West Nile virus (WNV) RNA was demonstrated in 5 of 25 (20%) urine samples collected from convalescent patients 573 to 2,452 days (1.6 to 6.7 years) after WNV infection. Four of the 5 amplicons sequenced showed >99% homology to the WNV NY99 strain. These findings show that individuals with chronic symptoms following WNV infection may have persistent renal infection over several years.
Mucociliary epithelia are essential for homeostasis of many organs and consist of mucus-secreting goblet cells and ciliated cells. Here, we present the ciliated epidermis of Xenopus embryos as a facile model system for in vivo molecular studies of mucociliary epithelial development. Using an in situ hybridization-based approach, we identified numerous genes expressed differentially in mucus-secreting cells or in ciliated cells. Focusing on genes expressed in ciliated cells, we have identified new candidate ciliogenesis factors, including several not present in the current ciliome. We find that TTC25-GFP is localized to the base of cilia and to ciliary axonemes, and disruption of TTC25 function disrupts ciliogenesis. Mig12-GFP localizes very strongly to the base of cilia and confocal imaging of this construct allows for simple visualization of the planar polarity of basal bodies that underlies polarized ciliary beating. Knockdown of Mig12 disrupts ciliogenesis. Finally, we show that ciliogenesis factors identified in the Xenopus epidermis are required in the midline to facilitate neural tube closure. These results provide further evidence of a requirement for cilia in neural tube morphogenesis and suggest that genes identified in the Xenopus epidermis play broad roles in ciliogenesis. The suites of genes identified here will provide a foundation for future studies, and may also contribute to our understanding of pathological changes in mucociliary epithelia that accompany diseases such as asthma.
The developmental bases for species differences in adult phenotypes remain largely unknown. An emerging system for studying such variation is the adult pigment pattern expressed by Danio fishes. These patterns result from several classes of pigment cells including black melanophores and yellow xanthophores, which differentiate during metamorphosis from latent stem cells of presumptive neural crest origin. In the zebrafish D. rerio,alternating light and dark horizontal stripes develop, in part, owing to interactions between melanophores and cells of the xanthophore lineage that depend on the fms receptor tyrosine kinase; zebrafish fmsmutants lack xanthophores and have disrupted melanophore stripes. By contrast,the closely related species D. albolineatus exhibits a uniform pattern of melanophores, and previous interspecific complementation tests identified fms as a potential contributor to this difference between species. Here, we survey additional species and demonstrate marked variation in the fms-dependence of hybrid pigment patterns, suggesting interspecific variation in the fms pathway or fmsrequirements during pigment pattern formation. We next examine the cellular bases for the evolutionary loss of stripes in D. albolineatus and test the simplest model to explain this transformation, a loss of fmsactivity in D. albolineatus relative to D. rerio. Within D. albolineatus, we demonstrate increased rates of melanophore death and decreased melanophore migration, different from wild-type D. rerio but similar to fms mutant D. rerio. Yet, we also find persistent fms expression in D. albolineatus and enhanced xanthophore development compared with wild-type D. rerio,and in stark contrast to fms mutant D. rerio. These findings exclude the simplest model in which stripe loss in D. albolineatusresults from a loss of fms-dependent xanthophores and their interactions with melanophores. Rather, our results suggest an alternative model in which evolutionary changes in pigment cell interactions themselves have contributed to stripe loss, and we test this model by manipulating melanophore numbers in interspecific hybrids. Together, these data suggest evolutionary changes in the fms pathway or fms requirements,and identify changes in cellular interactions as a likely mechanism of evolutionary change in Danio pigment patterns.
Houston, Texas, maintains an environment conducive to dengue virus (DENV) emergence; however, surveillance is passive and diagnostic testing is not readily available. To determine if DENV is present in the area, we tested 3768 clinical specimens (2138 cerebrospinal fluid [CSF] and 1630 serum) collected from patients with suspected mosquito-borne viral disease between 2003 and 2005. We identified 47 immunoglobulin M (IgM)-positive dengue cases, including two cases that were positive for viral RNA in serum for dengue serotype 2. The majority of cases did not report any history of travel outside the Houston area prior to symptom onset. The epidemic curve suggests an outbreak occurred in 2003 with continued low-level transmission in 2004 and 2005. Chart abstractions were completed for 42 of the 47 cases; 57% were diagnosed with meningitis and/or encephalitis, and 43% met the case definition for dengue fever. Two of the 47 cases were fatal, including one with illness compatible with dengue shock syndrome. Our results support local transmission of DENV during the study period. These findings heighten the need for dengue surveillance in the southern United States.
We conducted a case-control study to determine risk factors for developing encephalitis among West Nile virus cases when compared with age-, gender and race/ethnicity-matched hospitalized controls. In the multivariable conditional logistic regression analysis, we identified the following independent risk factors associated with being an encephalitis case: hypertension (OR 4.0; P = 0.005), immunosuppressing conditions (OR 5.6; P = 0.001) and cardiovascular disease (OR = 28.3; P < 0.001). Individuals with these comorbidities should be targeted for education on protecting themselves from mosquito exposures.
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