IRCCS Policlinico San Donato

Making a firm diagnosis of chronic heart failure with preserved ejection fraction (HFpEF) remains a challenge. We recommend a new stepwise diagnostic process, the 'HFA-PEFF diagnostic algorithm'. Step 1 (P=Pre-test assessment) is typically performed in the ambulatory setting and includes assessment for HF symptoms and signs, typical clinical demographics (obesity, hypertension, diabetes mellitus, elderly, atrial fibrillation), and diagnostic laboratory tests, electrocardiogram, and echocardiography. In the absence of overt non-cardiac causes of breathlessness, HFpEF can be suspected if there is a normal left ventricular ejection fraction, no significant heart valve disease or cardiac ischaemia, and at least one typical risk factor. Elevated natriuretic peptides support, but normal levels do not exclude a diagnosis of HFpEF. The second step (E: Echocardiography and Natriuretic Peptide Score) requires comprehensive echocardiography and is typically performed by a cardiologist. Measures include mitral annular early diastolic velocity (e'), left ventricular (LV) filling pressure estimated using E/e', left atrial volume index, LV mass index, LV relative wall thickness, tricuspid regurgitation velocity, LV global longitudinal systolic strain, and serum natriuretic peptide levels. Major (2 points) and Minor (1 point) criteria were defined from these measures. A score ≥5 points implies definite HFpEF; ≤1 point makes HFpEF unlikely. An intermediate score (2-4 points) implies diagnostic uncertainty, in which case Step 3 (F1: Functional testing) is recommended with echocardiographic or invasive haemodynamic exercise stress tests. Step 4 (F2: Final aetiology) is recommended to establish a possible specific cause of HFpEF or alternative explanations. Further research is needed for a better classification of HFpEF.

Acute aortic dissection (AAD) is a life-threatening condition associated with high morbidity and mortality rates, and it remains a challenge to diagnose and treat. The International Registry of Acute Aortic Dissection was established in 1996 with the mission to raise awareness of this condition and provide insights to guide diagnosis and treatment. Since then, >7300 cases have been included from >51 sites in 12 countries. Although presenting symptoms and physical findings have not changed significantly over this period, the use of computed tomography in the diagnosis has increased, and more patients are managed with interventional procedures: surgery in type A AAD and endovascular therapy in type B AAD; with these changes in care, there has been a significant decrease in overall in-hospital mortality in type A AAD but not in type B AAD. Herein, we summarized the key lessons learned from this international registry of patients with AAD over the past 20 years.

Hepatorenal syndrome (HRS) is a serious complication of end-stage liver disease, occurring mainly in patients with advanced cirrhosis and ascites, who have marked circulatory dysfunction,1 as well as in patients with acute liver failure.2 In spite of its functional nature, HRS is associated with a poor prognosis,3 4 and the only effective treatment is liver transplantation. During the 56th Meeting of the American Association for the Study of Liver Diseases, the International Ascites Club held a Focused Study Group (FSG) on HRS for the purpose of reporting the results of an international workshop and to reach a consensus on a new definition, criteria for diagnosis and recommendations on HRS treatment. A similar workshop was held in Chicago in 1994 in which standardised nomenclature and diagnostic criteria for refractory ascites and HRS were established.5 The introduction of innovative treatments and improvements in our understanding of the pathogenesis of HRS during the previous decade led to an increasing need to undertake a new consensus meeting. This paper reports the scientific rationale behind the new definitions and recommendations. The international workshop included four issues debated by four panels of experts (see Acknowledgements). The issues were: (1) evidence-based HRS pathogenesis; (2) treatment of HRS using vasoconstrictors; (3) other HRS treatments using transjugular intrahepatic portosystemic stent-shunt (TIPS) and extracorporeal albumin dialysis (ECAD); and (4) new definitions and diagnostic criteria for HRS and recommendations for its treatment.

Th subsets are defined according to their production of lineage-indicating cytokines and functions. In this study, we have identified a subset of human Th cells that infiltrates the epidermis in individuals with inflammatory skin disorders and is characterized by the secretion of IL-22 and TNF-alpha, but not IFN-gamma, IL-4, or IL-17. In analogy to the Th17 subset, cells with this cytokine profile have been named the Th22 subset. Th22 clones derived from patients with psoriasis were stable in culture and exhibited a transcriptome profile clearly separate from those of Th1, Th2, and Th17 cells; it included genes encoding proteins involved in tissue remodeling, such as FGFs, and chemokines involved in angiogenesis and fibrosis. Primary human keratinocytes exposed to Th22 supernatants expressed a transcriptome response profile that included genes involved in innate immune pathways and the induction and modulation of adaptive immunity. These proinflammatory Th22 responses were synergistically dependent on IL-22 and TNF-alpha. Furthermore, Th22 supernatants enhanced wound healing in an in vitro injury model, which was exclusively dependent on IL-22. In conclusion, the human Th22 subset may represent a separate T cell subset with a distinct identity with respect to gene expression and function, present within the epidermal layer in inflammatory skin diseases. Future strategies directed against the Th22 subset may be of value in chronic inflammatory skin disorders.

MicroRNAs (miRNAs) are small non-protein-coding RNAs that function as negative gene expression regulators. In the present study, we investigated miRNAs role in endothelial cell response to hypoxia. We found that the expression of miR-210 progressively increased upon exposure to hypoxia. miR-210 overexpression in normoxic endothelial cells stimulated the formation of capillary-like structures on Matrigel and vascular endothelial growth factor-driven cell migration. Conversely, miR-210 blockade via anti-miRNA transfection inhibited the formation of capillary-like structures stimulated by hypoxia and decreased cell migration in response to vascular endothelial growth factor. miR-210 overexpression did not affect endothelial cell growth in both normoxia and hypoxia. However, anti-miR-210 transfection inhibited cell growth and induced apoptosis, in both normoxia and hypoxia. We determined that one relevant target of miR-210 in hypoxia was Ephrin-A3 since miR-210 was necessary and sufficient to down-modulate its expression. Moreover, luciferase reporter assays showed that Ephrin-A3 was a direct target of miR-210. Ephrin-A3 modulation by miR-210 had significant functional consequences; indeed, the expression of an Ephrin-A3 allele that is not targeted by miR-210 prevented miR-210-mediated stimulation of both tubulogenesis and chemotaxis. We conclude that miR-210 up-regulation is a crucial element of endothelial cell response to hypoxia, affecting cell survival, migration, and differentiation. MicroRNAs (miRNAs) are small non-protein-coding RNAs that function as negative gene expression regulators. In the present study, we investigated miRNAs role in endothelial cell response to hypoxia. We found that the expression of miR-210 progressively increased upon exposure to hypoxia. miR-210 overexpression in normoxic endothelial cells stimulated the formation of capillary-like structures on Matrigel and vascular endothelial growth factor-driven cell migration. Conversely, miR-210 blockade via anti-miRNA transfection inhibited the formation of capillary-like structures stimulated by hypoxia and decreased cell migration in response to vascular endothelial growth factor. miR-210 overexpression did not affect endothelial cell growth in both normoxia and hypoxia. However, anti-miR-210 transfection inhibited cell growth and induced apoptosis, in both normoxia and hypoxia. We determined that one relevant target of miR-210 in hypoxia was Ephrin-A3 since miR-210 was necessary and sufficient to down-modulate its expression. Moreover, luciferase reporter assays showed that Ephrin-A3 was a direct target of miR-210. Ephrin-A3 modulation by miR-210 had significant functional consequences; indeed, the expression of an Ephrin-A3 allele that is not targeted by miR-210 prevented miR-210-mediated stimulation of both tubulogenesis and chemotaxis. We conclude that miR-210 up-regulation is a crucial element of endothelial cell response to hypoxia, affecting cell survival, migration, and differentiation. Hypoxia occurs during several physio-pathological circumstances such as rapid tissue growth, acute and chronic ischemia, organ and tumor development, and high altitude (1Giaccia A.J. Simon M.C. Johnson R. Genes Dev. 2004; 18: 2183-2194Crossref PubMed Scopus (297) Google Scholar). Diminished oxygen concentration induces an articulate program of responses aimed at relieving tissue hypoxia and removing irreversibly damaged cells (2Pouyssegur J. Dayan F. Mazure N.M. Nature. 2006; 441: 437-443Crossref PubMed Scopus (1384) Google Scholar, 3Pugh C.W. Ratcliffe P.J. Nat. Med. 2003; 9: 677-684Crossref PubMed Scopus (1999) Google Scholar). These responses include endothelial cell (EC) 2The abbreviations used are: EC, endothelial cell; HUVEC, human umbilical vein endothelial cells; miRNA, microRNA; qPCR, real-time PCR; pSUPER, p-SUPER.retro.puro vector; EFNA3, ephrin-A3; anti-miR-210, miR-210 complementary locked nucleic acid; VEGF, vascular endothelial growth factor; UTR, untranslated region. proliferation, migration, and angiogenesis, but also growth arrest and apoptotic cell death; the nature of the outcome depends on numerous parameters, including cell histological origin and genotype, as well as the severity and the duration of the hypoxic stress. Thus, it is of pivotal importance in understanding the molecular mechanisms triggered by cell exposure to low oxygen tension. Little is known about the role played by microRNAs (miRNAs) in EC response to hypoxia (4Kulshreshtha R. Davuluri R.V. Calin G.A. Ivan M. Cell Death Differ. 2008; 15: 667-671Crossref PubMed Scopus (223) Google Scholar). miRNAs are 21–23-nucleotide RNA molecules that regulate the stability or the translational efficiency of target messenger RNAs (5Bartel D.P. Cell. 2004; 116: 281-297Abstract Full Text Full Text PDF PubMed Scopus (29625) Google Scholar, 6Zamore P.D. Haley B. Science. 2005; 309: 1519-1524Crossref PubMed Scopus (1130) Google Scholar). The biogenesis of miRNAs begins with a primary transcript, termed the pri-miRNA, and the combined action of Drosha and Dicer ribonucleases generates the mature miRNA species. This product is loaded into the RNA-induced silencing complex, where it mediates the translational inhibition of target mRNA, albeit the opposite effect has been described as well (7Vasudevan S. Tong Y. Steitz J.A. Science. 2007; 318: 1931-1934Crossref PubMed Scopus (2198) Google Scholar). miRNAs have diverse functions, including the regulation of cellular differentiation, proliferation, and apoptosis (5Bartel D.P. Cell. 2004; 116: 281-297Abstract Full Text Full Text PDF PubMed Scopus (29625) Google Scholar). Although it is clear that miRNAs have essential functions in mammalian biology, few miRNA genes have been functionally linked to specific cellular pathways. In this study, we show that miR-210 is a key player of EC response to low oxygen tension and identify Ephrin-A3 as a relevant target of miR-210 in hypoxic conditions. Cell Cultures—Human umbilical vein EC (HUVEC; Clonetics) were grown in EGM-2 (BioWhittaker) containing 2% fetal bovine serum. U2OS osteosarcoma cell line and Phoenix-ampho cells (American Type Culture Collection) were grown in Dulbecco's modified Eagle's medium containing 10% fetal bovine serum. The induction of acidosis and hypoxia is described in supplemental materials. miRNA and mRNA Quantification—Total RNA was extracted using TRIzol (Invitrogen). Small RNA and mRNA fractions were enriched using the PureLink miRNA isolation kit and Micro-to-Midi isolation kit (Invitrogen), respectively, according to the manufacturer's instructions. miRNA levels were analyzed using the TaqMan real-time PCR (qPCR) method (1 ng/assay) and quantified with the ABI Prism 7000 SDS (Applied Biosystems). Primers for 157 miRNA, 28 positive and negative controls, and the reagents for reverse transcriptase and qPCR reactions were all obtained from Applied Biosystems. Relative expression was calculated using the comparative Ct method (2-[Δ][Δ]Ct) (8Livak K.J. Schmittgen T.D. Methods (Amst.). 2001; 25: 402-408Google Scholar). Different samples were normalized to miR-16 expression. For miRNA profiling, miRNAs were assayed in a 96-well format, and samples were also normalized to the median Ct value, obtaining almost identical results. mRNAs levels were analyzed using the SYBR-GREEN qPCR method (1–3 μg/assay, Ambion, see supplemental materials for details). Northern blottings are described in the supplemental materials. Small Interfering RNA-mediated Gene Silencing—Small interfering RNAs targeting HIF1α, HIF2α, or a scramble sequence (Santa Cruz Biotechnology) were transfected into HUVEC, according to the manufacturer's instruction (see the supplemental materials for details). miRNA Down-modulation and Overexpression—Locked Nucleic Acid oligonucleotides against miR-210 or a control scramble sequence (Exiqon) were transfected by small interfering RNA transfection reagent (Santa Cruz Biotechnology) in 40% confluent HUVEC (4 × 103/cm2) at the final concentration of 40 nm. After 16 h, cells were re-fed with fresh medium, and experiments were performed 24 h later. Alternatively, cells were incubated with fresh medium for 2 h and then shifted to hypoxic conditions. miRIDIAN miR-210 Mimic or a control scramble sequence (Dharmacon) were transfected using the same protocol. To obtain stable miR-210-overexpressing cells, HUVEC were infected by retroviral vectors bearing pre-miR210 sequence (see the supplemental materials). miRNAs Target Prediction—Bioinformatic prediction of target genes and miRNA binding sites was performed using four different programs: MiRanda (version 2005), TargetScan (version 3.1), Sanger MirBase (version 4), and PicTar (version 2006) (9Krek A. Grun D. Poy M.N. Wolf R. Rosenberg L. Epstein E.J. MacMenamin P. da Piedade I. Gunsalus K.C. Stoffel M. Rajewsky N. Nat. Genet. 2005; 37: 495-500Crossref PubMed Scopus (3903) Google Scholar, 10Sethupathy P. Megraw M. Hatzigeorgiou A.G. Nat. Methods. 2006; 3: 881-886Crossref PubMed Scopus (479) Google Scholar, 11Rajewsky N. Nat. Genet. 2006; 38: S8-S13Crossref PubMed Scopus (939) Google Scholar). Only common targets were considered for experimental analysis. Additional Information—See the supplemental materials for information on apoptosis, cell cycle analysis, adenoviral infection, capillary-like formation assay, chemotaxis, immunofluorescence, reporter construct generation and luciferase assay. Statistical Analysis—Variables were analyzed by both Student's t test and one-way analysis of variance and a of p ≤ 0.05 was deemed statistically significant. Values are expressed as ±standard error (S.E.). miR-210 Induction by Hypoxia—To assess whether hypoxia regulates miRNA expression in EC, HUVEC were exposed to 1% oxygen for different time periods. To control that cells responded to low oxygen tension, cell proliferation was measured. As expected, hypoxia induced cell death and growth arrest, as assessed by growth curves (Fig. S1A) and by the rate of DNA synthesis with bromodeoxyuridine incorporation (Fig. S1, B and C) (1Giaccia A.J. Simon M.C. Johnson R. Genes Dev. 2004; 18: 2183-2194Crossref PubMed Scopus (297) Google Scholar, 2Pouyssegur J. Dayan F. Mazure N.M. Nature. 2006; 441: 437-443Crossref PubMed Scopus (1384) Google Scholar, 3Pugh C.W. Ratcliffe P.J. Nat. Med. 2003; 9: 677-684Crossref PubMed Scopus (1999) Google Scholar). Low molecular weight RNA was extracted, and miRNA expression profile at each time point was determined (Tables S1 and S2). To normalize different samples, we used miR-16 expression, which previous experiments showed was not regulated by hypoxia (Fig. S2A). As found in different experimental systems (4Kulshreshtha R. Davuluri R.V. Calin G.A. Ivan M. Cell Death Differ. 2008; 15: 667-671Crossref PubMed Scopus (223) Google Scholar), miR-210 levels were strongly induced by hypoxia. miR-210 increased as early as 4 h after hypoxia induction, it was more than 35-fold higher than normoxic control at 48 h, and miRNA up-regulation was maintained for the next 72 h (Fig. 1A). miR-150 and 328 were up-regulated as well, albeit to a lower extent and with slower kinetics (Fig. S2, B and C). When miR-210 regulation by hypoxia was further investigated, it was found that its activation was inversely proportional to O2 tension (Fig. S3A). Moreover, upon HUVEC reoxygenation after 24 h of hypoxia, miR-210 levels remained high for the next 8 h and slowly declined thereafter, indicating the maintenance of this adaptive response (Fig. 1A). Finally, miR-210 induction by hypoxia was confirmed by northern blotting (Fig. 1B). Hypoxia is associated to increased oxidative stress and acidosis (12Zaccagnini G. Martelli F. Fasanaro P. Magenta A. Gaetano C. Di Carlo A. Biglioli P. Giorgio M. Martin-Padura I. Pelicci P.G. Capogrossi M.C. Circulation. 2004; 109: 2917-2923Crossref PubMed Scopus (103) Google Scholar, 13Mekhail K. Khacho M. Gunaratnam L. Lee S. Cell Cycle. 2004; 3: 1027-1029Crossref PubMed Scopus (25) Google Scholar, 14Guzy R.D. Schumacker P.T. Exp. Physiol. 2006; 91: 807-819Crossref PubMed Scopus (681) Google Scholar). Thus, it was assessed whether either oxidative stress or acidification in the absence of hypoxia were sufficient to induce miR-210 positive modulation (Fig. S3B). We found that HUVEC exposure to 400 μm H2O2 for 8 and 24 h did not induce miR-210 modulation; similarly, cell culture at both pH 6.6 and pH 7.0 for 24 and 48 h did not increase miR-210. In keeping with these data, a buffered medium that prevented hypoxia-induced acidosis (15Luo F. Liu X. Yan N. Li S. Cao G. Cheng Q. Xia Q. Wang H. BMC Cancer. 2006; 6: 26Crossref PubMed Scopus (60) Google Scholar) did not inhibit miR-210 activation by hypoxia. Finally, we found that glucose supplementation did not prevent miR-210 induction by hypoxia (Fig. S3C) and that this event was not endothelium-specific (Fig. S4). Many hypoxia effects are mediated by HIF transcription factor (1Giaccia A.J. Simon M.C. Johnson R. Genes Dev. 2004; 18: 2183-2194Crossref PubMed Scopus (297) Google Scholar, 2Pouyssegur J. Dayan F. Mazure N.M. Nature. 2006; 441: 437-443Crossref PubMed Scopus (1384) Google Scholar, 3Pugh C.W. Ratcliffe P.J. Nat. Med. 2003; 9: 677-684Crossref PubMed Scopus (1999) Google Scholar). To analyze the role of HIF in the induction of miR-210 by hypoxia in EC, the expression of HIF1α and HIF2α was knocked down by the transfection of specific small interfering RNAs. Although the knock down of both HIF isoforms was highly effective (Fig. S5, A and B), only HIF1α RNA interference decreased the induction of miR-210 by hypoxia significantly (Fig. S5C). In keeping with this observation, HIF1α overexpression was sufficient to induce miR-210 expression in the absence of hypoxia (Fig. S5, D and E). We conclude that miR-210 displays a rapid and dose-dependent induction in response to hypoxia and that its up-regulation is maintained over time. Neither oxidative stress nor acidosis appears to play a role in this event and, in keeping with previous observations (4Kulshreshtha R. Davuluri R.V. Calin G.A. Ivan M. Cell Death Differ. 2008; 15: 667-671Crossref PubMed Scopus (223) Google Scholar), HIF1α is necessary and sufficient for miR-210 activation. miR-210 Expression Stimulates Capillary-like Formation and Cell Migration—One main feature of hypoxia is the stimulation of angiogenesis (3Pugh C.W. Ratcliffe P.J. Nat. Med. 2003; 9: 677-684Crossref PubMed Scopus (1999) Google Scholar). Several aspects of angiogenesis can be studied in vitro, taking advantage of the ability of EC to form capillary-like structures once plated on Matrigel or other extracellular components (16Kubota Y. Kleinman H.K. Martin G.R. Lawley T.J. J. Cell Biol. 1988; 107: 1589-1598Crossref PubMed Scopus (984) Google Scholar). To this aim, HUVEC were first exposed to 24 h of hypoxia and, afterward, their ability to form capillary-like structures in low growth factor-containing medium was assessed. In keeping with previous reports (17Yamakawa M. Liu L.X. Date T. Belanger A.J. Vincent K.A. Akita G.Y. Kuriyama T. Cheng S.H. Gregory R.J. Jiang C. Circ. Res. 2003; 93: PubMed Scopus Google Scholar), hypoxia significantly increased tubulogenesis (Fig. A and To whether this event at in on miR-210 HUVEC were transfected with a miR-210 complementary Nucleic Acid that with high and to the complementary miRNA, its A and show that 24 h of miR-210 decreased the ability of HUVEC to form capillary-like both in cells exposed to hypoxia and in control To assess whether miR-210 induction capillary-like formation in the absence of hypoxia, HUVEC were a that expressed mature miR-210 levels with these in hypoxic cells (Fig. We found that miR-210 overexpression significantly increased capillary-like formation HUVEC were plated in low growth factor medium (Fig. D and E). EC migration is a crucial event in the (3Pugh C.W. Ratcliffe P.J. Nat. Med. 2003; 9: 677-684Crossref PubMed Scopus (1999) Google Scholar). Thus, we assessed whether the modulation of miR-210 expression chemotaxis. To this aim, HUVEC were transfected with anti-miR-210, and then their ability to in response to was A and show that miR-210 blockade significantly decreased chemotaxis. Conversely, miR-210 up-regulation to levels to these induced by hypoxia significantly increased HUVEC ability to in response to (Fig. and Finally, to the of miR-210 action in the gene expression the mRNA levels of hypoxia target genes were both in HUVEC exposed to hypoxia and in cells miR-210 in normoxic (Fig. Although hypoxia up-regulated the expression of all miR-210 did not affect their We that miR-210 expression not to affect the gene expression response to hypoxia by miR-210 EC was whether miR-210 induction EC To this we growth curves of HUVEC with retroviral vectors miR-210 or with in the or absence of hypoxia. was found that miR-210 expression did not affect cell significantly both in normoxic and in hypoxic (Fig. a HUVEC were transfected with anti-miR-210, and cells were We found that 24 h of miR-210 decreased HUVEC proliferation in normoxic cells and that exposure to hypoxia further decreased EC (Fig. This at in to apoptotic cell death since apoptotic DNA was increased by anti-miR-210 transfection (Fig. were obtained by a not Conversely, DNA synthesis was we found that anti-miR-210 only bromodeoxyuridine incorporation rate (Fig. Hypoxia Ephrin-A3 via further the of miR-210 regulation in cell response to hypoxia, an in of targets was performed using Sanger and (9Krek A. Grun D. Poy M.N. Wolf R. Rosenberg L. Epstein E.J. MacMenamin P. da Piedade I. Gunsalus K.C. Stoffel M. Rajewsky N. Nat. Genet. 2005; 37: 495-500Crossref PubMed Scopus (3903) Google Scholar, 10Sethupathy P. Megraw M. Hatzigeorgiou A.G. Nat. Methods. 2006; 3: 881-886Crossref PubMed Scopus (479) Google Scholar, 11Rajewsky N. Nat. Genet. 2006; 38: S8-S13Crossref PubMed Scopus (939) Google Scholar). of the common targets of these was Ephrin-A3 the crucial role of in the of the and in vascular S. Med. 2007; PubMed Scopus Google Scholar), we to this target To this aim, HUVEC were exposed to hypoxia for 24 and 48 h, and was by and show that was in normoxic cells, its expression decreased to almost levels hypoxia This was not to decreased mRNA levels since by qPCR an increase of mRNA (Fig. Although regulation further we can conclude that is by hypoxia. it was assessed whether was to increased miR-210 To this HUVEC were transfected with anti-miR-210 and exposed to hypoxia. that miR-210 prevented it was investigated whether miR-210 up-regulation in the absence of hypoxia regulated We found that was strongly in miR-210-overexpressing cells (Fig. in the absence of mRNA regulation (Fig. these a up-regulation and by hypoxia. To whether miR-210 regulated expression, an was in which the of the gene was of a luciferase Alternatively, to the interference of other miRNA binding only the miR-210 target and the were As we the sequence complementary to miR-210 sequence in this construct The different luciferase were transfected into U2OS cells with a a expression for miR-210 or for a control U2OS were for their high efficiency of A significant negative effect on luciferase was in both bearing an miR-210 binding with the control (Fig. levels of miR-210 induced by hypoxia were sufficient to and reporter was (Fig. We that is a direct target of miR-210. Down-modulation for miR-210-mediated of and investigated whether is an of increase of EC migration and To this aim, miR-210 was in the of an allele that is of sequence and be targeted by miR-210. was expressed using a retroviral miR-210 was transfected as mature that expression prevented increase of capillary-like the expression of miR-210 and decreased tubulogenesis control expression had effect We found that the same was also in cells, in the absence of miR-210 that the expression of prevented hypoxia-induced increase of EC tubulogenesis and that the of capillary-like structures was we assayed whether inhibition played a role in miR-210 stimulation of EC as that expression did not affect EC in response to VEGF, miR-210 and inhibited it the expression of prevented the increase in induced by hypoxia (Fig. In this study, we miR-210 regulation and its functional in EC response to hypoxia. was found that miR-210 up-regulation was rapid and and it did not a response to stress since was found that either pH or increased oxygen played a role in miR-210 activation. We also found that growth factor nor stress miR-210 Y. M. C. and F. the high of the hypoxic in miR-210 Moreover, miR-210 modulation by hypoxia is not to Thus, it is to a role of miR-210 induction in the hypoxic In keeping with this found that the of the miRNAs by hypoxia according to the cell used as as the and the time of hypoxia R. M. R. H. Davuluri R. Liu M. Calin G.A. Ivan M. Cell. Biol. 2006; Scholar, C. K. N. Cancer. 2007; 6: PubMed Scopus Google Scholar, Q. G. D. Y. C. Wang J. Y. 2006; PubMed Scopus Google Scholar, Y. 2007; PubMed Scopus Google Scholar, C. S. J. C. H. J. Res. 2008; PubMed Scopus Google Scholar). However, the activation of miR-210 not linked to experimental or to a specific cell R. M. R. H. Davuluri R. Liu M. Calin G.A. Ivan M. Cell. Biol. 2006; Scholar, C. K. N. Cancer. 2007; 6: PubMed Scopus Google Scholar, Q. G. D. Y. C. Wang J. Y. 2006; PubMed Scopus Google Scholar, C. S. J. C. H. J. Res. 2008; PubMed Scopus Google Scholar, A. R. J. S. J. K. Li C. A. D. Simon C. G. L. Biol. 2007; PubMed Scopus Google Scholar). other miR-210 information is almost to expression analysis. Thus, we on the of the functional of miR-210 regulation in EC response to hypoxia. was that miR-210 up-regulation in normoxic EC tubulogenesis and migration, miR-210 blockade in the of hypoxia capillary-like EC migration, and EC and induces In keeping with this it has been that miR-210 inhibition R. M. R. H. Davuluri R. Liu M. Calin G.A. Ivan M. Cell. Biol. 2006; Scholar, J. Nucleic Res. 2005; PubMed Scopus Google Scholar). that the effects on migration and tubulogenesis are mediated by Although this is a mechanisms play a role as both cell and apoptosis induced by anti-miR-210 transfection were only the inhibition of tubulogenesis was almost Moreover, anti-miR-210 transfected cells a of The specific effect of miR-210 blockade was to their ability to their migration in response to main that has the of miRNA is the of miRNA targets P. Megraw M. Hatzigeorgiou A.G. Nat. Methods. 2006; 3: 881-886Crossref PubMed Scopus (479) Google Scholar, 11Rajewsky N. Nat. Genet. 2006; 38: S8-S13Crossref PubMed Scopus (939) Google Scholar). the of only targets has been in to by the To genes regulated by a was using four target prediction and targets that were not by at of that is a miR-210 miR-210 overexpression induced the of but not of Hypoxia induced mRNA was miR-210 by complementary Nucleic Acid prevented induced by hypoxia. containing a miR-210 binding sequence decreased the expression of a reporter luciferase gene upon hypoxia or miR-210 expression. Although all these that miR-210 regulates expression it is that mechanisms increase the of miR-210 and their have been to play a crucial role in the of the and in vascular S. Med. 2007; PubMed Scopus Google Scholar). numerous have the importance of in the regulation of angiogenesis and S. Med. 2007; PubMed Scopus Google Scholar, A. H. P.J. Science. PubMed Scopus Google Scholar). Although the specific role of in the regulation of angiogenesis is has been to as well as S. T. M. Science. PubMed Scopus Google Scholar). We that is a necessary event of miR-210-mediated stimulation of capillary-like formation and EC in response to Thus, it is to that of expression to the response to We can conclude that further are the modulation of miR-210 expression be a to control angiogenesis, either or The of in experiments using the hypoxic and of of in O2 concentration is with

Acute renal failure (ARF) is a common complication in patients with decompensated cirrhosis. The traditional diagnostic criteria of renal failure in these patients were proposed in 19961 and have been refined in subsequent years.2 According to these criteria, ARF is defined as an increase in serum creatinine (sCr) of ≥50% from baseline to a final value >1.5 mg/dL (133 µmol/L). However, the threshold value of 1.5 mg/dL (133 µmol/L) sCr to define renal failure in patients with decompensated cirrhosis has been challenged.3 ,4 In addition, the timeframe to distinguish acute from chronic renal failure has not been clearly identified, the only exception being type 1 hepatorenal syndrome (HRS). Meanwhile, new definitions for ARF, now termed acute kidney injury (AKI), have been proposed and validated in patients without cirrhosis.5–7 Recently these new criteria were also proposed and applied in the diagnosis of AKI in patients with cirrhosis.3 ,8–15 Thus, in December 2012, the International Club of Ascites (ICA) organised a consensus development meeting in Venice, Italy, in order to reach a new definition of AKI in patients with cirrhosis. The discussion among the experts continued thereafter for 2 years, both online and through several meetings, between those experts who had different positions on crucial points on the subject. This paper reports the scientific evidence supporting the final proposal of a new approach to the diagnosis and treatment of this condition, on which the experts agreed.

Intussusception of the bowel is defined as the telescoping of a proximal segment of the gastrointestinal tract within the lumen of the adjacent segment. This condition is frequent in children and presents with the classic triad of cramping abdominal pain, bloody diarrhea and a palpable tender mass. However, bowel intussusception in adults is considered a rare condition, accounting for 5% of all cases of intussusceptions and almost 1%-5% of bowel obstruction. Eight to twenty percent of cases are idiopathic, without a lead point lesion. Secondary intussusception is caused by organic lesions, such as inflammatory bowel disease, postoperative adhesions, Meckel's diverticulum, benign and malignant lesions, metastatic neoplasms or even iatrogenically, due to the presence of intestinal tubes, jejunostomy feeding tubes or after gastric surgery. Computed tomography is the most sensitive diagnostic modality and can distinguish between intussusceptions with and without a lead point. Surgery is the definitive treatment of adult intussusceptions. Formal bowel resection with oncological principles is followed for every case where a malignancy is suspected. Reduction of the intussuscepted bowel is considered safe for benign lesions in order to limit the extent of resection or to avoid the short bowel syndrome in certain circumstances.

One of the most promising areas of health innovation is the application of artificial intelligence (AI), primarily in medical imaging. This article provides basic definitions of terms such as "machine/deep learning" and analyses the integration of AI into radiology. Publications on AI have drastically increased from about 100-150 per year in 2007-2008 to 700-800 per year in 2016-2017. Magnetic resonance imaging and computed tomography collectively account for more than 50% of current articles. Neuroradiology appears in about one-third of the papers, followed by musculoskeletal, cardiovascular, breast, urogenital, lung/thorax, and abdomen, each representing 6-9% of articles. With an irreversible increase in the amount of data and the possibility to use AI to identify findings either detectable or not by the human eye, radiology is now moving from a subjective perceptual skill to a more objective science. Radiologists, who were on the forefront of the digital era in medicine, can guide the introduction of AI into healthcare. Yet, they will not be replaced because radiology includes communication of diagnosis, consideration of patient's values and preferences, medical judgment, quality assurance, education, policy-making, and interventional procedures. The higher efficiency provided by AI will allow radiologists to perform more value-added tasks, becoming more visible to patients and playing a vital role in multidisciplinary clinical teams.

BACKGROUND: Implantable cardioverter-defibrillators (ICDs) prevent sudden death from cardiac causes in selected patients but require the use of transvenous lead systems. To eliminate the need for venous access, we designed and tested an entirely subcutaneous ICD system. METHODS: First, we conducted two short-term clinical trials to identify a suitable device configuration and assess energy requirements. We evaluated four subcutaneous ICD configurations in 78 patients who were candidates for ICD implantation and subsequently tested the best configuration in 49 additional patients to determine the subcutaneous defibrillation threshold in comparison with that of the standard transvenous ICD. Then we evaluated the long-term use of subcutaneous ICDs in a pilot study, involving 6 patients, which was followed by a trial involving 55 patients. RESULTS: The best device configuration consisted of a parasternal electrode and a left lateral thoracic pulse generator. This configuration was as effective as a transvenous ICD for terminating induced ventricular fibrillation, albeit with a significantly higher mean (+/-SD) energy requirement (36.6+/-19.8 J vs. 11.1+/-8.5 J). Among patients who received a permanent subcutaneous ICD, ventricular fibrillation was successfully detected in 100% of 137 induced episodes. Induced ventricular fibrillation was converted twice in 58 of 59 patients (98%) with the delivery of 65-J shocks in two consecutive tests. Clinically significant adverse events included two pocket infections and four lead revisions. After a mean of 10+/-1 months, the device had successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. CONCLUSIONS: In small, nonrandomized studies, an entirely subcutaneous ICD consistently detected and converted ventricular fibrillation induced during electrophysiological testing. The device also successfully detected and treated all 12 episodes of spontaneous, sustained ventricular tachyarrhythmia. (ClinicalTrials.gov numbers, NCT00399217 and NCT00853645.)

BACKGROUND: Follow-up survival studies in patients with acute type B aortic dissection have been restricted to a small number of patients in single centers. We used data from a contemporary registry of acute type B aortic dissection to better understand factors associated with adverse long-term survival. METHODS AND RESULTS: We examined 242 consecutive patients discharged alive with acute type B aortic dissection enrolled in the International Registry of Acute Aortic Dissection (IRAD) between 1996 and 2003. Kaplan-Meier survival curves were constructed, and Cox proportional hazards analysis was performed to identify independent predictors of follow-up mortality. Three-year survival for patients treated medically, surgically, or with endovascular therapy was 77.6+/-6.6%, 82.8+/-18.9%, and 76.2+/-25.2%, respectively (median follow-up 2.3 years, log-rank P=0.61). Independent predictors of follow-up mortality included female gender (hazard ratio [HR],1.99; 95% confidence interval [CI], 1.07 to 3.71; P=0.03), a history of prior aortic aneurysm (HR, 2.17; 95% CI, 1.03 to 4.59; P=0.04), a history of atherosclerosis (HR, 2.48; 95% CI, 1.32 to 4.66; P<0.01), in-hospital renal failure (HR, 2.55; 95% CI, 1.15 to 5.63; P=0.02), pleural effusion on chest radiograph (HR, 2.56; 95% CI, 1.18 to 5.58; P=0.02), and in-hospital hypotension/shock (HR, 12.5; 95% CI, 3.24 to 48.21; P<0.01). CONCLUSIONS: Contemporary follow-up mortality in patients who survive to hospital discharge with acute type B aortic dissection is high, approaching 1 in every 4 patients at 3 years. Current treatment and follow-up surveillance require further study to better understand and optimize care for patients with this complex disease.

BACKGROUND: Surgical ventricular reconstruction is a specific procedure designed to reduce left ventricular volume in patients with heart failure caused by coronary artery disease. We conducted a trial to address the question of whether surgical ventricular reconstruction added to coronary-artery bypass grafting (CABG) would decrease the rate of death or hospitalization for cardiac causes, as compared with CABG alone. METHODS: Between September 2002 and January 2006, a total of 1000 patients with an ejection fraction of 35% or less, coronary artery disease that was amenable to CABG, and dominant anterior left ventricular dysfunction that was amenable to surgical ventricular reconstruction were randomly assigned to undergo either CABG alone (499 patients) or CABG with surgical ventricular reconstruction (501 patients). The primary outcome was a composite of death from any cause and hospitalization for cardiac causes. The median follow-up was 48 months. RESULTS: Surgical ventricular reconstruction reduced the end-systolic volume index by 19%, as compared with a reduction of 6% with CABG alone. Cardiac symptoms and exercise tolerance improved from baseline to a similar degree in the two study groups. However, no significant difference was observed in the primary outcome, which occurred in 292 patients (59%) who were assigned to undergo CABG alone and in 289 patients (58%) who were assigned to undergo CABG with surgical ventricular reconstruction (hazard ratio for the combined approach, 0.99; 95% confidence interval, 0.84 to 1.17; P=0.90). CONCLUSIONS: Adding surgical ventricular reconstruction to CABG reduced the left ventricular volume, as compared with CABG alone. However, this anatomical change was not associated with a greater improvement in symptoms or exercise tolerance or with a reduction in the rate of death or hospitalization for cardiac causes. (ClinicalTrials.gov number, NCT00023595.)

PURPOSE: Artificial intelligence (AI) models are playing an increasing role in biomedical research and healthcare services. This review focuses on challenges points to be clarified about how to develop AI applications as clinical decision support systems in the real-world context. METHODS: A narrative review has been performed including a critical assessment of articles published between 1989 and 2021 that guided challenging sections. RESULTS: We first illustrate the architectural characteristics of machine learning (ML)/radiomics and deep learning (DL) approaches. For ML/radiomics, the phases of feature selection and of training, validation, and testing are described. DL models are presented as multi-layered artificial/convolutional neural networks, allowing us to directly process images. The data curation section includes technical steps such as image labelling, image annotation (with segmentation as a crucial step in radiomics), data harmonization (enabling compensation for differences in imaging protocols that typically generate noise in non-AI imaging studies) and federated learning. Thereafter, we dedicate specific sections to: sample size calculation, considering multiple testing in AI approaches; procedures for data augmentation to work with limited and unbalanced datasets; and the interpretability of AI models (the so-called black box issue). Pros and cons for choosing ML versus DL to implement AI applications to medical imaging are finally presented in a synoptic way. CONCLUSIONS: Biomedicine and healthcare systems are one of the most important fields for AI applications and medical imaging is probably the most suitable and promising domain. Clarification of specific challenging points facilitates the development of such systems and their translation to clinical practice.

Significant improvement in the understanding of mesenchymal stem cell (MSC) biology has opened the way to their clinical use. However, concerns regarding the possibility that MSCs undergo malignant transformation have been raised. We investigated the susceptibility to transformation of human bone marrow (BM)-derived MSCs at different in vitro culture time points. MSCs were isolated from BM of 10 healthy donors and propagated in vitro until reaching either senescence or passage (P) 25. MSCs in the senescence phase were closely monitored for 8 to 12 weeks before interrupting the cultures. The genetic characterization of MSCs was investigated through array-comparative genomic hybridization (array-CGH), conventional karyotyping, and subtelomeric fluorescent in situ hybridization analysis both before and after prolonged culture. MSCs were tested for the expression of telomerase activity, human telomerase reverse transcriptase (hTERT) transcripts, and alternative lengthening of telomere (ALT) mechanism at different passages. A huge variability in terms of proliferative capacity and MSCs life span was noted between donors. In eight of 10 donors, MSCs displayed a progressive decrease in proliferative capacity until reaching senescence. In the remaining two MSC samples, the cultures were interrupted at P25 to pursue data analysis. Array-CGH and cytogenetic analyses showed that MSCs expanded in vitro did not show chromosomal abnormalities. Telomerase activity and hTERT transcripts were not expressed in any of the examined cultures and telomeres shortened during the culture period. ALT was not evidenced in the MSCs tested. BM-derived MSCs can be safely expanded in vitro and are not susceptible to malignant transformation, thus rendering these cells suitable for cell therapy approaches.

Echo-derived pulmonary arterial systolic pressure (PASP) and right ventricular (RV) tricuspid annular plane systolic excursion (TAPSE; from the end of diastole to end-systole) are of basic relevance in the clinical follow-up of heart failure (HF) patients, carrying two- to threefold increase in cardiac risk when increased and reduced, respectively. We hypothesized that the relationship between TAPSE (longitudinal RV fiber shortening) and PASP (force generated by the RV) provides an index of in vivo RV length-force relationship, with their ratio better disclosing prognosis. Two hundred ninety-three HF patients with reduced (HFrEF, n = 247) or with preserved left ventricular (LV) ejection fraction (HFpEF, n = 46) underwent echo-Doppler studies and N-terminal pro-brain-type natriuretic peptide assessment and were tracked for adverse events. The median follow-up duration was 20.8 mo. TAPSE vs. PASP relationship showed a downward regression line shift in nonsurvivors who were more frequently presenting with higher PASP and lower TAPSE. HFrEF and HFpEF patients exhibited a similar distribution along the regression line. Given the TAPSE, PASP, and TAPSE-to-PASP ratio (TAPSE/PASP) collinearity, separate Cox regression and Kaplan-Meier analyses were performed: one with TAPSE and PASP as individual measures, and the other combining them in ratio form. Hazard ratios for variables retained in the multivariate regression were as follows: TAPSE/PASP </≥ 0.36 mm/mmHg [hazard ratio (HR): 10.4, P < 0.001]; TAPSE </≥ 16 mm (HR: 5.1, P < 0.01); New York Heart Association functional class </≥ 3 (HR: 4.4, P < 0.001); E/e' (HR: 4.1, P < 0.001). This study shows that the TAPSE vs. PASP relationship is shifted downward in nonsurvivors with a similar distribution in HFrEF and HFpEF, and their ratio improves prognostic resolution. The TAPSE vs. PASP relationship as a possible index of the length-force relationship may be a step forward for a more efficient RV function evaluation and is not affected by the quality of LV dysfunction.

BACKGROUND: Given the high mortality rates in patients with type A aortic dissection, predictive tools to identify patients at increased risk of death are needed to assist clinicians for optimal treatment. METHODS AND RESULTS: Accordingly, we evaluated 547 patients with this diagnosis enrolled in the International Registry of Acute Aortic Dissection (IRAD) between January 1996 and December 1999. Univariate testing followed by multivariate logistic regression analysis was performed to identify independent predictors of death. In-hospital mortality rate was 32.5% in type A dissection patients. In-hospital complications (neurological deficits, altered mental status, myocardial or mesenteric ischemia, kidney failure, hypotension, cardiac tamponade, and limb ischemia) were increased in patients who died compared with survivors (P<0.05 for all). Logistic regression identified the following presenting variables as predictors of death: age > or =70 years (OR, 1.70; 95% CI, 1.05 to 2.77; P=0.03), abrupt onset of chest pain (OR 2.60; 95% CI, 1.22 to 5.54; P=0.01), hypotension/shock/tamponade (OR, 2.97; 95% CI, 1.83 to 4.81; P<0.0001), kidney failure (OR, 4.77; 95% CI, 1.80 to 12.6; P=0.002), pulse deficit (OR, 2.03; 95% CI, 1.25 to 3.29, P=0.004), and abnormal ECG (OR, 1.77; 95% CI, 1.06 to 2.95; P=0.03) (area under receiver operating curve, 0.74; Hosmer-Lemeshow statistic, P=0.75). CONCLUSIONS: The in-hospital mortality rate in acute type A aortic dissection is high and can be predicted with the use of a clinical model incorporated in a simple risk prediction tool. This tool can be used to educate patients with dissection about their predicted risk and in clinical research for risk adjustment while comparing outcomes of different therapies.

Crohn's disease (CD) is a chronic progressive destructive disease. Currently available instruments measure disease activity at a specific point in time. An instrument to measure cumulative structural damage to the bowel, which may predict long-term disability, is needed. The aim of this article is to outline the methods to develop an instrument that can measure cumulative bowel damage. The project is being conducted by the International Program to develop New Indexes in Crohn's disease (IPNIC) group. This instrument, called the Crohn's Disease Digestive Damage Score (the Lémann score), should take into account damage location, severity, extent, progression, and reversibility, as measured by diagnostic imaging modalities and the history of surgical resection. It should not be "diagnostic modality driven": for each lesion and location, a modality appropriate for the anatomic site (for example: computed tomography or magnetic resonance imaging enterography, and colonoscopy) will be used. A total of 24 centers from 15 countries will be involved in a cross-sectional study, which will include up to 240 patients with stratification according to disease location and duration. At least 120 additional patients will be included in the study to validate the score. The Lémann score is expected to be able to portray a patient's disease course on a double-axis graph, with time as the x-axis, bowel damage severity as the y-axis, and the slope of the line connecting data points as a measure of disease progression. This instrument could be used to assess the effect of various medical therapies on the progression of bowel damage.

Acute renal failure (ARF) is a common complication in patients with decompensated cirrhosis. The traditional diagnostic criteria of renal failure in these patients were proposed in 1996 and have been refined in subsequent years. According to these criteria, ARF is defined as an increase in serum creatinine (sCr) of >/= 50% from baseline to a final value >1.5 mg/dl (133 umol/L). However, the threshold value of 1.5 mg/dl (133umol/L) sCr to define renal failure in patients with decompensated cirrhosis has been challenged. In addition, the timeframe to distinguish acute from chronic renal failure has not been clearly identified, the only exception being type 1 hepatorenal syndrome (HRS). Meanwhile, new definitions for ARF, now termed acute kidney injury (AKI), have been proposed and validated in patients without cirrhosis. Recently these new criteria were also proposed and applied in the diagnosis of AKI in patients with cirrhosis. Thus, in December 2012, the International Club of Ascites (ICA) organised a consensus development meeting in Venice, Italy, in order to reach a new definition of AKI in patients with cirrhosis. The discussion among the experts continued thereafter for 2 years, both online and through several meetings, between those experts who had different positions on crucial points on the subject. This paper reports the scientific evidence supporting the final proposal of a new approach to the diagnosis and treatment of this condition, on which the experts agreed.

OBJECTIVE: The aim of this study was to investigate 3-year survival following a randomized controlled trial comparing minimally invasive with open esophagectomy in patients with esophageal cancer. BACKGROUND: Research on minimally invasive esophagectomy (MIE) has shown faster postoperative recovery and a marked decrease in pulmonary complications. Debate is ongoing as to whether the procedure is equivalent to open resection regarding oncologic outcomes. The study is a follow-up study of the TIME-trial (traditional invasive vs minimally invasive esophagectomy, a multicenter, randomized trial). METHODS: Between June 2009 and March 2011, patients with a resectable intrathoracic esophageal carcinoma, including the gastroesophageal junction tumors (Siewert I), were randomized between open and MI esophagectomy with curative intent. Primary outcome was 3-year disease-free survival. Secondary outcomes include overall survival, lymph node yield, short-term morbidity, mortality, complications, radicality, local recurrence, and metastasis. Analysis was by intention-to-treat. This trial is registered with the Netherlands Trial Register, NTR TC 2452. Both trial protocol and short-term results have been published previously. RESULTS: One hundred fifteen patients were included from 5 European hospitals and randomly assigned to open (n = 56) or MI esophagectomy (n = 59). Combined overall 3-year survival was 40.4% (SD 7.7%) in the open group versus 50.5% (SD 8%) in the minimally invasive group (P = 0.207). The hazard ratio (HR) is 0.883 (0.540 to 1.441) for MIE compared with open surgery. Disease-free 3-year survival was 35.9% (SD 6.8%) in the open versus 40.2% (SD 6.9%) in the MI group [HR 0.691 (0.389 to 1.239). CONCLUSIONS: The study presented here depicted no differences in disease-free and overall 3-year survival for open and MI esophagectomy. These results, together with short-term results, further support the use of minimally invasive surgical techniques in the treatment of esophageal cancer.

Pulmonary hypertension (PH) is frequent in left heart disease (LHD), as a consequence of the underlying condition. Significant advances have occurred over the past 5 years since the 5th World Symposium on Pulmonary Hypertension in 2013, leading to a better understanding of PH-LHD, challenges and gaps in evidence. PH in heart failure with preserved ejection fraction represents the most complex situation, as it may be misdiagnosed with group 1 PH. Based on the latest evidence, we propose a new haemodynamic definition for PH due to LHD and a three-step pragmatic approach to differential diagnosis. This includes the identification of a specific "left heart" phenotype and a non-invasive probability of PH-LHD. Invasive confirmation of PH-LHD is based on the accurate measurement of pulmonary arterial wedge pressure and, in patients with high probability, provocative testing to clarify the diagnosis. Finally, recent clinical trials did not demonstrate a benefit in treating PH due to LHD with pulmonary arterial hypertension-approved therapies.

We obtained chest computed tomography (CT) sections in 12 normal subjects (controls) and 17 patients with the adult respiratory distress syndrome (ARDS) to investigate regional lung inflation. A basal CT section (just above the diaphragm) was obtained in the supine position at zero cm H2O end-expiratory pressure. In each CT section the distance from ventral to dorsal surface (hT) was divided into 10 equal intervals, and 10 lung levels from ventral (no. 1) to dorsal (no. 10) were defined. Knowing the average density and the volume of each level, we computed: (1) the tissue volume; (2) the gas/tissue (g/t) ratio (index of regional inflation); (3) the hydrostatic pressure superimposed on each level (SPL), estimated as density x height. The total volume of the basal CT section was 49 +/- 2.5 ml x m-2 (mean +/- SE) in control subjects and 43 +/- 2.3 ml x m-2 in patients with ARDS (p = not significant [NS]). The tissue volume, however, was 16.7 +/- 0.8 ml x m-2 in control subjects and 31.6 +/- 1.7 ml x m-2 in patients with ARDS (p < 0.01). The g/t ratio in level 1 averaged 4.7 +/- 0.5 in control subjects and 1.2 +/- 0.2 in patients with ARDS (p < 0.01), and this ratio decreased exponentially from level 1 to level 10, both in controls and patients with ARDS. The Kd constant of the exponential decrease was 13.9 +/- 1.3 cm in control subjects and 7.8 +/- 0.8 cm in patients with ARDS (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)