Lymphatic vessels arise from specialized angioblasts within a venous niche.

How cells acquire their fate is a fundamental question in developmental and regenerative biology. Multipotent progenitors undergo cell-fate restriction in response to cues from the microenvironment, the nature of which is poorly understood. In the case of the lymphatic system, venous cells from the cardinal vein are thought to generate lymphatic vessels through trans-differentiation. Here we show that in zebrafish, lymphatic progenitors arise from a previously uncharacterized niche of specialized angioblasts within the cardinal vein, which also generates arterial and venous fates. We further identify Wnt5b as a novel lymphatic inductive signal and show that it also promotes the 'angioblast-to-lymphatic' transition in human embryonic stem cells, suggesting that this process is evolutionarily conserved. Our results uncover a novel mechanism of lymphatic specification, and provide the first characterization of the lymphatic inductive niche. More broadly, our findings highlight the cardinal vein as a heterogeneous structure, analogous to the haematopoietic niche in the aortic floor.

Allele frequencies of microsatellite loci for genetic characterization of a Sicilian bovine population.

Short tandem repeats are used as an effective method to trace DNA markers in genotyping. Using a standardized kit, we tested 11 microsatellite markers recommended by the International Society for Animal Genetics (ISAG) in a sample of 495 Sicilian cattle. The aim of this study was to investigate the allele frequencies in the Sicilian cattle population to provide a reference database and at the same time to assess the use of the ISAG microsatellite panel for pedigree analysis. DNA samples were collected from blood and amplified in an 11-plex polymerase chain reaction (PCR); PCR products were injected in a 3130 Genetic Analyzer. All loci showed high mean polymorphism information content (0.768), and the observed mean heterozygosity was less than the expected value (0.732 vs 0.794, respectively). The exact test for Hardy-Weinberg proportions, allele number, and inbreeding coefficient were calculated. Our results indicated that equilibrium was not always maintained. The observed mean homozygote value exceeded the expected value (132.81 vs 102.14), but no evidence for allele dropout was found. These results could be explained by a non-random mating; further studies using a larger number of animals could confirm or invalidate this hypothesis. The probability of identity and exclusion of a locus were also estimated and proved to be useful in paternity testing. The ISAG microsatellite panel is useful to screen the Sicilian bovine kinship. Currently, an allele frequency database is being constructed.

Multilocus microsatellite polymorphism analysis to characterize Leishmania infantum strains isolated in Sicily.

Different approaches are being developed to improve the differentiation of Leishmania genus using biochemical and molecular methods. In this study, 11 independent polymorphic microsatellites were used for the typing of strains of L. infantum isolated in Sicily. Polymerase chain reaction was employed to amplify the microsatellites contained in 12 DNA regions selected from among more investigated loci. A total of 51 isolates of L. infantum from dogs were tested by using the same locus panel. The products were successively analysed using an automatic sequence detector (ABI PRISM 3130 AB), to discover relevant microsatellite polymorphisms. It was possible to discriminate between MON-1 and non-MON-1 groups. Moreover, the method permitted to distinguish various genotypes of L. infantum isolates within each zymodema. Model- and distance-based analyses of the data set showed comparable results. The frequency of heterozygosity in the alleles analysed varied extremely between the different groups of isolates. As the method exhibits a high level of discrimination, it is suitable for characterization of closely related strains in epidemiological studies.

High prevalence of subclinical cardiovascular abnormalities in patients with systemic lupus erythematosus in spite of a very low clinical damage index.

BACKGROUND AND AIM: To evaluate the prevalence of subclinical cardiovascular (CV) abnormalities in systemic lupus erythematosus (SLE) stratified according to SLE-related organ damage using the Systemic Lupus International Collaborating Clinics (SLICC) damage index. METHODS AND RESULTS: We selected SLE patients without clinically overt CV events (n=45, 56% with SLICC=0, 44% with SLICC=1-4). CV evaluation was performed using cardiac and vascular echo-Doppler techniques. Post-ischemic flow-mediated dilation (FMD) over nitroglycerine-mediated dilation (NMD) of the brachial artery <0.70 defined endothelial dysfunction. The prevalence of preclinical CV abnormalities (CVAbn, including at least one of the following-carotid atherosclerosis, left ventricular (LV) hypertrophy, low arterial compliance, LV wall motion abnormalities, aortic regurgitation, FMD/NMD<0.70)-was 64% (16/25) in patients with SLICC=0 and 80% (16/20) in those with SLICC>0 (p=not significant (NS)). In particular, the prevalence of carotid atherosclerosis (28% vs. 16%), of LV hypertrophy (12% vs. 6%) and of LV wall motion abnormalities (15% vs. 12%), of low global arterial compliance (18% vs. 10%), prevalence of aortic regurgitation (30% vs. 18%) and/or aortic valve fibrosclerosis (10% vs. 8%), FMD<10% (14+/-5% vs. 14%+/-6) and prevalence of FMD/NMD<0.70 (53% vs. 52%) were comparable in SLE patients with SLICC>0 and in those with SLICC=0 (all p=NS). Of the SLE patients without carotid atherosclerosis, LV hypertrophy, low arterial compliance, LV wall motion abnormalities and aortic regurgitation (n=17), endothelial dysfunction was detected in 50% of those with SLICC=0 (6/12) and in 40% of those with SLICC>0 (2/5, p=NS). CONCLUSIONS: SLE patients with SLICC=0 often have an elevated CV risk profile due to subclinical manifestations of CV disease detectable by cardiac and vascular echo-Doppler evaluations.

A developmental evaluation process for nurses: enhancing professional excellence.

Healthcare organizations are challenged to provide an environment that enhances professional growth. Miami Valley Hospital responded by examining its evaluation system for clinical nurses and designing a developmental evaluation process. The result is an objective position description outlining global responsibilities of a nurse and a comprehensive, unit-specific assessment of performance. As nurses are guided and nurtured in their development, the opportunities for them to excel are unlimited.

A clinical advancement program: creating an environment for professional growth.

Clinical ladders help maintain expert, motivated, and effective nurses in direct patient care roles. While many institutions were phasing out clinical ladders for registered nurses, Miami Valley Hospital was proactively evaluating the original version. The authors describe their clinical advancement program, based on Benner's model, with program evaluation results. The program participation rate has increased overall. Participants perceive their work and environment more positively than nonparticipants.