Prevalence and predictors of antibiotic prescription among patients hospitalized with viral lower respiratory tract infections in Southern Province, Sri Lanka.

BACKGROUND: Antimicrobial overprescription is common for lower respiratory tract infections (LRTI), as viral and bacterial infections generally present with similar clinical features. Overprescription is associated with downstream antimicrobial resistance. This study aims to identify the prevalence and predictors of antibiotic prescription among patients hospitalized with viral LRTI. METHODS: A prospective cohort study was conducted among patients aged ≥1 year hospitalized with viral LRTI in a tertiary care hospital in Southern Province, Sri Lanka from 2018-2021. Demographic, clinical, and laboratory data were recorded. Nasopharyngeal and blood samples were collected for multiplex polymerase chain reaction testing for 21 respiratory pathogens and procalcitonin (PCT) detection, respectively. Demographic and clinical features associated with antibiotic prescription were identified using Chi Square and t-tests; significant variables (p<0.05) were further included in multivariable logistic regression models. The potential impact of biomarker testing on antibiotic prescription was simulated using standard c-reactive protein (CRP) and PCT cut-offs. RESULTS: Of 1217 patients enrolled, 438 (36.0%) had ≥1 respiratory virus detected, with 48.4% of these patients being male and 30.8% children. Influenza A (39.3%) and human rhinovirus/ enterovirus (28.3%) were most commonly detected. A total of 114 (84.4%) children and 266 (87.8%) adults with respiratory viruses were treated with antibiotics. Among children, neutrophil percentage (median 63.6% vs 47.6%, p = 0.04) was positively associated with antibiotic prescription. Among adults, headache (60.6% vs 35.1%, p = 0.003), crepitations/crackles (55.3% vs 21.6%, p<0.001), rhonchi/wheezing (42.9% vs 18.9%, p = 0.005), and chest x-ray opacities (27.4% vs 8.1%, p = 0.01) were associated with antibiotic prescription. Access to CRP and procalcitonin test results could have potentially decreased inappropriate antibiotic prescription in this study by 89.5% and 83.3%, respectively. CONCLUSIONS: High proportions of viral detection and antibiotic prescription were observed among a large inpatient cohort with LRTI. Increased access to point-of-care biomarker testing may improve antimicrobial prescription.

Study protocol: improving response to malaria in the Amazon through identification of inter-community networks and human mobility in border regions of Ecuador, Peru and Brazil.

INTRODUCTION: Understanding human mobility's role in malaria transmission is critical to successful control and elimination. However, common approaches to measuring mobility are ill-equipped for remote regions such as the Amazon. This study develops a network survey to quantify the effect of community connectivity and mobility on malaria transmission. METHODS: We measure community connectivity across the study area using a respondent driven sampling design among key informants who are at least 18 years of age. 45 initial communities will be selected: 10 in Brazil, 10 in Ecuador and 25 in Peru. Participants will be recruited in each initial node and administered a survey to obtain data on each community's mobility patterns. Survey responses will be ranked and the 2-3 most connected communities will then be selected and surveyed. This process will be repeated for a third round of data collection. Community network matrices will be linked with each country's malaria surveillance system to test the effects of mobility on disease risk. ETHICS AND DISSEMINATION: This study protocol has been approved by the institutional review boards of Duke University (USA), Universidad San Francisco de Quito (Ecuador), Universidad Peruana Cayetano Heredia (Peru) and Universidade Federal Minas Gerais (Brazil). Results will be disseminated in communities by the end of the study.

Network Profile: Improving Response to Malaria in the Amazon through Identification of Inter-Community Networks and Human Mobility in Border Regions of Ecuador, Peru, and Brazil.

Objectives: Understanding human mobility's role on malaria transmission is critical to successful control and elimination. However, common approaches to measuring mobility are ill-equipped for remote regions such as the Amazon. This study develops a network survey to quantify the effect of community connectivity and mobility on malaria transmission. Design: A community-level network survey. Setting: We collect data on community connectivity along three river systems in the Amazon basin: the Pastaza river corridor spanning the Ecuador-Peru border; and the Amazon and Javari river corridors spanning the Brazil-Peru border. Participants: We interviewed key informants in Brazil, Ecuador, and Peru, including from indigenous communities: Shuar, Achuar, Shiwiar, Kichwa, Ticuna, and Yagua. Key informants are at least 18 years of age and are considered community leaders. Primary outcome: Weekly, community-level malaria incidence during the study period. Methods: We measure community connectivity across the study area using a respondent driven sampling design. Forty-five communities were initially selected: 10 in Brazil, 10 in Ecuador, and 25 in Peru. Participants were recruited in each initial node and administered a survey to obtain data on each community's mobility patterns. Survey responses were ranked and the 2-3 most connected communities were then selected and surveyed. This process was repeated for a third round of data collection. Community network matrices will be linked with eadch country's malaria surveillance system to test the effects of mobility on disease risk. Findings: To date, 586 key informants were surveyed from 126 communities along the Pastaza river corridor. Data collection along the Amazon and Javari river corridors is ongoing. Initial results indicate that network sampling is a superior method to delineate migration flows between communities. Conclusions: Our study provides measures of mobility and connectivity in rural settings where traditional approaches are insufficient, and will allow us to understand mobility's effect on malaria transmission.

Tension-dependent RHGF-1 recruitment to stress fibers drives robust spermathecal tissue contraction.

Contractile epithelial tubes are found in various organs, such as lung airways and blood capillaries. Their ability to sense luminal pressure and respond with adequate contractility is essential for their physiology, and its mis-regulation results in diseases such as asthma and hypertension. Here, we describe a mechanoresponsive regulatory pathway downstream of tissue stretching that controls contraction of the C. elegans spermatheca, a tubular structure where fertilization occurs. Using live-imaging, we show that ovulation-induced stretching of spermathecal cells leads to recruitment of the RhoGEF RHGF-1 to stress fibers, which activates RHO-1 and myosin II in a positive feedback loop. Through deletion analysis, we identified the PDZ domain of RHGF-1 as responsible for F-actin binding, and genetic epistasis analysis with the RhoGAP spv-1 demonstrated that tension-dependent recruitment of RHGF-1 to F-actin is required for robust spermathecal contractility. Our study illustrates how mechanosensitive regulators of Rho GTPases provide epithelial tubes the ability to tune their contractility in response to internal pressure.

Functional Insights into Protein Kinase A (PKA) Signaling from C. elegans.

Protein kinase A (PKA), which regulates a diverse set of biological functions downstream of cyclic AMP (cAMP), is a tetramer consisting of two catalytic subunits (PKA-C) and two regulatory subunits (PKA-R). When cAMP binds the PKA-R subunits, the PKA-C subunits are released and interact with downstream effectors. In Caenorhabditis elegans (C. elegans), PKA-C and PKA-R are encoded by kin-1 and kin-2, respectively. This review focuses on the contributions of work in C. elegans to our understanding of the many roles of PKA, including contractility and oocyte maturation in the reproductive system, lipid metabolism, physiology, mitochondrial function and lifespan, and a wide variety of behaviors. C. elegans provides a powerful genetic platform for understanding how this kinase can regulate an astounding variety of physiological responses.

Necesidad del desarrollo de competencias en cuidados paliativos durante el pregrado de la carrera de medicina / Need for the development of competencies in palliative care during the undergraduate of the medical career

Sr. Editor: Los Cuidados Paliativos (CP) tienen como finalidad mejorar la calidad de vida y aliviar el sufrimiento de los pacientes con padecimientos graves e incurables. Con el envejecimiento de la población y la mayor prevalencia de las enfermedades crónicas, el número de personas con necesidad de estos cuidados se ha incrementado. Los CP tienen carácter multidimensional e interdisciplinario, se pueden brindar en diferentes niveles de atención y están a cargo tanto de médicos generales como especialistas. Se requiere por lo tanto de una adecuada formación en esta disciplina durante el pregrado de la carrera de medicina, que permita el desarrollo de las competencias necesarias para su aplicación en la práctica médica.

Dear editor, Palliative Care (PC) aims to improve the quality of life and alleviate the suffering of patients with serious and incurable conditions. With the aging of the population and the higher prevalence of chronic diseases, the number of people in need of this care has increased. PC is multidimensional and interdisciplinary; and can be provided at different levels of care by both general practitioners and specialists. Therefore, adequate training in this discipline must be required during the medicine degree to allow the development of the necessary skills for its application in medical practice.

Biological, geological and chemical effects of oxygen injection in underground gas storage aquifers in the setting of biomethane deployment.

The last few years have seen the proliferation of anaerobic digestion plants to produce biomethane. Oxygen (O2) traces added to biogas during the desulfurization process are co-injected in the gas network and can be stored in Underground Gas Storage (UGS). However, there are no data available for the undesirable effects of O2 on these anoxic environments, especially on deep aquifers. In addition to mineral alteration, O2 can have an impact on the anaerobic autochthonous microbial life. In our study, the storage conditions of an UGS aquifer were reproduced in a high-pressure reactor and bio-geo-chemical interactions between the aqueous, gas and solid phases were studied. Sulfate was depleted from the liquid phase for three consecutive times during the first 130 days of incubation reproducing the storage conditions (36 °C, 60 bar, methane with 1% CO2). Sulfate-reducers, such as Desulfovibrionaceae, were identified from the high-pressure system. Simulations with PHREEQC were used to determine the thermodynamic equilibrium to confirm any gas consumption. CO2 quantities decreased in the gas phase, suggesting its use as carbon source by microbial life. Benzene and toluene, hydrocarbons found in traces and known to be biodegradable in storages, were monitored and a decrease of toluene was revealed and associated to the Peptococcaceae family. Afterwards, O2 was added as 1% of the gas phase, corresponding to the maximum quantity found in biomethane after desulfurization process. Re-oxidation of sulfide to sulfate was observed along with the end of sulfate reducing activity and toluene biodegradation and the disappearance of most of the community. H2 surprisingly appeared and accumulated as soon as hydrogenotrophic sulfate-reducers decreased. H2 would be produced via the necromass fermentation accomplished by microorganisms able to resist the oxic conditions of 4.42·10-4 mol.Kgw-1 of O2. The solid phase composed essentially of quartz, presented no remarkable changes.

A deep continental aquifer downhole sampler for microbiological studies.

To be effective, microbiological studies of deep aquifers must be free from surface microbial contaminants and from infrastructures allowing access to formation water (wellheads, well completions). Many microbiological studies are based on water samples obtained after rinsing a well without guaranteeing the absence of contaminants from the biofilm development in the pipes. The protocol described in this paper presents the adaptation, preparation, sterilization and deployment of a commercial downhole sampler (PDSshort, Leutert, Germany) for the microbiological studying of deep aquifers. The ATEX sampler (i.e., explosive atmospheres) can be deployed for geological gas storage (methane, hydrogen). To validate our procedure and confirm the need to use such a device, cell counting and bacterial taxonomic diversity based on high-throughput sequencing for different water samples taken at the wellhead or at depth using the downhole sampler were compared and discussed. The results show that even after extensive rinsing (7 bore volumes), the water collected at the wellhead was not free of microbial contaminants, as shown by beta-diversity analysis. The downhole sampler procedure was the only way to ensure the purity of the formation water samples from the microbiological point of view. In addition, the downhole sampler allowed the formation water and the autochthonous microbial community to be maintained at in situ pressure for laboratory analysis. The prevention of the contamination of the sample and the preservation of its representativeness are key to guaranteeing the best interpretations and understanding of the functioning of the deep biosphere.

ZYX-1/Zyxin plays a minor role in oocyte transit through the spermatheca in C. elegans.

In C. elegans, oocytes are ovulated into the spermatheca, where they are fertilized before being pushed into the uterus. Contraction in the C. elegans spermatheca is driven by circumferential acto-myosin fibers. The C. elegans zyxin homolog, zyx-1, is expressed in the body wall muscle, pharynx and spermatheca. To our surprise, a CRISPR-generated zyx-1 deletion allele results in no overt developmental phenotypes, and the spermathecal actin cytoskeleton appears wild type, however, oocyte transit through the spermatheca is slower than in wild type animals. This suggests ZYX-1/Zyxin may regulate spermathecal contraction magnitude or timing of spermathecal bag contraction and/or spermathecal-uterine valve dilation.

Gα/GSA-1 works upstream of PKA/KIN-1 to regulate calcium signaling and contractility in the Caenorhabditis elegans spermatheca.

Correct regulation of cell contractility is critical for the function of many biological systems. The reproductive system of the hermaphroditic nematode C. elegans contains a contractile tube of myoepithelial cells known as the spermatheca, which stores sperm and is the site of oocyte fertilization. Regulated contraction of the spermatheca pushes the embryo into the uterus. Cell contractility in the spermatheca is dependent on actin and myosin and is regulated, in part, by Ca2+ signaling through the phospholipase PLC-1, which mediates Ca2+ release from the endoplasmic reticulum. Here, we describe a novel role for GSA-1/Gαs, and protein kinase A, composed of the catalytic subunit KIN-1/PKA-C and the regulatory subunit KIN-2/PKA-R, in the regulation of Ca2+ release and contractility in the C. elegans spermatheca. Without GSA-1/Gαs or KIN-1/PKA-C, Ca2+ is not released, and oocytes become trapped in the spermatheca. Conversely, when PKA is activated through either a gain of function allele in GSA-1 (GSA-1(GF)) or by depletion of KIN-2/PKA-R, the transit times and total numbers, although not frequencies, of Ca2+ pulses are increased, and Ca2+ propagates across the spermatheca even in the absence of oocyte entry. In the spermathecal-uterine valve, loss of GSA-1/Gαs or KIN-1/PKA-C results in sustained, high levels of Ca2+ and a loss of coordination between the spermathecal bag and sp-ut valve. Additionally, we show that depleting phosphodiesterase PDE-6 levels alters contractility and Ca2+ dynamics in the spermatheca, and that the GPB-1 and GPB-2 Gß subunits play a central role in regulating spermathecal contractility and Ca2+ signaling. This work identifies a signaling network in which Ca2+ and cAMP pathways work together to coordinate spermathecal contractions for successful ovulations.

The Digital Divide in Health-Related Technology Use: The Significance of Race/Ethnicity.

Background and Objectives: Technology can enhance the health and quality of life of diverse populations and may play an important role in reducing health disparities. Although a "digital divide" between the young and the old has been noted, it is unclear whether the use of technology for managing health differs by race/ethnicity among older adults. This study uses nationally representative data from community-dwelling older Americans to characterize racial/ethnic differences in health-related technology use. Design and Methods: Data came from 1,336 white, black, and Hispanic adults aged 54 and older who completed the 2014 technology module of the Health and Retirement Study. Racial/ethnic differences in overall health-related technology use were assessed using Poisson regression. Then, F-tests were used to assess differences in the use of phone calls, text messages, E-mails, social media, health management sites, health-related mobile applications, web searches, and brain games for health purposes. Results: Compared to whites, older blacks and Hispanics were less likely to use technology for health-related purposes after accounting for demographic characteristics, education, and health conditions. They were also less likely to make or receive phone calls, use health management sites, search the web for health information, and use brain games for their health. Discussion and Implications: Older racial and ethnic minorities are less likely than whites to use certain technologies when managing their health. These findings highlight the importance of understanding the patterns of health-related technology use across racially and ethnically diverse populations to appropriately tailor interventions aimed at improving minority health and eliminating health disparities.

Soil Fungal:Bacterial Ratios Are Linked to Altered Carbon Cycling.

Despite several lines of observational evidence, there is a lack of consensus on whether higher fungal:bacterial (F:B) ratios directly cause higher soil carbon (C) storage. We employed RNA sequencing, protein profiling and isotope tracer techniques to evaluate whether differing F:B ratios are associated with differences in C storage. A mesocosm (13)C labeled foliar litter decomposition experiment was performed in two soils that were similar in their physico-chemical properties but differed in microbial community structure, specifically their F:B ratio (determined by PLFA analyses, RNA sequencing and protein profiling; all three corroborating each other). Following litter addition, we observed a consistent increase in abundance of fungal phyla; and greater increases in the fungal dominated soil; implicating the role of fungi in litter decomposition. Litter derived (13)C in respired CO2 was consistently lower, and residual (13)C in bulk SOM was higher in high F:B soil demonstrating greater C storage potential in the F:B dominated soil. We conclude that in this soil system, the increased abundance of fungi in both soils and the altered C cycling patterns in the F:B dominated soils highlight the significant role of fungi in litter decomposition and indicate that F:B ratios are linked to higher C storage potential.

Plant diversity increases soil microbial activity and soil carbon storage.

Plant diversity strongly influences ecosystem functions and services, such as soil carbon storage. However, the mechanisms underlying the positive plant diversity effects on soil carbon storage are poorly understood. We explored this relationship using long-term data from a grassland biodiversity experiment (The Jena Experiment) and radiocarbon ((14)C) modelling. Here we show that higher plant diversity increases rhizosphere carbon inputs into the microbial community resulting in both increased microbial activity and carbon storage. Increases in soil carbon were related to the enhanced accumulation of recently fixed carbon in high-diversity plots, while plant diversity had less pronounced effects on the decomposition rate of existing carbon. The present study shows that elevated carbon storage at high plant diversity is a direct function of the soil microbial community, indicating that the increase in carbon storage is mainly limited by the integration of new carbon into soil and less by the decomposition of existing soil carbon.

A complex mosaicism 45,X/46,X,del(Xq)/46,X,idic(Xq) in a patient with secondary amenorrhea.

A complex mosaicism involving the X chromosome was found in a 35-year-old female affected by secondary amenorrhea and short stature. Her karyotype was: 45,X[20]/46,X,del(X)(pter-->q26::qter)[15]/46,X,idic(X)(pter-->q26::q26-->pter)[9]. No cell contained both abnormal X chromosomes. This observation would suggest a possible mechanism underlying the formation of isodicentric chromosomes.

CD38 expression correlates with adverse biological features and predicts poor clinical outcome in B-cell chronic lymphocytic leukemia.

CD38 identifies a surface molecule with multi-functional activity. Its prognostic importance in B-cell chronic lymphocytic leukemia (B-CLL) is currently under investigation in view of the fact that two different groups have recently indicated that CD38 expression could be an independent prognostic marker in B-CLL. We analyzed the clinico-biological features of 61 immunologically typical (CD5+CD23+) B-CLL patients stratified according to the CD38 expression. Twenty-two (36%) patients expressed CD38 in more than 30% of CD19-positive cells and were considered as CD38-positive B-CLL. Atypical morphology (p 0.02), peripheral blood lymphocytosis (p 0.01) and diffuse histopathologic bone marrow pattern (p 0.003) were findings found to be closely associated with CD38 expression. On the other hand, A and B Binet stages (p 0.02) and interstitial bone marrow involvement (p 0.005) were more represented in the CD38-negative B-CLL group. Trisomy 12 was detected more frequently in the CD38-positive B-CLL group, while 13q14 deletions mainly occurred in CD38-negative group (p 0.005). Finally, median survival of CD38-positive B-CLL patients was 90 months, while it was not reached at 180 months in CD38-negative patients. Taken together, our data strongly suggest that the evaluation of CD38 expression may identify two groups patients with B-CLL greatly differing in their clinico-biological features.

Morphologically typical and atypical B-cell chronic lymphocytic leukemias display a different pattern of surface antigenic density.

Recent evidences suggest that B-cell chronic lymphocytic leukemia (B-CLL) may have heterogeneous biological and clinical features. Immunological phenotype may be useful for distinguishing these different forms of disease. We used a quantitative flow cytometric approach to analyze the expression of several membrane molecules (CD19, CD20, CD22, CD23, CD11c, CD5, CD79b) commonly used to diagnose and characterize B-CLL in a choort of 84 consecutive B-CLL patients diagnosed according to morphological and immunological findings. We found that morphologically so-called "atypical" B-CLL displayed a significantly higher number of CD20 and CD22 molecules than typical forms. On the other hand, CD19 was found to be more expressed in typical B-CLL, although without reaching statistical significance. Finally, no difference was detected with respect to CD23, CD79b, CD11c and CD5 number of molecules/per cell between typical and atypical B-CLL. Other clinico-biological features, such as surface membrane immunoglobulin density, percentage of CD79b and FMC7 expression, peripheral blood lymphocytosis, trisomy 12 and advanced clinical stages were also found to be more frequent in atypical B-CLL. In conclusion, our data confirm the hypothesis that atypical B-CLL is a disease sustained by more mature B-cells, closely related but, at the same time, clearly distincted from neoplastic cells of typical B-CLL.

Treatment of "poor risk" acute myeloid leukemia with fludarabine, cytarabine and G-CSF (flag regimen): a single center study.

We describe a single center experience of 41 consecutive patients with poor prognosis acute myeloid leukemia (AML) who received a single course of FLAG regimen consisting of Fludarabine 30 mg/m2/day plus Cytarabine 2 gr/m2/day (days 1-5) and G-CSF 5 mg/Kg/day (from day 0 to polymorphonuclear recovery) as salvage therapy. Eleven patients were primarily refractory to previous chemotherapy, 10 patients were in first relapse, 2 patients in second relapse and 7 patients in relapse after transplants. Eleven cases were defined as secondary AML (diagnosis of AML made after a preexisting diagnosis of myelodysplastic syndrome). The median age was 52.6 years (range 16-72); 29 patients were males and 12 females. Overall, 23 (56%) patients reached complete remission (CR), 3 patients died of infection (2) or hemorrhage (1) during induction, and 15 (36%) patients had resistant disease. The highest CR rates (80%) were obtained in relapsed cases; de novo and secondary AML registered 60% and 45% of CR rates, respectively. Patients achieving CR received a second FLAG course as consolidation and were submitted to an individualized program post-remission therapy, depending on the age and performance status. Hematological and non hematological toxicities were acceptable. In conclusion, our data confirm that FLAG is a an high effective treatment for poor prognosis AML and in young patients allows intensive post remissional therapy including allogeneic BMT.

Adding growth factors or interleukin-3 to erythropoietin has limited effects on anemia of transfusion-dependent patients with myelodysplastic syndromes unresponsive to erythropoietin alone.

BACKGROUND AND OBJECTIVES: Recombinant erythropoietin (r-EPO) induces erythroid responses in patients affected by myelodysplastic syndromes (MDS). However, the response rate declines to 10-15% in MDS with substantial transfusion needs. Both in vitro and in vivo studies have suggested that the addition of growth factors (G-CSF, GM-CSF) or interleukin-3 (IL-3) may potentiate the effect of r-EPO on dysplastic erythropoiesis. The aim of this study was to evaluate the effects of the combination of r-EPO with G-CSF, GM-CSF or IL-3 on the anemia of heavily transfusion-dependent MDS patients, previously unresponsive to r-EPO alone. PATIENTS AND METHODS: Sixty patients with transfusion-dependent MDS, already treated without significant erythroid response with r-EPO alone, were scheduled to receive, for at least 8 weeks, r-EPO subcutaneously at the dose of 300 U/kg t.i.w. in combination with G-CSF (300 microcg s.c. t.i.w., 27 patients), or GM-CSF (300 microcg s.c. t.i.w., 23 patients), or IL-3 (5 microcg/kg s.c. t.i.w., 10 patients), after a two-week pre-phase during which G-CSF, GM-CSF and IL-3 were administered daily at the same dose, as single drugs. RESULTS: Ten patients were not evaluable for erythroid response because of relevant side effects related to GM-CSF or IL-3 administration. Overall, among 50 patients who completed the study, there were 3 erythroid responses (as determined by complete abolition of red-cell transfusions): 1 (4%) in the G-CSF + r-EPO and 2 (10.5%) in the GM-CSF + r-EPO treated groups. No patient responded to the combination of r-EPO + IL-3. All responders had inappropriate serum levels of endogenous EPO and a relatively short disease duration. Both responders to GM-CSF + r-EPO developed acute myeloid leukemia 2-9 months after the start of the combined therapy. A third elderly patient, treated with the same association, developed marrow hypoplasia. A significant increase in leukocyte count occurred in 96% of patients who received r-EPO + G-CSF, 78.9% of those treated with r-EPO + GM-CSF and 66% of subjects receiving r-EPO + IL-3. A significant increase in platelet count was observed in a single patient receiving r-EPO and GM-CSF, while a slight decrease in platelet count with respect to baseline levels occurred in about 20% of patients. INTERPRETATION AND CONCLUSIONS: Our results suggest that the combination of r-EPO with G-CSF, GM-CSF or IL-3, at least at the doses and schedules employed in the present study, has limited efficacy on the anemia of heavily transfusion-dependent MDS patients previously unresponsive to r-EPO alone. However, in this setting of patients, the combination of G-CSF or GM-CSF + r-EPO may occasionally be effective in subjects with low circulating levels of serum EPO and short disease duration.

Minimally differentiated acute myeloid leukemia (AML M0): clinico-biological findings of 29 cases.

Twenty-nine cases of minimally differentiated acute myeloid leukemia or AML M0 identified among 441 AML diagnosed in the last 12 years are reported. In all cases, flow cytometric analysis using a large panel of monoclonal antibodies and cytogenetic and molecular studies (IgH, TcRbeta, BCR/ABL, AML1/ETO and CBFB-MYH11 rearrangements) were performed. Of the 29 patients, 27 were treated with intensive chemotherapy based on GIMEMA protocols. We noted a greater incidence of older (over 60 years) and male patients (52% and 65%, respectively). CD33, CD13, CD7 and TdT were expressed in 79.3%, 82.7%, 58.6% and 42.8% of cases, respectively. Antigenic MPO was present in 17 of 22 cases (77.3%). Most cases expressed CD34 (93.1%), HLA-DR (93.1%), CD117 (80%) and CD45RA (87%). CD45RO and CD90 were consistently negative. In all cases, we observed an up-expression of bcl-2 and a down-expression of CD95 with an inverse trend between the two markers (r -5253; p 0.03). Karyotypic abnormalities were demonstrated in 53.6% of cases. Of these, 6 involved chromosomes 5, 7 and 8, t(9;22), confirmed by the BCR/ABL transcript, was detected in one case. Rearrangements of the TcRbeta and IgH chains were observed in 3 and 2 cases, respectively. No AML1/ETO and CBFB-MYH11 transcripts were found. Twelve out of 27 patients (44%) achieved a complete remission (CR) (in 2 cases after rescue therapy). Seven early (range 1-9 months) and one late (32 months) relapses were observed. Five patients are alive, but only the 4 who underwent bone marrow transplantation are in persistent first CR. In conclusion, AML M0 is a subtype of AML antigenically well detectable, endowed with many adverse parameters (older age, TdT and CD34 expression, resistance to apoptosis, unfavorable cytogenetic abnormalities) and poor prognosis. A very aggressive consolidation treatment can be useful to improve the outcome.