Degradative enzymes for type II arabinogalactan side chains in Bifidobacterium longum subsp. longum.

Type II arabinogalactan (AG) is a soluble prebiotic fiber stimulating the proliferation of bifidobacteria in the human gut. Larch AG, which is comprised of type II AG, is known to be utilized as an energy source for Bifidobacterium longum subsp. longum (B. longum). We have previously characterized GH43_24 exo-ß-1,3-galactanase (Bl1,3Gal) for the degradation of type II AG main chains in B. longum JCM1217. In this study, we characterized GH30_5 exo-ß-1,6-galactobiohydrolase (Bl1,6Gal) and GH43_22 α-L-arabinofuranosidase (BlArafA), which are degradative enzymes for type II AG side chains in cooperation with exo-ß-1,3-galactanase. The recombinant exo-ß-1,6-galactobiohydrolase specifically released ß-1,6-galactobiose (ß-1,6-Gal2) from the nonreducing terminal of ß-1,6-galactooligosaccharides, and the recombinant α-L-arabinofuranosidase released arabinofuranose (Araf) from α-1,3-Araf-substituted ß-1,6-galactooligosaccharides. ß-1,6-Gal2 was additively released from larch AG by the combined use of type II AG degradative enzymes, including Bl1,3Gal, Bl1,6Gal, and BlArafA. The gene cluster encoding the type II AG degradative enzymes is conserved in all B. longum strains, but not in other bifidobacterial species. The degradative enzymes for type II AG side chains are thought to be important for the acquisition of type II AG in B. longum.

Bifidobacterium longum subsp. longum Exo-ß-1,3-Galactanase, an enzyme for the degradation of type II arabinogalactan.

Type II arabinogalactan (AG-II) is a suitable carbohydrate source for Bifidobacterium longum subsp. longum, but the degradative enzymes have never been characterized. In this study, we characterized an exo-ß-1,3-galactanase, BLLJ_1840, belonging to glycoside hydrolase family 43 from B. longum subsp. longum JCM1217. The recombinant BLLJ_1840 expressed in Escherichia coli hydrolyzed ß-1,3-linked galactooligosaccharides but not ß-1,4- and ß-1,6-linked galactooligosaccharides. The enzyme also hydrolyzed larch wood arabinogalactan (LWAG), which comprises a ß-1,3-linked galactan backbone with ß-1,6-linked galactan side chains. The kcat/Km ratio of dearabinosylated LWAG was 24-fold higher than that of ß-1,3-galactan. BLLJ_1840 is a novel type of exo-ß-1,3-galactanase with a higher affinity for the ß-1,6-substituted ß-1,3-galactan than for nonsubstituted ß-1,3-galactan. BLLJ_1840 has 27% to 28% identities with other characterized exo--1,3-galactanases from bacteria and fungi. The homologous genes are conserved in several strains of B. longum subsp. longum and B. longum subsp. infantis but not in other bifidobacteria. Transcriptional analysis revealed that BLLJ_1840 is intensively induced with BLLJ_1841, an endo-ß-1,6-galactanase candidate, in the presence of LWAG. This is the first report of exo-ß-1,3-galactanase in bifidobacteria, which is an enzyme used for the acquisition of AG-II in B. longum subsp. longum.

Quantification of lung perfusion blood volume with dual-energy CT: assessment of the severity of acute pulmonary thromboembolism.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of quantification of lung perfused blood volume (PBV) with dual-energy CT (DECT) for assessment of the severity of acute pulmonary thromboembolism (PTE). MATERIALS AND METHODS: We retrospectively analyzed the records of 72 patients with PTE and 168 without PTE who underwent DECT. The PTE patients were divided into high-, intermediate-, and low-risk groups based on clinical symptoms and right ventricular dysfunction. Correlations between quantification of whole-lung PBV and clinical severity were evaluated. Also evaluated was the relation between quantification of whole-lung PBV and right-to-left ventricular diameter ratio on CT images, which was used as an indicator of right ventricular dysfunction. RESULTS: In the PTE and control groups, the whole-lung PBVs were 27.6 ± 7.9 and 29.9 ± 6.8 HU with a significant difference between them (p < 0.0281). In the high-, intermediate-, and low-risk PTE groups, the whole-lung PBVs were 16.0 ± 2.9, 21.0 ± 4.2, and 31.4 ± 5.8 HU with a significant difference between them (p < 0.05). There was no significant difference in whole-lung PBV between the control group and the low-risk PTE group, but there was a significant difference between the control group and the other two PTE groups. In PTE patients, whole-lung PBV had negative correlation with right-to-left ventricular diameter ratio (R = -0.567, p < 0.001). CONCLUSION: Quantification of lung PBV with DECT is useful for assessment of the clinical severity of PTE and can be used as an indicator of right ventricular dysfunction.

Local recurrence after chemoembolization of hepatocellular carcinoma: uptake of gadoxetic acid as a new prognostic factor.

OBJECTIVE: The purpose of this article is to investigate whether there is a difference in susceptibility to transcatheter arterial chemoembolization between hepatocellular carcinomas (HCCs) showing high uptake and those showing low uptake of gadoxetic acid in the hepatobiliary phase of MRI. MATERIALS AND METHODS: One hundred HCCs that achieved optimal chemoembolization, as assessed by immediate CT in 60 patients, were classified as having high (n = 19) or low (n = 81) uptake of gadoxetic acid on MRI performed before chemoembolization. The local recurrence rates were estimated using the Kaplan-Meier method, and differences between the groups were compared using the log-rank test. The following factors were also correlated with the local recurrence rate using the Cox proportional hazards model for a univariate analysis: high uptake of gadoxetic acid, number of feeding arteries, extrahepatic arterial supply, Child-Pugh class, clinical tumor stage, size, location, and iodized oil accumulation in the noncancerous tissue surrounding the lesion. Parameters that were significant at p < 0.05 were entered into a multivariate model. RESULTS: The 1- and 3-year local recurrence-free rates were 95% in high-uptake HCCs and 66% and 54%, respectively, in low-uptake HCCs (log-rank test, p < 0.01). The low uptake of gadoxetic acid was the only significant predictor of early local recurrence (hazard ratio = 9.24; p = 0.03) by multivariate analysis. CONCLUSION: HCCs showing high uptake of gadoxetic acid appear to be susceptible to chemoembolization.

Usefulness of evaluating hepatic elasticity using artificial acoustic radiation force ultrasonography before hepatectomy.

AIM: To evaluate hepatic fibrosis and tumor diagnosis preoperatively, we investigated the elasticity calculated by the new parameter of ultrasonography, acoustic radiation force impulse (ARFI). METHODS: We examined ARFI of the non-tumorous right and left lateral liver and in the tumor by push pulse of probe in 95 patients with hepatic malignancies undergoing hepatectomy. Measurement of ARFI as hepatic stiffness was indicated as the Vs (m/s). RESULTS: Measuring the Vs in the non-tumor region was achieved in the right liver in 99% and at the left lateral liver in 94%. The Vs in the right liver was significantly lower than in the left lateral liver, and the Vs of the liver tumor was significantly higher than in the non-tumorous liver. The Vs in the right and left lateral liver was correlated with the platelet count, aspartate aminotransferase, fibrotic indices and indocyanine green test. The Vs in the right liver was significantly correlated with the fibrotic marker or index. The Vs of liver cirrhosis and histological stage 4 in the right and left liver was significantly the highest compared to the others. The Vs in the right liver showed a high area under the receiver-operator curve value predicting histological fibrosis. The Vs in the right was significantly correlated with blood loss and postoperative complications, particularly uncontrolled ascites. CONCLUSION: Non-invasive ARFI imaging elastography is useful in evaluating impaired liver function or in the differential diagnosis of liver malignancies, highly hepatic fibrosis and in predicting posthepatectomy morbidity.

Multiple hepatocellular adenomas in a patient with glycogen storage disease type I: various enhancement patterns in MRI with Gd-EOB-DTPA.

The patient is a 20-year-old man with glycogen storage disease type I (GSD-type I). In his teens, multiple focal hepatic masses were detected on abdominal ultrasonography (US), which were diagnosed as multiple hepatocellular adenomas from the imaging. During follow-up, these masses had shown intermittent growth in size. In the evaluation of Gd-EOB-DTPA (gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid) MR imaging, these masses showed various signal intensities from hypo- to hyperintense during the hepatocyte-specific phase. Intermittent growth and elevation of serum PIVKA-II levels indicate the potential for malignant transformation, so the patient underwent partial hepatectomy. The resected masses were all consistent with benign hepatocellular adenomas histopathologically.