The utility of adding expiratory or decubitus chest radiographs to the radiographic evaluation of suspected pediatric airway foreign bodies.

STUDY OBJECTIVE: This study aimed to compare test characteristics of standard (lateral and posteroanterior or anteroposterior) chest radiographs with and without special views (expiratory or bilateral decubitus) in the emergency department evaluation of children with suspected airway foreign bodies. METHODS: From 1997 to 2008, 328 patients with a suspected airway foreign body had standard and special view chest radiographs: 192 with left and right decubitus views, 133 with expiratory views, and 3 with both. Patients were excluded for cardiorespiratory disease, chest wall deformity, visible airway foreign bodies on standard views, or spontaneously expelled airway foreign bodies. After blinded radiologist review, standard plus special view test characteristics were compared to standard views. RESULTS: Nine upper airway and 70 tracheobronchial airway foreign bodies were identified by direct visualization or bronchoscopy, and the remainder were ruled out by bronchoscopy (50 patients) or clinically (199 patients). The sensitivity and specificity of the radiographs were, respectively, decubitus cohort, standard views, 56% and 79% and standard+decubitus views, 56% and 64%; expiratory radiograph cohort, standard views, 33% and 70% and standard+expiratory views, 62% and 72%. For standard plus decubitus views versus standard views alone, the relative sensitivity was 1.0 (0.56/0.56; 95% confidence interval [CI] 0.81 to 1.23) and the relative 1-specificity was 1.76 (0.36/0.21; 95% CI 1.3 to 2.37). For standard plus expiratory views versus standard views alone, the relative sensitivity was 1.87 (0.62/0.33; 95% CI 1.23 to 2.83) and the relative 1-specificity was 0.93 (0.28/0.3; 95% CI 0.6 to 1.44). CONCLUSION: The addition of decubitus to standard views increases false positives without increasing true positives and lacks clinical benefit. The addition of expiratory to standard views increases true positives without increasing false positives, but test accuracy remains low and the clinical benefit is uncertain.

Ex vivo comparison of microbicide efficacies for preventing HIV-1 genomic integration in intraepithelial vaginal cells.

Vaginally applied microbicides hold promise as a strategy to prevent sexual HIV transmission. Several nonspecific microbicides, including the polyanion cellulose sulfate, have been evaluated in large-scale clinical trials but have failed to show significant efficacy. These findings have prompted a renewed search for preclinical testing systems that can predict negative outcomes of microbicide trials. Moreover, the pipeline of potential topical microbicides has been expanded to include antiretroviral agents, such as reverse transcriptase, fusion, and integrase inhibitors. Using a novel ex vivo model of vaginal HIV-1 infection, we compared the prophylactic potentials of two forms of the fusion inhibitor T-20, the CCR5 antagonist TAK-778, the integrase inhibitor 118-D-24, and cellulose sulfate (Ushercell). The T-20 peptide with free N- and C-terminal amino acids was the most efficacious compound, causing significantly greater inhibition of viral genomic integration in intraepithelial vaginal leukocytes, measured by an optimized real-time PCR assay, than the more water-soluble N-acetylated T-20 peptide (Fuzeon) (50% inhibitory concentration [IC50], 0.153 microM versus 51.2 microM [0.687 ng/ml versus 230 ng/ml]; P<0.0001). In contrast, no significant difference in IC50s was noted in peripheral blood cells (IC50, 13.58 microM versus 7.57 microM [61 ng/ml versus 34 ng/ml]; P=0.0614). Cellulose sulfate was the least effective of all the compounds tested (IC50, 1.8 microg/ml). These results highlight the merit of our model for screening the mucosal efficacies of novel microbicides and their formulations and potentially rank ordering candidates for clinical evaluation.

Most DC-SIGNR transcripts at mucosal HIV transmission sites are alternatively spliced isoforms.

The repeat region of DC-SIGNR (CD209L) is polymorphic on the genomic level, and, in a separate study, we observed a correlation between the DC-SIGNR genotype and HIV-1 susceptibility during sexual contact. However, previous investigations using immunohistochemistry failed to detect membrane-bound DC-SIGNR on cells in the genital and rectal mucosa. We therefore explored the presence of DC-SIGNR in these compartments with a more sensitive limiting dilution RT-PCR, which also allowed for quantification of alternatively spliced mRNA isoforms. DC-SIGN (CD209) and DC-SIGNR mRNA transcript isoforms were found in all 12 vaginal and two rectal biopsies obtained from 14 healthy individuals. For DC-SIGNR, we detected significantly more isoform than full-length transcripts (mean copy numbers/mug RNA: 602 vs 26; P=0.0009). Four mucosal samples lacked full-length DC-SIGNR transcripts entirely. Cloning and sequencing of DC-SIGNR mRNA in three additional individuals revealed a diverse repertoire of DC-SIGNR isoforms, many of which encoded for proteins predicted to be soluble and secreted. Indeed, in one vaginal sample, we detected only soluble isoforms. In conjunction with our prior observation that the DC-SIGNR genotype has an effect on HIV-1 transmission in vivo, these findings emphasize that DC-SIGNR, in addition to DC-SIGN, should be considered as a cofactor in sexual HIV-1 transmission. Soluble isoforms, in particular, may modulate the efficiency of viral transmission and dissemination.

Initial events in establishing vaginal entry and infection by human immunodeficiency virus type-1.

Understanding the initial events in the establishment of vaginal human immunodeficiency virus type-1 (HIV-1) entry and infection has been hampered by the lack of appropriate experimental models. Here, we show in an ex vivo human organ culture system that upon contact in situ, HIV-1 rapidly penetrated both intraepithelial vaginal Langerhans and CD4(+) T cells. HIV-1 entered CD4(+) T cells almost exclusively by CD4 and CCR5 receptor-mediated direct fusion, without requiring passage from Langerhans cells, and overt productive infection ensued. By contrast, HIV-1 entered CD1a(+) Langerhans cells primarily by endocytosis, by means of multiple receptors, and virions persisted intact within the cytoplasm for several days. Our findings shed light on the very earliest steps of mucosal HIV infection in vivo and may guide the design of effective strategies to block local transmission and prevent HIV-1 spread.

Combined effect of CCR5-Delta32 heterozygosity and the CCR5 promoter polymorphism -2459 A/G on CCR5 expression and resistance to human immunodeficiency virus type 1 transmission.

Exposed seronegative individuals (ES) with persistent high-risk sexual behavior may be less susceptible to human immunodeficiency virus type 1 (HIV-1) infection because they carry the chemokine receptor (CR) gene alleles CCR5 open reading frame (ORF) Delta32, CCR5 promoter -2459G, or CCR2 ORF 64I (CCR2-64I), all of which have been found to diminish HIV-1 infectivity and/or disease progression. To investigate this, we determined the haplotypes for these three genetic loci in 93 ES and 247 low-risk control individuals. To test if protective haplotypes exert their effect by modulating CR expression, we measured the protein expression of CCR5 and CXCR4 on circulating CD4+ T cells and CD14+ monocytes in 71 ES and 92 controls. To avoid investigator bias, the analysis was performed without knowledge of each subject's risk and genotype. The CCR5 -2459G allele was significantly enriched in ES Caucasian men, who constituted the majority (84%) of the ES cohort, compared to the control Caucasian men (P = 0.02). This increase was mostly attributable to a higher frequency of the -2459 A/G versus the -2459 A/A genotype in individuals heterozygous for the delta32 allele (P = 0.012). No protective influence of the CCR2-64I allele was observed. The haplotypes CCR5 ORF delta32/CCR5 -2459A (in complete linkage disequilibrium) and CCR5 ORF wt/CCR5 -2459G had a cumulative negative effect on the expression of CCR5, since we measured significantly reduced CCR5 densities on both T-helper cells and monocytes only when both haplotypes were present. Densities of CCR5 on lymphocytes and monocytes were correlated (r = 0.59; P < 0.0001), indicating concordance of CCR5 expression patterns across different cell types. We conclude that the CCR5 ORF delta32/wt-CCR5 -2459 A/G genotype combination offers an advantage in resisting sexual HIV-1 transmission and that this effect is mediated by a relative paucity of CCR5 on potential target cells of HIV-1.