Germline genetic regulation of the colorectal tumor immune microenvironment.

OBJECTIVE: To evaluate the contribution of germline genetics to regulating the briskness and diversity of T cell responses in CRC, we conducted a genome-wide association study to examine the associations between germline genetic variation and quantitative measures of T cell landscapes in 2,876 colorectal tumors from participants in the Molecular Epidemiology of Colorectal Cancer Study (MECC). METHODS: Germline DNA samples were genotyped and imputed using genome-wide arrays. Tumor DNA samples were extracted from paraffin blocks, and T cell receptor clonality and abundance were quantified by immunoSEQ (Adaptive Biotechnologies, Seattle, WA). Tumor infiltrating lymphocytes per high powered field (TILs/hpf) were scored by a gastrointestinal pathologist. Regression models were used to evaluate the associations between each variant and the three T-cell features, adjusting for sex, age, genotyping platform, and global ancestry. Three independent datasets were used for replication. RESULTS: We identified a SNP (rs4918567) near RBM20 associated with clonality at a genome-wide significant threshold of 5 × 10- 8, with a consistent direction of association in both discovery and replication datasets. Expression quantitative trait (eQTL) analyses and in silico functional annotation for these loci provided insights into potential functional roles, including a statistically significant eQTL between the T allele at rs4918567 and higher expression of ADRA2A (P = 0.012) in healthy colon mucosa. CONCLUSIONS: Our study suggests that germline genetic variation is associated with the quantity and diversity of adaptive immune responses in CRC. Further studies are warranted to replicate these findings in additional samples and to investigate functional genomic mechanisms.

Against the Norm: Non Irving-Williams Transmetalation in Transition Metal Dimers.

We report the synthesis and characterization of three dinuclear 3d3d' complexes, CuCu ([Cu2IIL(NO3)2]), MnMn ([Mn2IIL(MeOH)2(NO3)2]), and CuMn ([CuIIMnIIL(NO3)2]), that utilize the ligand, H2L (6,6'-dimethoxy-2,2'-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol). The relative stabilities of these complexes were investigated using experimental and computational techniques, revealing a non-Irving-Williams transmetalation, whereby a MnII ion can displace a CuII ion from its binding pocket in CuCu to yield the more stable CuMn complex. Magnetic characterization of the reported complexes revealed an unexpected ferromagnetic coupling between the two CuII ions of CuCu with J = +63.0 cm-1.

Shot-to-shot 2D IR spectroscopy at 100 kHz using a Yb laser and custom-designed electronics.

The majority of 2D IR spectrometers operate at 1-10 kHz using Ti:Sapphire laser technology. We report a 2D IR spectrometer designed around Yb:KGW laser technology that operates shot-to-shot at 100 kHz. It includes a home-built OPA, a mid-IR pulse shaper, and custom-designed electronics with optional on-chip processing. We report a direct comparison between Yb:KGW and Ti:Sapphire based 2D IR spectrometers. Even though the mid-IR pulse energy is much lower for the Yb:KGW driven system, there is an 8x improvement in signal-to-noise over the 1 kHz Ti:Sapphire driven spectrometer to which it is compared. Experimental data is shown for sub-millimolar concentrations of amides. Advantages and disadvantages of the design are discussed, including thermal background that arises at high repetition rates. This fundamental spectrometer design takes advantage of newly available Yb laser technology in a new way, providing a straightforward means of enhancing sensitivity.

The Assessment of Forced Penetration: A Necessary and Further Step Toward Understanding Men's Sexual Victimization and Women's Perpetration.

A unique form of sexual victimization that often goes undiscussed and, therefore, underassessed is that of being forced to penetrate another person (i.e., forced penetration). Due to forced penetration being a relatively novel addition to the definition of rape, there is a lack of assessment tools that identify forced penetration cases. Thus, the goal of this study was to assess the utility and validity of new items designed to assess forced penetration. More than 1,000 participants were recruited across three different studies to assess forced penetration victimization and perpetration. The rate of forced penetration victimization ranged from 4.51% to 10.62%. Among men who reported victimization of any type, 33.8% to 58.7% of victimized men reported experiencing forced penetration across the samples, suggesting this experience is common. All new and unique cases of sexual victimization identified by the forced penetration items were those of heterosexual men. These findings suggest that assessing for forced penetration would increase the reported prevalence rates of sexual victimization, particularly in heterosexual men (and correspondingly, rates of perpetration in women).

Recurrence after hospitalization for acute coronary syndrome among HIV-infected and HIV-uninfected individuals.

OBJECTIVES: We evaluated the association of HIV infection and immunodeficiency with acute coronary syndrome (ACS) recurrence, and with all-cause mortality as a secondary outcome, after hospitalization for ACS among HIV-infected and HIV-uninfected individuals. METHODS: We conducted a retrospective cohort study within Kaiser Permanente Northern California of HIV-infected and HIV-uninfected adults discharged after ACS hospitalization [types: ST-elevation myocardial infarction (STEMI), non-STEMI, or unstable angina] during 1996-2010. We compared the outcomes of ACS recurrence and all-cause mortality within 3 years, both overall by HIV status and stratified by recent CD4 count, with HIV-uninfected individuals as the reference group. Hazard ratios (HRs) were obtained from Cox regression models with adjustment for age, sex, race/ethnicity, year, ACS type, smoking, and cardiovascular risk factors. RESULTS: Among 226 HIV-infected and 86 321 HIV-uninfected individuals with ACS, HIV-infected individuals had a similar risk of ACS recurrence compared with HIV-uninfected individuals [HR 1.08; 95% confidence interval (CI) 0.76-1.54]. HIV infection was independently associated with all-cause mortality after ACS hospitalization overall (HR 2.52; 95% CI 1.81-3.52). In CD4-stratified models, post-ACS mortality was higher for HIV-infected individuals with CD4 counts of 201-499 cells/µL (HR 2.64; 95% CI 1.66-4.20) and < 200 cells/µL (HR 5.41; 95% CI 3.14-9.34), but not those with CD4 counts ≥ 500 cells/µL (HR 0.67; 95% CI 0.22-2.08), compared with HIV-uninfected individuals (P trend < 0.001). CONCLUSIONS: HIV infection and immunodeficiency were not associated with recurrence of ACS after hospitalization. All-cause mortality was higher among HIV-infected compared with HIV-uninfected individuals, but there was no excess mortality risk among HIV-infected individuals with high CD4 counts.

Clostridium difficile toxin B induces autophagic cell death in colonocytes.

Toxin B (TcdB) is a major pathogenic factor of Clostridum difficile. However, the mechanism by which TcdB exerts its cytotoxic action in host cells is still not completely known. Herein, we report for the first time that TcdB induced autophagic cell death in cultured human colonocytes. The induction of autophagy was demonstrated by the increased levels of LC3-II, formation of LC3+ autophagosomes, accumulation of acidic vesicular organelles and reduced levels of the autophagic substrate p62/SQSTM1. TcdB-induced autophagy was also accompanied by the repression of phosphoinositide 3-kinase (PI3K)/Akt/mechanistic target of rapamycin (mTOR) complex 1 activity. Functionally, pharmacological inhibition of autophagy by wortmannin or chloroquine or knockdown of autophagy-related genes Beclin 1, Atg5 and Atg7 attenuated TcdB-induced cell death in colonocytes. Genetic ablation of Atg5, a gene required for autophagosome formation, also mitigated the cytotoxic effect of TcdB. In conclusion, our study demonstrated that autophagy serves as a pro-death mechanism mediating the cytotoxic action of TcdB in colonocytes. This discovery suggested that blockade of autophagy might be a novel therapeutic strategy for C. difficile infection.

Can an Emergency Department Observation Unit Reduce Hospital Admissions for COPD Exacerbation?

Studies on observation unit (OU) use to avoid a hospital admission from the emergency department (ED) have found variable effects on health care resource utilization, and these effects have not been studied in acute exacerbation of chronic obstruction pulmonary disease (AECOPD). We retrospectively collected data for all AECOPD-related ED visits (age > 40) to an urban, academic medical center between February 2013 and April 2017. We examined the total proportion of visits admitted to the hospital before and after availability of an OU and the proportion of visits discharged directly from the ED using segmented regression analysis. There was a 12.8% reduction in hospital admissions after OU availability (79.6 vs. 66.8%, p = 0.0049) without a change in the proportion discharged directly from the ED (p = 0.65). The availability of an OU can decrease hospital AECOPD admissions without affecting the number of patients discharged directly from the ED.

Isothermal titration calorimetry and vesicle leakage assays highlight the differential behaviors of tau repeat segments upon interaction with anionic lipid membranes.

Tau misfolding has been implicated in a variety of tauopathies, including Alzheimer's disease. The microtubule binding domain of tau consists of four repeat segments (R1-R4), and aggregation of these segments leads to the formation of neurofibrillary tangles. Previous studies indicate that misfolded tau associates with anionic phospholipid membranes, invoking structural transformations that could play a role in aggregation. Here, we investigated the role of membrane surface charge on the binding affinity of individual tau repeat segments, and whether these segments exhibit lytic activity. We quantified the thermodynamics of this process in terms of the affinity (Kd), enthalpy (ΔH), entropy (ΔS), and change in specific heat capacity (ΔCp). While neutral membranes exhibited weak interactions with each tau repeat segment, segments R2 and R3 exhibited relatively strong binding with anionic membranes with favorable ΔS and a negative value of ΔCp. Calcein leakage assays show that each repeat segment displays lytic activity, but only upon the interaction with anionic membranes. Taken together, these results distinguish the relative selectivity for anionic membranes by each repeat segment and the degree of membrane disruption that results.

Genome-wide association studies suggest sex-specific loci associated with abdominal and visceral fat.

BACKGROUND: To identify loci associated with abdominal fat and replicate prior findings, we performed genome-wide association (GWA) studies of abdominal fat traits: subcutaneous adipose tissue (SAT); visceral adipose tissue (VAT); total adipose tissue (TAT) and visceral to subcutaneous adipose tissue ratio (VSR). SUBJECTS AND METHODS: Sex-combined and sex-stratified analyses were performed on each trait with (TRAIT-BMI) or without (TRAIT) adjustment for body mass index (BMI), and cohort-specific results were combined via a fixed effects meta-analysis. A total of 2513 subjects of European descent were available for the discovery phase. For replication, 2171 European Americans and 772 African Americans were available. RESULTS: A total of 52 single-nucleotide polymorphisms (SNPs) encompassing 7 loci showed suggestive evidence of association (P<1.0 × 10(-6)) with abdominal fat in the sex-combined analyses. The strongest evidence was found on chromosome 7p14.3 between a SNP near BBS9 gene and VAT (rs12374818; P=1.10 × 10(-7)), an association that was replicated (P=0.02). For the BMI-adjusted trait, the strongest evidence of association was found between a SNP near CYCSP30 and VAT-BMI (rs10506943; P=2.42 × 10(-7)). Our sex-specific analyses identified one genome-wide significant (P<5.0 × 10(-8)) locus for SAT in women with 11 SNPs encompassing the MLLT10, DNAJC1 and EBLN1 genes on chromosome 10p12.31 (P=3.97 × 10(-8) to 1.13 × 10(-8)). The THNSL2 gene previously associated with VAT in women was also replicated (P=0.006). The six gene/loci showing the strongest evidence of association with VAT or VAT-BMI were interrogated for their functional links with obesity and inflammation using the Biograph knowledge-mining software. Genes showing the closest functional links with obesity and inflammation were ADCY8 and KCNK9, respectively. CONCLUSIONS: Our results provide evidence for new loci influencing abdominal visceral (BBS9, ADCY8, KCNK9) and subcutaneous (MLLT10/DNAJC1/EBLN1) fat, and confirmed a locus (THNSL2) previously reported to be associated with abdominal fat in women.

Suggestive evidence for the induction of colonic aberrant crypts in mice fed sodium nitrite.

A reported linkage between processed (nitrite-treated) meat products and the incidence of colon cancer could be due to sodium nitrite (NaNO2) itself or to N-nitroso compounds produced from the nitrite. Exposure to nitrite occurs due to residual nitrite in processed meat and to salivary nitrite arising by reduction of nitrate in vegetables and drinking water. Here we tested whether NaNO2 could induce colonic aberrant crypts (ABC) or ABC foci (ACF), which are putative precursors of colon cancer. We fed NaNO2 in drinking water for 20-25 wk to groups of 8-20 adult female mice. After sacrifice, ABC and ACF were counted in 2-cm distal colonic segments. In Experiment 1, no significant differences in ABC/ACF induction were seen between groups of 13-14 A/J mice fed 0, 0.5, or 1.0 g NaNO2/l drinking water. NaNO2 also did not affect fasting blood glucose levels. In Experiment 2, we fed 0, 1.0, 1.25, or 1.5 g NaNO2/l water to groups of 15 CF-1 mice. Five of the mice fed 1.5 g NaNO2/l showed ABC, whereas all other groups showed only 0-2 ABC/group, including 0 ABC for the group fed 1.25 g NaNO2/l. Overall statistical analysis indicated a dose-response p trends of 0.04. Pairwise comparison of ABC between groups fed 1.25 and 1.5 g NaNO2/l showed p 0.02 for both ABC and ACF, but a similar comparison between the untreated and 1.5 g/l groups showed no significant effects. In Experiment 3, hot dogs (18% of diet), which were fed to CF-1 mice previously treated with azoxymethane, inhibited ABC and ACF induction, but this effect was not significant (P = 0.10-0.12). In conclusion, these results support the view that NaNO2 may be a risk factor for colon carcinogenesis.

Rab proteins as regulators of lipid droplet formation and lipolysis.

Lipid droplets (LDs) are highly dynamic organelles that not only store neutral lipids but also are involved in multiple cellular processes. Dysregulation of lipogenesis or lipolysis greatly contributes to the pathogenesis of several human diseases, including obesity, diabetes, and fatty liver disease. Rab proteins have been found to be associated with LDs in proteomic studies and are also known to extensively regulate intracellular membrane traffic, suggesting that LDs actively communicate with other membrane compartments to maintain energy homeostasis. This review discusses recent studies that provide mechanistic insights into the regulation of LD formation and catabolism by Rab proteins in mammalian cells.

Impact of HIV on mortality among patients treated for tuberculosis in Lima, Peru: a prospective cohort study.

BACKGROUND: Human immunodeficiency virus (HIV)-associated tuberculosis deaths have decreased worldwide over the past decade. We sought to evaluate the effect of HIV status on tuberculosis mortality among patients undergoing treatment for tuberculosis in Lima, Peru, a low HIV prevalence setting. METHODS: We conducted a prospective cohort study of patients treated for tuberculosis between 2005 and 2008 in two adjacent health regions in Lima, Peru (Lima Ciudad and Lima Este). We constructed a multivariate Cox proportional hazards model to evaluate the effect of HIV status on mortality during tuberculosis treatment. RESULTS: Of 1701 participants treated for tuberculosis, 136 (8.0%) died during tuberculosis treatment. HIV-positive patients constituted 11.0% of the cohort and contributed to 34.6% of all deaths. HIV-positive patients were significantly more likely to die (25.1 vs. 5.9%, P < 0.001) and less likely to be cured (28.3 vs. 39.4%, P = 0.003). On multivariate analysis, positive HIV status (hazard ratio [HR] = 6.06; 95% confidence interval [CI], 3.96-9.27), unemployment (HR = 2.24; 95% CI, 1.55-3.25), and sputum acid-fast bacilli smear positivity (HR = 1.91; 95% CI, 1.10-3.31) were significantly associated with a higher hazard of death. CONCLUSIONS: We demonstrate that positive HIV status was a strong predictor of mortality among patients treated for tuberculosis in the early years after Peru started providing free antiretroviral therapy. As HIV diagnosis and antiretroviral therapy provision are more widely implemented for tuberculosis patients in Peru, future operational research should document the changing profile of HIV-associated tuberculosis mortality.

The Effect of Tissue Entrapment on Screw Loosening at the Implant/Abutment Interface of External- and Internal-Connection Implants: An In Vitro Study.

PURPOSE: To compare the removal of torque values of machined implant abutment connections (internal and external) with and without soft tissue entrapment using an in vitro model. MATERIALS AND METHODS: Thirty external- and 30 internal-connection implants were embedded in urethane dimethacrylate. Porcine tissue was prepared and measured to thicknesses of 0.5 and 1.0 mm. Six groups (n = 10) were studied: External- and internal-connection implants with no tissue (control), 0.5, and 1.0 mm of tissue were entrapped at the implant/abutment interface. Abutments were inserted to 20 Ncm for all six groups. Insertion torque values were recorded using a digital torque gauge. All groups were then immersed in 1 M NaOH for 48 hours to dissolve tissue. Subsequent reverse torque measurements were recorded. Mean and standard deviation were determined for each group, and one-way ANOVA and Bonferroni test were used for statistical analysis. RESULTS: All 60 specimens achieved a 20-Ncm insertion torque, despite tissue entrapment. Reverse torque measurements for external connection displayed a statistically significant difference (p < 0.05) between all groups with mean reverse torque values for the control (13.71 ± 1.4 Ncm), 0.5 mm (7.83 ± 2.4 Ncm), and 1.0 mm tissue entrapment (2.29 ± 1.4 Ncm) groups. Some statistically significant differences (p < 0.05) were found between internal-connection groups. In all specimens, tissue did not completely dissolve after 48 hours. CONCLUSIONS: External-connection implants were significantly affected by tissue entrapment; the thicker the tissue, the lower the reverse torque values noted. Internal-connection implants were less affected by tissue entrapment.

Autophagy Mediates HBx-Induced Nuclear Factor-κB Activation and Release of IL-6, IL-8, and CXCL2 in Hepatocytes.

Hepatitis B virus (HBV) and one of its encoded proteins, HBV X protein (HBx), have been shown to induce autophagy in hepatoma cells. Substantial evidence indicates that autophagy is a potent suppressor of inflammation. However, sporadic reports suggest that autophagy could promote pro-inflammatory cytokine expression and inflammation in some biological contexts. Here, we show that overexpression of HBx induces LC3B-positive autophagosome formation, increases autophagic flux and enhances the expression of ATG5, ATG7, and LC3B-II in normal hepatocytes. Abrogation of autophagy by small interfering RNA against ATG5 and ATG7 prevents HBx-induced formation of autophagosomes. Autophagy inhibition also abrogates HBx-induced activation of nuclear factor-κB (NF-κB) and production of interleukin-6 (IL-6), IL-8, and CXCL2. These findings suggest that autophagy is required for HBx-induced NF-κB activation and pro-inflammatory cytokine production and could shed new light on the complex role of autophagy in the modulation of inflammation.

Evaluation of genetic risk loci for intracranial aneurysms in sporadic arteriovenous malformations of the brain.

BACKGROUND: In genome-wide association studies (GWAS) five putative risk loci are associated with intracranial aneurysm. As brain arteriovenous malformations (AVM) and intracranial aneurysms are both intracranial vascular diseases and AVMs often have associated aneurysms, we investigated whether these loci are also associated with sporadic brain AVM. METHODS: We included 506 patients (168 Dutch, 338 American) and 1548 controls, all Caucasians. Controls had been recruited as part of previous GWAS. Dutch patients were genotyped by KASPar assay and US patients by Affymetrix SNP 6.0 array. Associations in each cohort were tested by univariable logistic regression modelling, with subgroup analysis in 205 American cases with aneurysm data. Meta-analysis was performed by a Mantel-Haenszel fixed-effect method. RESULTS: In the Dutch cohort none of the single nucleotide polymorphisms (SNPs) were associated with AVMs. In the American cohort, genotyped SNPs near SOX-17 (OR 0.74; 95% CI 0.56-0.98), RBBP8 (OR 0.76; 95% CI 0.62-0.94) and an imputed SNP near CDKN2B-AS1 (OR 0.79; 95% CI 0.64-0.98) were significantly associated with AVM. The association with SNPs near SOX-17 and CDKN2B-AS1 but not RBBP8 were strongest in patients with AVM with associated aneurysms. In the meta-analysis we found no significant associations between allele frequencies and AVM occurrence, but rs9298506, near SOX-17 approached statistical significance (OR 0.77; 95% CI 0.57-1.03, p=0.08). CONCLUSIONS: Our meta-analysis of two Caucasian cohorts did not show an association between five aneurysm-associated loci and sporadic brain AVM. Possible involvement of SOX-17 and RBBP8, genes involved in cell cycle progression, deserves further investigation.

Thermal lensing effect of CS2 studied with femtosecond laser pulses.

By chopping 820 nm 18 femtosecond (fs)-laser pulses, continuously generated by a self-mode locked Ti:Al2O3 laser at 82 MHz, into trains with both train-width and train-to-train separation considerably longer than the thermal diffusivity time constant τth of CS2, we conducted Z-scan measurements on it at various times relative to the leading pulse of each train (T's). As a result, we observed negative nonlinear refraction strengthening with T within τth and gradually stabilizing with T exceeding τth. We quantitatively explain the experimental results in terms of the thermal lensing effect. In particular, we attribute the heat generation to non-radiative relaxation of libration excited by individual 18 fs-pulses via stimulated Raman scattering. In contrast to the commonly held view of multi-photon excitation, we propose and verify a new heat-generating mechanism for the thermal lensing effect in CS2.

The chronic obstructive pulmonary disease-asthma overlap syndrome.

When asthma and chronic obstructive pulmonary disease (COPD) occur together the term COPD-asthma overlap syndrome has been applied. To date, there is no universally accepted definition of this overlap syndrome, just as there is no blood test or other technologic assessment that provides a simple way to distinguish asthma from COPD. One practical approach to the overlap diagnosis has been to include patients with a diagnosis of COPD by Global Initiative for Chronic Obstructive Lung Disease criteria and asthma defined by subject report of a physician diagnosis of asthma before the age of 40 years. Alternatively, it includes patients who meet criteria for COPD (fixed airflow obstruction) and who also have typical features of asthma (wheezing, atopy, eosinophilia, and positive bronchodilator response on spirometry). Compared with patients with COPD alone, the overlap patients are younger with less smoking intensity, have higher health-care utilization, have a worse disease-related quality of life, and have a higher mortality. Treatment with corticosteroids earlier in the course of the disease compared with the patient with only COPD has been recommended.

Concordance of resistance profiles in households of patients with multidrug-resistant tuberculosis.

We estimated the proportion of household contacts whose drug-susceptibility test results matched those of the purported source patient with multidrug-resistant tuberculosis. Ninety-nine (88.4%) contacts had isolates resistant to isoniazid and rifampin, and 41 (36.6%) contacts had isolates with results that also matched the purported source for ethambutol, streptomycin, and pyrazinamide.

Improving outcomes for multidrug-resistant tuberculosis: aggressive regimens prevent treatment failure and death.

BACKGROUND: Evidence is sparse regarding the optimal construction of regimens to treat multidrug-resistant (MDR) tuberculosis disease due to strains of Mycobacterium tuberculosis resistant to at least both isoniazid and rifampin. Given the low potency of many second-line antituberculous drugs, we hypothesized that an aggressive regimen of at least 5 likely effective drugs during the intensive phase, including a fluoroquinolone and a parenteral agent, would be associated with a reduced risk of death or treatment failure. METHODS: We conducted a retrospective cohort study of patients initiating MDR tuberculosis treatment between 2000 and 2004 in Tomsk, Russian Federation. We used a multivariate Cox proportional hazards model to assess whether monthly exposure to an aggressive regimen was associated with the risk of death or treatment failure. RESULTS: Six hundred fourteen individuals with confirmed MDR tuberculosis were eligible for analysis. On multivariable analysis that adjusted for extensively drug-resistant (XDR) tuberculosis-MDR tuberculosis isolates resistant to fluoroquinolones and parenteral agents-we found that monthly exposure to an aggressive regimen was significantly associated with a lower risk of death or treatment failure (hazard ratio, 0.52 [95% confidence interval, .29-.94]; P = .030). CONCLUSIONS: Receipt of an aggressive treatment regimen was a robust predictor of decreased risk of death or failure during MDR tuberculosis treatment. These findings further support the use of this regimen definition as the benchmark for the standard of care of MDR tuberculosis patients and should be used as the basis for evaluating novel therapies.

Urinary excretion of N-nitroso compounds in rats fed sodium nitrite and/or hot dogs.

Nitrite-treated meat is a reported risk factor for colon cancer. Mice that ingested sodium nitrite (NaNO2) or hot dogs (a nitrite-treated product) showed increased fecal excretion of apparent N-nitroso compounds (ANC). Here, we investigated for the first time whether rats excrete increased amounts of ANC in their urine after they are fed NaNO2 and/or hot dogs. Rats were treated for 7 days with NaNO2 in drinking water or were fed hot dogs. Their 24 h urine samples were analyzed for ANC by thermal energy analysis on days 1-4 after nitrite or hot dog treatment was stopped. For two rats fed 480 mg NaNO2/L drinking water, mean urinary ANC excretion on days 1-4 was 30, 5.2, 2.5, and 0.8 nmol/day, respectively. For two to eight rats/dose given varied NaNO2 doses, mean urinary ANC output on day 1 increased from 0.9 (for no nitrite) to 37 (for 1000 mg NaNO2/L drinking water) nmol ANC/day. Urine samples of four rats fed 40-60% hot dogs contained 12-13 nmol ANC on day 1. Linear regression analysis showed highly significant correlations between urinary ANC excretion on day 1 after stopping treatment and varied (a) NaNO2 level in drinking water for rats fed semipurified or commercials diet and (b) hot dog levels in the diet. Some correlations remained significant up to 4 days after nitrite treatment was stopped. Urinary output of ANC precursors (compounds that yield ANC after mild nitrosation) for rats fed semipurified or commercial diet was 11-17 or 23-48 µmol/day, respectively. Nitrosothiols and iron nitrosyls were not detected in urinary ANC and ANCP. Excretion of urinary ANC was about 60% of fecal ANC excretion for 1 to 2 days after NaNO2 was fed. Administered NaNO2 was not excreted unchanged in rat urine. We conclude that urinary ANC excretion in humans could usefully be surveyed to indicate exposure to N-nitroso compounds.