Exploring structural properties of kk-trees and block graphs

We present a new characterization of $k$-trees based on their reduced clique graphs and $(k+1)$-line graphs, which are block graphs. We explore structural properties of these two classes, showing that the number of clique-trees of a $k$-tree $G$ equals the number of spanning trees of the $(k+1)$-line graph of $G$. This relationship allows to present a new approach for determining the number of spanning trees of any connected block graph. We show that these results can be accomplished in linear time complexity.Comment: 6 pages, 1 figur

Some new aspects of main eigenvalues of graphs

An eigenvalue of the adjacency matrix of a graph is said to be main if the all-1 vector is non-orthogonal to the associated eigenspace. This paper explores some new aspects of the study of main eigenvalues of graphs, investigating specifically cones over strongly regular graphs and graphs for which the least eigenvalue is non-main. In this case, we characterize paths and trees with diameter-3 satisfying the property. We may note that the importance of least eigenvalues of graphs for the equilibria of social and economic networks was recently uncovered in literature.publishe

Incidence Of Periventricular/intraventricular Hemorrhage In Very Low Birth Weight Infants: A 15-year Cohort Study.

To assess the incidence of periventricular/intraventricular hemorrhage (PIVH) in very low birth rate neonates. This was a prospective cohort study conducted on a sample of very low birth weight infants over a 15-year period. Neonates who did not undergo cerebral ultrasonography, had malformations affecting the central nervous system, or died within the first 24 hours of life were excluded. Ultrasonography was performed through the anterior fontanelle using an Aloka® 620 scanner with a 5 mHz probe, between days 1 and 3 of life, at 7 days, and at 28 days (or at discharge). Incidence was analyzed by means of the chi-square test for trend or Cochran-Armitage test and through a simple linear regression model with a logarithmic trendline as the output. For assessment of potential associated factors, a variety of obstetric, perinatal, and neonatal data collected between 1991-1994 and 2002-2005 were analyzed, using the chi-square and Fisher's exact tests for statistical analysis. The significance level was set at 5%. Of 1,777 very low birth weight infants born during the study period, 1,381 (77.7%) were examined. Of these, 289 (20.9%) had PIVH. The yearly distribution of cases showed a progressive decline in incidence, from 50.9% in 1991 to 11.9% in 2005 (p < 0.0001). The incidence of PIVH decreased across all weight ranges as well as at grades I/II and III/IV. Significant differences in antenatal corticosteroid use, gender (male), weight (< 1,000 g), hyaline membrane disease, mechanical ventilation, administration of surfactant, patent ductus arteriosus, and sepsis were found. The incidence of PIVH in very low birth weight infants declined significantly during the study period.87505-1

Incidence of periventricular/intraventricular hemorrhage in very low birth weight infants: a 15-year cohort study

OBJECTIVE: To assess the incidence of periventricular/intraventricular hemorrhage (PIVH) in very low birth rate neonates. METHODS: This was a prospective cohort study conducted on a sample of very low birth weight infants over a 15-year period. Neonates who did not undergo cerebral ultrasonography, had malformations affecting the central nervous system, or died within the first 24 hours of life were excluded. Ultrasonography was performed through the anterior fontanelle using an Aloka® 620 scanner with a 5 mHz probe, between days 1 and 3 of life, at 7 days, and at 28 days (or at discharge). Incidence was analyzed by means of the chi-square test for trend or Cochran-Armitage test and through a simple linear regression model with a logarithmic trendline as the output. For assessment of potential associated factors, a variety of obstetric, perinatal, and neonatal data collected between 1991-1994 and 2002-2005 were analyzed, using the chi-square and Fisher's exact tests for statistical analysis. The significance level was set at 5%. RESULTS: Of 1,777 very low birth weight infants born during the study period, 1,381 (77.7%) were examined. Of these, 289 (20.9%) had PIVH. The yearly distribution of cases showed a progressive decline in incidence, from 50.9% in 1991 to 11.9% in 2005 (p < 0.0001). The incidence of PIVH decreased across all weight ranges as well as at grades I/II and III/IV. Significant differences in antenatal corticosteroid use, gender (male), weight (< 1,000 g), hyaline membrane disease, mechanical ventilation, administration of surfactant, patent ductus arteriosus, and sepsis were found. CONCLUSION: The incidence of PIVH in very low birth weight infants declined significantly during the study period.OBJETIVO: Avaliar a incidência da hemorragia peri-intraventricular (HPIV) em recém-nascidos de muito baixo peso. MÉTODOS: Foi realizado estudo de coorte prospectiva de recém-nascidos de muito baixo peso ao longo de 15 anos. Excluíram-se aqueles sem avaliação por ultrassonografia cerebral, com má-formação do sistema nervoso central ou falecidos antes de 24 horas de vida. Os exames foram realizados através da fontanela anterior, utilizando-se ecógrafo Aloka® 620 e transdutor de 5 mHz, entre o primeiro e o terceiro dia de vida, e também no sétimo e no 28º dia de vida e/ou na alta hospitalar. A incidência foi analisada pelo teste de qui-quadrado de tendência ou pelo Cochran-Armitage test, e pelo modelo de regressão linear simples (curva de tendência logarítmica). Para avaliação dos possíveis fatores associados, analisaram-se dados obstétricos, perinatais e neonatais nos períodos de 1991/1994 e 2002/2005, com cálculo do teste de qui-quadrado / Fisher e do risco relativo. O nível de significância foi de 5%. RESULTADOS: Nasceram 1.777 crianças de muito baixo peso, e 1.381 (77,7%) foram avaliadas. Dessas, 289 (20,9%) apresentaram HPIV. A distribuição anual mostrou queda na incidência, de 50,9% em 1991 para 11,9% em 2005 (p < 0,0001). A HPIV apresentou queda em todas as faixas de peso e nos grupos com grau I/II e III/IV. Observaram-se diferenças relacionadas a uso de esteroide antenatal, sexo masculino, peso < 1.000 g, doenças de membranas hialinas, ventilação mecânica, uso de surfactante, canal arterial e sepse. CONCLUSÃO: Houve queda significativa na incidência da doença em recém-nascidos de muito baixo peso ao nascer durante o período analisado.50551

Validation of a Novel, Sensitive, and Specific Urine-Based Test for Recurrence Surveillance of Patients With Non-Muscle-Invasive Bladder Cancer in a Comprehensive Multicenter Study

Bladder cancer (BC), the most frequent malignancy of the urinary system, is ranked the sixth most prevalent cancer worldwide. Of all newly diagnosed patients with BC, 70–75% will present disease confined to the mucosa or submucosa, the non-muscle-invasive BC (NMIBC) subtype. Of those, approximately 70% will recur after transurethral resection (TUR). Due to high rate of recurrence, patients are submitted to an intensive follow-up program maintained throughout many years, or even throughout life, resulting in an expensive follow-up, with cystoscopy being the most cost-effective procedure for NMIBC screening. Currently, the gold standard procedure for detection and follow-up of NMIBC is based on the association of cystoscopy and urine cytology. As cystoscopy is a very invasive approach, over the years, many different noninvasive assays (both based in serum and urine samples) have been developed in order to search genetic and protein alterations related to the development, progression, and recurrence of BC. TERT promoter mutations and FGFR3 hotspot mutations are the most frequent somatic alterations in BC and constitute the most reliable biomarkers for BC. Based on these, we developed an ultra-sensitive, urine-based assay called Uromonitor®, capable of detecting trace amounts of TERT promoter (c.1-124C > T and c.1-146C > T) and FGFR3 (p.R248C and p.S249C) hotspot mutations, in tumor cells exfoliated to urine samples. Cells present in urine were concentrated by the filtration of urine through filters where tumor cells are trapped and stored until analysis, presenting long-term stability. Detection of the alterations was achieved through a custom-made, robust, and highly sensitive multiplex competitive allele-specific discrimination PCR allowing clear interpretation of results. In this study, we validate a test for NMIBC recurrence detection, using for technical validation a total of 331 urine samples and 41 formalin-fixed paraffin-embedded tissues of the primary tumor and recurrence lesions from a large cluster of urology centers. In the clinical validation, we used 185 samples to assess sensitivity/specificity in the detection of NMIBC recurrence vs. cystoscopy/cytology and in a smaller cohort its potential as a primary diagnostic tool for NMIBC. Our results show this test to be highly sensitive (73.5%) and specific (93.2%) in detecting recurrence of BC in patients under surveillance of NMIBC.This study was supported by FCT (“Portuguese Foundation for Science and Technology”) through a PhD grant to RB (SFRH/ BD/111321/2015). Further funding was obtained from the project “Advancing cancer research: from basic knowledge to application” NORTE-01-0145-FEDER-000029: “Projetos Estruturados de I & D & I,” funded by Norte 2020—Programa Operacional Regional do Norte. This article is a result of the project PTDC/MED-ONC/31438/2017 (The Other Faces of Telomerase: Looking beyond Tumor Immortalization), supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), COMPETE 2020—Operacional Programme for Competitiveness and Internationalisation (POCI) and by Portuguese funds through FCT. Further funding by the European Regional Development Fund (ERDF) through the Operational Programme for Competitiveness and Internationalisation— COMPETE 2020, and Portuguese national funds via FCT, under project POCI-01-0145-FEDER-016390:CANCEL STEM