[Osteonecrosis of the jaws and bisphosphonates]

Widely prescribed, bisphosphonates inhibit bone resorption. They are not metabolised and have long half-lives. Two cases of osteonecrosis of the jaws have recently been attributed to bisphosphonates at the University Hospital of Geneva. The recent literature reveals more than a hundred similar cases throughout the world. Bone exposure appears spontaneously or after dental care. Treatment of the osteonecrosis is controversial and cure very difficult. This pathology is usually seen in patients on chemotherapy, steroids and i.v. bisphosphonates, but is sometimes seen with low-dose p.o. bisphosphonates. In view of the strong association between bisphosphonate therapy and osteonecrosis of the jaw, specialists have recommended dental and oral evaluation during bisphosphonate therapy as well as for several years after drug discontinuation.

[Early detection in prostate cancer and shared decision making]

Screening of prostate cancer with PSA is a challenge for the aid to decision. Beside the rather mediocre characteristics of the screening test, there the additional problem of the peculiar biology of this cancer, with its late development and its ability to remain latent for a prolonged period. On the other hand, the treatment (surgery, irradiation) is associated with important side-effects: impotence and urinary leakage. Several studies, which appear to be a form of aid to information than aid to shared decision, have been carried out to analyse the effect of various modes of information on the behaviour of potential candidates to screening of prostate cancer, with the following results: better knowledge of the problem, lower rate of acceptance of PSA testing and trend towards watchful waiting rather than surgery in case of discovery of cancer.

[The PROVE IT-TIMI-22 study or the biter being bit]

The importance of statins in secondary prevention is well established since the 4S, CARE and LIPID studies, their indications being now applied to even normocholesterolemic patients. To date, it is still unclear which statin to choose, and at what dose. A recent study entitled "PROVE IT-TIMI-22" has compared 80 mg of atorvastatin/day to 40 mg of pravastatin/day in early secondary prevention. It appears that the intensive treatment with atorvastatin has been more effective on the LDL-cholesterol levels and has had a more favourable effect on the clinical evolution based on a composite score. We herein propose a critical review of this study and recommend a somewhat cautious attitude before giving high doses of atorvastatin in the secondary prevention of all the patients with coronary heart disease.

[Application of evidence based medicine to the individual patient: the role of decision analysis]

INTRODUCTION

The objective of evidence based medicine (EBM) is to contribute to medical decision making by providing the best possible information in terms of validity and relevance. This allows evaluation in a specific manner of the benefits and risks of a decision.

METHODS

The limitations and hazards of this approach are discussed in relation to a clinical case where the diagnosis of pulmonary embolism was under consideration. The individual details and the limited availability of some technical procedures illustrate the need to adapt the data of EBM to the circumstances. The choice between two diagnostic tests (d-dimers and ultrasound of the legs) and their optimal timing is analysed with integration of the consequences for the patient of the treatments proposed. This allows discussion of the concept of utility and the use of sensitivity analysis.

CONCLUSIONS

If EBM is the cornerstone of rational and explicit practise it should also allow for the constraints of real life. Decision analysis, which depends on the same critical demands as EBM but can also take account of the individual features of each patient and test the robustness of a decision, gives a unique opportunity reconcile rigorous reasoning with individualisation of management.

Prospective evaluation of patients with syncope: a population-based study

PURPOSE

To determine the diagnostic yield of a standardized sequential evaluation of patients with syncope in a primary care teaching hospital.

PATIENTS AND METHODS

All consecutive patients who presented to the emergency department with syncope as a chief complaint were enrolled. Their evaluation included initial and routine clinical examination, including carotid sinus massage, as well as electrocardiography and basic laboratory testing. Targeted tests, such as echocardiography, were used when a specific entity was suspected clinically. Other cardiovascular tests (24-hour Holter monitoring, ambulatory loop recorder ECG, upright tilt test, and signal-averaged electrocardiography) were performed in patients with unexplained syncope after the initial steps. Electrophysiologic studies were performed in selected patients only as clinically appropriate. Follow-up information on recurrence and mortality were obtained every 6 months for as long as 18 months for 94% (n = 611) of the patients.

RESULTS

After the initial clinical evaluation, a suspected cause of syncope was found in 69% (n = 446) of the 650 patients, including neurocardiogenic syncope (n = 234, 36%), orthostatic hypotension (n = 156, 24%), arrhythmia (n = 24, 4%), and other diseases (n = 32, 5%). Of the 67 patients who underwent targeted tests, suspected diagnoses were confirmed in 49 (73%) patients: aortic stenosis (n = 8, 1%), pulmonary embolism (n = 8, 1%), seizures/stroke (n = 30, 5%), and other diseases (n = 3). Extensive cardiovascular workups, which were performed in 122 of the 155 patients in whom syncope remained unexplained after clinical assessment, provided a suspected cause of syncope in only 30 (25%) patients, including arrhythmias in 18 (60%), all of whom had abnormal baseline ECGs. The 18-month mortality was 9% (n = 55, including 8 patients with sudden death); syncope recurred in 15% (n = 95) of the patients.

CONCLUSION

The diagnostic yield of a standardized clinical evaluation of syncope was 76%, greater than reported previously in unselected patients. Electrocardiogram-based risk stratification was useful in guiding the use of specialized cardiovascular tests.

Assessing clinical probability of pulmonary embolism in the emergency ward: a simple score

OBJECTIVE

To develop a simple standardized clinical score to stratify emergency ward patients with clinically suspected pulmonary embolism (PE) into groups with a high, intermediate, or low probability of PE to improve and simplify the diagnostic approach.

METHODS

Analysis of a database of 1090 consecutive patients admitted to the emergency ward for suspected PE in whom diagnosis of PE was ruled in or out by a standard diagnostic algorithm. Logistic regression was used to predict clinical parameters associated with PE.

RESULTS

A total of 296 (27%) of 1090 patients were found to have PE. The optimal estimate of clinical probability was based on 8 variables: recent surgery, previous thromboembolic event, older age, hypocapnia, hypoxemia, tachycardia, band atelectasis, or elevation of a hemidiaphragm on chest x-ray film. A probability score was calculated by adding points assigned to these variables. A cutoff score of 4 best identified patients with low probability of PE. A total of 486 patients (49%) had a low clinical probability of PE (score </=4), of which 50 (10.3%) had a proven PE. The prevalence of PE was 38% in the 437 patients with an intermediate probability (score of 5-8; n = 437) and 81% in the 63 patients with a high probability (score >/=9).

CONCLUSIONS

This clinical score, based on easily available and objective variables, provides a standardized assessment of the clinical probability of PE. Applying this score to emergency ward patients suspected of having PE could allow a more effective diagnostic process.

Predicting adverse outcome in patients with acute pulmonary embolism: a risk score

Reliable prediction of adverse outcomes in acute pulmonary embolism may help choose between in-hospital and ambulatory treatment. We aimed to identify predictors of adverse events in patients with pulmonary embolism and to generate a simple risk score for use in clinical settings. We prospectively followed 296 consecutive patients with pulmonary embolism admitted through the emergency ward. Logistic regression was used to predict death, recurrent thromboembolic event, or major bleeding at 3 months. Thirty patients (10.1%) had one or more adverse events during the 3-month follow-up period: 25 patients (8.4%) died, thromboembolic events recurred in 10 patients (3.4%), and major bleeding occurred in 5 patients (1.7%). Factors associated with an adverse outcome in multivariate analysis were cancer, heart failure, previous deep vein thrombosis, systolic blood pressure <100 mmHg, arterial PaO2 <8 kPa, and presence of deep vein thrombosis on ultrasound. A risk score was calculated by adding 2 points for cancer and hypotension, and 1 point each for the other predictors. A score of 2 best identified patients at risk of an adverse outcome in a receiver operating characteristic curve analysis. Of 180 low-risk patients (67.2%) (score < or =2), only 4 experienced an adverse outcome (2.2%), compared to 23 (26.1%) of 88 high-risk patients (score > or =3). A simple risk score based on easily available variables can accurately identify patients with pulmonary embolism at low risk of an adverse outcome. Such a score may be useful for selecting patients with pulmonary embolism eligible for outpatient care.

[Evidence-based medicine: an approach without any weakness?]

Evidence-based medicine is a methodological approach giving access to the best information derived from clinical research for an individual patient. It requires the formulation of a question, a strategy to search for the best information, the selection of the latter, its critical appraisal and its application to the patient. The qualities, but also the limitations of this approach are discussed.

Reactive oxygen metabolites increase mitochondrial calcium in endothelial cells: implication of the Ca2+/Na+ exchanger

In endothelial cells, a bolus of hydrogen peroxide (H2O2) or oxygen metabolites generated by hypoxanthine-xanthine oxidase (HX-XO) increased the mitochondrial calcium concentration [Ca2+]m. Both agents caused a biphasic increase in [Ca2+]m which was preceded by a rise in cytosolic free calcium concentration [Ca2+]c (18 and 6 seconds for H2O2 and HX-XO, respectively). The peak and plateau elevations of [Ca2+] were consistently higher in the mitochondrial matrix than in the cytosol. In Ca2+-free/EGTA medium, the plateau phase of elevated [Ca2+] evoked by H2O2 due to capacitative Ca2+ influx was abolished in the cytosol, but was maintained in the mitochondria. In contrast to H2O2 and HX-XO, ATP which binds the P2Y purinoceptors induced an increase in [Ca2+]m that was similar to that of [Ca2+]c. When cells were first stimulated with inositol 1,4, 5-trisphosphate-generating agonists or the Ca2+-ATPase inhibitor cyclopiazonic acid (CPA), subsequent addition of H2O2 did not affect [Ca2+]c, but still caused an elevation of [Ca2+]m. Moreover, the specific inhibitor of the mitochondrial Ca2+/Na+ exchanger, 7-chloro-3,5-dihydro-5-phenyl-1H-4.1-benzothiazepine-2-on (CGP37157), did not potentiate the effects of H2O2 and HX-XO on [Ca2+]m, while causing a marked increase in the peak [Ca2+]m and a significant attenuation of the rate of [Ca2+]m efflux upon addition of histamine or CPA. In permeabilized cells, H2O2 mimicked the effects of CGP37157 causing an increase in the basal level of matrix free Ca2+ and decreased efflux. Dissipation of the electrochemical proton gradient by carbonylcyanide p-(trifluoromethoxy) phenylhydrazone (FCCP), and blocade of the Ca2+ uptake by ruthenium red prevented [Ca2+]m increases evoked by H2O2. These results demonstrate that the H2O2-induced elevation in [Ca2+]m results from a transfer of Ca2+ secondary to increased [Ca2+]c, and an inhibition of the Ca2+/Na+ electroneutral exchanger of the mitochondria.

Should there be systematic screening of coronary heart disease in asymptomatic patients with risk factors alone? A decision analysis approach

The problem of choosing between detection of asymptomatic coronary heart disease (CHD) in patients at risk and primary prevention was assessed in a decision analysis model. Most of the relevant data were derived from the WOSCOP study, which evaluated the effects of statins in asymptomatic hypercholesterolaemic subjects. This study is considered to be a model of primary prevention measurement. Over a 5-year period, 10% of control subjects had events related to CHD, with a 20% mortality rate which was reduced by 33% under statin administration. A decision tree was used to compare these two sets of data (controls and treated patients) with those of a third option in which an exercise test, 201Tl scintigraphy and, in certain cases, coronary arteriography were used to detect and treat CHD at an asymptomatic stage. The test characteristics and outcomes correspond as closely as possible to previously reported data, concerning what can be expected in this particular situation. Over a wide range of CHD probabilities, screening appeared to be better than primary prevention. This result is robust since it was not modified by sensitivity analysis for most of the data. A sharp decrease in the sensitivity of the first two tests and a marked increase in the effectiveness of primary prevention would alter the decision in favour of primary prevention, whereas an increased death rate from CHD and higher CHD probability would favour the utility of screening. As the cost-effectiveness of screening compares favourably with that of primary prevention, it may be useful to assess the validity of this model in a prospective controlled study.

Hydrogen peroxide-induced DNA damage is independent of nuclear calcium but dependent on redox-active ions

In cells undergoing oxidative stress, DNA damage may result from attack by .OH radicals produced by the Fenton reaction, and/or by nucleases activated by nuclear calcium. In the present study, the participation of these two mechanisms was investigated in HeLa cells. Nuclear-targeted aequorin was used for selectively monitoring Ca2+ concentrations within the nuclei ([Ca2+]n), in conjunction with the cell-permeant calcium chelator bis-(o-aminophenoxy)ethane-N,N,N', N'-tetraacetic acid acetoxymethyl ester (BAPTA/AM), the lipid-soluble broad-spectrum metal chelator with low affinity for Ca2+ and Mg2+ N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), and the high-affinity iron/copper chelator 1, 10-phenanthroline (PHE). In Ca2+-containing medium, H2O2 induced extensive DNA strand breaks and an increase in [Ca2+]n that was almost identical to that observed in the cytosol ([Ca2+]c). In cells bathed in Ca2+-free/EGTA medium, in which the increases in [Ca2+]n and [Ca2+]c due to H2O2 were significantly reduced, similar levels of DNA fragmentation also occurred. In cells preloaded with BAPTA/AM or TPEN, the small increase of [Ca2+]n normally elicited by H2O2 in Ca2+-free medium was completely buffered, and DNA damage was largely prevented. On the other hand, pretreatment with PHE did not affect the calcium response in the nuclei, but completely prevented DNA strand breakage induced by H2O2. Re-addition of 100 microM CuSO4 and 100 microM FeSO4 to TPEN- and PHE-treated cells prior to H2O2 challenge reversed the effect of TPEN and PHE, whereas 1 mM was necessary to negate the effect of BAPTA/AM. The levels of DNA strand breakage observed, however, did not correlate with the amounts of 8-hydroxy 2'-deoxyguanosine (8-OHdG): H2O2 did not produce 8-OHdG, whereas PHE alone slightly increased 8-OHdG levels. CuSO4 and FeSO4 enhanced the effects of PHE, particularly in the presence of H2O2. Exposure of cells to a mixture of CuSO4/FeSO4 also resulted in a significant increase in 8-OHdG levels, which was prevented in cells preloaded with BAPTA/AM. Similar results were obtained in a cell-free system using isolated calf thymus DNA exposed to CuSO4/FeSO4, regardless of whether H2O2 was present or not. These results suggest that BAPTA/AM prevents H2O2-induced DNA damage by acting as an iron/copper chelator. These data also indicate that caution must be exercised in using Ca2+ chelating agents as evidence for a role in cellular Ca2+ levels in experimental conditions in which transition-metal-ion-mediated oxidant production is also occurring.

Predictors of inappropriate hospital days in a department of internal medicine

BACKGROUND

This study aimed to identify predictors of inappropriate hospital days in a department of internal medicine, as a basis for quality improvement interventions.

METHODS

The appropriateness of 5665 hospital days contributed by 500 patients admitted to the Department of Internal Medicine, Geneva University Hospitals, Switzerland, was assessed by means of the Appropriateness Evaluation Protocol. Predictor variables included patient's age and sex, manner of admission and discharge, and characteristics of hospital days (weekend, holiday, sequence).

RESULTS

Overall, 15% of hospital admissions and 28% of hospital days were rated as inappropriate. In multivariate models, inappropriate hospital days were more frequent among patients whose admission was inappropriate (odds ratio [OR] = 5.3, 95% CI: 3.1-8.4) and among older patients (80-95 years: OR = 3.6, 95% CI: 1.7-7.0, versus <50 years). The likelihood of inappropriateness also increased with each subsequent hospital day, culminating on the day of discharge, regardless of the total length of stay.

CONCLUSIONS

This study identified both the admission and the discharge processes as important sources of inappropriate hospital use in a department of internal medicine. The oldest patients were also at high risk of remaining in the hospital inappropriately. Surprisingly, long hospital stays did not generate a higher proportion of inappropriate days than short hospital stays. This information proved useful in developing interventions to improve the hospitalization process.

Preventing stroke recurrence in patients with patent foramen ovale: antithrombotic therapy, foramen closure, or therapeutic abstention? A decision analytic perspective

Emphasis on the role of patent foramen ovale as a potential risk factor for ischemic paradoxical stroke has recently increased. Current therapeutic options for secondary stroke prevention include long-term antithrombotic therapies and invasive closure of the defect, but selective indications have not been evaluated. Therefore we developed a Markov-based decision analysis model for a hypothetical cohort of patients 55 years of age with presumed paradoxical embolism, measuring for each therapy the risks of stroke recurrence, treatment-related complications, and death after 5 years and the quality-adjusted life-years. Over a wide range of stroke risk recurrence (0.8% per year to 7% per year), the gain provided by closure of the defect exceeded the one obtained by other therapeutic options. When the risk exceeded 0.8% per year and 1.4% per year, respectively, this was also verified for anticoagulation and antiplatelet therapies compared with therapeutic abstention. Therapeutic abstention was the preferred strategy under 0.8% per year. Sensitivity analyses identified key parameters influencing the choice of therapy. These included estimates of stroke recurrence, bleeding rates, surgery-related case fatality rates, and age. Considering the risks of treatment and the devastating consequences of a recurrent stroke, our model suggests that if the estimated risk of paradoxical stroke recurrence is > 0.8% per year, therapeutic abstention becomes the worst option. Above this threshold secondary stroke prevention with anticoagulation therapy or surgical closure of the defect is the preferred strategy, and assessment of both the risk of stroke recurrence and the risk related to therapeutic options should guide individual therapeutic decision making.

Modulation of the DNA binding activity of transcription factors CREP, NFkappaB and HSF by H2O2 and TNF alpha. Differences between in vivo and in vitro effects

Human endothelial cells exposed to H2O2 showed reduced CREP DNA binding activity, enhanced HSF activation, and no induction of NFkappaB binding activity. Interestingly, H2O2 was able to induce NFkappaB subunit p65 translocation in the nucleus. In contrast, cells exposed to TNF alpha showed enhanced CREP binding activity, activation of NFkappaB and no induction of HSE-HSF complex. Addition of H2O2, diamide and iodoacetic acid to the binding reaction mixture markedly reduced the DNA binding ability of the three transcription factors. Thus free sulfhydryls were important in DNA binding activity of CREP, NFkappaB and HSF, and the lack of induction of NFkappaB by H2O2 in intact cells was likely caused by oxidation on a thiol, and not by a deficiency in the activation pathway.

Hyperoxia, unlike phorbol ester, induces glutathione peroxidase through a protein kinase C-independent mechanism

Human selenium-dependent glutathione peroxidase (GP) is implicated as a mechanism of resistance against oxygen free radicals. The 5' flanking sequence upstream from the coding region of GP contained an oxygen-responsive element termed ORE1 that is responsive to hypoxia, as well as several copies of the activator protein-1 (AP-1)- and AP-1-like-binding sites. In this study, we sought to define the molecular events that lead to GP gene transcription in response to hyperoxia in human umbilical-vein endothelial cells, and asked whether such induction is mimicked and sustained by activation of protein kinase C (PKC) by phorbol esters. Treatment of cells with 100 nM phorbol 12,13-dibutyrate (PdBu) induced a delayed (24-48 h) but significant (2-fold) increase in steady-state GP mRNA levels. Steady-state GP mRNA levels also rose after exposure to 95% O2, again after considerable delay (48-72 h). For both PdBu and oxygen, induction was transcriptionally regulated, as demonstrated by nuclear run-on experiments. The simulations by PdBu and oxygen were additive. In contrast with PdBu, hyperoxia did not stimulate translocation of PKC from the cytosol to the particulate fraction, although the specific activity of both cytosolic and particulate-associated PKC was increased 2-fold in cells exposed to 95% O2 for 5 days. In addition, gel mobility-shift assays using double-stranded tumour-promoting-agent-responsive element (TRE) and nuclear extracts derived from phorbol- and oxygen-treated cells revealed that PdBu, but not hyperoxia, increased AP-1 DNA-binding activity. On the other hand, the up-regulation of GP expression by oxygen could not be accounted for by the ORE1 core sequence, since no specific protein-DNA binding activity could be detected using nuclear extracts from hyperoxic cells and ORE1. Taken together, these results suggest that there may be different molecular mechanisms controlling GP expression. After exposure to PdBu, GP undergoes transcriptional activation via a process that can be readily explained by a classic AP-1 interaction with the TRE sites in the GP promoter. During hyperoxia, GP also undergoes transcriptional activity, but via a process that appears to involve neither TRE nor ORE1.

Risk factors for a medically inappropriate admission to a Department of Internal Medicine

OBJECTIVE

To identify patient- and admission-related risk factors for a medically inappropriate admission to a department of internal medicine.

METHODS

Cross-sectional study of a systematic sample of 500 admissions to the department of internal medicine of an urban teaching hospital. The appropriateness of each admission and reasons for inappropriate admissions were assessed using the Appropriateness Evaluation Protocol. Risk factors included the time (day of week and holidays) and manner (through emergency department or direct admission) of admission, patient age and sex, health status of patient and spouse, living arrangements, formal home care services, and informal support from family or friends.

RESULTS

Overall, 76 (15.2%) hospital admissions were rated as medically inappropriate by the Appropriateness Evaluation Protocol. In multivariate analysis, the likelihood of an inappropriate admission was increased by better physical functioning of the patient (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.1-2.1 [for 1 SD in Physical Functioning scores]), lower mental health status of the patient's spouse (OR, 2.6; 95% CI, 1.3-5.6), receipt of informal help from family or friends (OR, 3.3; 95% CI, 1.5-7.2), and hospitalization by one's physician (OR, 3.6; 95% CI, 1.7-7.5). Receiving formal adult home care was not associated with inappropriateness of hospitalization.

CONCLUSIONS

Inappropriate admissions to internal medicine wards are determined by a mix of factors, including the patient's health and social environment. In addition, the private practitioners' discretionary ability to hospitalize their patients directly may also favor medically inappropriate admissions.

Detecting acute thoracic aortic dissection in the emergency department: time constraints and choice of the optimal diagnostic test

STUDY OBJECTIVES

To compare diagnostic strategies for the emergency assessment of patients with suspected acute thoracic aortic dissection and to measure the effect of delays related to the availability of these tests on the selection of the most appropriate one.

METHODS

We carried out a decision analysis representing the risks of performing one or two sequential tests, the tests' accuracy, the risks and benefits of treatment, and the time-dependent mortality rate in untreated patients with dissection (1%/hour). Data were drawn from a Medline search. Our subjects were patients who presented to the emergency department with chest pain in whom acute thoracic aortic dissection was suspected. For different clinical probabilities of aortic dissection, we compared the risks and benefits of testing using the following procedures (alone and in combinations): aortography, computed tomography (CT), magnetic resonance imaging (MRI), and both transesophageal (TEE) and transthoracic echocardiography (TTE). We then measured the effect of delays in these tests on the selection of the appropriate procedure. The outcome studied was 30-day survival.

RESULTS

We determined that the "threshold" clinical probability of aortic dissection above which the benefits of testing outweigh its risks is low. It ranges from 2% with the most reliable procedure (MRI) to 9% with the least (TTE). At low probability of dissection (< 15%), the accuracy of all tests except TTE is sufficient to rule out dissection. Delays have negligible effect on these results. When the likelihood of dissection is higher, the preferred option is to order a second diagnostic test if the results of the first are negative. The threshold probabilities above which to order a second test range from 15% (CT, then aortography) to 35% (MRI, then aortography). Excessive delays may affect the selection of tests when the likelihood of dissection is high (eg, 50%). Thus, although it is less accurate, a CT scan obtained within 2 hours or a TEE obtained within 6 hours of presentation to the ED yields a higher survival rate than an MRI obtained within 9 hours. Similarly, the benefits of ordering a second test, if the result of the first are negative, outweigh the risks only if the delay in obtaining the test does not exceed 10 hours.

CONCLUSION

All patients in whom aortic dissection is suspected, even if the index of suspicion is very low, should undergo one of the available diagnostic procedures (except TTE). A patient with a moderate to high probability of disease should undergo a second investigation if the findings of the first are negative. When the probability of dissection is high, the physician must consider delays in obtaining specific diagnostic tests and order those that will be the most quickly available.

Role of oxygen free radicals in cancer development

In aerobic life, oxidative stress arises from both endogenous and exogenous sources. Despite antioxidant defence mechanisms, cell damage from oxygen free radicals (OFR) is ubiquitous. OFR-related lesions that do not cause cell death can stimulate the development of cancer. This review discusses the effects of oxidative stress at the different stages of carcinogenesis. Mutagenesis through oxidative DNA damage is widely hypothesised to be a frequent event in the normal human cell. A large body of evidence suggests important roles of OFR in the expansion of tumour clones and the acquisition of malignant properties. In view of these facts, OFR may be considered as an important class of carcinogens. Therefore, the ineffectiveness of preventive antioxidant treatments, as documented in several recent clinical trials, is surprising. However, the difficulties of antioxidant intervention are explained by the complexity of both free radical chemistry and cancer development. Thus, reducing the avoidable endogenous and exogenous causes of oxidative stress is, for the present, the safest option. In the near future, new insights in the action of tumour suppressor genes and the DNA repair mechanisms may lead the way to additional tools against carcinogenesis from OFR.

Effects of oxidative stress and Ca2+ agonists on molecular chaperones in human umbilical vein endothelial cells

Endothelial cell dysfunction is a key factor in oxidative stress-related pathology. Disruption of Ca2+ homeostasis is thought to be responsible for much of the endothelial cell dysfunction in oxidative stress. The expression of molecular chaperones (MC), which stabilize protein structures in normal and in stress conditions, reflects the Ca(2+)-dependent and -independent stress effects in the different cell compartments. By two-dimensional (2-D) gel electrophoresis combined with immunoblotting or microsequencing, we have identified 12 major MC in human umbilical vein endothelial cells (HUVEC): (i) the endoplasmic reticulum-located MC GRP78, GRP94, protein disulfide isomerase, and calreticulin; (ii) the mitochondrial MC HSP65 and GRP75; and (iii) the cytosolic/nuclear MC HSP27, HSC70, HSP70, HSP90, cyclophilin, and ubiquitin. To differentiate oxidative stress- and Ca(2+)-mediated effects, HUVEC were exposed to 1) xanthine oxidase plus hypoxanthine to generate oxidative stress, 2) ionomycin plus ethylene glycol-bis(beta-aminoethylether)-N,N,N', N'-tetraacetic acid (EGTA) to deplete intracellular Ca2+ stores, or 3) thrombin to increase cytosolic Ca2+. De novo protein synthesis after exposure was quantified by the incorporation of [35S]methionine. Image processing with the MELANIE system was used to create and compare the 2-D maps of [35S]methionine-labeled proteins under conditions 1)-3) with those of the controls. In a total of 24 2-D gels, 9 different MC were detected in at least 5 out 6 experimental replicates and were subjected to numeric analysis. The statistics showed a > 10% increase in GRP78 (p < 0.05), HSP27, cyclophilin, and ubiquitin after oxidative stress.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential regulation of glutathione peroxidase by selenomethionine and hyperoxia in endothelial cells

We have studied the effect of selenomethionine (SeMet) and hyperoxia on the expression of glutathione peroxidase (GP) in human umbilical vein endothelial cells. Incubation of HUVEC with 1 x 10(-6) M SeMet for 24 h and 48 h caused a 65% and 86% increase in GP activity respectively. The same treatment did not result in significant changes in GP gene transcription and mRNA levels. Pactamycin, a specific inhibitor of the initiation step of translation, prevented the rise in GP activity induced by SeMet and caused an increase in GP mRNA in both cells grown in normal and SeMet-supplemented medium. Interestingly, SeMet supplementation stimulated the recruitment of GP mRNA from an untranslatable pool on to polyribosomes, so that the concentration of GP mRNA in polyribosomal translatable pools was 50% higher in cells grown in SeMet-supplemented medium than in cells grown in normal medium. On the other hand, cells exposed to 95% O2 for 3 days in normal medium showed a 60%, 394% and 81% increase in GP gene transcription rate, mRNA levels and activity respectively. Hyperoxia also stabilized GP mRNA. Hyperoxic cells grown in SeMet-supplemented medium did not show any change in GP gene transcription and mRNA levels, but expressed an 81% and 100% increase in GP activity and amount of GP mRNA associated with polyribosomes respectively, when compared with hyperoxic cells maintained in normal medium. Thus, GP appeared to be regulated post-transcriptionally, most probably co-translationally, in response to selenium availability, and transcriptionally and post-transcriptionally in response to oxygen.

Effects of hypoxanthine-xanthine oxidase on Ca2+ stores and protein synthesis in human endothelial cells

We have investigated the effects of reactive O2 metabolites generated by the hypoxanthine-xanthine oxidase (HX-XO) system on intracellular Ca2+ and its relation with protein synthesis in human umbilical vein endothelial cells (HUVECs). Spectrofluorometry with fura 2 showed that the oxidative stress induced a rapid transient rise in cytosolic [Ca2+], followed by a sustained elevation above the baseline value. In the presence of La3+, which blocks Ca2+ influx from the extracellular medium, a transient [Ca2+] increase was still observed, but the sustained rise was suppressed. The HX-XO-related [Ca2+] changes were completely prevented by pretreatment with thapsigargin, which depletes intracellular Ca2+ stores. Hence, the effects of HX-XO on Ca2+ homeostasis were due to mobilization of Ca2+ from the intracellular stores with subsequent influx of extracellular Ca2+. HX-XO mobilized more of sequestered Ca2+ than did thrombin, a receptor agonist that depletes only a part of the intracellular Ca2+ stores (the hormone-sensitive stores). To determine the relevance of the HX-XO-related depletion of Ca2+ stores for cell function, we investigated the role of Ca2+ mobilization in the regulation of protein synthesis. Overall protein synthesis in HUVECs was markedly reduced by thapsigargin, which depletes both hormone-sensitive and -insensitive stores, but was not substantially affected by thrombin. Manipulation of the refilling of the Ca2+ stores via the availability of extracellular Ca2+ significantly influenced the thapsigargin-related and the HX-XO-related inhibition of overall protein synthesis. A corresponding effect of extracellular [Ca2+] was seen in polyribosome distribution profiles, which reflected an inhibition of translation initiation in both treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of superoxide, hydrogen peroxide, and hydroxyl radical on intracellular calcium in human endothelial cells

Changes in intracellular Ca2+ homeostasis are thought to contribute to cell dysfunction in oxidative stress. The hypoxanthine-xanthine oxidase system (X-XO) mobilizes Ca2+ from intracellular stores and induces a marked rise in cytosolic calcium in different cell types. To identify the reactive O2 species involved in the disruption of calcium homeostasis by X-XO, we studied the effect of X-XO on [Ca2+]i by spectrofluorimetry with fura-2 in human umbilical vein endothelial cells (HUVEC). The [Ca2+]i response to X-XO was essentially diminished by superoxide dismutase (SOD) (200 U/ml) and catalase (CAT) (200 U/ml), which scavenge the superoxide anion, O2-, or H2O2, respectively. The [Ca2+]i increase stimulated by 10 nmol H2O2/ml/min, generated from the glucose-glucose oxidase system, or 10 microM H2O2, given as bolus, was about a third of that induced by X-XO (10 nmol O2-/ml/min) but was comparable to that induced by X-XO in the presence of SOD. The X-XO-stimulated [Ca2+]i increase was significantly reduced by 100 microM o-phenanthroline, which inhibits the iron-catalysed formation of the hydroxyl radical. On the other hand, the [Ca2+]i response to low dose X-XO (1 nmol O2-/ml/min) was markedly enhanced in the presence of 1 microM H2O2, which itself had no effect on [Ca2+]i. More than 50% of this synergistic effect was prevented by o-phenanthroline. These results indicate that the effect of X-XO on calcium homeostasis appears to result from an interaction of O2- and H2O2, which could be explained by the formation of the hydroxyl radical.

Applicability of decision analysis to everyday clinical practice: a controlled feasibility trial

OBJECTIVE

To determine whether decision analysis is applicable to routine management of suspected pulmonary embolism in an emergency care setting.

DESIGN

Controlled feasibility trial.

SETTING

Emergency center of a university hospital.

PATIENTS

Outpatients (n = 84) admitted with clinical and scintigraphic evidence of pulmonary embolism.

INTERVENTIONS

Patients were treated either with the usual clinical work-up for pulmonary embolism (control group) or using a decision analysis model with three options: no action: angiography followed by treatment if positive; treatment without angiography.

RESULTS

All six senior residents in the decision analysis group agreed to fully participate for the 16 months of the study. Summarizing the decision analysis model in a graph was critical to obtain acceptance from all the physicians. Decision analysis (n = 43) and control (n = 41) patients underwent similar numbers of angiographies. However, angiographies for patients who had intermediate clinical probabilities of pulmonary embolism, between 25 and 75%, were more frequent in the decision analysis group (9/13 = 69%) than in the control group (7/20 = 35%). Agreement between clinical probability and lung-scan result was stronger in the decision analysis group.

CONCLUSIONS

Decision analysis was successfully used to manage all patients suspected of having pulmonary embolism admitted to an emergency center during the 16-month trial. There was no insuperable obstacle to acceptance of clinical decision analysis by the physicians. Decision analysis may have resulted in a better discrimination between low and intermediate clinical probabilities of pulmonary embolism.

Effects of inhibition of catalase and superoxide dismutase activity on antioxidant enzyme mRNA levels

We examined the effects of inhibition of Cu,Zn superoxide dismutase (Cu,Zn SOD) and catalase (Cat) activities on the steady-state mRNA levels of the three major antioxidant enzymes [Cu,Zn SOD, Cat, and glutathione peroxidase (GP)] in human umbilical vein endothelial cells under normoxia and hyperoxia. Inhibition of Cat activity by aminotriazole was not associated with alteration of the other antioxidant enzymes or with potentiation of cell injury. On the other hand, inhibition of Cu,Zn SOD activity by N-N'-diethyl-dithiocarbamate (DDC) was associated with an increase in Cu,Zn SOD mRNA level and a decrease in Cat and GP mRNA level. The combination of DDC and hyperoxia treatments was associated with an additive effect on Cu,Zn SOD message. We propose that these coordinate mRNA changes might be an adaptation to the oxidative environment. This proposal supports the concept that the intracellular O2 metabolites themselves could be the signals that trigger the antioxidant enzymes gene expression.

Satellite PET and lung cancer: a prospective study in surgical patients

Positron emission tomography (PET) appears to be an innovative method for imaging the proliferative activity of malignant tissue, in particular by means of 18F-labelled fluorodeoxyglucose (FDG). The potential role of PET scanning was investigated in a satellite centre as an adjunct to conventional methods for estimating the likelihood of pulmonary malignancy. Therefore the sensitivity of detection of lung cancer in candidates was determined prior to exploratory or therapeutic thoracotomy by FDG PET imaging. The study involved 36 patients with abnormal chest roentgenogram and suspected lung cancer who were due for thoracotomy. The PET scans were evaluated qualitatively and semiquantitatively. Pulmonary malignancy was found in 31/36 patients and 29 had a focal increase in FDG pulmonary uptake. Benign pulmonary lesions were found in 5/36 patients, three of whom had a negative PET scan. The sensitivity of detection of lung cancer by FDG PET was therefore 93.5%. Bayesian study shows that FDG PET could be the most useful method in a population with a low prevalence of lung cancer. As illustrated by our study, a simple FDG PET scanning protocol in a satellite PET centre could provide adequate clinical information and help in deciding subsequent patient management.

Variable glutathione levels and expression of antioxidant enzymes in human endothelial cells

We have investigated the relationship between intracellular glutathione levels and the inducibility of the mRNAs encoding the major antioxidant enzymes Cu,Zn superoxide dismutase (Cu,Zn SOD), catalase (CAT), glutathione peroxidase (GP), and the stress protein heme oxygenase (HO) following exposure of human umbilical vein endothelial cells (HUVEC) to either hypoxanthine-xanthine oxidase or 95% O2. Treatment of HUVEC with 2 and 200 microM buthionine sulfoximine (BSO) for 16 h reduced total glutathione (GSH) levels by 51 and 95%, respectively, whereas treatment with 100 microM diethylmaleate (DEM) for 24 h increased the cellular GSH content by 58%. None of these treatments affected the responsiveness of HUVEC to a subsequent oxidant challenge, in terms of antioxidant enzymes activities and mRNA levels. On the contrary, HO mRNA was significantly induced by both BSO and DEM, as well as by hyperoxia, albeit to a different extent. We conclude that intracellular redox changes do not appear to regulate the expression of the mRNAs encoding Cu,Zn SOD, CAT, and GP. Furthermore, factors other than endogenous thiols may play a role in the control of HO mRNA expression.

Spontaneous heat shock protein synthesis by alveolar macrophages in interstitial lung disease associated with phagocytosis of eosinophils

Synthesis of heat shock proteins (HSPs) is induced in all cells and tissues after exposure to elevated temperatures, or a variety of other types of injury, including oxidative injury. We have previously reported that stress proteins are induced in monocytes-macrophages during phagocytosis of red blood cells. Receptor-mediated phagocytosis is associated with activation of the respiratory burst, generation of the lipid mediators of inflammation, and increased production of cytokines. Similar activation events have been described in the alveolar macrophage (AM) during pulmonary fibrosis. We therefore analysed the pattern of proteins synthesized by human AMs recovered by bronchoalveolar lavage (BAL) in interstitial lung disease, both under basal conditions and after in vitro exposure to heat or hydrogen peroxide (H2O2). In two out of the 17 cases studied, we observed a high alveolar eosinophilia (10 and 24%, respectively) and phagocytosis, by the AMs, of eosinophilic material. Whereas exposure to heat or H2O2 induced in all AMs the synthesis of the classical HSPs, in these two cases, we found spontaneous synthesis of HSPs and of a 32 kD oxidation-specific stress protein, haeme oxygenase (HO). Exposure of AM to purified eosinophil-derived proteins, such as major basic protein (MBP), eosinophil peroxidase (EPO), eosinophil-derived neurotoxin (EDN), alone or in combination, did not induce stress protein synthesis, further suggesting that phagocytosis is involved in this induction. Stress protein synthesis by AMs may represent a new cellular marker of pulmonary injury and eosinophilic inflammation, and an autoprotective mechanism against oxidative stress.

Alterations in inspiratory and leg muscle force and recovery pattern after a marathon

We measured lung mechanics and metabolic parameters, first in a series of 15 marathon (M) and 12 half-marathon (H) runners, before and 2.5 h after the race, in order to assess the running effect on respiratory muscles. Maximal static inspiratory (Pi) and expiratory (Pe) pressures, maximal voluntary ventilation (MVV), blood lactate (LAC), arterialized blood gases (ABG), plasma glucose (GLU), and, with a visual analog scale, subjective tiredness were assessed. Pi decreased in M and H without change in Pe, MVV, or lung mechanics; it was still abnormal 2.5 h after the race and did not correlate with LAC, ABG, training parameters, running times, or subjective tiredness. A second study of six other M compared Pi, Pe, adductor pollicis longus (Ppol), and triceps surae (Ptri) forces, aiming to: 1) assess the reproducibility of the prolonged Pi decrease without Pe change, 2) prove that such a decrease corresponded to a real reduction in inspiratory muscle force and was not due to a poor collaboration of the subjects, 3) correlate Pi decrease with the force loss of a potentially tired leg muscle: the triceps surae. We observed a significant and similar decrease in Pi and Ptri, but no change in Ppol and Pe. Moreover, the high correlation between Pi and Ptri diminutions suggested a similar recovery pattern for inspiratory and leg muscles. In conclusion, the prolonged decrease in Pi after such races is compatible with inspiratory muscle fatigue, which, as well as its recovery, is similar to leg muscle tiredness.(ABSTRACT TRUNCATED AT 250 WORDS)

Spontaneous heat shock protein synthesis by alveolar macrophages in interstitial lung disease associated with phagocytosis of eosinophils

Synthesis of heat shock proteins (HSPs) is induced in all cells and tissues after exposure to elevated temperatures, or a variety of other types of injury, including oxidative injury. We have previously reported that stress proteins are induced in monocytes-macrophages during phagocytosis of red blood cells. Receptor-mediated phagocytosis is associated with activation of the respiratory burst, generation of the lipid mediators of inflammation, and increased production of cytokines. Similar activation events have been described in the alveolar macrophage (AM) during pulmonary fibrosis. We therefore analysed the pattern of proteins synthesized by human AMs recovered by bronchoalveolar lavage (BAL) in interstitial lung disease, both under basal conditions and after in vitro exposure to heat or hydrogen peroxide (H2O2). In two out of the 17 cases studied, we observed a high alveolar eosinophilia (10 and 24%, respectively) and phagocytosis, by the AMs, of eosinophilic material. Whereas exposure to heat or H2O2 induced in all AMs the synthesis of the classical HSPs, in these two cases, we found spontaneous synthesis of HSPs and of a 32 kD oxidation-specific stress protein, haeme oxygenase (HO). Exposure of AM to purified eosinophil-derived proteins, such as major basic protein (MBP), eosinophil peroxidase (EPO), eosinophil-derived neurotoxin (EDN), alone or in combination, did not induce stress protein synthesis, further suggesting that phagocytosis is involved in this induction. Stress protein synthesis by AMs may represent a new cellular marker of pulmonary injury and eosinophilic inflammation, and an autoprotective mechanism against oxidative stress.

Costovertebral joint dysfunction: another misdiagnosed cause of atypical chest pain

The diagnostic work-up of atypical chest pain frequently leads to invasive procedures. However, this painful symptomatology can sometimes be of benign origin and respond to simple therapeutic manoeuvres. A number of musculoskeletal conditions such as costovertebral joint dysfunctions should be carefully considered. We report five cases in which patient discomfort and high costs could have been avoided if awareness of these conditions had led to a correct diagnosis upon initial physical examination.

Hypoxaemia and liver cirrhosis: a new argument in favour of a "diffusion-perfusion defect"

Liver cirrhosis is sometimes associated with very severe hypoxaemia, which is thought to be the result of intrapulmonary vascular dilatations (IPVDs). These vascular abnormalities, although close to the gas exchange units, are so dilated that diffusion of oxygen molecules to their centre is impaired, causing an increase in alveolar-arterial oxygen tension difference (P(A-a)O2). On the other hand, administration of 100% oxygen provides enough driving pressure to overcome this relative diffusion defect and rules out a true intrapulmonary shunt. We report a case in which, in spite of a normal increase in arterial oxygen tension (PaO2) under 100% oxygen, exercising results in a marked impairment of oxygen exchange and a large intrapulmonary shunt. This is probably due to the increased cardiac output and preferential blood flow through these low resistance IPVDs.

Hypoxaemia and liver cirrhosis: a new argument in favour of a "diffusion-perfusion defect"

Liver cirrhosis is sometimes associated with very severe hypoxaemia, which is thought to be the result of intrapulmonary vascular dilatations (IPVDs). These vascular abnormalities, although close to the gas exchange units, are so dilated that diffusion of oxygen molecules to their centre is impaired, causing an increase in alveolar-arterial oxygen tension difference (P(A-a)O2). On the other hand, administration of 100% oxygen provides enough driving pressure to overcome this relative diffusion defect and rules out a true intrapulmonary shunt. We report a case in which, in spite of a normal increase in arterial oxygen tension (PaO2) under 100% oxygen, exercising results in a marked impairment of oxygen exchange and a large intrapulmonary shunt. This is probably due to the increased cardiac output and preferential blood flow through these low resistance IPVDs.

Response of human endothelial cell antioxidant enzymes to hyperoxia

To explore the level of regulation of the expression of the major antioxidant enzymes in response to hyperoxia, we exposed human umbilical vein endothelial cells to 95% O2 for 3 and 5 days and measured (1) the steady-state mRNA levels, (2) the activities, and (3) the immunoreactive content of CuZn and Mn superoxide dismutases (SOD), catalase (CAT), and glutathione peroxidase (GP). We found that a 3-day exposure to 95% O2 caused (1) an increase in CuZnSOD mRNA (by 41%), CAT mRNA (by 26%), and GP mRNA (by 173%); (2) an increase in CuZnSOD activity (by 30%), a decrease in CAT activity (by 37%), and an increase in GP activity (by 60%); and (3) an increase in CuZnSOD immunodetectable protein (by 26%) and a loss in CAT immunoreactive protein (by 27%). After a 5-day exposure to 95% O2, there was (1) a 93% increase in CuZnSOD mRNA, a 71% increase in CAT mRNA, and a 127% increase in GP mRNA; (2) a 56% increase in CuZnSOD activity, a 70% decrease in CAT activity, and an 89% increase in GP activity; and (3) a 35% increase in CuZnSOD immunoreactive protein and a 55% loss in CAT immunoreactive protein. There was no change in the steady-state MnSOD mRNA level after 3 days in 95% O2, but a 100% increase was observed on day 5 of oxygen exposure. MnSOD activity was unchanged in cells exposed to hyperoxia for 3 and 5 days. These data suggest that, in human umbilical vein endothelial cells, the regulation of antioxidant enzymes expression in response to O2 is complex and exerted at different levels.

Differential protective effects of O-phenanthroline and catalase on H2O2-induced DNA damage and inhibition of protein synthesis in endothelial cells

The respective roles of H2O2 and .OH radicals was assessed from the protective effects of catalase and the iron chelator o-phenanthroline on 1) the inhibition of protein synthesis, and 2) DNA damage and the related events (activation of the DNA repairing enzyme poly(ADP)ribose polymerase with the associated depletion of NAD and ATP stores) in cultured endothelial cells exposed to the enzyme reaction hypoxanthine-xanthine oxidase (HX-XO) or pure H2O2. Catalase added in the extracellular phase completely prevented all of these oxidant-induced changes. O-phenanthroline afforded a complete protective effect against DNA strand breakage and the associated activation of the enzyme poly(ADP)ribose polymerase. By contrast, iron chelation was only partially effective in maintaining the cellular NAD and ATP contents, as well as the protein synthetic activity. In addition, the ATP depletion following oxidant injury was much more profound than NAD depletion. These results indicate that: 1) .OH radical was most likely the ultimate O2 species responsible for DNA damage and activation of poly(ADP)ribose polymerase; 2) both H2O2 and .OH radicals were involved in the other cytotoxic effects (inhibition of protein synthesis and reduction of NAD and ATP stores); and 3) NAD and ATP depletion did not result solely from activation of poly(ADP)ribose polymerase, but other mechanisms are likely to be involved. These observations are also compatible with the existence of a compartmentalized intracellular iron pool.

Mode of presentation and diagnosis of bacterial pneumonia in human immunodeficiency virus-infected patients

Bacterial pneumonia (BP) has recently been reported to be more frequent in human immunodeficiency virus (HIV)-infected patients than in normal hosts. This study reviews the clinical and radiologic manifestations of BP in 132 consecutive pulmonary episodes over a 15-month period. BP was defined on a clinical basis as a pulmonary infiltrate accompanied by fever and improving in a few days with conventional antibiotics (trimethoprim-sulfamethoxazole excluded). In patients undergoing bronchoscopy (97 procedures), semiquantitative cultures and cell differentials of bronchoalveolar lavage (BAL) were performed, in addition to conventional staining and cultures for opportunistic infections. BP were frequent (45%), and the usual community-acquired pathogens were found. The radiologic manifestations of BP were often unusual, however, and 47% were indistinguishable from the typical appearance of Pneumocystis carinii pneumonia. BAL cultures had a sensitivity of 83 or 23%, depending on whether antibiotics were administered before bronchoscopy, using a cutoff value of greater than or equal to 10(4) bacteria/ml. The specificity of BAL culture was of 80.5% if patients with P. carinii pneumonia were taken as a control group. We conclude that BP is frequently encountered in HIV-infected patients. The clinical and radiologic presentation of BP may be indistinguishable from that of opportunistic infections. Semiquantitative cultures of BAL appear a valuable diagnostic tool to avoid unnecessary invasive diagnostic procedures or treatments.

Differential expression of hsp70 stress proteins in human endothelial cells exposed to heat shock and hydrogen peroxide

The potential role of oxidative stress conditions in the induction of heat shock proteins was studied in human umbilical vein endothelial cells. We compared the effects of temperature (43 to 45 degrees C), exposure to hydrogen peroxide (H2O2) and oxygen metabolites generated by the enzyme system hypoxanthine-xanthine oxidase (O2- plus H2O2), as well as exposure to 95% O2, on the expression of the major 70-kD heat shock proteins (hsp70). Northern blot analysis indicated that: (1) heat shock induced a rapid and marked increase in hsp70 mRNA levels that reached a maximum during recovery from a 30-min exposure to 45 degrees C; (2) treatment with a 5-mM H2O2 bolus or 50 mU/ml xanthine oxidase also increased hsp70 mRNA levels but to a lesser extent than heat shock (about 10 and 25 times less, respectively); (3) no change was detected after a 5-day exposure to 95% O2. Nuclear run on transcription data and kinetics of mRNA decay in the presence of actinomycin D indicated that the observed increase in hsp70 mRNA levels in both heat-shocked and H2O2-treated cells was mainly due to a transcriptional induction. The kinetics of hsp70 synthesis correlated with the accumulation of hsp70 mRNA. Two-dimensional gel electrophoresis and immunologic analysis of these heat shock proteins revealed a series of at least five distinct hsp70 isoforms induced in heat-shocked cells, whereas only a specific subset of these proteins, mainly one acidic isoform, was induced in very low amounts in response to H2O2 treatment. These results clearly indicate that the endothelial cell responses to oxidative stress and heat shock differ in both qualitative and quantitative terms in respect to hsp70 induction. They also suggest that the intensity of this response to oxidative stress conditions may vary depending on the nature of the oxidative challenge.

[Prevention and screening: which decisions should be made?]

The definition of the various types of prevention, of screening and of case-finding are recalled, and the particular requirements of screening within an apparently normal population are analyzed. The characteristics of a screening test are reviewed, with emphasis on the prevalence of the disease, which, together with the specificity of the test, conditions the positive predictive value. The consequences of the false positive and false negative are briefly detailed and the benefit/cost ratio is defined. Interpretation of the results is rendered difficult by the existence of certain biases including the lead-time bias and the length-time bias. These complex elements should be taken into consideration in a physician's regular case-finding in his patients.

Characterization of a specific 20- to 25-kD interleukin-1 inhibitor from cultured human lung macrophages

Alveolar macrophages have the ability to downregulate immune processes in vitro. We have recently suggested the presence of interleukin-1 (IL-1) inhibitors in the supernatants of human bronchoalveolar lavage cells from patients with idiopathic pulmonary fibrosis or sarcoidosis. In the present study, we further analyze the cellular origin and the biologic properties of a 20- to 25-kD IL-1 inhibitor spontaneously produced by cultured human alveolar macrophages (AM). The inhibitor blocks IL-1-induced prostaglandin E2 production by human fibroblasts and the IL-1-related increase of phytohemagglutinin-induced murine thymocyte proliferation. After rigorous IL-1 alpha and IL-1 beta depletion, supernatants of lung macrophages specifically block the binding of IL-1 to its receptor on the murine thymoma cell line EL4-6.1 in a dose-dependent manner. These results indicate that AM from both normal donors and patients produce a specific IL-1 inhibitor that may be of importance in protecting the alveolar environment from the deleterious effects of excessive IL-1 production.

Fibroblast-alveolar cell interactions in sarcoidosis and idiopathic pulmonary fibrosis: evidence for stimulatory and inhibitory cytokine production by alveolar cells

To better understand how the activity of inflammatory cells collected by bronchoalveolar lavage (BAL) could affect the outcome of granulomatous and fibrotic pulmonary diseases, we studied secretory products and messenger ribonucleic acid (mRNA) expression for certain cytokines of BAL cells in 10 controls, 14 patients with interstitial pulmonary fibrosis (IPF) and 22 patients with sarcoidosis. We assayed the activity of 48 h conditioned media for: 1) their biological action on fibroblast proliferation and prostaglandin E2 (PGE2), collagenase and collagen production by fibroblasts; 2) TNF alpha levels by bioassay and radioimmunoassay; 3) interleukin 1 (IL-1) alpha and beta and beta levels by solid phase enzyme immunoassay (EIA); 4) tumor necrosis factor (TNF) and IL-1 inhibitory activity. We also measured, in freshly isolated BAL cells: 1) mRNA levels for IL-1 alpha and beta and TNF alpha; 2) cell-associated IL-1 alpha and beta by EIA. The only difference found in the assessment of the biological activity of BAL cells conditioned medium was an increase in fibroblast proliferation in sarcoidosis vs IPF patients. The IL-1 alpha and beta, and TNF alpha contents of conditioned media were similar in the three groups. Inhibitory activity against IL-1 and TNF alpha was found in a few patients. Further analysis revealed two peaks of inhibitory activity against IL-1 (20-25 kD and 35-40 kD), as well as a distinct TNF alpha inhibitory activity which could be retained on a TNF alpha-binding affinity column. No mRNA expression for TNF alpha was found in freshly isolated BAL cells, whereas very variable levels of IL-1 alpha and beta mRNA levels were detected in the three groups. Because of these variable results of differences in functional state between freshly isolated and cultured BAL cells, and of the presence of inhibitory substances against IL-1 and TNF alpha, it is unlikely that the development of fibrosis could be ascribed to a single disorder or abnormality.

Fibroblast-alveolar cell interactions in sarcoidosis and idiopathic pulmonary fibrosis: evidence for stimulatory and inhibitory cytokine production by alveolar cells

To better understand how the activity of inflammatory cells collected by bronchoalveolar lavage (BAL) could affect the outcome of granulomatous and fibrotic pulmonary diseases, we studied secretory products and messenger ribonucleic acid (mRNA) expression for certain cytokines of BAL cells in 10 controls, 14 patients with interstitial pulmonary fibrosis (IPF) and 22 patients with sarcoidosis. We assayed the activity of 48 h conditioned media for: 1) their biological action on fibroblast proliferation and prostaglandin E2 (PGE2), collagenase and collagen production by fibroblasts; 2) TNF alpha levels by bioassay and radioimmunoassay; 3) interleukin 1 (IL-1) alpha and beta and beta levels by solid phase enzyme immunoassay (EIA); 4) tumor necrosis factor (TNF) and IL-1 inhibitory activity. We also measured, in freshly isolated BAL cells: 1) mRNA levels for IL-1 alpha and beta and TNF alpha; 2) cell-associated IL-1 alpha and beta by EIA. The only difference found in the assessment of the biological activity of BAL cells conditioned medium was an increase in fibroblast proliferation in sarcoidosis vs IPF patients. The IL-1 alpha and beta, and TNF alpha contents of conditioned media were similar in the three groups. Inhibitory activity against IL-1 and TNF alpha was found in a few patients. Further analysis revealed two peaks of inhibitory activity against IL-1 (20-25 kD and 35-40 kD), as well as a distinct TNF alpha inhibitory activity which could be retained on a TNF alpha-binding affinity column. No mRNA expression for TNF alpha was found in freshly isolated BAL cells, whereas very variable levels of IL-1 alpha and beta mRNA levels were detected in the three groups. Because of these variable results of differences in functional state between freshly isolated and cultured BAL cells, and of the presence of inhibitory substances against IL-1 and TNF alpha, it is unlikely that the development of fibrosis could be ascribed to a single disorder or abnormality.

[Is pulmonary interstitial pathology an entity?]

Pulmonary interstitial diseases cannot be defined as an entity because of the existence of multiple pathogenic factors, and of various radiological expressions, as well as of the involvement of different types of inflammatory cells. Moreover, several hypotheses can be considered to explain the fibroblastic hyperplasia often present in this condition. It could be the result of an excess of secretion of growth factors, of an enhanced sensitivity of the target cells to these factors, of a decrease of factors inhibiting fibroblast replication, or of a relative deficiency of monokine antagonists. A similar analysis could be applied to chemotactic factors for fibroblasts as well as for those stimulating collagen production.

[The rational use of various tests for the diagnosis of pulmonary embolism]

The patient's history, physical examination, chest X-ray, electrocardiogram and blood gas analysis cannot provide a firm diagnosis of pulmonary embolism, but they can help to assess its clinical or a priori probability. Lung perfusion scan, associated with ventilation scan or not, can modulate the probability of pulmonary embolism (post-test or a posteriori) as a function of the scan result (high probability, low probability, or indeterminate result). To define the proper indication for pulmonary angiography, it is necessary to examine all the factors related to the nature of the test, the risk, and the data related to pulmonary embolism (outcome, efficacy and side effects of treatment). Decision analysis provides an opportunity to integrate all these factors, and may help in the diagnosis of pulmonary embolism by establishing the indication for pulmonary angiography, depending on clinical probability and the result of the lung scan.

Differential effects of hyperoxia and hydrogen peroxide on DNA damage, polyadenosine diphosphate-ribose polymerase activity, and nicotinamide adenine dinucleotide and adenosine triphosphate contents in cultured endothelial cells and fibroblasts

The effects of oxidative stress on DNA damage and associated reactions, increased polyadenosine diphosphate-ribose polymerase (PARP) activity and decreased nicotinamide adenine dinucleotide (NAD) and adenosine triphosphate (ATP) contents, have been tested in primary cultures of porcine aortic endothelial cells. The cells were treated with 50-500 microM H2O2 for 20 min or 100 microM paraquat for 3 days or were exposed to 95% O2 for 2 and 5 days. The administration of 250-500 microM H2O2 resulted in a marked increase in PARP activity and a profound depletion of ATP and NAD. Although hyperoxia had no effect on PARP activity and reduced only slightly the ATP and NAD stores, it markedly reduced the ability of endothelial cells to increase PARP activity upon exposure to DNase. Paraquat had a similar effect. Human dermal fibroblasts were also exposed to 50-500 microM H2O2 for 20 min or 95% O2 for 5 days. Their response to H2O2 differed from that of endothelial cells by their ability to maintain the ATP content at a normal level. Fibroblasts were also insensitive to the effect of hyperoxia. These results suggest that the oxidant-related DNA damage is a function of the type of oxidative stress used and may be cell-specific.