinoma]

Radical surgical treatment of localized prostate cancer is performed to heal the patient of his malignant disease. Surgery for advanced prostate cancer, e.g. transurethral resection for obstruction or hemorrhage, is always a palliative modality and has to be seen in the context of systemic treatment. Radical prostatectomy is a major intervention which allows complete removal of the prostate gland and the seminal vesicles at the same time. Due to resection at the distal end of the prostatic urethra, the bladder sphincter system is partially destroyed. In general, to guarantee radicality, the erectile nerves and vessels are sectioned, resulting in erectile impotency. Preservation of these structures to maintain potency is indicated only exceptionally. Radical prostatectomy is today a routine operation with minimal mortality (0.5-1%) and minor complication rate. Average hospitalization is about 10 days. Long-term postoperative morbidity is characterized by urinary incontinence and erectile impotency. Incontinence takes a long time to heal. A certain number of patients will keep a generally not very bothersome stress dribbling; however, some may show complete leakage, necessitating an anti-incontinence operation. For an indication of radical prostatectomy, two essential factors have to be considered: the usually extremely slow growth of prostate cancer and the high prevalence of clinically insignificant latent carcinomas. It is for these reasons and for the consequences on live quality that radical prostatectomy should not be performed on patients with a life expectancy of less than 10 years.