Measurement of serum branched-chain amino acids to tyrosine ratio level is useful in a prediction of a change of serum albumin level in chronic liver disease

Unique metabolomics characteristics for distinguishing cirrhosis related to different liver diseases: A systematic review and meta-analysis

BACKGROUND AND AIM

Clinical evidence for early identification and diagnosis of liver cirrhosis (LC) caused by different types of liver disease is limited. We investigated this topic through a meta-analysis of quantitative metabolomics.

METHODS

Four databases were searched until October 31, 2022 for studies comparing metabolite levels between patients with different types of liver disease and control individuals. A random-effects model was applied for the meta-analysis.

RESULTS

This study included 55 studies with 8266 clinical participants, covering 348 metabolites. In LC related to drug-induced liver injury (DILI), hepatitis B virus (HBV) infection, and non-alcoholic fatty liver disease (NAFLD), the primary bile acid biosynthesis (taurocholic acid: SMD, 1.08[0.81, 1.35]; P < 0.00001; glycocholic acid: SMD, 1.35[1.07, 1.62]; P < 0.00001; taurochenodeoxycholic acid: SMD, 1.36[0.94, 1.78]; P < 0.00001; glycochenodeoxycholic acid: SMD, 1.49[0.93, 2.06]; P < 0.00001), proline and arginine (l-proline: SMD, 1.06[0.53, 1.58]; P < 0.0001; hydroxyproline: SMD, 0.81[0.30, 1.33]; P = 0.002), and fatty acid biosynthesis (palmitic acid: SMD, 0.44[0.21, 0.67]; P = 0.0002; oleic acid: SMD, 0.46[0.19, 0.73]; P = 0.0008; stearic acid: SMD, 0.37[0.07, 0.68]; P = 0.02) metabolic pathways were significantly altered.

CONCLUSION

We identified key biomarkers and metabolic characteristics for distinguishing and identifying LC related to different types of liver disease, providing a new perspective for early diagnosis, disease monitoring, and precise treatment.

Branched-chain amino acids supplementation has beneficial effects on the progression of liver cirrhosis: A meta-analysis

BACKGROUND

Liver cirrhosis (LC) is currently the 11^th most common cause of death and 15^th cause of morbidity globally. The treatment of LC is mainly aimed at etiological intervention, lifestyle intervention, prevention and treatment of complications and nutritional treatment. Nutritional treatment of LC mainly includes increasing dietary intake, food intake time and branched-chain amino acids (BCAAs). Despite the recommendation of BCAAs in some guidelines, adverse effects have been reported in studies so the efficacy and safety of BCAAs remain controversial. Currently, BCAAs have been widely used in chronic liver disease, while the summary of the effect of BCAAs on long-term prognosis is rare.

AIM

To determine the effects of BCAAs in patients with LC.

METHODS

The PubMed, Cochrane Library, Embase and Web of Science databases were searched. The retrieval deadline was 1 October 2021 and there were no language restrictions set in the retrieval. The study was performed in strict accordance with the inclusion and exclusion criteria. Nine studies were finally included. The primary outcome was complications of LC. The secondary outcomes were nutritional status and liver function. This meta-analysis used the Review Manager, version 5 statistical package (Cochrane Collaboration, Oxford, England) for analysis.

RESULTS

The analysis included nine studies that consisted of 1080 patients (554 in the BCAA groups and 526 in the control groups). The nine studies were randomized control trials (RCTs). The quality of the studies was assessed using the risk of bias method recommended by the Cochrane Collaboration. BCAAs reduced the rate of complications in LC patients [Risk ratio: 0.70, 95% confidence interval (CI): 0.56-0.88, P = 0.002] and improved patients’ albumin levels [std mean difference SMD: 0.26, 95%CI: 0.12-0.40, P = 0.0002]. Meanwhile, BCAAs significantly ameliorated the levels of alanine transaminase (SMD: -2.03, 95%CI: -2.52 to -1.53, P < 0.00001) and aspartate aminotransferase (SMD: -1.8, 95%CI: -2.14 to -1.46, P < 0.00001). Meanwhile, glucose in the LC was significantly increased in BCAA-treated patients (MD: 13.04, 95%CI: 6.81-19.89, P = 0.0002).

CONCLUSION

BCAAs reduce the incidence of complications in patients with LC and ameliorate nutritional status.

The Crystal Structure of L-Leucine Dehydrogenase from Pseudomonas aeruginosa

Leucine dehydrogenase (LDH, EC 1.4.1.9) catalyzes the reversible deamination of branched-chain L-amino acids to their corresponding keto acids using NAD+ as a cofactor. LDH generally adopts an octameric structure with D4 symmetry, generating a molecular mass of approximately 400 kDa. Here, the crystal structure of the LDH from Pseudomonas aeruginosa (Pa-LDH) was determined at 2.5 Å resolution. Interestingly, the crystal structure shows that the enzyme exists as a dimer with C2 symmetry in a crystal lattice. The dimeric structure was also observed in solution using multiangle light scattering coupled with size-exclusion chromatography. The enzyme assay revealed that the specific activity was maximal at 60°C and pH 8.5. The kinetic parameters for three different amino acid and the cofactor (NAD+) were determined. The crystal structure represents that the subunit has more compact structure than homologs' structure. In addition, the crystal structure along with sequence alignments indicates a set of non-conserved arginine residues which are important in stability. Subsequent mutation analysis for those residues revealed that the enzyme activity reduced to one third of the wild type. These results provide structural and biochemical insights for its future studies on its application for industrial purposes.

Clinical significance of the latency period of abnormal ammonia metabolism in chronic liver disease: Proposal of a new concept

The liver is a key organ in regulating metabolism, and chronic liver disease is associated with several metabolic disorders. In the later stages of liver cirrhosis, the urea cycle is impaired, which disrupts of ammonia detoxification and eventually causes hyperammonemia and hepatic encephalopathy. Although hyperammonemia is not detected during the period between the late stage of chronic hepatitis and the early stage of liver cirrhosis, hepatic albumin synthesis capacity decreases as the fibrosis progresses. Increased ammonia levels are associated with a decreased capacity of the liver to synthesize albumin as well as activation of hepatic stellate cells, which promote fibrosis. Herein, we discuss the possibility that abnormal ammonia metabolism might play an important role in the pathogenesis of liver diseases even without hyperammonemia. We consider the disease period without hyperammonemia as the latency period of abnormal ammonia metabolism and discuss its clinical significance.

Structural insights into the enhanced thermostability of cysteine substitution mutants of L-histidine decarboxylase from Photobacterium phosphoreum

Enzymatic amino acid assays are important in physiological research and clinical diagnostics because abnormal amino acid concentrations in biofluids are associated with various diseases. L-histidine decarboxylase from Photobacterium phosphoreum (PpHDC) is a pyridoxal 5'-phosphate-dependent enzyme and a candidate for use in an L-histidine quantitation assay. Previous cysteine substitution experiments demonstrated that the PpHDC C57S mutant displayed improved long-term storage stability and thermostability when compared with those of the wild-type enzyme. In this study, combinational mutation experiments of single cysteine substitution mutants of PpHDC were performed, revealing that the PpHDC C57S/C101V/C282V mutant possessed the highest thermostability. The stabilizing mechanism of these mutations were elucidated by solving the structures of PpHDC C57S and C57S/C101V/C282V mutants by X-ray crystallography. In the crystal structures, two symmetry-related PpHDC molecules form a domain-swapped homodimer. The side chain of S57 is solvent exposed in the structure, indicating that the C57S mutation eliminates chemical oxidation or disulfide bond formation with a free thiol group, thereby providing greater stability. Residues 101 and 282 form hydrophobic interactions with neighboring hydrophobic residues. Mutations C101V and C282V enhanced thermostability of PpHDC by filling a cavity present in the hydrophobic core (C101V) and increasing hydrophobic interactions.

Easy clinical predictor for low BCAA to tyrosine ratio in chronic liver disease patients with hepatocellular carcinoma: Usefulness of ALBI score as nutritional prognostic marker

BACKGROUND/AIM

Low branched-chain amino acid (BCAA) to tyrosine ratio (BTR) is known as an indicator of amino acid imbalance. We elucidated usefulness of newly developed albumin-bilirubin (ALBI) score as alternative methods of BTR in patients with naïve hepatocellular carcinoma (HCC) retrospectively.

MATERIALS/METHODS

In 842 patients with HCC and without BCAA supplementation (71 years, male 614, Child-Pugh A:B:C = 689:116:37), relationships among BTR and clinical features were evaluated. Of those, 438 patients, with Milan criteria HCC, treated curatively were divided into the high-BTR (>4.4) (n = 293) and low-BTR (≤4.4) (n = 145) groups. The prognostic value of BTR was evaluated using inverse probability weighting (IPW) with propensity score.

RESULTS

The low-BTR group showed worse prognosis than the other (3-, 5-, 10-year overall survival rates: 88.9% vs. 86.3%/70.5% vs. 78.1%/38.1% vs. 52.3%, respectively; p < 0.001). Multivariate Cox-hazard analysis adjusted for IPW showed elderly (≥65 years) HR 2.314, p = 0.001), female gender (HR 0.422, p < 0.001), ECOG PS ≥2 (HR 3.032, p = 0.002), low platelet count (HR 1.757, p = 0.010), and low BTR (≤4.4) (HR 1.852, p = 0.005) to be significant prognostic factors. Both serum albumin level (r = 0.370, p < 0.001) and ALBI score (r = -0.389, p < 0.001) showed a significant relationship with BTR. Child-Pugh class B, modified ALBI grade (mALBI) 2a, and mALBI 2b predictive values for BTR were 3.589, 4.509, and 4.155 (AUC range: 0.735-0.770), respectively, while the predictive value of ALBI score for low-BTR (≤4.4) was -2.588 (AUC 0.790).

CONCLUSION

ALBI score -2.588 was a predictor for low-BTR (≤4.4), which was prognostic factors for early HCC patients, and at least patients with mALBI 2b might have an amino acid imbalance.

Significance of serum branched-chain amino acid to tyrosine ratio measurement in athletes with high skeletal muscle mass

BACKGROUND

Few nutritional markers reflect the hypermetabolic state of athletes with high levels of skeletal muscle. Although branched-chain amino acids (BCAA) play crucial roles in protein metabolism in skeletal muscle, the relationship between skeletal muscle mass and amino acid imbalances caused by the metabolism of BCAA and aromatic amino acids remains unclear. The aim of this study is to test the hypothesis that athletes with high levels of skeletal muscle mass have plasma amino acid imbalances, assessed by serum BCAA to tyrosine ratio (BTR) which can be measured conveniently.

METHODS

The study enrolled 111 young Japanese men: 70 wrestling athletes and 41 controls. None of them were under any medications, extreme dietary restrictions or intense exercise regimens. Each participant's body composition, serum concentrations of albumin and rapid turnover proteins including transthyretin and transferrin, BTR, and thyroid function were assessed.

RESULTS

Compared to the controls, the athletes had significantly higher skeletal muscle index (SMI) (p < 0.001), and lower serum albumin concentration (p < 0.001) and BTR (p < 0.001). Kruskal-Wallis tests showed that serum albumin concentration and BTR were significantly lower in the participants with higher SMI. Serum albumin concentration and BTR were inversely correlated with SMI by multiple regression analysis (logarithmic albumin, β = - 0.358, p < 0.001; BTR, β = - 0.299, p = 0.001). SMI was inversely and transthyretin was positively correlated with serum albumin (SMI, β = - 0.554, p < 0.001; transthyretin, β = 0.379, p < 0.001). Serum concentration of free 3,5,3'-triiodothyronine (FT₃) was inversely correlated with BTR, and, along with SMI and albumin, was independent predictor of BTR (SMI, β = - 0.321, p < 0.001; FT₃, β = - 0.253, p = 0.001; logarithmic albumin, β = 0.261, p = 0.003). However, FT₃ was not correlated with SMI or serum albumin. Serum concentrations of rapid turnover proteins were not correlated with BTR.

CONCLUSIONS

Increased skeletal muscle mass enhances the circulating amino acid imbalances, and is independently facilitated by thyroid hormones. Serum BTR may be a useful biomarker to assess the hypermetabolic state of wrestling athletes with high levels of skeletal muscle.

Evaluation of treatment with zinc acetate hydrate in patients with liver cirrhosis complicated by zinc deficiency

AIM

In Japan, no zinc preparation had been approved for therapeutic purposes before March 2017. Zinc acetate hydrate was recently approved for the treatment of hypozincemia. We evaluated the efficacy and safety of treatment with zinc acetate hydrate.

METHODS

A total of 97 patients with cirrhosis complicated by hypozincemia were treated with zinc acetate hydrate, and their serum zinc normalization rates; factors contributing to normalization; changes in blood ammonia levels; branched-chain amino acids-to-tyrosine ratios; levels of albumin, hemoglobin, alkaline phosphatase, serum copper, and iron; incidence of adverse events; improvement in subjective symptoms; and serum zinc levels taken at 3 months post-treatment were determined.

RESULTS

The cumulative serum zinc normalization rates, when normalization was defined as achievement of a serum zinc level ≥80 μg/dL, after 2, 4, and 6 months of treatment were 64.9%, 80.3%, and 82.5%, respectively. Multivariate analysis identified an albumin level of ≥3.3 g/dL and branched-chain amino acids to tyrosine ratio of ≥3.46 as factors contributing to zinc normalization within 3 months of treatment. Treatment resulted in a significant decrease in blood ammonia and serum copper levels, and significant increases in branched-chain amino acids-to-tyrosine ratios and alkaline phosphatase levels. Seven (7.2%) patients prematurely discontinued treatment due to hypocupremia. By the end of treatment, subjective symptoms had resolved in 46.2% of patients. By 3 months post-treatment, serum zinc levels had reverted to levels close to those at baseline.

CONCLUSIONS

Treatment with zinc acetate hydrate resulted in normalization of serum zinc levels at a high rate. The main reasons for discontinuation of treatment included hypocupremia.

Switching from branched-chain amino acid granules to branched-chain amino acid-enriched nutrient improves the branched-chain amino acid-to-tyrosine ratio in patients with cirrhosis with hypoalbuminemia: a prospective study

OBJECTIVE

The present study aimed to elucidate the effect of switching from branched-chain amino acid granules to branched-chain amino acid-enriched nutrient in patients with cirrhosis with hypoalbuminemia.

METHODS

Twenty-six patients with cirrhosis with hypoalbuminemia despite treatment with branched-chain amino acid granules containing 12 g of branched-chain amino acid were enrolled in the prospective study. The branched-chain amino acid-enriched nutrient and control groups were composed of 16 and 10 patients, respectively. The patients in branched-chain amino acid-enriched nutrient group switched to branched-chain amino acid-enriched nutrient mixture containing 12.2 g of branched-chain amino acid and 410 kcal with a half of it consumed as a late evening snack, and the patients in the control group continued branched-chain amino acid granules. Laboratory data related to nutrition parameter were assessed at baseline, 3 months after baseline, and at 6 months after baseline.

RESULTS

Two patients were withdrawn; hence, nine and 15 patients in the branched-chain amino acid granules and branched-chain amino acid-enriched nutrient groups, respectively, were subjected to full analysis. Serum albumin levels and total lymphocyte counts in both groups did not change in the study period. The branched-chain amino acid-to-tyrosine ratio in the branched-chain amino acid-enriched nutrient group significantly increased from baseline to 6 months after baseline (P = 0.030), whereas that in the control group did not increase.

CONCLUSION

Switching from branched-chain amino acid granules to branched-chain amino acid-enriched nutrients improves branched-chain amino acid-to-tyrosine ratio in patients with cirrhosis with hypoalbuminemia.

Assessment of Malnutrition, Sarcopenia and Frailty in Patients with Cirrhosis: Which Tools Should We Use in Clinical Practice?

Malnutrition is a common comorbidity in patients with cirrhosis. Its prognostic value is indisputable as it greatly affects the evolution of liver diseases. It has a major impact on both morbi-mortality before and after liver transplantation. Being now integrated in the definition of malnutrition and recognized as a new entity in the international classification of diseases, physicians have taken great interest in sarcopenia. Its negative consequences on the fate of patients with cirrhosis are well-demonstrated. The concept of frailty has recently been enlarged to chronic liver diseases as symptoms of impaired global physical functioning. In this article, we will discuss the definitions of malnutrition and emphasize its links with sarcopenia and frailty. We will show the relevance of frailty and sarcopenia in the course of liver diseases. The emerging role of muscle depletion on the cardiorespiratory system will also be highlighted. The importance of body composition will be demonstrated and the main tools reviewed. Finally, we adapted the definition of malnutrition to patients with cirrhosis based on the assessment of sarcopenia together with reduced food intakes.

Zinc and protein metabolism in chronic liver diseases

The capacity to metabolize proteins is closely related to the hepatic functional reserve in patients with chronic liver disease, and hypoalbuminemia and hyperammonemia develop along with hepatic disease progression. Zinc deficiency, which is frequently observed in patients with chronic liver disease, significantly affects protein metabolism. Ornithine transcarbamylase is a zinc enzyme involved in the urea cycle. Its activity decreases because of zinc deficiency, thereby reducing hepatic capacity to metabolize ammonia. Because the glutamine-synthesizing system in skeletal muscles compensates for the decrease in ammonia metabolism, hyperammonemia does not develop in the early stages of chronic liver disease. However, branched-chain amino acids (BCAAs) are consumed with the increase in glutamine-synthesizing system reactions, leading to a decreased capacity to synthesize proteins, including albumin, due to amino acid imbalance. Upon further disease progression, skeletal muscle mass decreases because of nutritional deficiency, as well as the further decreased capacity to metabolize ammonia in the liver, whereby the capacity to detoxify ammonia reduces as a whole, resulting in hyperammonemia. BCAA supplementation therapy for nutritional deficiency in liver cirrhosis improves survival by correcting amino acid imbalance via recovery of the capacity to synthesize albumin, while zinc supplementation therapy improves the capacity to metabolize ammonia in the liver. Here, the efficacy of a combination of BCAA and zinc preparation for nutritional deficiency in liver cirrhosis, as well as its theoretical background, was reviewed.

Structural insights into thermostabilization of leucine dehydrogenase from its atomic structure by cryo-electron microscopy

Leucine dehydrogenase (LDH, EC 1.4.1.9) is a NAD⁺-dependent oxidoreductase that catalyzes the deamination of branched-chain l-amino acids (BCAAs). LDH of Geobacillus stearothermophilus (GstLDH) is a highly thermostable enzyme that has been applied for the quantification or production of BCAAs. Here the cryo-electron microscopy (cryo-EM) structures of apo and NAD⁺-bound LDH are reported at 3.0 and 3.2 Å resolution, respectively. On comparing the structures, the two overall structures are almost identical, but it was observed that the partial conformational change was triggered by the interaction between Ser147 and the nicotinamide moiety of NAD⁺. NAD⁺ binding also enhanced the strength of oligomerization interfaces formed by the core domains. Such additional interdomain interaction is in good agreement with our experimental results showing that the residual activity of NAD⁺-bound form was approximately three times higher than that of the apo form after incubation at 80 °C. In addition, sequence comparison of three structurally known LDHs indicated a set of candidates for site-directed mutagenesis to improve thermostability. Subsequent mutation analysis actually revealed that non-conserved residues, including Ala94, Tyr127, and the C-terminal region, are crucial for oligomeric thermostability.

The profiling of plasma free amino acids and the relationship between serum albumin and plasma-branched chain amino acids in chronic liver disease: a single-center retrospective study

BACKGROUND

It is poorly understood how an imbalance of plasma-free amino acids (PFAAs) occurs and how the imbalance shows an association with the serum albumin (sAlb) level during the progression of chronic liver disease (CLDs). The aim of this study is to elucidate the profiles of PFAAs and the relationship between sAlb and PFAAs in recent patients with CLDs during the progression.

METHODS

We retrospectively evaluated the 1569 data of PFAAs data obtained from 908 patients with various CLDs (CHC, CHB. alcoholic, NAFLD/NASH, PBC, AIH, PSC, and cryptogenic). In total, 1140 data of PFAAs could be analyzed in patients with CLDs dependent of their Child-Pugh (CP) score.

RESULTS

Various imbalances in PFAAs were observed in each CLDs during the progression. Univariate and multivariate analysis revealed that among 24 PFAAs, the level of plasma-branched chain amino acids (pBCAAs) was significantly associated with the CP score, especially the sAlb score, in patients with chronic hepatitis C virus (CHC), NAFLD/NASH and PBC. The correlation coefficient values between sAlb and pBCAAs-to-Tyrosine ratio (BTR) in these patients were 0.53, 0.53 and 0.79, respectively. Interestingly, although the pBCAAs in NAFLD/NASH patients varied even when the sAlb was within the normal range, the pBCAAs tended to be low when the sAlb was below the normal range.

CONCLUSIONS

Although a decrease in the level of pBCAAs was observed during the progression regardless of the CLD etiology, the level of total pBCAAs was independently associated with the sAlb level in the PFAAs of CHC, PBC and NAFLD/NASH. The correlation between sAlb and BTR showed the highest value in PBC patients among the patients with CLDs. A decrease in pBCAAs often occurred in NASH even when the sAlb level was kept in the normal range.

Branched-chain amino acids in liver diseases

Branched chain amino acids (BCAAs) are involved in various bioprocess such as protein metabolism, gene expression, insulin resistance and proliferation of hepatocytes. BCAAs have also been reported to suppress the growth of hepatocellular carcinoma (HCC) cells in vitro and to be required for immune cells to perform the function. In advanced cirrhotic patients, it has been clarified that serum concentrations of BCAA are decreased, whereas those of aromatic amino acids (AAAs) are increased. These alterations are thought to be the causes of hepatic encephalopathy (HE), sarcopenia and hepatocarcinogenesis and may be associated with the poor prognosis of patients with these conditions. Administration of BCAA-rich medicines has shown positive results in patients with cirrhosis.

Predictors Associated with Increase in Skeletal Muscle Mass after Sustained Virological Response in Chronic Hepatitis C Treated with Direct Acting Antivirals

Aims: We aimed to examine changes in skeletal muscle mass in chronic hepatitis C (CHC) patients undergoing interferon (IFN)-free direct acting antivirals (DAAs) therapy who achieved sustained virological response (SVR). Patients and methods: A total of 69 CHC patients treated with DAAs were analyzed. We compared the changes in skeletal muscle index (SMI) using bio-impedance analysis at baseline and SMI at SVR. SMI was calculated as the sum of skeletal muscle mass in upper and lower extremities divided by height squared (cm²/m²). Further, we identified pretreatment parameters contributing to the increased SMI at SVR. Results: SMI in males at baseline ranged from 6.73 to 9.08 cm²/m² (median, 7.65 cm²/m²), while that in females ranged from 4.45 to 7.27 cm²/m² (median, 5.81 cm²/m²). At SVR, 36 patients (52.2%) had increased SMI as compared with baseline. In the univariate analysis, age (p = 0.0392), hyaluronic acid (p = 0.0143), and branched-chain amino acid to tyrosine ratio (BTR) (p = 0.0024) were significant pretreatment factors linked to increased SMI at SVR. In the multivariate analysis, only BTR was an independent predictor linked to the increased SMI at SVR (p = 0.0488). Conclusion: Pretreatment BTR level can be helpful for predicting increased SMI after SVR in CHC patients undergoing IFN-free DAAs therapy.

Impact of Virtual Touch Quantification in Acoustic Radiation Force Impulse for Skeletal Muscle Mass Loss in Chronic Liver Diseases

Background and aims: We sought to clarify the relationship between virtual touch quantification (VTQ) in acoustic radiation force impulse and skeletal muscle mass as assessed by bio-electronic impedance analysis in patients with chronic liver diseases (CLDs, n = 468, 222 males and 246 females, median age = 62 years). Patients and methods: Decreased skeletal muscle index (D-SMI) was defined as skeletal muscle index (SMI) <7.0 kg/m² for males and as SMI <5.7 kg/m² for females, according to the recommendations in current Japanese guidelines. We examined the correlation between SMI and VTQ levels and investigated factors linked to D-SMI in the univariate and multivariate analyses. The area under the receiver operating curve (AUROC) for the presence of D-SMI was also calculated. Results: In patients with D-SMI, the median VTQ level was 1.64 meters/second (m/s) (range, 0.93–4.32 m/s), while in patients without D-SMI, the median VTQ level was 1.11 m/s (range, 0.67–4.09 m/s) (p < 0.0001). In the multivariate analysis, higher VTQ was found to be an independent predictor linked to the presence of D-SMI (p < 0.0001). In receiver operating characteristic analysis, body mass index had the highest AUROC (0.805), followed by age (0.721) and VTQ (0.706). Conclusion: VTQ levels can be useful for predicting D-SMI in patients with CLDs.

Changes in skeletal muscle mass after endoscopic treatment in patients with esophageal varices

To the best of our knowledge, no available data with regard to changes in skeletal muscle mass for liver cirrhosis (LC) patients with esophageal varices (EVs) undergoing endoscopic therapy as a primary prophylaxis could exist. As endoscopic therapies, such as endoscopic injection sclerotherapy or endoscopic band ligation for EVs, accompany invasive procedure and patients with EVs receiving endoscopic therapies mostly rest in bed during hospitalization, clarifying these issues are clinically of importance. The purposes of this study were therefore to examine changes in skeletal muscle mass for LC patients with EVs undergoing endoscopic therapy as a primary prophylaxis and to identify pretreatment predictors which are associated with the amelioration in skeletal muscle mass. This is a subgroup analysis in our previous randomized controlled trial. A total of 51 LC patients with EVs were analyzed. Skeletal muscle mass was assessed using bioimpedance analysis (BIA). Skeletal muscle index (SMI) was defined as sum of skeletal muscle mass in body trunk and upper and lower extremities divided by height squared (cm/m) using data for BIA. We compared the changes in SMI at baseline and SMI at Day 50 after endoscopic treatment for EVs. Our study cohort included 33 males and 18 females with median (range) age of 62 (29-81) years. There were 31 patients with Child-Pugh A and 20 with Child-Pugh B. The median SMI for the entire cohort at baseline was 8.96 cm/m (range, 5.87-13.11 cm/m), while the median SMI for the entire cohort at Day 50 was 8.83 cm/m (range, 5.59-12.29 cm/m) (P = .9995). In baseline characteristics, prealbumin (P = .0477), branched-chain amino acid to tyrosine ratio (BTR) (P = .0056), and retinol-binding protein (P = .0296) in the increased SMI group (n = 15) were significantly higher than those in the nonincreased SMI group (n = 36). Multivariate analysis for the above 3 significant factors showed that only BTR was a significant prognostic pretreatment factor linked to the presence of increased SMI (P = .0235). In conclusion, pretreatment BTR level can be helpful for predicting increased SMI after endoscopic therapy as a primary prophylaxis for LC patients with EVs.

Improvement in the Amino Acid Imbalance in Hepatitis C Virus Infected Patients After Viral Eradication by Interferon Treatment

BACKGROUND

In patients with chronic liver diseases (CLDs), hepatitis C virus (HCV) infection in particular may cause various metabolic disorders. We previously reported that the value of the ratio of branched-chain amino acids to tyrosine (BTR) decreased with the progression of liver fibrosis.

OBJECTIVES

We investigated the changes in clinical variables during interferon (IFN) treatment and assessed whether HCV eradication improved the amino acid imbalance in HCV infected patients.

PATIENTS AND METHODS

We retrospectively collected the clinical data of HCV-related CLD patients whose BTR values had been measured both pre- and post-IFN treatment. A total of 17 patients with a sustained viral response (SVR) (mean observational period: 1085.0 days) and 19 patients without an SVR (Non-SVR) (mean observational period: 1002.5 days) were studied.

RESULTS

In patients with an SVR, the serum levels of aminotransferases were decreased after HCV eradication. Although general liver functional tests (albumin and total bilirubin) did not significantly change, the BTR values significantly increased. However, in patients without an SVR, an improvement in the BTR value was not observed after IFN treatment.

CONCLUSIONS

HCV eradication can improve the amino acid imbalance in HCV infected patients.

Branched-chain amino acids reduce hepatic iron accumulation and oxidative stress in hepatitis C virus polyprotein-expressing mice

BACKGROUND & AIMS

Branched-chain amino acids (BCAA) reduce the incidence of hepatocellular carcinoma (HCC) in patients with cirrhosis. However, the mechanisms that underlie these effects remain unknown. Previously, we reported that oxidative stress in male transgenic mice that expressed hepatitis C virus polyprotein (HCVTgM) caused hepatic iron accumulation by reducing hepcidin transcription, thereby leading to HCC development. This study investigated whether long-term treatment with BCAA reduced hepatic iron accumulation and oxidative stress in iron-overloaded HCVTgM and in patients with HCV-related advanced fibrosis.

METHODS

Male HCVTgM were fed an excess-iron diet that comprised either casein or 3.0% BCAA, or a control diet, for 6 months.

RESULTS

For HCVTgM, BCAA supplementation increased the serum hepcidin-25 levels and antioxidant status [ratio of biological antioxidant potential (BAP) relative to derivatives of reactive oxygen metabolites (dROM)], decreased the hepatic iron contents, attenuated reactive oxygen species generation, and restored mitochondrial superoxide dismutase expression and mitochondrial complex I activity in the liver compared with mice fed the control diet. After 48 weeks of BCAA supplementation in patients with HCV-related advanced fibrosis, BAP/dROM and serum hepcidin-25 increased and serum ferritin decreased compared with the pretreatment levels.

CONCLUSIONS

BCAA supplementation reduced oxidative stress by restoring mitochondrial function and improved iron metabolism by increasing hepcidin-25 in both iron-overloaded HCVTgM and patients with HCV-related advanced fibrosis. These activities of BCAA may partially account for their inhibitory effects on HCC development in cirrhosis patients.

Effects of branched-chain amino acids and zinc-enriched nutrients on prognosticators in HCV-infected patients: a multicenter randomized controlled trial

Branched‑chain amino acids (BCAAs) and trace element deficiencies are associated with poor prognosis in hepatitis C virus (HCV)‑infected patients. The aim of this study was to investigate the effects of BCAA and zinc‑enriched supplementation on prognostic factors in HCV‑infected patients. Fifty‑three HCV‑infected patients were enrolled in this multicenter randomized controlled trial. The patients were assigned to either the placebo (n=27) or supplement group (n=26; 6,400 mg/day BCAAs and 10 mg/day zinc) and were followed up for 60 days. Primary outcomes were prognostic factors for chronic liver disease, including the serum BCAA‑to‑tyrosine ratio (BTR), zinc levels and α‑fetoprotein (AFP) levels. There were no significant differences in any of the prognostic factors between the placebo and supplement groups at baseline. In the supplement group, the BTR and zinc levels were significantly increased compared with the placebo group (BTR: 5.14 ± 1.59 vs. 4.23 ± 1.14, P=0.0290; zinc: 76 ± 11 vs. 68 ± 11 µg/dl, P=0.0497). No significant differences were observed in AFP levels between the groups in the whole analysis. However, a stratification analysis showed a significant reduction in ΔAFP levels in the supplement group, with elevated AFP levels compared with the other groups (‑2.72 ± 3.45 ng/ml, P=0.0079). It was demonstrated that BCAA and zinc‑enriched supplementation increased the BTR and zinc levels in the HCV‑infected patients. Furthermore, the supplementation reduced the serum AFP levels in patients who had elevated serum AFP levels at baseline. Thus, BCAA and zinc‑enriched supplementation may prolong the survival of HCV‑infected patients by improving amino acid imbalance and zinc deficiency, and by partly downregulating AFP.

Association of tyrosine with insulin resistance in hepatitis C virus-related chronic liver disease

AIM

Insulin resistance (IR) increases during the early stages of hepatitis C virus (HCV)-related chronic liver disease and is a sign of poor prognosis as well as a risk factor for hepatic fibrosis and hepatocellular carcinoma. We aimed to determine the factors affecting IR in HCV-related chronic liver disease.

METHODS

We retrospectively examined 71 patients with HCV-related chronic liver disease and analyzed various parameters, including amino acids, as possible predictors of IR. IR was assessed using the Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR). Amino acids were assayed by examining branched-chain amino acids (BCAA), tyrosine level, and the ratio of BCAA to tyrosine level (BTR).

RESULTS

HOMA-IR was significantly correlated with body mass index, platelet count, prothrombin time, hemoglobin, total bilirubin, total protein, albumin, total cholesterol, fasting glucose, BTR (r = -0.46, P = 0.0001) and tyrosine (r = 0.55, P < 0.0001). However, BCAA were not significantly correlated with HOMA-IR (r = -0.21, P = 0.082). In multivariate analysis, only two factors were identified as independent parameters contributing to a HOMA-IR of 2.5 or more: total cholesterol (odds ratio [OR], 6.511; 95% confidence interval [95% CI], 1.554-27.284; P = 0.010) and tyrosine (OR, 4.839; 95% CI, 1.087-21.549; P = 0.039).

CONCLUSION

Serum tyrosine levels may be associated with IR in patients with HCV-related chronic liver disease.

Serum albumin level is a notable profiling factor for non-B, non-C hepatitis virus-related hepatocellular carcinoma: A data-mining analysis

AIM

Various factors are underlying for the onset of non-B, non-C hepatitis virus-related hepatocellular carcinoma (NBNC-HCC). We aimed to investigate the independent risk factors and profiles associated with NBNC-HCC using a data-mining technique.

METHODS

We conducted a case-control study and enrolled 223 NBNC-HCC patients and 669 controls from a health checkup database (n = 176 886). Multivariate analysis, random forest analysis and a decision-tree algorithm were employed to examine the independent risk factors, factors distinguishing between the case and control groups, and to identify profiles for the incidence of NBNC-HCC, respectively.

RESULTS

In multivariate analysis, besides γ-glutamyltransferase (GGT) levels and the Brinkman index, albumin level was an independent negative risk factor for the incidence of NBNC-HCC (odds ratio = 0.67; 95% confidence interval = 0.60-0.70; P < 0.0001). In random forest analysis, serum albumin level was the highest-ranked variable for distinguishing between the case and control groups (98 variable importance). A decision-tree algorithm was created for albumin and GGT levels, the aspartate aminotransferase-to-platelet ratio index (APRI) and the Brinkman index. The serum albumin level was selected as the initial split variable, and 82.5% of the subjects with albumin levels of less than 4.01 g/dL were found to have NBNC-HCC.

CONCLUSION

Data-mining analysis revealed that serum albumin level is an independent risk factor and the most distinguishable factor associated with the incidence of NBNC-HCC. Furthermore, we created an NBNC-HCC profile consisting of albumin and GGT levels, the APRI and the Brinkman index. This profile could be used in the screening strategy for NBNC-HCC.

Branched-chain amino acids prevent hepatocarcinogenesis and prolong survival of patients with cirrhosis

BACKGROUND & AIMS

Although a low plasma level of branched-chain amino acids (BCAAs) is a marker of cirrhosis, it is not clear whether BCAA supplements affect disease progression. We performed a multicenter study to evaluate the effects of BCAA supplementation on hepatocarcinogenesis and survival in patients with cirrhosis.

METHODS

We enrolled 299 patients from 14 medical institutions in Japan in a prospective, multicenter study in 2009; 267 patients were followed through 2011. Patients were given BCAA supplements (5.5-12.0 g/day) for more than 2 years (n = 85) or no BCAAs (controls, n = 182). The primary end points were onset of hepatocellular carcinoma (HCC) and death. Factors associated with these events were analyzed by competing risk analysis.

RESULTS

During the study period, 41 of 182 controls and 11 of 85 patients given BCAAs developed HCC. On the basis of the Cox and the Fine and Gray models of regression analyses, level of α-fetoprotein, ratio of BCAA:tyrosine, and BCAA supplementation were associated with development of HCC (relative risk for BCAAs, 0.45; 95% confidence interval, 0.24-0.88; P = .019). Sixteen controls and 2 patients given BCAAs died. Factors significantly associated with death were Child-Pugh score, blood level of urea nitrogen, platelet count, male sex, and BCAA supplementation (relative risk of death for BCAAs, 0.009; 95% confidence interval, 0.0002-0.365; P = .015) in both regression models.

CONCLUSIONS

On the basis of a prospective study, amino acid imbalance is a significant risk factor for the onset of HCC in patients with cirrhosis. BCAA supplementation reduces the risk for HCC and prolongs survival of patients with cirrhosis.

Erosive esophagitis associated with metabolic syndrome, impaired liver function, and dyslipidemia

AIM: To investigate whether erosive esophagitis is correlated with metabolic syndrome and its components, abnormal liver function, and lipoprotein profiles.

METHODS: We conducted a cross-sectional, case control study of subjects who underwent upper endoscopy during a health examination at the Health Management and Evaluation Center of a tertiary medical care facility located in Southern Taiwan. Metabolic syndrome components, body mass index (BMI), liver function, dyslipidemia, and cardiovascular risk factors, as defined by the ratio of total cholesterol to high-density lipoprotein cholesterol (HDL-C), and the ratio of low-density lipoprotein cholesterol to HDL-C were compared between individuals with and without erosive esophagitis. Risk factors for erosive esophagitis were evaluated by multivariate logistic regression.

RESULTS: Erosive esophagitis was diagnosed in 507 of 5015 subjects who were individually age and sex matched to 507 esophagitis-free control subjects. In patients with erosive esophagitis, BMI, waist circumference, blood pressure, fasting plasma glucose, triglyceride levels, aspartate aminotransferase, alanine aminotransferase, the ratio of total cholesterol to HDL-C, and the ratio of low-density lipoprotein cholesterol to HDL-C were significantly higher and HDL-C was significantly lower compared to patients without erosive esophagitis (all P < 0.05). In a multivariate analysis, central obesity (OR = 1.38; 95%CI: 1.0-1.86), hypertension (OR = 1.35; 95%CI: 1.04-1.76), hypertriglyceridemia (OR = 1.34; 95%CI: 1.02-1.76), cardiovascular risk factors as defined by a ratio of total cholesterol to HDL-C > 5 (OR = 1.45; 95%CI: 1.06-1.97), and aspartate aminotransferase (OR = 1.59; 95%CI: 1.08-2.34) were significantly associated with erosive esophagitis.

CONCLUSION: Metabolic syndrome, impaired liver function, and a higher ratio of total cholesterol to HDL-C were associated with erosive esophagitis.

Fast and quantitative analysis of branched-chain amino acids in biological samples using a pillar array column

In this study, a fast and quantitative determination method for branched-chain amino acids (BCAAs), namely leucine, isoleucine, and valine, was developed using a pillar array column. A pillar array column with low-dispersion turns was fabricated on a 20 × 20-mm(2) microchip using multistep ultraviolet photolithography and deep reactive ion etching. The BCAAs were fluorescently labeled with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F), followed by reversed-phase separation on the pillar array column. The NBD derivatives of the three BCAAs and an internal standard (6-aminocaproic acid) were separated in 100 s. The calibration curves for the NBD-BCAAs had good linearity in the range of 0.4-20 μM, using an internal standard. The intra- and interday precisions were found to be in the ranges of 1.42-3.80 and 2.74-6.97%, respectively. The accuracies for the NBD-BCAA were from 90.2 to 99.1%. The method was used for the analysis of sports drink and human plasma samples. The concentrations of BCAAs determined by the developed method showed good agreements with those determined using a conventional high-performance liquid chromatography system. As BCAAs are important biomarkers of some diseases, these results showed that the developed method could be a potential diagnostic tool in clinical research.

Correlation between plasma amino acid profiles and the various stages of hepatitis B infection

The amino acid metabolism in patients with hepatitis B virus (HBV) infection is significantly changed. In this study, we analyzed the relationship between the amino acid profiles and varying clinical stages of HBV infection, and investigated their significance. The plasma amino acid concentrations in 115 patients with HBV infection and 32 healthy donors were detected and analyzed, and the main indicators of liver function were measured. Correlation analysis was performed between the amino acid profiles (Fischer's ratio, branched-chain amino acid to tyrosine ratio [BTR]) and the key indicators of liver function in patients with HBV infection. Fisher's ratio and the BTR of patients with HBV infection was found to differ from that of the healthy controls, and was also found to significantly correlate with the stage of HBV infection. Changes in the BTR were closely related to the level of key indicators of liver function, and a significant relationship was detected between the Fischer's ratio and the BTR (r=0.928, p<0.001). These results suggest that Fischer's ratio and the BTR can indirectly reflect the degree of liver cell injury. Determining and tracking the plasma amino acid profiles could, therefore, be used for the diagnosis, treatment selection, and prognosis of patients with varying stages of HBV infection.

Early administration of branched-chain amino acid granules

The effect of malnutrition on survival in patients with decompensated liver cirrhosis has not been well defined. Nutritional intervention with branched-chain amino acid (BCAA) can increase serum albumin concentration in patients with decompensated cirrhosis but its effects on survival are unclear. The BCAA to tyrosine ratio (BTR) is a surrogate marker (the normal range of BTR is between 4.41 and 10.05, and a Fischer’s ratio of 1.8 corresponds to a BTR of 3.5) in patients with decompensated liver cirrhosis, and BCAA inhibits hepatic carcinogenesis in patients with compensated cirrhosis. This review discusses data regarding the effect of early administration of BCAA granules based on the ratio of BCAA to BTR on prognosis in patients with cirrhosis.

Branched-chain amino acids to tyrosine ratio value as a potential prognostic factor for hepatocellular carcinoma

The prognosis of hepatocellular carcinoma (HCC) depends on tumor extension as well as hepatic function. Hepatic functional reserve is recognized as a factor affecting survival in the treatment of HCC; the Child-Pugh classification system is the most extensively used method for assessing hepatic functional reserve in patients with chronic liver disease, using serum albumin level to achieve accurate assessment of the status of protein metabolism. However, insufficient attention has been given to the status of amino acid (AA) metabolism in chronic liver disease and HCC. Fischer’s ratio is the molar ratio of branched-chain AAs (BCAAs: leucine, valine, isoleucine) to aromatic AAs (phenylalanine, tyrosine) and is important for assessing liver metabolism, hepatic functional reserve and the severity of liver dysfunction. Although this ratio is difficult to determine in clinical situations, BCAAs/tyrosine molar concentration ratio (BTR) has been proposed as a simpler substitute. BTR correlates with various liver function examinations, including markers of hepatic fibrosis, hepatic blood flow and hepatocyte function, and can thus be considered as reflecting the degree of hepatic impairment. This manuscript examines the literature to clarify whether BTR can serve as a prognostic factor for treatment of HCC.

Branched-chain amino acids as pharmacological nutrients in chronic liver disease

Branched-chain amino acids (BCAAs) are a group of essential amino acids comprising valine, leucine, and isoleucine. A low ratio of plasma BCAAs to aromatic amino acids is a physiological hallmark of liver cirrhosis, and BCAA supplementation was originally devised with the intention of normalizing amino acid profiles and nutritional status. However, recent studies on BCAAs have revealed that, in addition to their role as protein constituents, they may have a role as pharmacological nutrients for patients with chronic liver disease. Large-scale, multicenter, randomized, double-blinded, controlled trials on BCAA supplementation have been performed in Italy and Japan, and results demonstrate that BCAA supplementation improves not only nutritional status, but also prognosis and quality of life in patients with liver cirrhosis. Moreover, accumulating experimental evidence suggests that the favorable effects of BCAA supplementation on prognosis may be supported by unforeseen pharmacological actions of BCAAs. This review summarizes the possible effects of BCAAs on albumin synthesis and insulin resistance from clinical and basic viewpoints. We also review the newly discovered clinical impact of BCAAs on hepatocellular carcinoma and the prognosis and quality of life of patients with liver cirrhosis.

Prognostic impact of preoperative the branched-chain amino acid to the tyrosine ratio in hepatocellular carcinoma patients after initial hepatectomy

INTRODUCTION

The branched-chain amino acid/tyrosine ratio (BTR) reflects the amino acid balance and the severity of liver disease. The aim of the present study was to determine the relationship between BTR and liver function in patients with hepatocellular carcinoma (HCC). Furthermore, we evaluated the clinical usefulness of BTR as a prognostic indicator of disease-free and overall patient survival after initial hepatectomy.

METHODS

Between January 2004 and December 2008, 105 consecutive HCC patients who underwent initial hepatectomy were enrolled in this study. The correlation between BTR and preoperative liver functional indicators was evaluated. The cutoff levels of BTR for 2-year survival prediction were evaluated using a dot blot diagram. The patients were divided into high BTR (4.5 or higher) and low BTR (4.4 or lower) groups and these were compared in terms of clinical variables such as liver functional indicators, operative variables, and tumor characteristics.

RESULTS

The preoperative BTR level decreased according to the severity of liver disease. BTR was correlated with the albumin, bilirubin, and prealbumin levels, as well as the prothrombin time. Although the preoperative liver function was significantly different between the high BTR and low BTR groups, the operative variables and tumor-related variables were not found to be significantly different. Postoperative complications in the high BTR group were significantly less frequent than in the low BTR group (p = 0.003). Disease-free and overall patient survival in the high BTR group were significantly longer than in the low BTR group (p < 0.001 and p = 0.021, respectively).

CONCLUSIONS

BTR reflected the pathological liver background with a high correlation to the other liver functional indicators. BTR is thus considered to be a useful marker to predict postoperative complications, disease-free survival, and overall survival of HCC patients after initial hepatectomy. It is, therefore, a useful indicator of liver function and a predictor for the risk of cancer recurrence and overall survival in HCC patients.

Plasma amino acid imbalance: dangerous in chronic diseases?

PURPOSE OF REVIEW

In various diseases amino acid imbalances occur which have been described especially in the 1980s of the last century. It was noted that some of these imbalances may exert specific negative physiological effects. However, mainly because of economic reasons, no real attempts have been made to develop special amino acid solutions for disease processed associated with amino acid imbalances to restore normal amino acid concentrations.

RECENT FINDINGS

A recent study performed in the fruit-fly Drosophila indicated that modifying the amino acid supply may influence both lifespan and fecundity. It was shown that adding amino acids but not carbohydrates or fat to a restricted diet decreases lifespan. In contrast, administration of certain amino acids especially of methionine increased fecundity without decreasing lifespan. It is known that dietary restriction can decrease fecundity at the cost of a prolonged lifespan.

SUMMARY

Recent investigations revealed that amino acids are powerful molecules in mediating cell signalling. Therefore, it can be hypothesized that the severe amino acid imbalances as observed in uraemia or liver failure may exert a relevant impact on various physiologic processes and on organ function. The recent results described in Drosophila should stimulate a new research area on the effect of amino acid supply in various disease processes.

Importance of hepatitis C virus-associated insulin resistance: Therapeutic strategies for insulin sensitization

Insulin resistance is one of the pathological features in patients with hepatitis C virus (HCV) infection. Generally, persistence of insulin resistance leads to an increase in the risk of life-threatening complications such as cardiovascular diseases. However, these complications are not major causes of death in patients with HCV-associated insulin resistance. Indeed, insulin resistance plays a crucial role in the development of various complications and events associated with HCV infection. Mounting evidence indicates that HCV-associated insulin resistance may cause (1) hepatic steatosis; (2) resistance to anti-viral treatment; (3) hepatic fibrosis and esophageal varices; (4) hepatocarcinogenesis and proliferation of hepatocellular carcinoma; and (5) extrahepatic manifestations. Thus, HCV-associated insulin resistance is a therapeutic target at any stage of HCV infection. Although the risk of insulin resistance in HCV-infected patients has been documented, therapeutic guidelines for preventing the distinctive complications of HCV-associated insulin resistance have not yet been established. In addition, mechanisms for the development of HCV-associated insulin resistance differ from lifestyle-associated insulin resistance. In order to ameliorate HCV-associated insulin resistance and its complications, the efficacy of the following interventions is discussed: a late evening snack, coffee consumption, dietary iron restriction, phlebotomy, and zinc supplements. Little is known regarding the effect of anti-diabetic agents on HCV infection, however, a possible association between use of exogenous insulin or a sulfonylurea agent and the development of HCC has recently been reported. On the other hand, insulin-sensitizing agents are reported to improve sustained virologic response rates. In this review, we summarize distinctive complications of, and therapeutic strategies for, HCV-associated insulin resistance. Furthermore, we discuss supplementation with branched-chain amino acids as a unique insulin-sensitizing strategy for patients with HCV-associated insulin resistance.

Amino acid imbalance in patients with chronic liver diseases

AIM

The aim of this study is to clarify the amino acid imbalance in patients with chronic hepatitis (CH) as well as those with liver cirrhosis (LC).

METHODS

We assayed total branched-chain amino acids (BCAA), tyrosine (Tyr) levels and their ratio (BTR) in sera of 101 patients with CH (37 in fibrosis stage F1, 23 in F2, 21 in F3) and 20 with LC (F4) who were diagnosed by liver biopsy. Their levels in relation to the staging of liver fibrosis were analyzed.

RESULTS

The percentage of patients whose BTR was less than the normal range was 32.1% in CH and 75.0% in LC. The levels of BTR and BCAA were significantly lower (P < 0.001, P < 0.05, respectively) and that of Tyr was significantly higher (P < 0.001) in patients with LC than those in CH. The levels of BTR decreased according to the staging. The levels of Tyr increased according the staging, whereas the levels of BCAA deceased prominently in F4 (487 +/- 103 in F1, 483 +/- 122 in F2, 487 +/- 111 in F3 and 423 +/- 94 in F4).

CONCLUSION

A considerable number of patients not only with LC but also with CH showed lower levels of BTR. It has been clarified that amino acid imbalance of Tyr was found in the early stage of liver disease, whereas decrease of BCAA was found mainly in F4 stage.

Epidemiology and clinical characteristics of GERD in the Japanese population

We reviewed articles on the epidemiology and clinical characteristics of gastroesophageal reflux disease (GERD) in Japan to clarify these features of GERD in this country. Although the definition of GERD depends on the individual study, the prevalence of GERD has been increasing since the end of the 1990s. The reasons for the increase in the prevalence of GERD may be due to increases in gastric acid secretion, a decrease in the Helicobacter pylori infection rate, more attention being paid to GERD, and advances in the concept of GERD. More than half of GERD patients had non-erosive reflux disease, and the majority (87%) of erosive esophagitis was mild type, such as Los Angeles classification grade A and grade B. There were several identified risk factors, such as older age, obesity, and hiatal hernia. In particular, mild gastric atrophy and absence of H. pylori infection influence the characteristics of GERD in the Japanese population. We also discuss GERD in the elderly; asymptomatic GERD; the natural history of GERD; and associations between GERD and peptic ulcer disease and H. pylori eradication. We examined the prevalence of GERD in patients with specific diseases, and found a higher prevalence of GERD, compared with that in the general population, in patients with diabetes mellitus, those with obstructive sleep apnea syndrome, and those with bronchial asthma. We provide a comprehensive review of GERD in the Japanese population and raise several clinical issues.