Choclo virus (CHOV) recovered from deep metatranscriptomics of archived frozen tissues in natural history biorepositories.

BACKGROUND: Hantaviruses are negative-stranded RNA viruses that can sometimes cause severe disease in humans; however, they are maintained in mammalian host populations without causing harm. In Panama, sigmodontine rodents serve as hosts to transmissible hantaviruses. Due to natural and anthropogenic forces, these rodent populations are having increased contact with humans. METHODS: We extracted RNA and performed Illumina deep metatranscriptomic sequencing on Orthohantavirus seropositive museum tissues from rodents. We acquired sequence reads mapping to Choclo virus (CHOV, Orthohantavirus chocloense) from heart and kidney tissue of a two-decade old frozen museum sample from a Costa Rican pygmy rice rat (Oligoryzomys costaricensis) collected in Panama. Reads mapped to the CHOV reference were assembled and then validated by visualization of the mapped reads against the assembly. RESULTS: We recovered a 91% complete consensus sequence from a reference-guided assembly to CHOV with an average of 16X coverage. The S and M segments used in our phylogenetic analyses were nearly complete (98% and 99%, respectively). There were 1,199 ambiguous base calls of which 93% were present in the L segment. Our assembled genome varied 1.1% from the CHOV reference sequence resulting in eight nonsynonymous mutations. Further analysis of all publicly available partial S segment sequences support a clear relationship between CHOV clinical cases and O. costaricensis acquired strains. CONCLUSIONS: Viruses occurring at extremely low abundances can be recovered from deep metatranscriptomics of archival tissues housed in research natural history museum biorepositories. Our efforts resulted in the second CHOV genome publicly available. This genomic data is important for future surveillance and diagnostic tools as well as understanding the evolution and pathogenicity of CHOV.

Viral infection and allergy status impact severity of asthma symptoms in children with asthma exacerbations.

BACKGROUND: Although viral infection is known to be associated with asthma exacerbations, prior research has not identified reliable predictors of acute symptom severity in virus-related asthma exacerbations (VRAEs). OBJECTIVE: To determine the effect of asthma control and viral infection on the severity of current illness and evaluate biomarkers related to acute symptoms during asthma exacerbations. METHODS: We prospectively enrolled 120 children with physician-diagnosed asthma and current wheezing who presented to Arkansas Children's Hospital emergency department. The asthma control test (ACT) stratified controlled (ACT > 19) and uncontrolled (ACT ≤ 19) asthma, whereas pediatric respiratory symptom scores evaluated symptoms. Nasopharyngeal swabs were obtained for viral analysis, and inflammatory mediators were evaluated by nasal filter paper and Luminex assays. RESULTS: There were 33 children with controlled asthma and 87 children with uncontrolled asthma. In those with uncontrolled asthma, 77% were infected with viruses during VRAE compared with 58% of those with controlled asthma. Uncontrolled subjects with VRAE had more acute symptoms compared with the controlled subjects with VRAE or uncontrolled subjects without a virus. The uncontrolled subjects with VRAE and allergy had the highest acute symptom scores (3.363 point pediatric respiratory symptom; P = .04). Children with asthma with higher symptom scores had more periostin (P = .02). CONCLUSION: Detection of respiratory viruses is frequent in those with uncontrolled asthma. Uncontrolled subjects with viruses have more acute symptoms during exacerbations, especially in those with allergy. Periostin was highest in subjects with the most acute symptoms, regardless of control status. Taken together, these data imply synergy between viral infection and allergy in subjects with uncontrolled asthma when considering acute asthma symptoms and nasal inflammation during an exacerbation of asthma.

Non-autophagy Role of Atg5 and NBR1 in Unconventional Secretion of IL-12 Prevents Gut Dysbiosis and Inflammation.

Intestinal myeloid cells play a critical role in balancing intestinal homeostasis and inflammation. Here, we report that expression of the autophagy-related 5 [Atg5] protein in myeloid cells prevents dysbiosis and excessive intestinal inflammation by limiting IL-12 production. Mice with a selective genetic deletion of Atg5 in myeloid cells [Atg5ΔMye] showed signs of dysbiosis preceding colitis, and exhibited severe intestinal inflammation upon colitis induction that was characterised by increased IFNγ production. The exacerbated colitis was linked to excess IL-12 secretion from Atg5-deficient myeloid cells and gut dysbiosis. Restoration of the intestinal microbiota or genetic deletion of IL-12 in Atg5ΔMye mice attenuated the intestinal inflammation in Atg5ΔMye mice. Additionally, Atg5 functions to limit IL-12 secretion through modulation of late endosome [LE] acidity. Last, the autophagy cargo receptor NBR1, which accumulates in Atg5-deficient cells, played a role by delivering IL-12 to LE. In summary, Atg5 expression in intestinal myeloid cells acts as an anti-inflammatory brake to regulate IL-12, thus preventing dysbiosis and uncontrolled IFNγ-driven intestinal inflammation.

Tracing Transmission of Sin Nombre Virus and Discovery of Infection in Multiple Rodent Species.

Sin Nombre orthohantavirus (SNV), a negative-sense, single-stranded RNA virus that is carried and transmitted by the North American deer mouse Peromyscus maniculatus, can cause infection in humans through inhalation of aerosolized excreta from infected rodents. This infection can lead to hantavirus cardiopulmonary syndrome (HCPS), which has an ∼36% case-fatality rate. We used reverse transcriptase quantitative PCR (RT-qPCR) to confirm SNV infection in a patient and identified SNV in lung tissues in wild-caught rodents from potential sites of exposure. Using viral whole-genome sequencing (WGS), we identified the likely site of transmission and discovered SNV in multiple rodent species not previously known to carry the virus. Here, we report, for the first time, the use of SNV WGS to pinpoint a likely site of human infection and identify SNV simultaneously in multiple rodent species in an area of known host-to-human transmission. These results will impact epidemiology and infection control for hantaviruses by tracing zoonotic transmission and investigating possible novel host reservoirs. IMPORTANCE Orthohantaviruses cause severe disease in humans and can be lethal in up to 40% of cases. Sin Nombre orthohantavirus (SNV) is the main cause of hantavirus disease in North America. In this study, we sequenced SNV from an infected patient and wild-caught rodents to trace the location of infection. We also discovered SNV in rodent species not previously known to carry SNV. These studies demonstrate for the first time the use of virus sequencing to trace the transmission of SNV and describe infection in novel rodent species.

Emergence in late 2020 of multiple lineages of SARS-CoV-2 Spike protein variants affecting amino acid position 677.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (S) plays critical roles in host cell entry. Non-synonymous substitutions affecting S are not uncommon and have become fixed in a number of SARS-CoV-2 lineages. A subset of such mutations enable escape from neutralizing antibodies or are thought to enhance transmission through mechanisms such as increased affinity for the cell entry receptor, angiotensin-converting enzyme 2 (ACE2). Independent genomic surveillance programs based in New Mexico and Louisiana contemporaneously detected the rapid rise of numerous clade 20G (lineage B.1.2) infections carrying a Q677P substitution in S. The variant was first detected in the US on October 23, yet between 01 Dec 2020 and 19 Jan 2021 it rose to represent 27.8% and 11.3% of all SARS-CoV-2 genomes sequenced from Louisiana and New Mexico, respectively. Q677P cases have been detected predominantly in the south central and southwest United States; as of 03 Feb 2021, GISAID data show 499 viral sequences of this variant from the USA. Phylogenetic analyses revealed the independent evolution and spread of at least six distinct Q677H sub-lineages, with first collection dates ranging from mid-August to late November 2020. Four 677H clades from clade 20G (B.1.2), 20A (B.1.234), and 20B (B.1.1.220, and B.1.1.222) each contain roughly 100 or fewer sequenced cases, while a distinct pair of clade 20G clusters are represented by 754 and 298 cases, respectively. Although sampling bias and founder effects may have contributed to the rise of S:677 polymorphic variants, the proximity of this position to the polybasic cleavage site at the S1/S2 boundary are consistent with its potential functional relevance during cell entry, suggesting parallel evolution of a trait that may confer an advantage in spread or transmission. Taken together, our findings demonstrate simultaneous convergent evolution, thus providing an impetus to further evaluate S:677 polymorphisms for effects on proteolytic processing, cell tropism, and transmissibility.

Severe Acute Respiratory Syndrome Coronavirus 2: Genomic Observations and Emerging Therapies.

Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), the etiologic agent of the disease COVID-19, first emerged in late December 2019 in China, and has subsequently become a pandemic with unprecedented clinical impact. The virus appears to more severely affect older individuals and those with co-morbid medical conditions, specifically those with chronic lung disease, obesity, heart failure and diabetes. Fortunately, children appear to be less severely affected, though mortality and severe disease have been reported. In addition, children's role in spreading the disease (potentially through asymptomatic shedding of the virus) remains an important area requiring further investigation. The emergence of SARS-CoV-2 has highlighted the importance of metagenomic next generation sequencing as a tool for pandemic investigation. Though no proven therapeutic options currently exist, ongoing genomic and clinical trial data may help inform the identification and development of both repurposed and novel therapeutic agents for use in this disease.

Defining the relationship between vaginal and urinary microbiomes.

BACKGROUND: Although the vaginal and urinary microbiomes have been increasingly well-characterized in health and disease, few have described the relationship between these neighboring environments. Elucidating this relationship has implications for understanding how manipulation of the vaginal microbiome may affect the urinary microbiome and treatment of common urinary conditions. OBJECTIVE: To describe the relationship between urinary and vaginal microbiomes using 16S rRNA gene sequencing. We hypothesized that the composition of the urinary and vaginal microbiomes would be significantly associated, with similarities in predominant taxa. STUDY DESIGN: This multicenter study collected vaginal swabs and catheterized urine samples from 186 women with mixed urinary incontinence enrolled in a parent study and 84 similarly aged controls. Investigators decided a priori that if vaginal and/or urinary microbiomes differed between continent and incontinent women, the groups would be analyzed separately; if similar, samples from continent and incontinent women would be pooled and analyzed together. A central laboratory sequenced variable regions 1-3 (v1-3) and characterized bacteria to the genus level. Operational taxonomic unit abundance was described for paired vaginal and urine samples. Pearson's correlation characterized the relationship between individual operational taxonomic units of paired samples. Canonical correlation analysis evaluated the association between clinical variables (including mixed urinary incontinence and control status) and vaginal and urinary operational taxonomic units, using the Canonical correlation analysis function in the Vegan package (R version 3.5). Linear discriminant analysis effect size was used to find taxa that discriminated between vaginal and urinary samples. RESULTS: Urinary and vaginal samples were collected from 212 women (mean age 53±11 years) and results from 197 paired samples were available for analysis. As operational taxonomic units in mixed urinary incontinence and control samples were related in canonical correlation analysis and since taxa did not discriminate between mixed urinary incontinence or controls in either vagina or urine, mixed urinary incontinence and control samples were pooled for further analysis. Canonical correlation analysis of vaginal and urinary samples indicated that that 60 of the 100 most abundant operational taxonomic units in the samples largely overlapped. Lactobacillus was the most abundant genus in both urine and vagina (contributing on average 53% to an individual's urine sample and 64% to an individual's vaginal sample) (Pearson correlation r=0.53). Although less abundant than Lactobacillus, other bacteria with high Pearson correlation coefficients also commonly found in vagina and urine included: Gardnerella (r=0.70), Prevotella (r=0.64), and Ureaplasma (r=0.50). Linear discriminant analysis effect size analysis identified Tepidimonas and Flavobacterium as bacteria that distinguished the urinary environment for both mixed urinary incontinence and controls as these bacteria were absent in the vagina (Tepidimonas effect size 2.38, P<.001, Flavobacterium effect size 2.15, P<.001). Although Lactobacillus was the most abundant bacteria in both urine and vagina, it was more abundant in the vagina (linear discriminant analysis effect size effect size 2.72, P<.001). CONCLUSION: Significant associations between vaginal and urinary microbiomes were demonstrated, with Lactobacillus being predominant in both urine and vagina. Abundance of other bacteria also correlated highly between the vagina and urine. This inter-relatedness has implications for studying manipulation of the urogenital microbiome in treating conditions such as urgency urinary incontinence and urinary tract infections.

The urinary microbiome in women with mixed urinary incontinence compared to similarly aged controls.

INTRODUCTION & HYPOTHESIS: Previous studies have suggested that women with urinary incontinence have an altered urinary microbiome. We hypothesized that the microbiome in women with mixed urinary incontinence (MUI) differed from controls and tested this hypothesis using bacterial gene sequencing techniques. METHODS: This multicenter study compared the urinary microbiome in women with MUI and similarly aged controls. Catheterized urine samples were obtained; v4-6 regions of the 16S rRNA gene were sequenced to identify bacteria. Bacterial predominance (> 50% of an individual's genera) was compared between MUI and controls. Bacterial sequences were categorized into "community types" using Dirichlet multinomial mixture (DMM) methods. Generalized linear mixed models predicted MUI/control status based on clinical characteristics and community type. Post-hoc analyses were performed in women < 51 and ≥ 51 years. Sample size estimates required 200 samples to detect a 20% difference in Lactobacillus predominance with P < 0.05. RESULTS: Of 212 samples, 97.6% were analyzed (123 MUI/84 controls, mean age 53 ± 11 years). Overall Lactobacillus predominance did not differ between MUI and controls (45/123 = 36.6% vs. 36/84 = 42.9%, P = 0.36). DMM analyses revealed six community types; communities differed by age (P = 0.001). A High-Lactobacillus (89.2% Lactobacillus) community had a greater proportion of controls (19/84 = 22.6%, MUI 11/123 = 8.9%). Overall, bacterial community types did not differ in MUI and controls. However, post-hoc analysis of women < 51 years found that bacterial community types distinguished MUI from controls (P = 0.041); Moderate-Lactobacillus (aOR 7.78, CI 1.85-32.62) and Mixed (aOR 7.10, CI 1.32-38.10) community types were associated with MUI. Community types did not differentiate MUI and controls in women ≥ 51 years (P = 0.94). CONCLUSIONS: Women with MUI and controls did not differ in overall Lactobacillus predominance. In younger women, urinary bacterial community types differentiated MUI from controls.

Complete Genome Sequences of Four Novel Human Coronavirus OC43 Isolates Associated with Severe Acute Respiratory Infection.

We report here the complete genome sequences of four human coronavirus (HCoV) OC43 isolates generated using targeted viral nucleic acid capture and next-generation sequencing; the isolates were collected in New Mexico and Arkansas, USA, in February (HCoV-OC43/USA/TCNP_0070/2016) and March (HCoV-OC43/USA/ACRI_0052/2016) 2016 and January 2017 (HCoV-OC43/USA/TCNP_00204/2017 and HCoV-OC43/USA/TCNP_00212/2017).

Comprehensive viral enrichment enables sensitive respiratory virus genomic identification and analysis by next generation sequencing.

Next generation sequencing (NGS) technologies have revolutionized the genomics field and are becoming more commonplace for identification of human infectious diseases. However, due to the low abundance of viral nucleic acids (NAs) in relation to host, viral identification using direct NGS technologies often lacks sufficient sensitivity. Here, we describe an approach based on two complementary enrichment strategies that significantly improves the sensitivity of NGS-based virus identification. To start, we developed two sets of DNA probes to enrich virus NAs associated with respiratory diseases. The first set of probes spans the genomes, allowing for identification of known viruses and full genome sequencing, while the second set targets regions conserved among viral families or genera, providing the ability to detect both known and potentially novel members of those virus groups. Efficiency of enrichment was assessed by NGS testing reference virus and clinical samples with known infection. We show significant improvement in viral identification using enriched NGS compared to unenriched NGS. Without enrichment, we observed an average of 0.3% targeted viral reads per sample. However, after enrichment, 50%-99% of the reads per sample were the targeted viral reads for both the reference isolates and clinical specimens using both probe sets. Importantly, dramatic improvements on genome coverage were also observed following virus-specific probe enrichment. The methods described here provide improved sensitivity for virus identification by NGS, allowing for a more comprehensive analysis of disease etiology.

Role of the Airway Microbiome in Respiratory Infections and Asthma in Children.

The respiratory tract can be colonized with bacterial, fungal, and viral microorganisms, and the whole of the microbiota, their genes, and the surrounding environment is collectively termed the microbiome. Increasing evidence indicates that the respiratory microbiome has an important role in respiratory health and disease and is both impacted by and potentially contributes to the severity of symptomatic respiratory viral infections and asthma in children. A deeper understanding of the complex interactions between bacteria, viruses, and the host will provide further comprehension into the drivers and mechanisms of respiratory health and disease and will impart opportunities for clinical therapies.

Erratum: Constellation: a tool for rapid, automated phenotype assignment of a highly polymorphic pharmacogene, CYP2D6, from whole-genome sequences.

[This corrects the article DOI: 10.1038/npjgenmed.2015.7.].

The role of next generation sequencing in infection prevention in human parainfluenza virus 3 infections in immunocompromised patients.

BACKGROUND: Respiratory viral infections are a significant problem in patients with hematologic malignancies. We report a cluster of HPIV 3 infections in our myeloma patients, and describe the utility of next generation sequencing (NGS) to identify transmission linkages which can assist in infection prevention. OBJECTIVES: To evaluate the utility of NGS to track respiratory viral infection outbreaks and delineate between community acquired and nosocomial infections in our cancer units. STUDY DESIGN: Retrospective chart review conducted at a single site. All patients diagnosed with multiple myeloma who developed symptoms suggestive of upper respiratory tract infection (URTI) or lower respiratory tract infection (LRTI) along with a respiratory viral panel (RVP) test positive for HPIV 3 between April 1, 2016, to June 30, 2016, were included. Sequencing was performed on the Illumina MiSeq™. To gain understanding regarding community strains of HPIV 3 during the same season, we also performed NGS on HPIV3 strains isolated from pediatric cases. RESULTS: We saw a cluster of 13 cases of HPIV3 infections in the myeloma unit. Using standard epidemiologic criteria, 3 cases were considered community acquired, 7 cases developed infection during treatment in the cancer infusion center, while an additional 3 developed infections during hospital stay. Seven patients required hospitalization for a median duration of 20days. NGS enabled sensitive discrimination of the relatedness of the isolates obtained during the outbreak and provided evidence for source of transmission. Two hospital onset infections could be tracked to an index case; the genome sequences of HPIV 3 strains from these 3 patients only differed by a single nucleotide. CONCLUSIONS: NGS offers a significantly higher discriminatory value as an epidemiologic tool, and can be used to gather real-time information and identification of transmission linkages to assist in infection prevention in immunocompromised patients.

Methodology for a vaginal and urinary microbiome study in women with mixed urinary incontinence.

INTRODUCTION AND HYPOTHESIS: We describe the rationale and methods of a study designed to compare vaginal and urinary microbiomes in women with mixed urinary incontinence (MUI) and similarly aged, asymptomatic controls. METHODS: This paper delineates the methodology of a supplementary microbiome study nested in an ongoing randomized controlled trial comparing a standardized perioperative behavioral/pelvic floor exercise intervention plus midurethral sling versus midurethral sling alone for MUI. Women in the parent study had at least "moderate bother" from urgency and stress urinary incontinence symptoms (SUI) on validated questionnaire and confirmed MUI on bladder diary. Controls had no incontinence symptoms. All participants underwent vaginal and urine collection for DNA analysis and conventional urine culture. Standardized protocols were designed, and a central lab received samples for subsequent polymerase chain reaction (PCR) amplification and sequencing of the bacterial16S ribosomal RNA (rRNA) gene. The composition of bacterial communities will be determined by dual amplicon sequencing of variable regions 1-3 and 4-6 from vaginal and urine specimens to compare the microbiome of patients with controls. Sample-size estimates determined that 126 MUI and 84 control participants were sufficient to detect a 20 % difference in predominant urinary genera, with 80 % power and 0.05 significance level. RESULTS: Specimen collection commenced January 2015 and finished April 2016. DNA was extracted and stored for subsequent evaluation. CONCLUSIONS: Methods papers sharing information regarding development of genitourinary microbiome studies, particularly with control populations, are few. We describe the rigorous methodology developed for a novel urogenital microbiome study in women with MUI.

Complete genome sequence of a KI polyomavirus isolated from an otherwise healthy child with severe lower respiratory tract infection.

Unbiased, deep sequencing of a nasal specimen from an otherwise healthy 13-month-old boy hospitalized in intensive care revealed high gene expression and the complete genome of a novel isolate of KI polyomavirus (KIPyV). Further investigation detected minimal gene expression of additional viruses, suggesting that KIPyV was potentially the causal agent. Analysis of the complete genome of isolate NMKI001 revealed it is different from all previously reported genomes and contains two amino acid differences as compared to the closest virus isolate, Stockholm 380 (EF127908). J. Med. Virol. 89:926-930, 2017. © 2016 Wiley Periodicals, Inc.

Complete Genome Sequence of a Novel Human WU Polyomavirus Isolate Associated with Acute Respiratory Infection.

We report here the complete genome sequence of a WU polyomavirus (WUPyV) isolate, NM040708, collected from a patient with an acute respiratory infection in New Mexico. The double-stranded DNA (dsDNA) genome of NM040708 is 5,229 bp in length and differs from the WUPyV reference with accession no. NC_009539 by 6 nucleotides and 2 amino acids.

Constellation: a tool for rapid, automated phenotype assignment of a highly polymorphic pharmacogene, CYP2D6, from whole-genome sequences.

An important component of precision medicine-the use of whole-genome sequencing (WGS) to guide lifelong healthcare-is electronic decision support to inform drug choice and dosing. To achieve this, automated identification of genetic variation in genes involved in drug absorption, distribution, metabolism, excretion and response (ADMER) is required. CYP2D6 is a major enzyme for drug bioactivation and elimination. CYP2D6 activity is predominantly governed by genetic variation; however, it is technically arduous to haplotype. Not only is the nucleotide sequence of CYP2D6 highly polymorphic, but the locus also features diverse structural variations, including gene deletion, duplication, multiplication events and rearrangements with the nonfunctional, neighbouring CYP2D7 and CYP2D8 genes. We developed Constellation, a probabilistic scoring system, enabling automated ascertainment of CYP2D6 activity scores from 2×100 paired-end WGS. The consensus reference method included TaqMan genotyping assays, quantitative copy-number variation determination and Sanger sequencing. When compared with the consensus reference Constellation had an analytic sensitivity of 97% (59 of 61 diplotypes) and analytic specificity of 95% (116 of 122 haplotypes). All extreme phenotypes, i.e., poor and ultrarapid metabolisers were accurately identified by Constellation. Constellation is anticipated to be extensible to functional variation in all ADMER genes, and to be performed at marginal incremental financial and computational costs in the setting of diagnostic WGS.

A 26-hour system of highly sensitive whole genome sequencing for emergency management of genetic diseases.

While the cost of whole genome sequencing (WGS) is approaching the realm of routine medical tests, it remains too tardy to help guide the management of many acute medical conditions. Rapid WGS is imperative in light of growing evidence of its utility in acute care, such as in diagnosis of genetic diseases in very ill infants, and genotype-guided choice of chemotherapy at cancer relapse. In such situations, delayed, empiric, or phenotype-based clinical decisions may meet with substantial morbidity or mortality. We previously described a rapid WGS method, STATseq, with a sensitivity of >96 % for nucleotide variants that allowed a provisional diagnosis of a genetic disease in 50 h. Here improvements in sequencing run time, read alignment, and variant calling are described that enable 26-h time to provisional molecular diagnosis with >99.5 % sensitivity and specificity of genotypes. STATseq appears to be an appropriate strategy for acutely ill patients with potentially actionable genetic diseases.

Renal systems biology of patients with systemic inflammatory response syndrome.

A systems biology approach was used to comprehensively examine the impact of renal disease and hemodialysis (HD) on patient response during critical illness. To achieve this, we examined the metabolome, proteome, and transcriptome of 150 patients with critical illness, stratified by renal function. Quantification of plasma metabolites indicated greater change as renal function declined, with the greatest derangements in patients receiving chronic HD. Specifically, 6 uremic retention molecules, 17 other protein catabolites, 7 modified nucleosides, and 7 pentose phosphate sugars increased as renal function declined, consistent with decreased excretion or increased catabolism of amino acids and ribonucleotides. Similarly, the proteome showed increased levels of low-molecular-weight proteins and acute-phase reactants. The transcriptome revealed a broad-based decrease in mRNA levels among patients on HD. Systems integration revealed an unrecognized association between plasma RNASE1 and several RNA catabolites and modified nucleosides. Further, allantoin, N1-methyl-4-pyridone-3-carboxamide, and N-acetylaspartate were inversely correlated with the majority of significantly downregulated genes. Thus, renal function broadly affected the plasma metabolome, proteome, and peripheral blood transcriptome during critical illness; changes were not effectively mitigated by hemodialysis. These studies allude to several novel mechanisms whereby renal dysfunction contributes to critical illness.