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HCV May Directly Cause Insulin resistance
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By Michelle Rizzo
"In conclusion, this large prospective study provides direct evidence that IR is specifically associated with HCV infection independently of metabolic factors and severity of liver disease. This study also shows that IR is an independent predictor of significant fibrosis in CHC patients.....These data suggest that IR represents not only a metabolic disorder related to obesity and adipose tissue inflammation with subsequent imbalance in the secretion of specific cytokines40, 41 but also a direct viral feature. Several mechanisms have been proposed to explain HCV-induced IR,42, 43 and all suggest direct impairment of the insulin-signaling pathway."
NEW YORK (Reuters Health) - Insulin resistance, a "prediabetic" abnormality of blood sugar, is a specific feature of chronic hepatitis C virus (HCV) infection, independent of the severity of HCV or the presence of other metabolic factors, French investigators report.
HCV infection is now recognized as a system-wide disease, Dr. Rami Moucari, of Universite Denis Diderot-Paris, and colleagues note in a report in the journal Gastroenterology. Some previous studies have linked HCV infection to an increased risk of insulin resistance or full-blown diabetes.
Insulin is the body's key blood sugar-regulating hormone. Normally, insulin is secreted to clear glucose (sugar) from the blood and deposit into cells to use as fuel. Insulin resistance occurs when cells become desensitized to insulin.
In their study, Moucari's team found that 150 (32.4 percent) of 462 chronic HCV patients who did not have diabetes were insulin resistant. In this group, insulin resistance was associated with the metabolic syndrome (a cluster of heart disease and diabetes risk factors), as well as HCV genotypes 1 and 4, significant liver scarring or "fibrosis," severe fatty liver disease, and being older than age 40.
Among 145 chronically HCV infected patients without metabolic syndrome or significant fibrosis, insulin resistance was diagnosed in 22 (15 percent). Insulin resistance in this population was also associated with infection with HCV genotypes 1 and 4, high blood levels of HCV, and moderate-to-severe liver inflammation.
"Insulin resistance should be assessed in the routine management of patients with chronic hepatitis C," Moucari noted in an interview with Reuters Health.
SOURCE: Gastroenterology, February 2008.
Insulin Resistance in Chronic Hepatitis C: Association With Genotypes 1 and 4, Serum HCV RNA Level, and Liver Fibrosis
Gastroenterology Volume 134, Issue 2, Pages 416-423 (February 2008)
Rami Moucari_, Tarik Asselah_, Dominique Cazals-Hatem, Helene Voitot, Nathalie Boyer_, Marie-Pierre Ripault_, Rodolphe Sobesky_, Michele Martinot-Peignoux_, Sarah Maylin, Marie-Helene Nicolas-Chanoine, Valerie Paradis, Michel Vidaud, Dominique Valla_, Pierre Bedossa, Patrick Marcellin_
ABSTRACT
Background & Aims: Our study was designed to test the association between insulin resistance (IR) and hepatitis C virus (HCV) genotypes, serum HCV RNA level and liver fibrosis stage in a large prospective cohort of chronic hepatitis C (CHC) patients. Methods: Six hundred consecutive patients (CHC, n = 500; chronic hepatitis B (CHB), n = 100) were evaluated on the day of liver biopsy. IR (Homeostasis Model for Assessment of Insulin Resistance) and all components of the metabolic syndrome were assessed. By logistic regression, independent factors associated with IR and those associated with significant fibrosis were assessed in nondiabetic and noncirrhotic CHC, respectively. Parameters of IR were compared between hepatitis B and 240 CHC matched by epidemiologic, metabolic, and histologic features.
Results: IR was present in 32.4% of the 462 nondiabetic CHC and associated with the metabolic syndrome, genotypes 1 and 4, significant fibrosis, and severe steatosis. IR was diagnosed in 15% of 145 CHC without metabolic syndrome or significant fibrosis, and associated with genotypes 1 and 4, high serum HCV RNA level, and moderate-severe necroinflammation. Significant fibrosis was present in 51.1% of the 454 noncirrhotic CHC patients and associated with male sex, age >40 years, IR, moderate-severe necroinflammation, and severe steatosis. IR was less frequent in CHB than in matched CHC (5% vs 35%, respectively, P < .001).
Conclusions: IR is a specific feature of CHC, associated with genotypes 1 and 4 and high serum HCV RNA level. Significant fibrosis is associated with IR independent from steatosis.
Discussion
In this large prospective study including 600 consecutive unselected patients with CHC (n = 500) or CHB (n = 100), IR was assessed using HOMA-IR, which has been shown to correlate closely with the glucose clamp technique.35 In addition, results were validated using QUICKI as an alternative surrogate marker of IR.
IR: Evidence for a Direct Role of HCV
In this study, the metabolic syndrome was diagnosed in 12% of CHC patients, a prevalence similar to that in the general French population.39 IR was more frequent, and 32% of nondiabetic CHC patients had HOMA-IR >3. In multivariate analysis, IR was associated with both the metabolic syndrome and HCV genotypes 1 and 4 (Table 2). These data suggest that IR represents not only a metabolic disorder related to obesity and adipose tissue inflammation with subsequent imbalance in the secretion of specific cytokines40, 41 but also a direct viral feature. Several mechanisms have been proposed to explain HCV-induced IR,42, 43 and all suggest direct impairment of the insulin-signaling pathway. 44, 45, 46 To our knowledge, only one previous study11 has shown a negative independent association between IR and genotype 3. Interestingly, patients in the present study infected with genotypes 1 or 4 had similar IR confounding factors as those infected with genotypes 2 or 3 (age, BMI, waist circumference, metabolic disorders, liver necroinflammation, and fibrosis). Furthermore, IR was diagnosed in 22 of 145 patients with normal BMI and without significant fibrosis, and these patients were only infected with HCV genotypes 1 or 4.
In this study, IR was independently and significantly associated with high serum HCV RNA levels in patients infected with genotype 1 or 4. Of note, in one previous study, univariate analysis showed a correlation between IR and high viral loads.47 Although hyperinsulinemia was shown to increase HCV RNA replication in a recent HCV replicon system,48 this hypothesis seems unlikely in the present study. In fact, in the absence of overweight and significant fibrosis, HOMA-IR correlated significantly with serum HCV RNA levels (Figure 2), suggesting a direct role of viral replication on the development of IR. A recent study supports this hypothesis, showing an improvement of IR in patients who developed viral eradication after antiviral treatment.49 In addition, IR was more frequent and IR parameters higher (P < .001) in CHC patients than in CHB patients chosen as a control group in this study and very well matched with CHC patients for clinical, biologic, and also histologic features (Table 4).
Liver Fibrosis: Evidence for an Independent Role of IR
The relationship between liver fibrosis and IR is difficult to assess. Because of the role of the liver in carbohydrate metabolism and insulin degradation, advanced liver fibrosis may impair insulin clearance, resulting in increased serum insulin levels regardless of the insulin secretion status.19 In this study, significant fibrosis was independently associated with IR after exclusion of cirrhotic patients (Table 3). Furthermore, HOMA-IR increased progressively and significantly with the fibrosis stage (Figure 1), whereas the C-peptide/insulin ratio was not significantly different. These findings suggest that the real connection between IR and HCV infection is initiated at early stages of liver disease. The underlying mechanism of the progression of fibrosis in relation to IR could be a direct stimulation of liver stellate cells by hyperinsulinemia/hyperglycemia, resulting in increased production of the connective tissue growth factor and subsequent accumulation of extracellular matrix.50, 51 Understanding the mechanisms associated with the progression of fibrosis is of major interest in CHC.52, 53, 54 In multivariate analysis, significant fibrosis was also independently associated with severe steatosis. The association between steatosis and fibrosis is controversial in CHC patient studies.55, 56, 57, 58, 59, 60 Mechanisms linking steatosis and liver fibrosis are probably related to the oxidative stress generated from fat accumulation within hepatocytes, with subsequent secretion of inflammatory cytokines and activation of stellate cells.61 Finally, a recent study has shown that IR impairs the response to antiviral therapy.62 Whether the treatment of IR will improve the sustained response in CHC patients remains to be demonstrated.
In conclusion, this large prospective study provides direct evidence that IR is specifically associated with HCV infection independently of metabolic factors and severity of liver disease. This study also shows that IR is an independent predictor of significant fibrosis in CHC patients.
BACKGROUND
Hepatitis C virus (HCV) infection is now recognized as a systemic disease involving lipid metabolism, oxidative stress, and mitochondrial function.1, 2 In some previous studies, HCV infection was associated with an increased risk of diabetes mellitus3, 4, 5, 6, 7, 8, 9 or insulin resistance (IR).10, 11, 12, 13, 14, 15 IR is the main feature of the metabolic syndrome, a common metabolic disorder that is a result of the increasing prevalence of obesity worldwide.16, 17, 18 IR and glucose metabolism impairment are also associated with cirrhosis, regardless of etiology.19 In addition, IR seems to be associated with liver necroinflammation11 and steatosis.20, 21, 22
The early studies linking HCV to diabetes were retrospective and did not assess metabolic parameters and/or liver histology. Furthermore, diabetes seemed to be related to cirrhosis rather than HCV infection in studies taking into account the severity of liver disease.4, 5, 6, 7 Recent studies linking HCV to IR have also several limitations. First, case-control studies have mainly compared chronic hepatitis C (CHC) patients with healthy subjects or patients with chronic nonviral liver diseases11, 12; moreover, control subjects were not always matched with CHC patients,13 and IR was not always associated with CHC.12, 14 Furthermore, chronic hepatitis B (CHB) patients were not matched for liver necroinflammation when chosen as controls.15 Finally, no study has demonstrated an independent association between IR and specific HCV genotypes or serum HCV RNA levels.
Interestingly, IR has been shown to play a crucial role in the progression of fibrosis in patients with nonalcoholic fatty liver disease.23, 24, 25, 26 In CHC, recent studies have assessed the relationship between IR and fibrosis. It is difficult to draw conclusions because (1) fibrosis was associated with steatosis and not IR in multivariate analysis20, 21, 22; (2) IR was not tested as an independent predictor of fibrosis27, 28, 29; and (3) serum C-peptide was not available; therefore, insulin secretion could not have been evaluated, and hyperinsulinemia in relation to reduced hepatic insulin extraction from liver dysfunction could not be clearly excluded.30, 31, 32 In fact, C-peptide and insulin are secreted in equimolar quantities, and, whereas more than 50% of insulin is degraded in the liver at first pass, C-peptide is degraded by the kidneys.33
In this prospective study, we evaluated the prevalence of IR in 600 consecutive unselected patients with CHC (n = 500) or CHB (n = 100) on the day of liver biopsy. We tested the hypothesis that IR is independently associated with specific HCV genotypes and serum HCV RNA level. We tested the association between IR and liver fibrosis stage. We compared IR parameters between CHB and matched CHC patients.
Results
Patient Characteristics
The characteristics of the 500 CHC patients are listed in Table 1. Two hundred eighty-six patients (57.2%) were male. Mean age was 47.8 ± 10.2 years, and 385 patients (77.0%) were older than 40 years of age. Mean BMI was 24.8 ± 4.4; 163 patients (32.6%) were overweight, 48 (9.6%) were obese, and 138 (27.6%) had central obesity. Sixty-one patients (12.2%) met the criteria of the metabolic syndrome. Twenty-four patients were previously known to have diabetes, among them 10 were treated with oral antidiabetic drugs and 14 with diet regimen. Fourteen additional patients were classified as diabetics according to their fasting blood glucose on the day of liver biopsy. IR was present in 150 among the 462 nondiabetic patients (32.4%). Thyroid stimulating hormone level was normal for all except 10 patients; however, thyroid hormones (free T3, T4) level was normal for all of these 10 patients. Mean serum ALT levels averaged 2.7- ± 2.3-fold the upper limit of normal values (ULN). Genotype distribution was as follows: 1 (n = 285, 57.0%), 2 (n = 30, 6.0%), 3 (n = 78, 15.6%), and 4 (n = 96, 19.2%). Mean serum viral load was 5.6 ± 0.6 log10 IU/mL, and 238 patients (47.6%) had a high viral load (>600,000 IU/mL). According to the METAVIR score, necroinflammation was moderate-severe (A2-A3) in 146 patients (29.2%). Fibrosis was significant (F2-F4) in 278 patients (55.6%), among whom 46 patients had cirrhosis (F4). Steatosis was moderate in 97 patients (19.4%) and severe in 156 patients (31.2%).
The characteristics of the 100 CHB patients were as follows: male sex (75.0%); mean age, 40.2 ± 12.4 years; mean BMI, 23.7 ± 3.1 kg/m2; mean waist circumference, 87.1 ± 9.1 cm; mean serum ALT level, 2.4- ± 3.4-fold ULN; moderate-severe necroinflammation (30.0%); significant fibrosis (49.0%); and severe steatosis (12.0%).
Diabetes Mellitus
The prevalence of diabetes mellitus in the CHC population was 7.6% (n = 38). The characteristics of diabetic patients are illustrated in Table 1. They were mainly men older than 40 years. The metabolic syndrome was diagnosed in nearly half of them. Serum HCV RNA levels tended to be higher, but HCV genotype distribution was similar in comparison with nondiabetic patients. Histologic analysis showed a significant fibrosis in the majority of diabetic patients (84%) and severe steatosis in 47% of them.
IR
IR was present in 150 of the 462 nondiabetic CHC patients (32.4%). Patients with IR were older than those without IR (50 ± 10 vs 45 ± 9 years, respectively, P < .001), older than 40 years in 83.3% vs 71.7% (P = .007) respectively. Patients with IR were more frequently overweight than those without IR (60.6% vs 29.8%, respectively, P < .001), and HOMA-IR correlated significantly with BMI and waist circumference (Spearman rank correlation 0.47, P < .001). The metabolic syndrome was diagnosed more frequently in patients with than in those without IR (18.6% vs 4.8%, respectively, P < .001). IR was not associated with excessive alcohol consumption (HOMA-IR, 2.53 ± 1.87 vs 2.68 ± 2.32, respectively, P = .6).
Genotypes 1 and 4 were found more frequently in patients with IR (86.6% vs 71.4%, respectively, P < .001), whereas genotypes 2 and 3 more frequently in patients without IR (26.2% vs 11.3%, respectively, P < .001). In addition, patients with IR had high serum viral load more frequently than those without IR (55.3% vs 42.3%, respectively, P = .009). Of note, patients with genotypes 1 and 4 were similar to patients with genotypes 2 and 3 regarding age, BMI, waist circumference, the metabolic syndrome, liver necroinflammation, and fibrosis (Table 1).
IR was associated with moderate-severe necroinflammation (36.0% vs 25.3%, respectively, P = .01), significant fibrosis (66.6% vs 46.7%, respectively, P < .001), and severe steatosis (42.0% vs 24.0%, respectively, P < .001). It is interesting to note that HOMA-IR increased significantly with the fibrosis stage (P < .001): 2.2 ± 2.0 (F0-F1), 2.6 ± 1.8 (F2), 3.2 ± 2.2 (F3), 4.5 ± 3.8 (F4) (Figure 1), whereas C-peptide/insulin ratio was not significantly different (P = .2): 0.28 ± 0.11 (F0-F1), 0.28 ± 0.15 (F2), 0.26 ± 0.09 (F3), 0.25 ± 0.12 (F4).
By logistic regression, IR was independently and significantly associated with age >40 years, the metabolic syndrome, HCV genotypes 1 and 4, significant fibrosis, and severe steatosis (Table 2). Analysis showed consistent results when QUICKI was used as a surrogate marker of IR instead of HOMA-IR (results not shown).
IR According to HCV Genotypes
IR was present in 130 (36.8%) of the 353 nondiabetic CHC patients infected with genotypes 1 and 4. With univariate analyses, IR was associated with age >40 years (84.6% vs 69.5%, respectively, P = .002), the metabolic syndrome (19.2% vs 5.3%, respectively, P < .001), high serum viral load (60.0% vs 45.2%, respectively, P = .008), moderate-severe necroinflammation (36.1% vs 22.8%, respectively, P = .007), significant fibrosis (67.6% vs 43.9%, respectively, P < .001), and severe steatosis (43.8% vs 16.1%, respectively, P < .001). By logistic regression, IR was associated with age >40 years (OR, 1.9; 95% CI: 1.05-3.49, P = .03), the metabolic syndrome (OR, 2.6; 95% CI: 1.2-5.8, P = .01), high serum viral load (OR, 1.7; 95% CI: 1.05-2.7, P = .02), significant fibrosis (OR, 2.1; 95% CI: 1.3-3.5, P = .002), and severe steatosis (OR, 2.9; 95% CI: 1.7-5.0, P < .001). In contrast, IR was present in 17 (17.1%) of the 99 nondiabetic CHC patients infected with genotypes 2 and 3 and was associated only with being overweight (70.5% vs 30.4%, respectively, P = .002).
IR: Direct Role of HCV Genotypes and Serum HCV RNA Level
To confirm a direct relationship between IR and viral factors, we excluded patients who were overweight and/or with significant fibrosis. One hundred forty-five patients had BMI <25 kg/m2 and F0-F1 in the METAVIR fibrosis stage. Although these patients had normal BMI, IR was present in 22 (15%). Patients with IR were almost exclusively infected with genotypes 1 or 4 (21/22, 95.4%). IR was associated with high serum viral load (72.7% vs 44.7%, respectively, P = .01), and HOMA-IR correlated significantly with serum HCV RNA level (Spearman rank correlation 0.22, P = .007) (Figure 2). IR was also associated with moderate-severe necroinflammation (45.4% vs 8.9%, respectively, P < .001). By logistic regression, IR was associated with both high serum viral load (OR, 3.7; 95% CI: 1.2-11.2, P = .01) and moderate-severe necroinflammation (OR, 9.4; 95% CI: 3.1-28.5, P < .001).
Liver Fibrosis
Fibrosis was significant (F2-F4) in 278 patients (55.6%). Although the C-peptide/insulin ratio was not significantly different among the stages of fibrosis, as shown before, we excluded patients with cirrhosis (F4, n = 46) to test the influence of IR on liver fibrosis. Analyses were performed therefore in the 454 noncirrhotic patients. Patients with significant fibrosis (F2-F3) compared with those with mild fibrosis (F0-F1) were more frequently male (63.3% vs 48.1%, respectively, P = .001) and older than 40 years (81.4% vs 70.7%, respectively, P = .007). Significant fibrosis was also associated with IR (42.2% vs 22.9%, respectively, P < .001), moderate-severe necroinflammation (41.8% vs 14.8%, respectively, P < .001), and severe steatosis (42.2% vs 22.9%, P < .001).
By logistic regression, significant fibrosis was independently and significantly associated with male sex, age >40 years, IR, moderate-severe necroinflammation, and severe steatosis (Table 3). Analysis showed consistent results when QUICKI was used as a surrogate marker of IR instead of HOMA-IR (results not shown).
IR: HCV vs HBV
To identify a direct relationship between IR and HCV infection, we included 100 consecutive unselected CHB patients who were admitted for liver biopsy in our department during the same study period. Two hundred forty nondiabetic patients of the 500 CHC patients were then matched by sex, age, BMI, waist circumference, ALT levels, necroinflammation, and fibrosis with 80 non-Asian, nondiabetic patients of the 100 CHB patients. Comparison of CHB and matched CHC patients showed that IR was present in 84 CHC patients (35.0%) but only 4 CHB patients (5.0%), P < .001. In addition, all IR parameters (fasting glucose, insulin, C-peptide, and HOMA-IR) were significantly higher in CHC patients (P < .001) (Table 4).
Materials and Methods
Patient Population
This study included 600 consecutive patients with CHC (n = 500) or CHB (n = 100), who underwent liver biopsy in our department between September 2005 and February 2007. All CHC patients had antibodies against HCV (AxSYM, Anti-HCV; Abbott, Chicago, IL) and detectable serum HCV RNA (TMA, Bayer's Versant HCV RNA Qualitative Assay, Tarrytown, NY). HCV genotyping was performed (sequencing) and serum HCV RNA quantified (Bayer's Versant HCV RNA 3.0 Assay [bDNA]) for all patients.34 High viral load was defined as serum HCV RNA level >600,000 IU/mL. Ninety-eight patients (19.6%) had received previous antiviral therapy (interferon or pegylated interferon with ribavirin) and were either nonresponders (n = 67) or relapsers (n = 31). Liver biopsies were performed at least 6 months after the end of antiviral therapy. All CHB patients had positive hepatitis B surface antigen (HBsAg) and detectable serum HBV DNA (Bayer's Versant HBV DNA 3.0 Assay [bDNA]). No patient had clinical evidence of hepatic decompensation.
The following conditions were excluded: positive HBsAg (for CHC patients), positive anti-HCV (for CHB patients), human immunodeficiency virus infection, autoimmune hepatitis, hemochromatosis, ƒ¿1-antitrypsin deficiency, and Wilson's disease. All patients gave their informed consent before liver biopsy.
Clinical and Laboratory Assessment
The following data were collected at liver biopsy: sex, age, daily alcohol intake in the past 6 months (grams/day), weight (kilograms), height (meters), waist circumference (centimeters), blood pressure, and concomitant medications. Patients were considered excessive drinkers if there was a daily alcohol intake of ≥30 g (male) and ≥20 g (female). The estimated duration of infection was defined as the time from the presumed date of infection (date of transfusion, first year of intravenous drug use) to the date of liver biopsy. Body mass index (BMI) was calculated as weight divided by the square of the height (kg/m2). Overweight was defined as a BMI 25-30 and obesity as a BMI >30. The metabolic syndrome was diagnosed according to the National Cholesterol Education Program's Adult Treatment Panel III definition16, 17 as the presence of 3 or more of the following criteria: central obesity (waist circumference >102 cm [male] and >88 cm [female]), hypertension (blood pressure ≥135/85 mm Hg), fasting plasma glucose ≥110 mg/dL, triglycerides ≥150 mg/dL, high-density lipoprotein (HDL) cholesterol <40 mg/dL (male) or <50 mg/dL (female). After an overnight fast of 12 hours, venous blood flow was drawn to determine serum levels of alanine aminotransferase (ALT), aspartate aminotransferase, γ- glutamyltransferase, thyroid stimulating hormone, ferritin, glucose, triglyceride, HDL cholesterol, insulin, and C-peptide. Serum insulin and C-peptide were determined by Electrochemiluminescence Immunoassay (Elecsys 2010; Roche Diagnostics, Indianapolis, IN). Diabetes was diagnosed using the 1997 American Diabetes Association fasting criteria (fasting glucose ≥126 mg/dL). IR was assessed by the Homeostasis Model for Assessment of Insulin Resistance (HOMA-IR) method,35 using the following equation: HOMA-IR = fasting insulin (μU/mL) X fasting glucose (mmo/L)/22.5 and was defined as HOMA-IR >3. Analyses were repeated using the quantitative insulin sensitivity check index (QUICKI) as an alternative marker of IR [QUICKI = 1/[log(fasting insulin-μU/mL) + log(fasting glucose-mg/dL)].36 Insulin secretion was assessed using the C-peptide/insulin ratio.33
Liver Histology
Liver biopsy specimens were analyzed by a single experienced pathologist, who was blinded to clinical and biologic data. Necroinflammation and fibrosis were assessed using the METAVIR score.37 Necroinflammation activity (A) was graded as A0 (absent), A1 (mild), A2 (moderate), or A3 (severe). Fibrosis stage (F) was scored as F0 (absent), F1 (portal fibrosis), F2 (portal fibrosis with few septa), F3 (septal fibrosis), and F4 (cirrhosis). In accordance with the American Association for the Study of Liver Diseases (AASLD) guidelines,38 fibrosis was considered to be clinically significant for F2-F4 stages. Steatosis was assessed as the percentage of hepatocytes containing macrovesicular fat droplets. It was graded as follows: 0 (absent [<5%]), 1 (moderate [5%-30%]), and 2 (severe [>30%]).
Statistical Analyses
Continuous variables were summarized as mean (±SD) and categorical variables as frequency and percentage. Comparisons between groups were performed using the Student t test or the Mann-Whitney U test for continuous variables and the ƒÔ2 test or the Fischer exact test for categorical data. Comparisons between different groups were performed using analysis of variance (standard or nonparametric as appropriate). Correlations between pairs of numerical variables were performed using the Spearman rank correlation method. All P values were based on a 2-sided test of statistical significance. Significance was accepted at P < .05. Multiple logistic regression with forward stepwise variable selection was used to identify independent factors associated with IR in nondiabetic hepatitis C patients and significant fibrosis in noncirrhotic hepatitis C patients. P < .05 and P > .10 were used as the entry and exit criteria in the stepwise models. Variables were described as odds ratio (OR) with 95% confidence interval (CI). All analyses were performed with SPSS software for windows, version 12.0 (SPSS Inc, Chicago, IL).
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