355 results on '"Delfino, D."'
Search Results
52. Role of caspase-8 in thymus function.
- Author
-
Pozzesi, N, Fierabracci, A, Liberati, A M, Martelli, M P, Ayroldi, E, Riccardi, C, and Delfino, D V
- Subjects
CASPASES ,APOPTOSIS ,GLUCOCORTICOIDS ,CELL death ,THYMOCYTES - Abstract
The thymus is the primary organ responsible for de novo generation of immunocompetent T cells that have a diverse repertoire of antigen recognition. During the developmental process, 98% of thymocytes die by apoptosis. Thus apoptosis is a dominant process in the thymus and occurs through either death by neglect or negative selection or through induction by stress/aging. Caspase activation is an essential part of the general apoptosis mechanism, and data suggest that caspases may have a role in negative selection; however, it seems more probable that caspase-8 activation is involved in death by neglect, particularly in glucocorticoid-induced thymocyte apoptosis. Caspase-8 is active in double-positive (DP) thymocytes in vivo and can be activated in vitro in DP thymocytes by T-cell receptor (TCR) crosslinking to induce apoptosis. Caspase-8 is a proapoptotic member of the caspase family and is considered an initiator caspase, which is activated upon stimulation of a death receptor (e.g., Fas), recruitment of the adaptor molecule FADD, and recruitment and subsequent processing of procaspase-8. The main role of caspase-8 seems to be pro-apoptotic and, in this review, we will discuss about the involvement of caspase-8 in (1) TCR-triggered thymic apoptosis; (2) death receptor-mediated thymic apoptosis; and (3) glucocorticoid-induced thymic apoptosis. Regarding TCR triggering, caspase-8 is active in medullary, semi-mature heat-stable antigen
hi (HAShi SP) thymocytes as a consequence of strong TCR stimulation. The death receptors Fas, FADD, and FLIP are involved upstream of caspase-8 activation in apoptosis; whereas, Bid and HDAC7 are involved downstream of caspase-8. Finally, caspase-8 is involved in glucocortocoid-induced thymocyte apoptosis through an activation loop with the protein GILZ. GILZ activates caspase-8, promoting GILZ sumoylation and its protection from proteasomal degradation. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
53. Compositional Analysis of the Major Capsular Polysaccharides of Cryptococcus Neoformans by Highperformance Anion-Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD)
- Author
-
Corradini, C., primary, Canali, G., additional, Cavazza, A., additional, Delfino, D., additional, and Teti, G., additional
- Published
- 1998
- Full Text
- View/download PDF
54. Role of the capsule in microglial cell—Cryptococcus neoformansinteraction: impairment of antifungal activity but not of secretory functions
- Author
-
Barluzzi, R., primary, Brozzetti, A., additional, Delfino, D., additional, Bistoni, F., additional, and Blasi, E., additional
- Published
- 1998
- Full Text
- View/download PDF
55. Interleukin-6 production by human monocytes stimulated with Cryptococcus neoformans components
- Author
-
Delfino, D, primary, Cianci, L, additional, Lupis, E, additional, Celeste, A, additional, Petrelli, M L, additional, Curró, F, additional, Cusumano, V, additional, and Teti, G, additional
- Published
- 1997
- Full Text
- View/download PDF
56. Tumor necrosis factor-inducing activities of Cryptococcus neoformans components
- Author
-
Delfino, D, primary, Cianci, L, additional, Migliardo, M, additional, Mancuso, G, additional, Cusumano, V, additional, Corradini, C, additional, and Teti, G, additional
- Published
- 1996
- Full Text
- View/download PDF
57. Role of gamma interferon in a neonatal mouse model of group B streptococcal disease
- Author
-
Cusumano, V, primary, Mancuso, G, additional, Genovese, F, additional, Delfino, D, additional, Beninati, C, additional, Losi, E, additional, and Teti, G, additional
- Published
- 1996
- Full Text
- View/download PDF
58. Tumor Cell Death Induced through the Receptor for Interleukin-2
- Author
-
Migliorati, G., primary, Delfino, D. V., additional, Nocentini, G., additional, Nicoletti, I., additional, and Riccardi, C., additional
- Published
- 1995
- Full Text
- View/download PDF
59. Apoptosis induced by dexamethasone is inhibited by CD44 activation
- Author
-
Ayroldi, E., primary, Cannarile, L., additional, D'Adamio, F., additional, Bartoli, A., additional, Delfino, D., additional, Migliorati, G., additional, and Riccardi, C., additional
- Published
- 1995
- Full Text
- View/download PDF
60. Beneficial effects of interleukin-6 in neonatal mouse models of group B streptococcal disease
- Author
-
Mancuso, G, primary, Tomasello, F, additional, Migliardo, M, additional, Delfino, D, additional, Cochran, J, additional, Cook, J A, additional, and Teti, G, additional
- Published
- 1994
- Full Text
- View/download PDF
61. On the Inequality λ(R/R) ≤ t(R)λ(R/C) for One-Dimensional Local Rings
- Author
-
Delfino, D., primary
- Published
- 1994
- Full Text
- View/download PDF
62. Role of CD44 in the development of natural killer cells from precursors in long-term cultures of mouse bone marrow.
- Author
-
Delfino, D V, primary, Patrene, K D, additional, DeLeo, A B, additional, DeLeo, R, additional, Herberman, R B, additional, and Boggs, S S, additional
- Published
- 1994
- Full Text
- View/download PDF
63. Dysuria as Presenting Symptom of Necrotizing Glomerulonephritis
- Author
-
Catalano, C., primary, Enia, G., additional, Delfino, D., additional, Martorano, C., additional, and Zoccali, C., additional
- Published
- 1993
- Full Text
- View/download PDF
64. Generation of Superoxide Anion and Candidacidal Activity by Lipopolysaccharide-Treated Macrophages from Patients Affected by Neoplasia
- Author
-
Merendino, R.A., primary, Arena, A., additional, Delfino, D., additional, Zummo, S., additional, Mesiti, M., additional, Chillemi, S., additional, and Bonina, L., additional
- Published
- 1992
- Full Text
- View/download PDF
65. Glucocorticoid-induced activation of caspase-8 protects the glucocorticoid-induced protein Gilz from proteasomal degradation and induces its binding to SUMO-1 in murine thymocytes.
- Author
-
Delfino, D. V., Spinicelli, S., Pozzesi, N., Pierangeli, S., Velardi, E., Bruscoli, S., Martelli, M. P., Pettirossi, V., Falchi, L., Kang, T.-b., and Riccardi, C.
- Subjects
- *
GLUCOCORTICOIDS , *LEUCINE zippers , *DEXAMETHASONE , *MESSENGER RNA , *UBIQUITIN , *LYMPHOCYTES , *PROTEOLYTIC enzymes - Abstract
In this study, we evaluated the possible cross-talk between glucocorticoid (GC)-induced leucine zipper (Gilz) and caspase-8 in dexamethasone (Dex)-treated thymocytes. We determined that expression of Dex-induced Gilz protein was reduced when caspase-8 activity was inhibited, and this effect was not partially due to altered Gilz mRNA expression. Inhibition of the proteasome abrogated this reduction in Gilz expression, suggesting that Dex-induced caspase-8 activation protects Gilz from degradation. We hypothesized that the caspase-8-dependent protection of Gilz could be due to caspase-8-driven sumoylation. As a putative small ubiquitin-like modifier (SUMO)-binding site was identified in the Gilz sequence, we assessed whether SUMO-1 interacted with Gilz. We identified a 30-kDa protein that was compatible with the size of a Gilz-SUMO-1 complex and was recognized by the anti-SUMO-1 and anti-Gilz antibodies. In addition, Gilz bound to SUMO ubiquitin-conjugating (E2)-conjugating enzyme Ube21 (Ubc9), the specific SUMO-1 E2-conjugating enzyme, in vitro and coimmunoprecipitated with Ubc9 in vivo. Furthermore, Gilz coimmunoprecipitated with SUMO-1 both in vitro and in vivo, and this interaction depended on caspase-8 activation. This requirement for caspase-8 was further evaluated in caspase-8-deficient thymocytes and lymphocytes in which Gilz expression was reduced. In summary, our results suggest that caspase-8 activation protects Gilz from proteasomal degradation and induces its binding to SUMO-1 in GC-treated thymocytes. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
66. Cytokines release in macrophage interaction with viable and killed leishmania
- Author
-
Chiofalo, M.S., primary, Delfino, D., additional, and Iannello, D., additional
- Published
- 1991
- Full Text
- View/download PDF
67. MOTIVO DE LOGRO Y ELECCIÓN DE LA CARRERA DE PSICOLOGÍA.
- Author
-
Rovella, A., Sans de Uhrlandt, M., Solares, E., Delfino, D., and Diaz, D.
- Subjects
MOTIVATION testing ,OCCUPATIONAL sociology ,AFFILIATION (Psychology) ,ACHIEVEMENT ,POWER (Social sciences) ,OCCUPATIONAL prestige - Abstract
Copyright of Revista Electrónica de Psicología Política is the property of Universidad Nacional de San Luis, Facultad de Ciencias Humanas and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2008
68. Survival of a neglected case of brain abscess caused by Cladophialophora bantiana.
- Author
-
Delfino, D., De Hoog, S., Polonelli, L., Benecchi, M., Fanti, F., Galatioto, S., Manti, G., and Cusumano, V.
- Abstract
Cladophialophora bantiana is an uncommon fungus related to the black yeasts which causes, if untreated, mostly fatal cerebral infections in immunosuppressed and competent patients. We report a case of a patient who survived a recurrent cerebral abscess caused by C. bantiana despite delayed and apparently inappropriate therapy. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
69. Immunopharmacology of natural reactivity: Mechanisms of cytokines-dependent generation of natural killer (NK) cells
- Author
-
Riccardi, C., primary, D'Adamio, F., additional, Delfino, D., additional, Ayroldi, E., additional, Cannarile, L., additional, and Migliorati, G., additional
- Published
- 1990
- Full Text
- View/download PDF
70. Effect of Ultrafiltration on Plasma Concentrations of Atrial Natriuretic Peptide in Haemodialysis Patients.
- Author
-
Zoccali, C., Ciccarelli, M., Mallamaci, F., Delfino, D., Salnitro, F., Parlongo, S., and Maggiore, Q.
- Abstract
We have investigated the influence of body fluid volume status on plasma levels of immunoreactive atrial natriuretic peptide (irANP) in eight uraemic patients on chronic haemodialysis, including two diabetics with severely impaired reflex control of the heart. IrANP was significantly higher in volume-expanded uraemic patients (36±16 pg/ml) than in a group of seven age and sex-matched normal subjects (14±2 pg/ml), and fell consistently, approaching the normal range after the removal of 2.0–4.3 litres of isotonic plasma ultrafiltrate (by isolated ultrafiltration). Plasma levels of the hormone were strictly related to right atrial pressure. The irANP response to ultrafiltration in the two diabetics was similar to that of the other uraemic patients. The results suggest that the elevated irANP levels found in volume-expanded uraemic patients depend largely on fluid overload per Se. The preserved irANP response to ultrafiltration of the two diabetics with severe autonomic neuropathy indicates that in chronic renal failure irANP secretion may be regulated independently from autonomic influences. [ABSTRACT FROM PUBLISHER]
- Published
- 1986
71. Double-blind randomized, crossover trial of calcium supplementation in essential hypertension.
- Author
-
Zoccali, Carmine, Mallamaci, Francesca, Delfino, Diego, Ciccarelli, Maurizio, Parlongo, Saverio, lellamo, Domenico, Moscato, Domenico, Maggiore, Quirino, Zoccali, C, Mallamaci, F, Delfino, D, Ciccarelli, M, Parlongo, S, Iellamo, D, Moscato, D, and Maggiore, Q
- Published
- 1988
- Full Text
- View/download PDF
72. A vanishing theorem for local cohomology modules
- Author
-
Delfino, D.
- Published
- 1997
- Full Text
- View/download PDF
73. Cofinite modules and local cohomology
- Author
-
Delfino, D. and Marley, T.
- Published
- 1997
- Full Text
- View/download PDF
74. Double-blind randomized, crossover trial of calcium supplementation in essential hypertension
- Author
-
Moscato D, Francesca Mallamaci, M. Ciccarelli, Iellamo D, Delfino D, Carmine Zoccali, Quirino Maggiore, and Saverio Parlongo
- Subjects
Adult ,Male ,medicine.medical_specialty ,Mean arterial pressure ,Physiology ,Urology ,Blood Pressure ,Essential hypertension ,Plasma renin activity ,Placebos ,chemistry.chemical_compound ,Random Allocation ,Calcitriol ,Double-Blind Method ,Internal medicine ,Internal Medicine ,medicine ,Humans ,Calcium metabolism ,Clinical Trials as Topic ,Aldosterone ,business.industry ,Middle Aged ,medicine.disease ,Crossover study ,Urinary calcium ,Blood pressure ,Endocrinology ,chemistry ,Hypertension ,Calcium ,Female ,Cardiology and Cardiovascular Medicine ,business - Abstract
In a double-blind, randomized, placebo-controlled, crossover trial, 23 middle-aged patients with mild to moderate essential hypertension were given an oral calcium supplement (1 g/day) for 8 weeks. At the end of this period, eight patients continued with this treatment for an additional 2 weeks but were also given 0.5 micrograms/day of 1,25-(OH)2 vitamin D3. In the 21 patients who completed the study, arterial pressure during the calcium-supplemented phase was almost identical to that of the placebo phase. In eight patients, mean arterial pressure (MAP) had changed by greater than 5 mmHg at the end of the calcium-supplemented period, compared with the end of the placebo phase (six patients showed an increase in MAP and two a decrease). Changes in arterial pressure were unrelated to age, plasma ionized calcium, parathyroid hormone (PTH), plasma renin activity (PRA), plasma aldosterone, 24-h urinary calcium, sodium and potassium and were only weakly related to body weight. In the eight patients who continued with the treatment of calcium plus 1,25-(OH)2 vitamin D3 after the 8-week study period, arterial pressure changed very little and not significantly. These results do not support the suggestion that calcium supplements lower arterial pressure in middle-aged subjects with mild to moderate essential hypertension.
- Published
- 1988
75. The restoration of impaired macrophages functions using as immunomodulator the Corynebacterium granulosum derived P40 fraction
- Author
-
Mastroeni, P., Bizzini, B., Bonina, L., Iannello, D., Merendino, R. A., Delfino, D., Berlinghieri, M. C., Leonardi, M. S., Arena, Adriana, Liberto, M. C., and Gazzara, D.
- Published
- 1985
76. Glucocorticoid hormones in the regulation of cell death
- Author
-
Riccardi C, Zollo O, Nocentini G, Bruscoli S, Andrea Bartoli, D'Adamio F, Cannarile L, Delfino D, Ayroldi E, and Migliorati G
- Subjects
Cell death ,glucocorticoids ,Cell Death ,T-Lymphocytes ,Animals ,Humans ,Apoptosis ,Glucocorticoids - Abstract
The immune T-cell compartment maintains the capability to respond to a wide variety of antigens (Ag). This whole process is regulated by lymphocyte apoptosis (programmed cell death, PCD) and involves the coordinated expression of a great number of genes including those coding for cytokines and their receptors, such as for example IL-2/IL-2R and the Fas/FasL systems and those coding for transcription factors, including the NF-kB complex, involved in T-cell activation and apoptosis in that they simultaneously activate cell suicide and an anti-death programme. This binary effect, PCD activation and inhibition, is due on one hand to GCH-induced activation of the caspases cascade and on the other to the induction of expression of a new gene that we have named GILZ. In fact, GILZ over-expression in transfected cells inhibits the sequential increase of NF-kB/DNA-binding activity, IL-2 production and IL-2R expression, and transcription of the Fas/FasL complex that follows TCR triggering and plays an important role in the control of T-lymphocyte apoptosis. These results indicate a new mechanism responsible for the GCH-mediated inhibition of T-cell death and activation that could contribute to anti-inflammatory and immunosuppressive efficacy.
77. Determinants of eating behaviour: The contribution of twin studies,Determinanti del comportamento alimentare: Il contributo degu studi sui gemelli
- Author
-
Corrado Fagnani, Toccaceli, V., Delfino, D., Medda, E., and Stazi, M. A.
78. Effects of ultrafiltration on plasma concentrations of atrial natriuretic peptide in haemodialysis patients
- Author
-
Saverio Parlongo, F. Salnitro, Delfino D, Quirino Maggiore, Carmine Zoccali, Francesca Mallamaci, and M. Ciccarelli
- Subjects
Adult ,Male ,medicine.medical_specialty ,medicine.medical_treatment ,Ultrafiltration ,Atrial natriuretic peptide ,Diabetic Neuropathies ,Renal Dialysis ,Internal medicine ,Diabetes mellitus ,medicine ,Intravascular volume status ,Dysautonomia, Familial ,Humans ,Uremia ,Body fluid ,Transplantation ,business.industry ,Central venous pressure ,Middle Aged ,medicine.disease ,Autonomic nervous system ,Endocrinology ,Nephrology ,Hemodialysis ,business ,Atrial Natriuretic Factor ,Hormone - Abstract
We have investigated the influence of body fluid volume status on plasma levels of immunoreactive atrial natriuretic peptide (irANP) in eight uraemic patients on chronic haemodialysis, including two diabetics with severely impaired reflex control of the heart. IrANP was significantly higher in volume-expanded uraemic patients (36 +/- 16 pg/ml) than in a group of seven age and sex-matched normal subjects (14 +/- 2 pg/ml), and fell consistently, approaching the normal range after the removal of 2.0-4.3 litres of isotonic plasma ultrafiltrate (by isolated ultrafiltration). Plasma levels of the hormone were strictly related to right atrial pressure. The irANP response to ultrafiltration in the two diabetics was similar to that of the other uraemic patients. The results suggest that the elevated irANP levels found in volume-expanded uraemic patients depend largely on fluid overload per se. The preserved irANP response to ultrafiltration of the two diabetics with severe autonomic neuropathy indicates that in chronic renal failure irANP secretion may be regulated independently from autonomic influences.
79. Blood temperature and cardiovascular stability in hemofiltration
- Author
-
Pizzarelli, F., Sisca, S., Carmine Zoccali, Parlongo, S., Nicolò, F., Creazzo, G., Delfino, D., and Maggiore, Q.
80. Glucocorticoids and apoptosis: Role in the control of T lymphocyte development | Glucocorticoidi e apoptosi: Ruolo nel controllo dello sviluppo dei linfociti T
- Author
-
Riccardi, C., Bruscoli, S., Massimiliano Agostini, Delfino, D., Marchetti, M. C., and Migliorati, G.
81. Effect of a new peptidyl-hypoxanthine derivative on natural killer cells and antitumor activity
- Author
-
Graziella MIGLIORATI, Cornaglia-Ferraris, P., Cannarile, L., Delfino, D., D Adamio, F., Mosci, F., Stradi, R., Rossi, E., Guidi, G., and Riccardi, C.
82. Differentiation of Ly49s-positive or -negative natural killer cells is inhibited by anti-H-2b monoclonal antibodies acting at the level of bone marrow progenitors from B6 mice
- Author
-
Delfino, D. V., Salcedo, M., Di Marco, B., Emira Ayroldi, Nocentini, G., Bruscoli, S., Brunetti, L., Ljunggren, H. -G, and Riccardi, C.
83. Studies on NK cell precursors in mice
- Author
-
Carlo Riccardi, Ayroldi, E., Cannarile, L., Delfino, D., D Adamio, F., D Adamio, L., and Migliorati, G.
- Subjects
Killer Cells, Natural ,Mice ,Cultured ,Cells ,Natural ,Animals ,Killer Cells ,Bone Marrow Cells ,Hematopoietic Stem Cells ,Cells, Cultured
84. Access site-related infection in dialysis: The AStRID project. A multicenter prospective Italian study
- Author
-
Viale, P. L., Brunori, G., Petrosillo, N., Luigia Scudeller, Beltrame, A., Sottini, L., Cancarini, G., Brusaferro, S., Maiorca, R., Carosi, G., Piazza, V., Efficace, E., Fregonese, C., Mioni, G., Bracchi, M., Pola, A., Marinis, S., Delfino, D. F., Zoccali, C., La Russa, A., Malberti, F., Losi, B., Brancaccio, D., Talassi, E., Tarchini, R., Lucchi, L., and Albertazzi, A.
85. Effect of lymphokines on the IL-2-dependent generation of NK cells from bone marrow precursors
- Author
-
Riccardi, C., primary, Cannarile, L., additional, Delfino, D., additional, and Migliorati, G., additional
- Published
- 1988
- Full Text
- View/download PDF
86. Effect of oral administration of a variety of bacteria on depressed macrophage functions in tumour-bearing rats
- Author
-
Iannello, D., primary, Bonina, L., additional, Delfino, D., additional, Berlinghieri, M.C., additional, Gismondo, M.R., additional, and Mastroeni, P., additional
- Published
- 1984
- Full Text
- View/download PDF
87. To Sr. Lic Alonzo S. Perales, From S. [illegible] Delfino D. Hingos, 1-31-50.
- Author
-
Hingos, Delfino D.
- Subjects
LETTERS ,TRAFFIC accidents - Published
- 1925
88. On the Inequality λ( [formula omitted]/ R) ≤ t( R)λ( R/ [formula omitted]) for One-Dimensional Local Rings
- Author
-
Delfino, D.
- Published
- 1994
- Full Text
- View/download PDF
89. To Sr. Lic. Alonzo S. Perales, From Delfino D. Hinojos, 3/1/50.
- Author
-
Hinojos, Delfino D.
- Subjects
LETTERS - Published
- 1925
90. Editorial: The Role of Natural Killer Cells in Autoimmune Diseases
- Author
-
Antonio La Cava, Alessandra Fierabracci, Domenico Vittorio Delfino, Mary A. Markiewicz, Fierabracci, A., Delfino, D. V., Markiewicz, M. A., and La Cava, A.
- Subjects
Immunology ,autoimmunity ,immune regulation ,Immune regulation ,autoimmune disease ,NK cells ,Biology ,RC581-607 ,medicine.disease_cause ,Natural (archaeology) ,Autoimmunity ,immune system ,Immune system ,medicine ,Immunology and Allergy ,autoimmune diseases ,Immunologic diseases. Allergy - Published
- 2021
91. Microsatellite-based genotyping of Candida parapsilosis sensu stricto isolates reveals dominance and persistence of a particular epidemiological clone among neonatal intensive care unit patients
- Author
-
Daniela Petronilla Romeo, Orazio Romeo, Carla Lo Passo, Demetrio Delfino, I Pernice, Maria Amorini, Antonio Cascio, Romeo, O., Delfino, D., Cascio, A., Passo, C., Amorini, M., Romeo, D., and Pernice, I.
- Subjects
Microbiology (medical) ,medicine.medical_specialty ,Candida parapsilosis ,Neonatal intensive care unit ,Genotype ,Settore MED/17 - Malattie Infettive ,Infectious Disease ,Microbiology ,Disease Outbreaks ,Candida orthopsilosis ,Genetic ,Candida orthopsilosi ,Intensive Care Units, Neonatal ,Epidemiology ,Genetics ,medicine ,Humans ,Molecular Biology ,Genotyping ,Ecology, Evolution, Behavior and Systematics ,Candida ,Dominance (genetics) ,ITS-sequencing ,Cross Infection ,Disease Outbreak ,biology ,Candidiasis ,Infant, Newborn ,Outbreak ,Candida metapsilosis ,biology.organism_classification ,Molecular epidemiology ,Microsatellite genotyping ,Ecology, Evolution, Behavior and Systematic ,Candida metapsilosi ,Infectious Diseases ,Candidiasi ,Candida parapsilosi ,Microsatellite Repeat ,Microsatellite ,Microsatellite Repeats ,Human ,Multilocus Sequence Typing - Abstract
In this study, using multilocus microsatellite analysis, we report the genetic characterization of 27 Candida parapsilosis isolates recovered in two different periods of time (2007-2009 and 2011-2012) from infants hospitalized in the neonatal intensive care unit of a hospital in Messina, Italy. The results revealed the persistence and dominance of a particular infectious genotype among NICU patients and highlight the power of the used microsatellite markers in clarifying epidemiologic associations, detect micro-evolutionary variations and facilitating the recognition of outbreaks. © 2012 Elsevier B.V.
- Published
- 2013
92. Multilocus microsatellite analysis of European and African Candida glabrata isolates
- Author
-
Burcu Dalyan Cilo, Nnaemeka Emmanuel Nnadi, Fabio Scordino, V. Chillemi, H.-J. Tietz, C. Lo Passo, Demetrio Delfino, Antonio Cascio, Paula Sampaio, Giuseppe Criseo, S. Rharmitt, A.D. van Diepeningen, Javier Pemán, Orazio Romeo, [et al.], Chillemi, V., Lo Passo, C., Van Diepeningen, A., Rharmitt, S., Delfino, D., Cascio, A., Nnadi, N., Cilo, B., Sampaio, P., Tietz, H., Pemã¡n, J., Criseo, G., Romeo, O., Scordino, F., Uludağ Üniversitesi/Tıp Fakültesi/Tıbbi Mikrobiyoloji Anabilim Dalı., Cilo, Burcu Dalyan, and Universidade do Minho
- Subjects
0301 basic medicine ,Settore MED/07 - Microbiologia E Microbiologia Clinica ,Clonal complex ,Epidemiology ,Multilocus microsatellite analysis ,Candida glabrata ,Molecular phylogeny ,Gene locus ,Central type ,Related genotype ,Genotype ,Environmental Microbiology ,Haplotype ,DNA, Fungal ,Priority journal ,Genetics ,Allele ,Candidiasis ,General Medicine ,Classification ,Europe ,Phenotype ,Infectious Diseases ,Candida Glabrata ,Adhesins ,Fluconazole ,Candidiasi ,Microsatellite ,Microsatellite Repeat ,Microbiological examination ,Human ,Microbiology (medical) ,Settore MED/17 - Malattie Infettive ,Microsatellite DNA ,030106 microbiology ,Biology ,European ,Microbiology ,Article ,03 medical and health sciences ,Genetic variation ,Microsatellite repeats ,Humans ,Genotyping ,Alleles ,Science & Technology ,Microsatellite marker ,African ,Genetic Variation ,biology.organism_classification ,Nonhuman ,030104 developmental biology ,Fungal DNA ,Haplotypes ,Isolation and purification ,Genetic Loci ,Africa ,Multilocus sequence typing ,Fungus isolation ,Genetic variability ,Microsatellite genotype ,Multilocus Sequence Typing - Abstract
This study aimed to elucidate the genetic relatedness and epidemiology of 127 clinical and environmental Candida glabrata isolates from Europe and Africa using multilocus microsatellite analysis. Each isolate was first identified using phenotypic and molecular methods and subsequently, six unlinked microsatellite loci were analyzed using automated fluorescent genotyping. Genetic relationships were estimated using the minimum-spanning tree (MStree) method. Microsatellite analyses revealed the existence of 47 different genotypes. The fungal population showed an irregular distribution owing to the over-representation of genetically different infectious haplotypes. The most common genotype was MG-9, which was frequently found in both European and African isolates. In conclusion, the data reported here emphasize the role of specific C. glabrata genotypes in human infections for at least some decades and highlight the widespread distribution of some isolates, which seem to be more able to cause disease than others., This research was supported in part by the EU Mare Nostrum (EUMN-III Call) program of the European Union, grant agreement number 2011-4050/001-EMA2. Dr Sanae Rharmitt was the recipient of a scholarship (10 months) signed within the EUMN program for PhD students (F.S. 1.04.11.01 UORI) under the supervision of Prof Orazio Romeo., info:eu-repo/semantics/publishedVersion
- Published
- 2016
93. Descritores fractais aplicados à análise de texturas
- Author
-
João Batista Florindo, Odemir Martinez Bruno, Nestor Felipe Caticha Alfonso, Nelson Delfino d\'Ávila Mascarenhas, Luis Gustavo Nonato, and Hélio Pedrini
- Abstract
Este projeto descreve o desenvolvimento, estudo e aplicação de descritores fractais em análise de texturas. Nos últimos anos, a literatura vem apresentando a geometria fractal como uma ferramenta poderosa para a análise de imagens, com aplicações em variados campos da ciência. A maior parte destes trabalhos faz uso direto da dimensão fractal como um descritor do objeto representado na imagem. Entretanto, em função da complexidade de muitos problemas nesta área, algumas soluções foram propostas para melhorar essa análise, usando não apenas o valor da dimensão fractal, mas um conjunto de medidas que pudessem ser extraídas pela geometria fractal e que descrevessem as texturas com maior riqueza e precisão. Entre essas técnicas, destacam-se a metodologia de multifractais, de dimensão fractal multiescala e, mais recentemente, os descritores fractais. Esta última técnica tem se mostrado eficiente na solução de problemas relacionados à discriminação de imagens de texturas e formas, uma vez que os descritores gerados fornecem uma representação direta do padrão de complexidade (distribuição dos detalhes ao longo das escalas de observação) da imagem. Assim, essa solução permite que se tenha uma descrição rica da imagem estudada pela análise da distribuição espacial e/ou espectral dos pixels e intensidade de cores/tons de cinza, com uma modelagem que pode se aproximar da percepção visual humana para a geração de um método automático e preciso. Ocorre, entretanto, que os trabalhos apresentados até o momento sobre descritores fractais focam em métodos de estimativa de dimensão fractal mais conhecidos como Bouligand-Minkowski e Box-counting. Este projeto visa estudar mais a fundo o conceito, generalizando para outras abordagens de dimensão fractal, bem como explorando diferentes formas de se extraírem os descritores a partir da curva logarítmica associada à dimensão. Os métodos desenvolvidos são aplicados à análise de texturas, em problemas de classificação de bases públicas, cujos resultados podem ser comparados com métodos da literatura, bem como a segmentação de imagens de satélite e à identificação automática de amostras obtidas em estudos de nanotecnologia. Os resultados alcançados demonstram o potencial da metodologia desenvolvida para a solução destes problemas, mostrando tratar-se de uma nova fronteira a ser usada e explorada em análise de imagens e visão computacional como um todo. This project describes the development, study and application of fractal descriptors to texture analysis. Recently, the literature has shown fractal geometry as a powerful tool for image analysis, with applications to several areas of science. Most of these works use fractal dimension as a descriptor of the object depicted in the image. However, due to the complexity of many problems in this context, some solutions have been proposed to improve this analysis. These proposed methods use not only the value of fractal dimension, but a set of measures which could be extracted by fractal geometry to describe the textures with greater richness and accuracy. Among such techniques, we emphasize the multifractal methodology, multiscale fractal dimension and, more recently, fractal descriptors. This latter technique has demonstrated to be efficient in solving problems related to the discrimination of texture and shape images. This is possible as the extracted descriptors provide a direct representation of the complexity (the details distribution along the scales of observation) in the image. Thus, this solution allows for a rich description of the image studied by analyzing the spatial/spectral distribution of pixels and intensity of colors/gray-levels, with a model which can approximate the human visual perception, generating an automatic and precise method. However, the works about fractal descriptors presented in the literature focus on classical methods to estimate fractal dimension, such as Bouligand-Minkowski and Box-counting. This project aims at studying more deeply the concept, generalizing to other approaches in fractal dimension, as well as exploring different ways of extracting the key features from the logarithmic curve associated with the dimension. The developed methods are applied to texture analysis, in classification problems over public databases, whose results can be compared with literature methods, as well as to the segmentation of satellite images and automatically identifying samples obtained from studies on nanotechnology. The results demonstrate the potential of the methodology developed to solve such problems, showing that this is a new frontier to be explored and used in image analysis and computer vision at all.
- Published
- 2015
94. Estudo avaliativo da informação mútua generalizada e de métricas clássicas como medidas de similaridade para corregistro em imagens fractais e cerebrais
- Author
-
Ivan Christensen Nali, Ubiraci Pereira da Costa Neves, Luiz Otavio Murta Junior, Odemir Martinez Bruno, Joaquim Cezar Felipe, Nelson Delfino d\'Ávila Mascarenhas, and Carlos Ernesto Garrido Salmon
- Abstract
A integração de diferentes modalidades de imagens médicas possibilita uma análise mais detalhada de seu conteúdo, visando-se um diagnóstico mais preciso da patologia presente. Este processo, conhecido como corregistro, busca o alinhamento das imagens através da transformação rígida (ou não rígida) das mesmas, por algoritmos matemáticos de distorção, translação, rotação e ajuste de escala. A amplitude de cada transformação é determinada por uma medida de similaridade das imagens. Quanto menor a similaridade, maior será a transformação aplicada. Neste sentido, a métrica de similaridade é uma peça chave do processo de corregistro. No presente trabalho, inicialmente são propostas novas definições para o cálculo dos erros de alinhamento nas transformações de translação, rotação e escala, com o objetivo de se avaliar o desempenho do corregistro. Em seguida, cinco experimentos são realizados. No primeiro, a Informação Mútua Generalizada é avaliada como medida de similaridade para corregistro em imagens fractais e cerebrais. Neste caso, os resultados sugerem a viabilidade do emprego desta métrica, pois em geral conduz a erros de alinhamento muito pequenos, mas sem vantagens aparentes em relação à formulação de Shannon. No segundo experimento, um estudo comparativo entre a Informação Mútua e as métricas clássicas (Coeficiente de Correlação, Média dos Quadrados, Diferença de Gradiente e Cardinalidade) é então realizado. Para as imagens binárias analisadas, as métricas com menores valores de erro de alinhamento para os corregistros de translação e rotação foram a Informação Mútua e a Diferença de Gradiente. Para o corregistro de escala, todas as métricas conduziram a erros de alinhamento próximos de zero. No terceiro experimento, o processo de alinhamento é investigado em termos do número de iterações do algoritmo de corregistro. Considerando-se ambas as variáveis erro de alinhamento e número de iterações, conclui-se que o uso da Informação Mútua Generalizada com q = 1.0 é adequado ao corregistro. No quarto experimento, a influência da dimensão fractal no corregistro de imagens fractais binárias foi estudada. Para algumas métricas, a tendência geral observada é a de uma diminuição do erro de alinhamento em resposta ao aumento da dimensão fractal. Finalmente, no quinto experimento, constatou-se a existência de correlação linear entre os erros de alinhamento de imagens em tons de cinza do córtex cerebral e de fractais do conjunto Julia. The integration of different modalities of medical images provides a detailed analysis of its contents, aiming at a more accurate diagnosis of the pathology. This process, known as coregistration, seeks to align the images through rigid (or non-rigid) transformations, by mathematical algorithms of distortion, translation, rotation and scaling. The amplitude of each transformation is determined by a similarity measure of the images. The lower the similarity, the greater the transformation applied. In this sense, the similarity metric is the key for the coregistration process. In this work, new definitions are proposed for the calculation of alignment errors in the transformations of translation, rotation and scale, with the objective of evaluating the performance of coregistration. Then, five experiments are performed. In the first one, the Generalized Mutual Information is evaluated as a similarity measure for coregistration of brain images and fractals. In this case, the results suggest the feasibility of using this measure, since it leads to very small alignment errors, although no advantages in relation to Shannon formulation are evident. In the second experiment, a comparative study between Mutual Information and the classical metrics (Correlation Coefficient, Mean Squares, Gradient Difference and Cardinality) is performed. For the binary images analyzed, the metrics with lower alignment errors for translation and rotation are the Mutual Information and Gradient Difference. For scaling transformation, all the metrics lead to alignment errors close to zero. In the third experiment, the alignment process is investigated in terms of number of iterations of the coregistration algorithm. Considering both variables alignment error and number of iterations, it is concluded that the use of Generalized Mutual Information with q =1 is appropriate for coregistration. In the fourth experiment, it is studied the influence of fractal dimension in coregistration of binary fractal images. For some metrics, as a general trend, one observes the decay of the alignment error in response to the increase of the fractal dimension. Finally, in the fifth experiment, the results indicate the existence of a linear correlation between the alignment errors of grayscale images of the cerebral cortex and Julia set fractals.
- Published
- 2015
95. Combinação de modelos de campos aleatórios markovianos para classificação contextual de imagens multiespectrais
- Author
-
Alexandre L. M. Levada, Nelson Delfino D\'Ávila Mascarenhas, João do Espírito Santo Batista Neto, Max Henrique Machado Costa, Francisco Aparecido Rodrigues, and Ricardo da Silva Torres
- Abstract
Este projeto de doutorado apresenta uma nova abordagem MAP-MRF para a classificação contextual de imagens multiespectrais utilizando combinação de modelos de Campos Aleatórios Markovianos definidos em sistemas de ordens superiores. A modelagem estatística para o problema de classificação segue o paradigma Bayesiano, com a definição de um modelo Markoviano para os dados observados (Gaussian Markov Random Field multiespectral) e outro modelo para representar o conhecimento a priori (Potts). Nesse cenário, o parâmetro β do modelo de Potts atua como um parâmetro de regularização, tendo papel fundamental no compromisso entre as observações e o conhecimento a priori, de modo que seu correto ajuste é necessário para a obtenção de bons resultados. A introdução de sistemas de vizinhança de ordens superiores requer a definição de novos métodos para a estimação dos parâmetros dos modelos Markovianos. Uma das contribuições desse trabalho é justamente propor novas equações de pseudo-verossimilhança para a estimação desses parâmetros no modelo de Potts em sistemas de segunda e terceira ordens. Apesar da abordagem por máxima pseudo-verossimilhança ser amplamente utilizada e conhecida na literatura de campos aleatórios, pouco se conhece acerca da acurácia dessa estimação. Foram derivadas aproximações para a variância assintótica dos estimadores propostos, caracterizando-os completamente no caso limite, com o intuito de realizar inferências e análises quantitativas sobre os parâmetros dos modelos Markovianos. A partir da definição dos modelos e do conhecimento dos parâmetros, o próximo estágio é a classificação das imagens multiespectrais. A solução para esse problema de inferência Bayesiana é dada pelo critério de estimação MAP, onde a solução ótima é determinada maximizando a probabilidade a posteriori, o que define um problema de otimização. Como não há solução analítica para esse problema no caso de prioris Markovianas, algoritmos iterativos de otimização combinatória foram empregados para aproximar a solução ótima. Nesse trabalho, adotam-se três métodos sub-ótimos: Iterated Conditional Modes, Maximizer of the Posterior Marginals e Game Strategy Approach. Porém, é demonstrado na literatura que tais métodos convergem para máximos locais e não globais, pois são altamente dependentes de sua condição inicial. Isto motivou o desenvolvimento de uma nova abordagem para combinação de classificadores contextuais, que utiliza múltiplas inicializações simultâneas providas por diferentes classificadores estatísticos pontuais. A metodologia proposta define um framework MAP-MRF bastante robusto para solução de problemas inversos, pois permite a utilização e a integração de diferentes condições iniciais em aplicações como classificação, filtragem e restauração de imagens. Como medidas quantitativas de desempenho, são adotados o coeficiente Kappa de Cohen e o coeficiente Tau de Kendall para verificar a concordância entre as saídas dos classificadores e a verdade terrestre (amostras pré-rotuladas). Resultados obtidos mostram que a inclusão de sistemas de vizinhança de ordens superiores é de fato capaz de melhorar significativamente não apenas o desempenho da classificação como também a estimação dos parâmetros dos modelos Markovianos, reduzindo tanto o erro de estimação quanto a variância assintótica. Além disso, a combinação de classificadores contextuais através da utilização de múltiplas inicializações simultâneas melhora significativamente o desempenho da classificação se comparada com a abordagem tradicional com apenas uma inicialização. This work presents a novel MAP-MRF approach for multispectral image contextual classification by combining higher-order Markov Random Field models. The statistical modeling follows the Bayesian paradigm, with the definition of a multispectral Gaussian Markov Random Field model for the observations and a Potts MRF model to represent the a priori knowledge. In this scenario, the Potts MRF model parameter (β) plays the role of a regularization parameter by controlling the tradeoff between the likelihood and the prior knowledge, in a way that a suitable tunning for this parameter is required for a good performance in contextual classification. The introduction of higher-order MRF models requires the specification of novel parameter estimation methods. One of the contributions of this work is the definition of novel pseudo-likelihood equations for the estimation of these MRF parameters in second and third order neighborhood systems. Despite its widely usage in practical MRF applications, little is known about the accuracy of maximum pseudo-likelihood approach. Approximations for the asymptotic variance of the proposed MPL estimators were derived, completely characterizing their behavior in the limiting case, allowing statistical inference and quantitative analysis. From the statistical modeling and having the model parameters estimated, the next step is the multispectral image classification. The solution for this Bayesian inference problem is given by the MAP criterion, where the optimal solution is obtained by maximizing the a posteriori distribution, defining an optimization problem. As there is no analytical solution for this problem in case of Markovian priors, combinatorial optimization algorithms are required to approximate the optimal solution. In this work, we use three suboptimal methods: Iterated Conditional Modes, Maximizer of the Posterior Marginals and Game Strategy Approach, a variant approach based on non-cooperative game theory. However, it has been shown that these methods converge to local maxima solutions, since they are extremelly dependent on the initial condition. This fact motivated the development of a novel approach for combination of contextual classifiers, by making use of multiple initializations at the same time, where each one of these initial conditions is provided by different pointwise pattern classifiers. The proposed methodology defines a robust MAP-MRF framework for the solution of general inverse problems since it allows the use and integration of several initial conditions in a variety of applications as image classification, denoising and restoration. To evaluate the performance of the classification results, two statistical measures are used to verify the agreement between the classifiers output and the ground truth: Cohens Kappa and Kendalls Tau coefficient. The obtained results show that the use of higher-order neighborhood systems is capable of significantly improve not only the classification performance, but also the MRF parameter estimation by reducing both the estimation error and the asymptotic variance. Additionally, the combination of contextual classifiers through the use of multiple initializations also improves the classificatoin performance, when compared to the traditional single initialization approach.
- Published
- 2015
96. Análise e quantificação tridimensional em imagens de ultra-som intravascular
- Author
-
Fernando José Ribeiro Sales, Sergio Shiguemi Furuie, Pedro Alves Lemos Neto, Hae Yong Kim, Nelson Delfino D\'Ávila Mascarenhas, Koichi Sameshima, and Harki Tanaka
- Abstract
INTRODUÇÂO: A análise da composição das lesões in-vivo tem sido objeto de estudo de uma série de grupos de estudo sobre a doença aterosclerótica. Os métodos disponíveis para esse fim utilizam técnicas de análise espectral do sinal ultra-sônico retroespalhado antes deste ser transformado em imagens de ultra-som intravascular (IVUS), uma vez que não existem métodos que realizem tal inferência somente a partir das imagens. Neste trabalho, utilizamos técnicas de processamento de imagens e de reconhecimento de padrões para analisar a composição das lesões de acordo com a classificação proposta pela metodologia de Ultra-Som Intravascular com Histologia Virtual (IVUS-VH). MÉTODOS: Neste estudo utilizamos uma amostra de oito (08) artérias coronárias provenientes de cinco (05) pacientes, resultando num total de 96492 regiões de interesse para inferência da composição. Para a segmentação automática da interface lúmen-íntima e íntima-adventícia, aplicamos as técnicas de contornos ativos do tipo Snakes e para a determinação da energia potencial dos contornos, utilizamos técnicas de filtragem baseadas na difusão anisotrópica convencional e restritiva. Utilizamos três janelas quadradas diferentes de tamanhos 5x5, 7x7 e 9x9 pixels para extração dos atributos de texturas, dentre eles treze (13) baseados nas matrizes de co-ocorrência, seis (06) momentos invariantes à rotação, escala, translação e a ganho multiplicativo, baseados nos Momentos de Hu e propostos neste trabalho. Visando avaliar o efeito dos níveis de quantização das imagens nas matrizes de co-ocorrência, requantizamos originais de 256 níveis de cinza para 128, 64 e 32 tons. Como classificador, utilizamos o método dos k-vizinhos mais próximos (k-nn) e escolhemos os sete (07) vizinhos mais próximos como parâmetro de comparação. Como o k-nn é sensível com relação à métrica utilizada, testamos a distância euclidiana e a métrica de Mahalanobis. RESULTADOS: A segmentação automática da interface lúmen-íntima teve taxa média de acerto de 72,23% e a mediana da taxa de acertos foi de 81,20%, enquanto a taxa média de acertos para a interface íntima-adventícia foi de 80,86% e a mediana foi igual a 91,36%, considerando 495 quadros manualmente segmentados por um especialista. A melhor configuração do classificador foi utilizando a normalização de intensidades, com 256 níveis de cinza, com a janela 9x9 e usando a métrica de Mahalanobis. A taxa média de erros foi de 2.35%(DC), 20.51%(NC), 92.21%(FF) e 0.04%(FT), no entanto, se considerarmos somente três classes sem diferenciarmos os tecidos FF do FT temos a seguinte composição: 2.35% (DC), 20.51%(NC) e 0.04%(FT+FF), o que leva a uma taxa média de erros total de 5,15%. CONCLUSÕES: A classificação das lesões baseada somente em atributos de textura das imagens ainda não é possível com a nosso modelo se considerarmos os quatro tipos de tecido, uma vez que não conseguimos diferenciar de forma satisfatória dos componentes FF e FT. No entanto, se considerarmos somente três classes, temos resultados animadores, uma vez que conseguiremos identificar os componentes associados às placas ditas de maior risco de ruptura, os fibroateromas de capa fina (TCFA). Além disso, conseguimos um experimento associado ao trabalho, mostrar quantitativamente que há uma possível superestimação do componente NC ao redor de estruturas calcificadas nas imagens de IVUS-VH INTRODUCTION: Several efforts for in vivo atherosclerotic plaque estimation has been realized worldwide. Current methods for related application are based on spectral analysis of backscattered ultrasound signals before intravascular image formation (IVUS), once there is not available techniques to perform composition analysis only from IVUS images. On this study, image processing and pattern recognition techniques has been used to classify plaques according to Intravascular Ultrasound Virtual Histology (IVUS-VH) classification. METHODS: A sample set of eight (08) coronary arteries from five (05) different patients, resulting on 96492 regions of interest for plaque analysis. For automatic segmentation of lumen-intima interface and intima-adventitia interface, active contours technique has been used. Conventional and restrictive anisotropic diffusion filters have been used for estimating the potential energy of active contours. Haralicks co-occurrence matrix and invariant moments based in Hu moments were used as features for pattern classification. Three different windows has been used on feature extraction procedure: 5x5,7x7 and 9x9 pixels. In order to analyze the influence of grey-scale quantization levels into Haralicks co-occurrence matrix, we tested four different types numbers of grey-scale levels: 32, 64,128 and 256. KNearest Neighbors algorithm as the classification rule, and we tested both Mahalanobis and Euclidian Metrics in this analysis. RESULTS: Segmentation of luminal-intimal layers average accuracy for was 72.30% and its median was 81.20%. Segmentation of intimal-adventitia layers average accuracy for was 80,86% and its median was 91,36%, for 495 manually segmented frames. Plaque classification according to IVUS-VH four classes scheme has shown not feasible with the proposed model, once average classification error-rate foe every component: 2.35%(DC), 20.51%(NC), 92.21%(FF) e 0.04%(FT). Our approach has not the ability to differentiate fibrotic tissue from fibro-fatty tissue. However, in the three classes scheme: DC, NC and (FF+FT), we achieved some encouraging results: 2.35% (DC), 20.51%(NC) e 0.04%(FT+FF), leading to an average error rate of 5,15%. With these results, a thin-cap fibroatheroma (TCFA) lesions detection algorithm for conventional IVUS images should be developed using our approach. Once TCFA plaques has been assigned to have an association with plaque rupture and sudden death, those results should be used for in vivo IVUS based TCFA detection. In an experiment related to this work, we have shown that there is an artifactual relationship between NC and DC components into VH images
- Published
- 2015
97. Otimização do algoritmo de block matching aplicado a estudos elastográficos
- Author
-
Lucio Pereira Neves, Antonio Adilton Oliveira Carneiro, Nelson Delfino D\'Ávila Mascarenhas, and Luiz Otavio Murta Junior
- Abstract
Este trabalho apresenta uma análise sobre um novo método de formação de imagem, utilizando aparelhos de ultra-som a elastografia. Esta técnica baseia-se no fato de que quando um meio elástico, como o tecido, é deformado por uma tensão constante e uniaxial, todos os pontos no meio possuem um nível de deformação longitudinal cujo componente principal está ao longo do eixo de deformação. Se elementos do tecido possuem um módulo elástico diferente dos demais, a deformação nestes elementos será relativamente maior ou menor. Elementos mais rígidos geralmente deformam-se menos. Desta forma, pode-se mapear e identificar estruturas com diferentes níveis de dureza. A comparação entre os mapas de RF de pré e pós-deformação foi realizada pela técnica de block matching. Esta técnica consiste em comparar regiões, ou kernels, no mapa de pré-deformação com regiões de mesmo tamanho no mapa de pós-deformação. Esta comparação é feita pela minimização de uma função custo. Nesta técnica, o tamanho do kernel, é um dos principais parâmetros para melhorar a precisão das medidas de deslocamento. O principal objetivo neste trabalho é aperfeiçoar o algoritmo de block matching visando melhorar a precisão da determinação de deslocamento em técnicas de deformação dinâmica e estática, mantendo o custo computacional baixo. Para isto, foram utilizados phantoms com e sem inclusões mais duras que o meio. Os phantoms foram submetidos a deformações estáticas e dinâmicas. Foi possível determinar o comportamento destes phantoms sob estas formas de deformação, e as faixas de kernel e funções custo que forneceram os melhores resultados. Também foram gerados elastogramas do phantom com inclusão. Estas imagens permitiram avaliar a influência dos diferentes kernels sobre a resolução dos elastogramas e a capacidade em diferenciar a lesão do tecido circundante. Comparando os elastogramas obtidos sobre deformação dinâmica, utilizando os kernels que apresentaram o melhor desempenho, com as respectivas imagens em modo B, pôde-se observar que a inclusão estava clara e bem delimitada. This work provides an analysis about a new method for image formation using ultrasound devices elastography. This technique is based on the fact that when an elastic medium, as the tissue, is deformed under a constant and directional stress, all the points in the medium have a deformation level whose main component is along the deformation axis. If tissues elements have different elastic modules, the deformation in these elements will be higher or lower. Normally harder elements have lower deformations. In this way, one can detect and identify structures with different elastic levels. The comparisons between the pre and post-deformation RF maps were done by the block matching technique. This technique is based on the comparison of regions, or kernels, in the pre-deformation maps with regions of the same size in the post-deformation map. This is done by the minimization of a cost function. In this technique, the kernel size is one of the most important parameters to obtain better resolution and precision in the displacement measurements. The goal of this work is to optimize the block matching algorithm to improve the displacement estimates precision in both dynamic and static deformations, while keeping a low computational cost. To obtain this, we used phantoms with and without inclusions harder than the medium. These phantoms were submitted to both static and dynamic deformations. It was possible to estimate the behavior of these phantoms under these deformations, and the kernel range and cost functions that provided the best results. Also, we generated the elastograms of the phantom with the inclusion. These images allowed us to evaluate the influence of the different kernel sizes under the elastograms resolution and their capability in differentiate the lesion from the embedding tissue. Comparing the elastograms obtained under dynamic deformation that had the best performance, with the B mode images, we could conclude that the inclusion was well delimited and clear.
- Published
- 2015
98. Reconstrução tridimensional de imagens com o uso de deconvolução a partir de seções bidimensionais obtidas em microscopia óptica
- Author
-
Murillo Rodrigo Petrucelli Homem, Luciano da Fontoura Costa, Nelson Delfino d\'Ávila Mascarenhas, Junior Barrera, Jarbas Caiado de Castro Neto, Alejandro César Frery Orgambide, and Eduardo Antonio Barros da Silva
- Subjects
Physics - Abstract
A restauração de imagens obtidas através de microscopia de seccionamento óptico computacional, utilizando técnicas de fluorescência, é um problema relevante em muitas aplicações biológicas. Diversos métodos foram propostos nos últimos anos com diferentes graus de sucesso para melhorar a qualidade destas imagens, mas a complexidade dos dados e o custo computacional do processamento ainda permanecem como fatores limitantes neste tipo de problema. Consideramos, neste trabalho, várias metodologias para a deconvolução de imagens tridimensionais obtidas em microscopia de fluorescência wide-field, onde propomos métodos lineares não iterativos e também algoritmos iterativos não lineares, que incorporam a presença do ruído Poisson nas observações devido à baixa contagem de fótons. Ainda, propomos duas abordagens específicas para a redução do ruído Poisson, sendo a primeira baseada em um critério de máximo a posteriori e a segunda na transformação de Anscombe. O primeiro algoritmo de deconvolução linear não iterativo é um método de dois passos baseado em um filtro de restauração não linear derivado a partir de um critério de máximo a posteriori, que considera uma distribuição de Poisson para modelar o ruído presente na imagem observada. O segundo, é um filtro de mínimo erro médio quadrático derivado usando o princípio da ortogonalidade no domínio de Fourier a partir de um modelo para o ruído Poisson. Os métodos iterativos não lineares são baseados na teoria de Projeções sobre Conjuntos Convexos, sendo que propomos o uso de cinco conjuntos de restrições convexas. Estas restrições são derivadas de forma a deconvoluir a imagem observada com a função de espalhamento pontual do microscópio, recuperar parte das freqüências perdidas devido à função de transferência óptica do sistema, garantir a positividade da solução e, também, prevenir erros introduzidos pelo processo de regularização. Os algoritmos foram analisados utilizando imagens sintéticas, com diferentes níveis de ruído Poisson e com imagens de espécimes reais. Os métodos também foram comparados com os algoritmos Maximum Likelihood Expectation Maximization e Regularized Linear Least Squares, apresentando boa performance em termos visuais e também uma boa relação custo-benefício. Ainda, propomos uma metodologia eficiente para a esqueletização tridimensional de estruturas tubulares, como neurônios e artérias, através do cálculo numérico de campos vetoriais e da estimação de curvaturas principais usando o mapa de Weingarten. Dada uma imagem binária, o método consiste em gerar uma imagem em tons de cinza, correspondente à magnitude de um campo de vetores, seguido por uma busca de pontos que pertencem aos vales de potenciais. Pode-se mostrar que estes pontos correspondem à transformação do eixo médio. Apresentamos resultados para contornos bidimensionais e também para imagens tridimensionais de neurônios e artérias. O algoritmo demonstrou uma boa performance, uma vez que o campo vetorial pode ser rapidamente calculado usando algoritmos de transformada rápida de Fourier The deconvolution of images obtained by means of optical-sectioning widefield fluorescence rnicroscopy, is a relevant problem in biological applications. Several methods have been proposed in the last few years, with different degrees of success, to improve the quality of the images, but the data complexity and the computational cost remain a limiting factor in this problem. We present in this work several methodologies to perform the deconvolution of three-dimensional data obtained by wide-field fluorescence microscopy. We present both linear, non-iterative and non-linear, iterative methods that take into accont the nature of the noise due to the low leve1 of photon counts. We also propose two algoritms to reduce the Poisson noise. The first one is based on a maximum a posteriori approach and the second one is based on the Anscombe transformation. The first linear, non-iterative algorithm is a two-pass method based on a nonlinear maximum a posteriori restoration filter derived using the Poisson noise model. The second linear, non-iterative deconvolution algorithm is a pointwise, space invariant, minimum mean square restoration filter for the Poisson image noise model derived using the orthogonality principle in the Fourier domain. The non-linear, iterative methods are based on the Projection onto Convex Sets theory. In the restoration algorithms, we combine five constraints sets in order to restore the out-of-focus blur, to retrieve the missing frequencies due to the transfer function of the optical system, to guarantee positiveness, and also to prevent the regularization errors. The methods were analysed using phantoms with several degrees of Poisson noise and with real ceil images. Also, they were compared with the Maximum Likelihood Expectation Maximization and Regularized Linear Least Squares algorithms. All the metodologies demonstrate good performance in terms of both visual results and cost-benefit analysis. We also propose an approach for efficient three-dimensional skeletonization of tubular structures, such as neurons and arteries, through fast numerical calculation of vector fields and curvature estimation by using the Weingarten formulae. In short, given a binary image, the method consists in generating a grayscale image corresponding to the magnitude of a vector field followed by a search of the points that belong to the botton of the potencial valleys. It can be shown that these points correspond to the media1 axis transformation. We present results for both two-dimensional shapes and three-dimensional arteries and neurons images. The algorithm has demonstrated a good performance due to the fact that the vector field can be easy and fastly calculated using the fast Fourier transform algorithm
- Published
- 2015
99. Potential association of specific Candida parapsilosis genotypes, bloodstream infections and colonization of health workers' hands
- Author
-
C. Lo Passo, Roberta Galbo, Antonio David, Giuseppe Criseo, Orazio Romeo, Fabio Scordino, I Pernice, Ignazio Barberi, Antonio Cascio, Demetrio Delfino, Delfino, D., Scordino, F., Pernice, I., Lo Passo, C., Galbo, R., David, A., Barberi, I., Criseo, G., Cascio, A., and Romeo, O.
- Subjects
Microbiology (medical) ,Candida parapsilosis ,microsatellite genotyping ,Settore MED/17 - Malattie Infettive ,Genotype ,Sepsi ,Hospitalized patients ,Health Personnel ,Fungal pathogen ,Nosocomial fungal infection ,Infectious Disease ,Biology ,Persistence (computer science) ,Microbiology ,Candida species ,Candidaemia ,fungal pathogens ,healthcare workers ,nosocomial fungal infections ,Retrospective Studie ,Sepsis ,Disease Transmission, Infectious ,Humans ,Colonization ,DNA, Fungal ,Mycological Typing Techniques ,Candida ,Retrospective Studies ,Genetic diversity ,Cross Infection ,Molecular Epidemiology ,Medicine (all) ,Fungal pathogens ,Healthcare workers ,Microsatellite genotyping ,Nosocomial fungal infections ,Hand ,Molecular Typing ,Infectious Diseases ,General Medicine ,biology.organism_classification ,Disease Transmission, Infectiou ,Microsatellite Analysis ,Candida specie ,Healthcare worker ,Candida parapsilosi ,Mycological Typing Technique ,Human - Abstract
Fungal nosocomial infections continue to be a serious problem among hospitalized patients, decreasing quality of life and adding millions of euros to healthcare costs. The aim of this study was to describe the pattern of fungi associated with the hands of healthcare workers and to genotype Candida parapsilosis isolates in order to understand whether their high clinical prevalence stems from endemic nosocomial genotypes or from the real emergence of epidemiologically-unrelated strains. Approximately 39% (50/129) of healthcare workers were positive for yeasts and among 77 different fungal isolates recovered, C. parapsilosis was the most frequent (44/77; 57%). Twenty-seven diverse genotypes were obtained by microsatellite analysis of 42 selected blood and hand isolates. Most of the isolates from hands showed a new, unrelated, genotype, whereas a particular group of closely related genotypes prevailed in blood samples. Some of the latter genotypes were also found on the hands of healthcare workers, indicating a persistence of these clones within our hospital. C. parapsilosis genotypes from the hands were much more heterogeneous than clinical ones, thus reflecting a high genetic diversity among isolates, which is notably unusual and unexpected for this species.
- Published
- 2014
100. Neonatal liver abscesses associated with candidemia: three cases and review of literature
- Author
-
Orazio Romeo, Ignazio Barberi, Giuseppina Corona, Dario Pantaleo, Antonio Cascio, Giuseppina Barberi, Chiara Iaria, Demetrio Delfino, Cascio A, Pantaleo D, Corona G, Barberi G, Delfino D, Romeo O, Iaria C, and Barberi I.
- Subjects
Male ,medicine.medical_specialty ,Liver Abscess ,MEDLINE ,Infant, Premature, Diseases ,Candida ,Candidemia ,Liver abscess ,Preterm infant ,Sepsis ,medicine ,Humans ,Antibiotic use ,Candida albicans ,biology ,business.industry ,Infant, Newborn ,Obstetrics and Gynecology ,medicine.disease ,biology.organism_classification ,Surgery ,Parenteral nutrition ,Solitary lesion ,Candida, Candidemia Liver, abscess ,Pediatrics, Perinatology and Child Health ,Female ,Ultrasonography ,business ,Infant, Premature - Abstract
BACKGROUND: Our aim was to identify risk factors for the development of neonatal Candida liver abscess and to find useful information to better manage this potentially fatal complication. METHODS: A computerized search was conducted using PubMed. Overall, three articles describing the history of seven infants were finally considered. The characteristics of these seven cases were analyzed together with those of three new cases that we treated in the recent past. RESULTS: All the neonates were premature. Previous antibiotic use was reported in all the cases, umbilical venous catheterization in 9/10 and total parenteral nutrition in 8/10. Candida albicans was isolated in 9/10. All the patients presented with aspecific signs of sepsis. Liver abscesses were described as "microabscesses" or "miliary abscesses" in three cases, as solitary lesion in two cases. In one case two lesions and in one four lesions were reported. Three infants died. CONCLUSIONS: Liver ultrasonography should be performed in all the neonates with signs of sepsis, especially in the presence of candidemia and/or hepatomegaly and/or significant change in liver enzymes. Umbilical venous catheter should be removed, and peripheral IV access should be used until there is documented clearance from the blood with three or more negative blood cultures.
- Published
- 2013
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.