Quantitative Analysis of Pancreatic Fat in Children with Obesity Using Magnetic Resonance Imaging and Ultrasonography / 대한소아소화기영양학회지

Purpose@#The aim of this study was to evaluate the pancreatic fat fraction (PFF) using magnetic resonance imaging (MRI) in children with and without obesity and to correlate PFF with body mass index (BMI) z-score, hepatic fat fraction (HFF), and ultrasonography-derived pancreato-perihepatic fat index (PPHFI). @*Methods@#This prospective study included 45 children with obesity and 19 without obesity (control group). PFF and HFF were quantitatively assessed using the abdominal multi-echo Dixon method for MRI. The PPHFI was assessed using transabdominal ultrasonography. Anthropometric, MRI, and ultrasonographic characteristics were compared between the two groups. Correlations between PFF, HFF, PPHFI, and BMI z-scores in each group were also analyzed. @*Results@#The PFF, HFF, PPHFI, and BMI z-score were higher in the group with obesity than in the control group (PFF: 6.65±3.42 vs. 1.78±0.55, HFF: 19.5±13.0 vs. 2.31±1, PPHFI: 3.65 ±1.63 vs. 0.94±0.31, BMI z-score: 2.27±0.56 vs. 0.42±0.54, p<0.01, respectively). PFF was correlated with BMI z-scores, PPHFI, and HFF in the obesity group, and multivariate analysis showed that PFF was strongly correlated with BMI z-score and PPHFI (p<0.05). The BMI z-score was strongly correlated with PFF in the control group (p<0.01). @*Conclusion@#These results suggest that MRI-derived PFF measures are associated with childhood obesity. PFF and PPHFI were also highly correlated in the obesity group. Therefore, PFF may be an objective index of pancreatic fat content and has the potential for clinical utility as a non-invasive biomarker for the assessment of childhood obesity.

Imbalance of Gut Streptococcus, Clostridium, and Akkermansia Determines the Natural Course of Atopic Dermatitis in Infant

PURPOSE: The roles of gut microbiota on the natural course of atopic dermatitis (AD) are not yet fully understood. We investigated whether the composition and function of gut microbiota and short-chain fatty acids (SCFAs) at 6 months of age could affect the natural course of AD up to 24 months in early childhood.METHODS: Fecal samples from 132 infants were analyzed using pyrosequencing, including 84 healthy controls, 22 transient AD and 26 persistent AD subjects from the Cohort for Childhood Origin of Asthma and Allergic Diseases (COCOA) birth cohort. The functional profile of the gut microbiome was analyzed by whole-metagenome sequencing. SCFAs were measured using gas chromatography-mass spectrometry.RESULTS: Low levels of Streptococcus and high amounts of Akkermansia were evident in transient AD cases, and low Clostridium, Akkermansia and high Streptococcus were found in children with persistent AD. The relative abundance of Streptococcus positively correlated with scoring of AD (SCORAD) score, whereas that of Clostridium negatively correlated with SCORAD score. The persistent AD group showed decreased gut microbial functional genes related to oxidative phosphorylation compared with healthy controls. Butyrate and valerate levels were lower in transient AD infants compared with healthy and persistent AD infants.CONCLUSIONS: Compositions, functions and metabolites of the early gut microbiome are related to natural courses of AD in infants.

Cavernous Hemangioma of the Gallbladder: a Case Report

Cavernous hemangioma of the gallbladder is an extremely rare benign tumor. The tumor has only a few cases being reported in literature. However, to the best of our knowledge, no reports focusing on the MRI findings of cavernous hemangioma of the gallbladder have been published. This study reports a case of gallbladder hemangioma with pathologic and radiologic reviews, including MRI findings.

Optimization of the Flip Angle and Scan Timing in Hepatobiliary Phase Imaging Using T1-Weighted, CAIPIRINHA GRE Imaging

PURPOSE: This study was designed to optimize the flip angle (FA) and scan timing of the hepatobiliary phase (HBP) using the 3D T1-weighted, gradient-echo (GRE) imaging with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique on gadoxetic acid-enhanced 3T liver MR imaging. MATERIALS AND METHODS: Sixty-two patients who underwent gadoxetic acid-enhanced 3T liver MR imaging were included in this study. Four 3D T1-weighted GRE imaging studies using the CAIPIRINHA technique and FAs of 9° and 13° were acquired during HBP at 15 and 20 min after intravenous injection of gadoxetic acid. Two abdominal radiologists, who were blinded to the FA and the timing of image acquisition, assessed the sharpness of liver edge, hepatic vessel clarity, lesion conspicuity, artifact severity, and overall image quality using a five-point scale. Quantitative analysis was performed by another radiologist to estimate the relative liver enhancement (RLE) and the signal-to-noise ratio (SNR). Statistical analyses were performed using the Wilcoxon signed rank test and one-way analysis of variance. RESULTS: The scores of the HBP with an FA of 13° during the same delayed time were significantly higher than those of the HBP with an FA of 9° in all the assessment items (P < 0.01). In terms of the delay time, images at the same FA obtained with a 20-min-HBP showed better quality than those obtained with a 15-min-HBP. There was no significant difference in qualitative scores between the 20-min-HBP and the 15-min-HBP images in the non-liver cirrhosis (LC) group except for the hepatic vessel clarity score with 9° FA. In the quantitative analysis, a statistically significant difference was found in the degree of RLE in the four HBP images (P = 0.012). However, in the subgroup analysis, no significant difference in RLE was found in the four HBP images in either the LC or the non-LC groups. The SNR did not differ significantly in the four HBP images. In the subgroup analysis, 20-min-HBP imaging with a 13° FA showed the highest SNR value in the LC-group, whereas 15-min-HBP imaging with a 13° FA showed the best value of SNR in the non-LC group. CONCLUSION: The use of a moderately high FA improves the image quality and lesion conspicuity on 3D, T1-weighted GRE imaging using the CAIPIRINHA technique on gadoxetic acid, 3T liver MR imaging. In patients with normal liver function, the 15-min-HBP with a 13° FA represents a feasible option without a significant decrease in image quality.

Feasibility of Quadruple Arterial Phase of Motion Insensitive Radial Volumetric Imaging Breath-Hold Examination with k-Space Weighted Image Contrast in the Detection of Hepatocellular Carcinoma in Patients with Chronic Liver Disease

PURPOSE@#To evaluate the detection performance of hepatocellular carcinoma and image quality in patients with chronic liver disease with quadruple arterial MR imaging using radial volumetric imaging breath-hold examination (VIBE) with k-space weighted image contrast (KWIC).@*MATERIALS AND METHODS@#Forty-four patients underwent liver MR examinations with quadruple arterial imaging using radial VIBE-KWIC sequence (full-frame and four sub-frame images). Diagnostic performance was evaluated with receiver operating characteristics (ROC) for detection of hepatocellular carcinoma. The image quality and severity of artifact were scored by using the five-point scale.@*RESULTS@#The area under the ROC curve (Az) value of Hepatocelluar Carcinoma (HCC) detectability was the highest on third sub-frame images, followed by full-frame images. The Az values of third sub-frame and full-frame about the detection of HCC were statistically significantly different from the Az value of first sub-frame images. The full-frame and four sub-frame images showed acceptable image quality and low degree artifact with rating of higher than grade 3.@*CONCLUSION@#Quadruple arterial MRI using radial VIBE-KWIC is a feasible method for detecting hepatocellular carcinoma in patients with chronic liver disease without deterioration of image quality. The third sub-frame and full-frame image are superior to other sub-frame images in detecting hepatocellular carcinoma.

Preliminary study on Low Intensity Focused Ultrasound system For neuromodulation.

A Prototype Low Intensity Focused Ultrasound for brain targeting in a rat model was developed and tested. Accordingly, were evaluated low intensity focused ultrasound accuracy and performance. By utilizing the Rat Brain, no death or necrosis of cells, it was confirmed that the energy is gathered at that targeted.

Comparison of Three, Motion-Resistant MR Sequences on Hepatobiliary Phase for Gadoxetic Acid (Gd-EOB-DTPA)-Enhanced MR Imaging of the Liver

PURPOSE: To compare three, motion-resistant, T1-weighted MR sequences on the hepatobiliary phase for gadoxetic acid-enhanced MR imaging of the liver. MATERIALS AND METHODS: In this retrospective study, 79 patients underwent gadoxetic acid-enhanced, 3T liver MR imaging. Fifty-nine were examined using a standard protocol, and 20 were examined using a motion-resistant protocol. During the hepatocyte-specific phase, three MR sequences were acquired: 1) gradient recalled echo (GRE) with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA); 2) radial GRE with the interleaved angle-bisection scheme (ILAB); and 3) radial GRE with golden-angle scheme (GA). Two readers independently assessed images with motion artifacts, streaking artifacts, liver-edge sharpness, hepatic vessel clarity, lesion conspicuity, and overall image quality, using a 5-point scale. The images were assessed by measurement of liver signal-to-noise ratio (SNR), and tumor-to-liver contrast-to-noise ratio (CNR). The results were compared, using repeated post-hoc, paired t-tests with Bonferroni correction and the Wilcoxon signed rank test with Bonferroni correction. RESULTS: In the qualitative analysis of cooperative patients, the results for CAIPIRINHA had significantly higher ratings for streak artifacts, liver-edge sharpness, hepatic vessel clarity, and overall image quality as compared to, radial GRE, (P < 0.016). In the imaging of uncooperative patients, higher scores were recorded for ILAB and GA with respect to all of the qualitative assessments, except for streak artifact, compared with CAIPIRINHA (P < 0.016). However, no significant differences were found between ILAB and GA. For quantitative analysis in uncooperative patients, the mean liver SNR and lesion-to-liver CNR with radial GRE were significantly higher than those of CAIPIRINHA (P < 0.016). CONCLUSION: In uncooperative patients, the use of the radial GRE sequence can improve the image quality compared to GRE imaging with CAIPIRINHA, despite the data acquisition methods used. The GRE imaging with CAIPIRINHA is applicable for patients without breath-holding difficulties.

Comparison of Three, Motion-Resistant MR Sequences on Hepatobiliary Phase for Gadoxetic Acid (Gd-EOB-DTPA)-Enhanced MR Imaging of the Liver

PURPOSE: To compare three, motion-resistant, T1-weighted MR sequences on the hepatobiliary phase for gadoxetic acid-enhanced MR imaging of the liver. MATERIALS AND METHODS: In this retrospective study, 79 patients underwent gadoxetic acid-enhanced, 3T liver MR imaging. Fifty-nine were examined using a standard protocol, and 20 were examined using a motion-resistant protocol. During the hepatocyte-specific phase, three MR sequences were acquired: 1) gradient recalled echo (GRE) with controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA); 2) radial GRE with the interleaved angle-bisection scheme (ILAB); and 3) radial GRE with golden-angle scheme (GA). Two readers independently assessed images with motion artifacts, streaking artifacts, liver-edge sharpness, hepatic vessel clarity, lesion conspicuity, and overall image quality, using a 5-point scale. The images were assessed by measurement of liver signal-to-noise ratio (SNR), and tumor-to-liver contrast-to-noise ratio (CNR). The results were compared, using repeated post-hoc, paired t-tests with Bonferroni correction and the Wilcoxon signed rank test with Bonferroni correction. RESULTS: In the qualitative analysis of cooperative patients, the results for CAIPIRINHA had significantly higher ratings for streak artifacts, liver-edge sharpness, hepatic vessel clarity, and overall image quality as compared to, radial GRE, (P < 0.016). In the imaging of uncooperative patients, higher scores were recorded for ILAB and GA with respect to all of the qualitative assessments, except for streak artifact, compared with CAIPIRINHA (P < 0.016). However, no significant differences were found between ILAB and GA. For quantitative analysis in uncooperative patients, the mean liver SNR and lesion-to-liver CNR with radial GRE were significantly higher than those of CAIPIRINHA (P < 0.016). CONCLUSION: In uncooperative patients, the use of the radial GRE sequence can improve the image quality compared to GRE imaging with CAIPIRINHA, despite the data acquisition methods used. The GRE imaging with CAIPIRINHA is applicable for patients without breath-holding difficulties.

Six-week Diet Correction for Body Weight Reduction and Its Subsequent Changes of Gut Microbiota: A Case Report

Impact of intestinal microbes on obesity and health is a new topic recently started to get attention. Comparing to the global concern and research trends, there are few research on the association between intestinal bacteria and life style disease in Korean. One voluntary case (female) was reported to show the change in gut microbiota and weight by diet intervention. She was overweight (BMI 23.2 kg/m2) and has abnormal liver function, and the causes of overweight were frequent drinking and meat consumption at the late evening hours. For 47 days, she was administered an improved diet on breakfast and dinner with reduction of meat consumption frequency by 50%. Alcohol consumption was reduced to once a week. As a result, she lost 3 kilograms of body weight. Her fecal sample was collected before and after the intervention, and gut microbiota change was compared using a high-throughput sequencing technique. After diet correction, the shift of gut microbiota was clearly observed with decreased proportion of Firmicutes (from 75.7% to 47.3% in total microbiota) but increased proportion of Bacteroidetes upto 47.7%. After incorporating the diet intervention, it is meaningful to confirm the changes in dominant gut microbiota and weight loss.

Regression of esophageal varices during entecavir treatment in patients with hepatitis-B-virus-related liver cirrhosis

Recent studies suggest that liver cirrhosis is reversible after administering oral nucleos(t)ide analogue therapy to patients with hepatitis B virus (HBV) infection. However, few studies have addressed whether esophageal varices can regress after such therapy. We report a case of complete regression of esophageal varices during entecavir therapy in patients with HBV-related liver cirrhosis, suggesting that complications of liver cirrhosis such as esophageal varices can regress after the long-term suppression of HBV replication.

Regression of esophageal varices and splenomegaly in two patients with hepatitis-C-related liver cirrhosis after interferon and ribavirin combination therapy

Some recent studies have found regression of liver cirrhosis after antiviral therapy in patients with hepatitis C virus (HCV)-related liver cirrhosis, but there have been no reports of complete regression of esophageal varices after interferon/peg-interferon and ribavirin combination therapy. We describe two cases of complete regression of esophageal varices and splenomegaly after interferon-alpha and ribavirin combination therapy in patients with HCV-related liver cirrhosis. Esophageal varices and splenomegaly regressed after 3 and 8 years of sustained virologic responses in cases 1 and 2, respectively. To our knowledge, this is the first study demonstrating that complications of liver cirrhosis, such as esophageal varices and splenomegaly, can regress after antiviral therapy in patients with HCV-related liver cirrhosis.

Solitary Rectal Ulcer Syndrome Mimicking Rectal Cancer / 이화의대지

Solitary rectal ulcer syndrome (SRUS) is a rare benign and chronic rectal disease that has a wide spectrum of clinical presentations and variable endoscopic findings. It is usually diagnosed by histopathological examination through biopsy. A 68-year-old man was referred to our hospital with anal pain and difficulty on bowel movement. Colonoscopy showed a hemorrhagic ulcerated mass in the rectum. All radiologic findings such as abdominopelvic computed tomography (CT), positron emission tomography-CT and magnetic resonance imaging were suspicious of rectal cancer. Although the patient underwent repeat endoscopic biopsy and one surgical biopsy, the results were not indicative of malignancy. Two months after conservative management, clinical symptoms and colonoscopic findings were markedly improved. Thus, we report this rare case of a 68-year-old man who had a central ulcerated mass that mimicked rectal cancer on gross colonoscopic and radiologic findings, representing an SRUS variant.

The Practicality of Targeted Prostate Biopsy Procedures on the Dominant Side of the Tumor Determined by Magnetic Resonance Imaging in Elderly Patients with High Serum Levels of Prostate-Specific Antigen

PURPOSE: To examine the possibility of reducing the number of cores per prostate biopsy in elderly patients with high levels of prostate-specific antigen (PSA) without significantly lowering the detection rate of prostate cancer. MATERIALS AND METHODS: Two hundreds sixteen men with PSA levels >20 ng/mL who underwent prostate biopsies from May 2009 to April 2013 were retrospectively reviewed. With the help of magnetic resonance imaging (MRI), the laterality of the dominant tumor burden in patients was determined. The results of targeted biopsies were compared with those of conventional biopsy procedures. RESULTS: The mean age and PSA level were 79.5 years and 81.3 ng/mL, respectively, and the overall diagnostic rate of sextant biopsies was 81.9% (177/216). MRI was able to show the tumor burden in 189 of the 216 patients. The detection rate of transrectal ultrasonography (TRUS)-guided targeted biopsies was 87.3% (165/189). Detection rates were comparable with conventional biopsies (81.9% [177/216]) (p=0.23). Of the 177 men in whom the results of the sextant biopsy were positive, 12 men (6.8%) with PSA levels <29 ng/mL did not have any cancer cells according to targeted biopsies. However, all other patients were diagnosed with prostate cancer using the abovementioned techniques. CONCLUSIONS: We believe that TRUS-guided targeted biopsies of the prostate in elderly men with high PSA levels could reduce the number of unnecessary cores per biopsy. However, a risk of detection loss remains. Therefore, we recommend that at least a sextant biopsy should be performed, even in elderly patients, in order to detect prostate cancer.

Comparison of the gut microbiota profile in breast-fed and formula-fed Korean infants using pyrosequencing

BACKGROUND/OBJECTIVES: Feeding in infancy is the most significant determinant of the intestinal microbiota in early life. The aim of this study was to determine the gut microbiota of Korean infants and compare the microbiota obtained between breast-fed and formula-fed Korean infants. SUBJECTS/METHODS: We analyzed the microbial communities in fecal samples collected from twenty 4-week old Korean (ten samples in each breast-fed or formula-fed) infants using pyrosequencing. RESULTS: The fecal microbiota of the 4-week-old Korean infants consisted of the three phyla Actinobacteria, Firmicutes, and Proteobacteria. In addition, five species, including Bifidocbacterium longum, Streptococcus salivarius, Strepotococcus lactarius, Streptococcus pseudopneumoniae, and Lactobacillus gasseri were common commensal intestinal microbiota in all infants. The predominant intestinal microbiota in the breast-fed infants (BFI) included the phylum Actinobacteria (average 70.55%), family Bifidobacteriacea (70.12%), genus Bifidobacterium (70.03%) and species Bifidobacterium longum (69.96%). In the microbiota from the formula-fed infants (FFI), the proportion of the phylum Actinobacteria (40.68%) was less, whereas the proportions of Firmicutes (45.38%) and Proteobacteria (13.85%) as well as the diversity of each taxonomic level were greater, compared to those of the BFI. The probiotic species found in the 4-week-old Korean infants were Bifidobacterium longum, Streptococcus salivarius, and Lactobacillus gasseri. These probiotic species accounted for 93.81% of the microbiota from the BFI, while only 63.80% of the microbiota from the FFI. In particular, B. longum was more abundant in BFI (69.96%) than in FFI (34.17%). CONCLUSIONS: Breast milk supports the growth of B. longum and inhibits others. To the best of our knowledge, this study was the first attempt to analyze the gut microbiota of healthy Korean infants according to the feeding type using pyrosequencing. Our data can be used as a basis for further studies to investigate the development of intestinal microbiota with aging and disease status.

Two Cases of Hepatic Sinusoidal Dilatation Mimicking Hepatic Metastases / 대한소화기학회지

Hepatic sinusoidal dilatation is a rare benign vascular disorder characterized by focal dilatation of the sinusoidal spaces. In most cases, the underlying etiology is unclear but it may be related to the impairment of venous outflow or sinusoidal infiltration by diverse causes. Diagnosing hepatic sinusoidal dilatation based soley on imaging study is not easy since there are no pathognomonic radiologic findings indicative of this condition. Recently, the authors experience two cases of hepatic sinusoidal infiltration. The first patient was a 53-year-old man detected to have multiple hepatic nodules on ultrasonography (US) during a routine medical check-up. The second patient was an 82-year-old woman with abdominal discomfort who was referred from local clinic with high suspicion of hepatic metastases on US. In both cases, CT scan demonstrated multiple nodules with rim enhancement on arterial phase that became iso-dense to adjacent liver parenchyma on delayed phase. On MRI, these nodules showed rim enhancement on arterial phase, had high signal intensity on T2 weighted images, and became iso-intense with partial defect on hepatobiliary phase. Because imaging studies could not exclude the presence of hepatic metastases, liver biopsy was performed and it demonstrated hepatic sinusoidal dilatation with well preserved reticulin fiber without any evidence of malignancy. Herein, we report two cases of idiopathic hepatic sinusoidal dilatation mimicking hepatic metastases.

A Case of Acute Emphysematous Gastritis Associated with Invasive Aspergillosis

Emphysematous gastritis is a subtype of phlegmonous gastritis characterized by emphysematous change of the gastric wall. It is associated with infection of gas forming organism and is often fatal because of suppurative bacterial infection. Streptococci is the most commonly involved microorganism of emphysematous gastritis. Aspergillus is a very rare pathogen of this disease, because invasive aspergillosis often presents as pulmonary infections and rarely involves the gastro-intestinal tract. Treatment should be aimed to cover various organism using broad spectrum antibiotics, and sometimes aggressive surgical management may be needed to enhance survival. We report a case of severe emphysematous gastritis caused by invasive aspergillosis with a review of the literature.

A Case of Acute Emphysematous Gastritis Associated with Invasive Aspergillosis

Emphysematous gastritis is a subtype of phlegmonous gastritis characterized by emphysematous change of the gastric wall. It is associated with infection of gas forming organism and is often fatal because of suppurative bacterial infection. Streptococci is the most commonly involved microorganism of emphysematous gastritis. Aspergillus is a very rare pathogen of this disease, because invasive aspergillosis often presents as pulmonary infections and rarely involves the gastro-intestinal tract. Treatment should be aimed to cover various organism using broad spectrum antibiotics, and sometimes aggressive surgical management may be needed to enhance survival. We report a case of severe emphysematous gastritis caused by invasive aspergillosis with a review of the literature.

Current Status and Future Promise of the Human Microbiome / 대한소아소화기영양학회지

The human-associated microbiota is diverse, varies between individuals and body sites, and is important in human health. Microbes in human body play an essential role in immunity, health, and disease. The human microbiome has been studies using the advances of next-generation sequencing and its metagenomic applications. This has allowed investigation of the microbial composition in the human body, and identification of the functional genes expressed by this microbial community. The gut microbes have been found to be the most diverse and constitute the densest cell number in the human microbiota; thus, it has been studied more than other sites. Early results have indicated that the imbalances in gut microbiota are related to numerous disorders, such as inflammatory bowel disease, colorectal cancer, diabetes, and atopy. Clinical therapy involving modulating of the microbiota, such as fecal transplantation, has been applied, and its effects investigated in some diseases. Human microbiome studies form part of human genome projects, and understanding gleaned from studies increase the possibility of various applications including personalized medicine.

Comparison of the Clinical Characteristics of Patients with Small Bowel and Gastric Anisakiasis in Jeju Island

BACKGROUND/AIMS: Anisakiasis is frequent in Jeju Island because of the people's habit of ingesting raw fish. This study evaluated the clinical characteristics of patients with small bowel anisakiasis and compared them with those of patients with gastric anisakiasis. METHODS: We retrospectively reviewed the medical records of 109 patients diagnosed with anisakiasis between May 2003 and November 2011. RESULTS: Of the 109 patients diagnosed with anisakiasis, those with suspicious anisakiasis (n=38) or possible anisakiasis (n=12) were excluded. The age and gender distributions did not differ between patients with small bowel anisakiasis (n=30; age, 45+/-13 years) and those with gastric anisakiasis (n=29; age, 46+/-10 years). The mean duration of hospitalization was 5.4+/-4.3 days for patients with small bowel anisakiasis and 0.5+/-1.7 days for patients with gastric anisakiasis. Small bowel anisakiasis was accompanied by leukocytosis (76.7% vs 25.5%, p=0.003) and elevated C-reactive protein levels (3.4+/-3.2 mg/dL vs 0.5+/-0.3 mg/dL, p=0.009). Contrast-enhanced abdominopelvic computed tomography showed small bowel wall thickening with dilatation in 93.3% (28/30) of patients and a small amount of ascites in 80.0% (24/30) of patients with small bowel anisakiasis. CONCLUSIONS: Compared with gastric anisakiasis patients, small bowel anisakiasis patients had a longer hospitalization time, higher inflammatory marker levels, and small bowel wall thickening with ascites.

Analytical Tools and Databases for Metagenomics in the Next-Generation Sequencing Era

Metagenomics has become one of the indispensable tools in microbial ecology for the last few decades, and a new revolution in metagenomic studies is now about to begin, with the help of recent advances of sequencing techniques. The massive data production and substantial cost reduction in next-generation sequencing have led to the rapid growth of metagenomic research both quantitatively and qualitatively. It is evident that metagenomics will be a standard tool for studying the diversity and function of microbes in the near future, as fingerprinting methods did previously. As the speed of data accumulation is accelerating, bioinformatic tools and associated databases for handling those datasets have become more urgent and necessary. To facilitate the bioinformatics analysis of metagenomic data, we review some recent tools and databases that are used widely in this field and give insights into the current challenges and future of metagenomics from a bioinformatics perspective.