Low frequency of drug-resistant virus did not affect the therapeutic efficacy in daclatasvir plus asunaprevir therapy in patients with chronic HCV genotype-1 infection

BACKGROUND

The efficacy of a direct-acting antiviral agent (DAA) is compromised by the development of drug resistance. The associations between resistance-associated virus (RAV) and therapeutic outcomes have not been well-understood.

METHODS

A total of 30 patients with HCV genotype-1b were enrolled and treated for 24 weeks with asunaprevir (ASV) and daclatasvir (DCV). Viral sequences in non-structural (NS) regions 3 and 5A in serum and liver tissue before treatment were examined with direct sequencing, next-generation sequencing (NGS) and the PCR-invader method to evaluate the importance of drug-resistance in the prediction of the outcomes of ASV plus DCV therapy.

RESULTS

Of 30 patients (22 treatment-naive patients, 2 interferon-intolerant patients and 6 non-responders), 25 patients (83.3%) achieved sustained virological response (SVR) 24 weeks after the treatment. Viral breakthrough occurred in three treatment-naive patients and one non-responder. One treatment-naive patient experienced viral relapse. Among 25 patients without RAV, 24 obtained SVR, whereas 5 patients had RAV with a 1.3 to 88% frequency, resulting in various therapeutic outcomes. As for HCV compartments, similar RAVs were detected in serum and liver tissue for a patient obtaining SVR despite HCV NS5A Y93H and another developed viral breakthrough although no RAV was detected. Direct sequencing could not detect RAVs in low frequency (1.3 to 12%) for three of four patients.

CONCLUSIONS

Low frequency of RAVs might not affect the outcomes of ASV plus DCV therapy. Deep sequencing and PCR-invader methods can detect clinically significant RAVs for ASV plus DCV therapy.

Serum N-glycan profiles in patients with intraductal papillary mucinous neoplasms of the pancreas

BACKGROUND/OBJECTIVES

Diagnosing the invasiveness of intraductal papillary mucinous neoplasms (IPMNs) is difficult, especially by blood test. Alterations in serum glycan profiles have been reported for several cancers, but changes in serum glycan profiles have not been investigated in patients with IPMNs. The objectives of this study were to determine the serum N-glycan profile and to investigate its clinical utility in patients with IPMNs.

METHODS

We measured serum N-glycan profiles in 79 patients with IPMNs, including 13 invasive IPMNs, by performing comprehensive glycome analysis and assessed the relationship between N-glycan changes and clinical parameters.

RESULTS

Seventy glycans were identified and their expression profiles were significantly different depending on the cyst size, the presence of an enhancing solid component, and the histological grade of the IPMN. Nine glycans were highly expressed in patients with invasive IPMNs. The glycan m/z 3195, which is a fucosylated tri-antennary glycan, had the highest diagnostic value for distinguishing invasive IPMNs from non-invasive IPMNs (area under the receiver operating characteristic curve = 0.803). Multivariate analyses revealed high levels of m/z 3195 [odds ratio (OR), 20.5; 95% confidence interval (CI) 2.60-486.4] and the presence of enhancing solid components (OR, 35.8; 95% CI, 5.39-409.6) were significant risk factors for invasive IPMNs.

CONCLUSIONS

We performed a comprehensive evaluation of the changes in serum N-glycan profiles in patients with IPMNs for the first time. We determined that increased expression of fucosylated complex-type glycans, especially m/z 3195, is a potential marker for invasive IPMNs.

EGFR inhibitors prevent induction of cancer stem-like cells in esophageal squamous cell carcinoma by suppressing epithelial-mesenchymal transition

There exists a highly tumorigenic subset of esophageal squamous cell carcinoma (ESCC) cells defined by high expression of CD44. A novel therapy targeting these cancer stem-like cells (CSCs) is needed to improve prognosis of ESCC. CSCs of ESCC have a mesenchymal phenotype and epithelial-mesenchymal transition (EMT) is critical to enrich and maintain CSCs. EGFR, frequently overexpressed in ESCC, has pivotal roles in EMT induced by TGF-β in invasive fronts. Thus, EMT in invasive fronts of ESCC might be important for CSCs and EGFR could be a target of a novel therapy eliminating CSCs. However, effects of EGFR inhibitors on CSCs in ESCC have not been fully examined. EGFR inhibitors, erlotinib and cetuximab, significantly suppressed enrichment of CSCs via TGF-β1-mediated EMT. Importantly, EGFR inhibitors sharply suppressed ZEB1 that is essential for EMT in ESCC. Further, EGFR inhibitors activated Notch1 and Notch3, leading to squamous cell differentiation. EGFR inhibition may suppress expression of ZEB1 and induce differentiation, thereby blocking EMT-mediated enrichment of CSCs. In organotypic 3D culture, a form of human tissue engineering, tumor cells in invasive nests showed high expression of CD44. Erlotinib significantly blocked invasion into the matrix and CD44 high expressing CSCs were markedly suppressed by erlotinib in organotypic 3D culture. In conclusion, EMT is a critical process for generation of CSCs and the invasive front of ESCC, where EMT occurs, might form a CSC niche in ESCC. EGFR inhibitors could suppress EMT in invasive fronts and be one therapeutic option targeting against generation of CSCs in ESCC.

Use of non-invasive serum glycan markers to distinguish non-alcoholic steatohepatitis from simple steatosis

BACKGROUND AND AIMS

Serum glycans have been reported to be promising diagnostic markers for many inflammatory diseases and cancers. The aims of this study were to investigate whole glycan expression in patients with non-alcoholic fatty liver diseases and to evaluate the potential use of glycan profiles as new clinical biomarkers to distinguish non-alcoholic steatohepatitis (NASH) from simple steatosis (SS).

METHODS

We collected sera from 42 histologically proven NASH and 15 SS patients prior to treatment. Serum glycan profiles were measured by comprehensive, quantitative, high-throughput glycome analysis, and diagnostic values of serum glycans for NASH prediction were examined.

RESULTS

Among the 41 serum glycans examined, the expression levels of 8 glycans in NASH were significantly higher than those of SS. Out of these eight glycans, three glycans (m/z 1955, 2032, and 2584) showed high areas under the receiver operating characteristic curve (0.833, 0.863, and 0.866, respectively) for distinguishing NASH from SS. In multivariate analyses with clinical parameters and serum glycans, these three glycans were significant predictive factors for distinguishing NASH from SS. The odds ratio of m/z 1955, 2032, and 2584 were 48.5, 6.46, and 11.8, respectively. These glycans also correlated significantly with lobular inflammation, ballooning, and fibrosis, but not with steatosis.

CONCLUSION

We clearly demonstrated whole-serum glycan profiles in NASH patients, and the feasibility of serum glycans (m/z 1955, 2032, and 2584) as new noninvasive biomarkers for distinguishing NASH from SS.

Involvement of platelets in extrahepatic metastasis of hepatocellular carcinoma

AIM

Recently, a relationship between platelets and cancer metastasis has been reported. The aim of this study is to elucidate the risk factors for extrahepatic metastasis (EHM), with emphasis on association with platelets in patients, with hepatocellular carcinoma (HCC).

METHODS

We examined risk factors for EHM in 1613 consecutive, newly diagnosed HCC patients by logistic regression analysis (case-control study). We also examined the factors by Cox proportional hazard model in a retrospective cohort fashion in 803 patients who received non-curative treatment for HCC.

RESULTS

In the case-control study, multivariate analysis revealed that high platelet counts (odds ratio [OR] = 4.84; 95% confidence interval [CI] = 1.29-29.54; P = 0.01), high tumor number and the presence of macroscopic vascular invasion were significantly associated with EHM. In the cohort study, EHM was diagnosed in 71 patients during the study period (mean observation time = 23.3 months). On multivariate analysis, high tumor number, high des-γ-carboxyprothrombin (DCP) and Child-Pugh class A were significantly correlated with EHM, and the patients with high platelet counts tended to develop EHM (OR = 1.73; 95% CI = 0.99-3.14; P = 0.055).

CONCLUSION

HCC patients with high platelet counts, as well as large numbers of tumors, high serum DCP and Child-Pugh class A, are at risk for EHM.

IGFBP3 promotes esophageal cancer growth by suppressing oxidative stress in hypoxic tumor microenvironment

Insulin-like growth factor binding protein 3 (IGFBP3), a hypoxia-inducible gene, regulates a variety of cellular processes including cell proliferation, senescence, apoptosis and epithelial-mesenchymal transition (EMT). IGFBP3 has been linked to the pathogenesis of cancers. Most previous studies focus upon proapoptotic tumor suppressor activities of IGFBP3. Nevertheless, IGFBP3 is overexpressed in certain cancers including esophageal squamous cell carcinoma (ESCC), one of the most aggressive forms of squamous cell carcinomas (SCCs). The tumor-promoting activities of IGFBP3 remain poorly understood in part due to a lack of understanding as to how the tumor microenvironment may influence IGFBP3 expression and how IGFBP3 may in turn influence heterogeneous intratumoral cell populations. Here, we show that IGFBP3 overexpression is associated with poor postsurgical prognosis in ESCC patients. In xenograft transplantation models with genetically engineered ESCC cells, IGFBP3 contributes to tumor progression with a concurrent induction of a subset of tumor cells showing high expression of CD44 (CD44H), a major cell surface receptor for hyaluronic acid, implicated in invasion, metastasis and drug resistance. Our gain-of-function and loss-of-function experiments reveal that IGFBP3 mediates the induction of intratumoral CD44H cells. IGFBP3 cooperates with hypoxia to mediate the induction of CD44H cells by suppressing reactive oxygen species (ROS) in an insulin-like growth factor-independent fashion. Thus, our study sheds light on the growth stimulatory functions of IGFPB3 in cancer, gaining a novel mechanistic insight into the functional interplay between the tumor microenvironment and IGFBP3.

Prognotic impact of serum follistatin in patients with hepatocellular carcinoma

BACKGROUND AND AIM

Follistatin (FST) is a glycoprotein expressed in most organs, which interacts with activins or other members of the transforming growth factor beta family. Recently, several reports have shown that FST regulates a variety of processes during tumor progression. Here, serum FST in patients with liver diseases was measured, and its clinical utility as a biomarker was assessed.

METHODS

Serum was collected from 162 patients (91 hepatocellular carcinoma [HCC], 43 liver cirrhosis, and 28 chronic hepatitis) as well as from 16 healthy volunteers. FST was quantified by enzyme-linked immunosorbent assays, and levels were compared with clinical parameters including survival of the HCC patients.

RESULTS

Median serum FST levels in HCC, liver cirrhosis, chronic hepatitis, and healthy volunteers were 1168, 1606, 1324, and 1661 pg/mL, respectively, not significantly different. In HCC patients, higher serum FST was associated with greater age, hepatitis C virus antibody-negativity, large tumor size, g-glutamyl transpeptidase, des-gamma carboxyprothrombin and presence of portal vein tumor thrombus. Survival of HCC patients with high FST levels was significantly shorter than for those with low levels (P = 0.004). Multivariate analysis revealed that in addition to large tumor size and presence of portal vein thrombus, high FST levels were independently correlated with poor prognosis (hazard ratio = 2.41, 95% confidence interval = 1.16-5.00, P = 0.02).

CONCLUSIONS

Serum FST levels are significantly associated with HCC prognosis and could represent a predictive biomarker in this disease.

Clinical utility of serum fucosylated hemopexin in Japanese patients with hepatocellular carcinoma

AIM

  Hepatocellular carcinoma (HCC) is a common clinical problem all over the world. Fucosylated hemopexin (Fuc-Hpx) is a newly reported glycoprotein for the diagnosis of HCC, however, its clinical implications are unclear. The aim of this study was to elucidate the clinical utility of Fuc-Hpx in Japanese patients with HCC.

METHODS

  The sera from 331 HCC patients, 45 with liver cirrhosis (LC), 85 with chronic hepatitis (CH) and 22 healthy people were examined for the expression of Fuc-Hpx; the level was compared with clinical parameters as well as hemopexin (Hpx) expression. The expressions of Fuc-Hpx in 12 HCC tissues and corresponding adjacent non-cancerous liver tissues were also examined.

RESULTS

  No correlation was observed between Hpx and Fuc-Hpx level. The median Fuc-Hpx levels in healthy people and CH, LC and HCC patients were 3.8, 3.7, 6.1 and 7.6 AU/mL, respectively (CH vs LC, P = 0.002; CH vs HCC, P < 0.001; LC vs HCC, P = 0.02). Multivariate analysis revealed that low albumin, low prothrombin time and the presence of HCC were significantly correlated with high Fuc-Hpx (P = 0.013, =0.001 and <0.001, respectively). Among the HCC patients, albumin was correlated with high Fuc-Hpx; however, none of the tumor factors, such as tumor size, tumor number and tumor stage, was correlated with Fuc-Hpx level. The expression of Fuc-Hpx in cancer tissue was not different from that in non-cancerous tissue.

CONCLUSION

  Fuc-Hpx is a valuable biomarker for HCC but it might be a marker for hypercarcinogenic liver rather than a marker for tumor-bearing liver.

Notch receptor inhibition reveals the importance of cyclin D1 and Wnt signaling in invasive esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive forms of squamous cell carcinomas. Common genetic lesions in ESCC include p53 mutations and EGFR overexpression, both of which have been implicated in negative regulation of Notch signaling. In addition, cyclin D1 is overexpressed in ESCC and can be activated via EGFR, Notch and Wnt signaling. To elucidate how these genetic lesions may interact during the development and progression of ESCC, we tested a panel of genetically engineered human esophageal cells (keratinocytes) in organotypic 3D culture (OTC), a form of human tissue engineering. Notch signaling was suppressed in culture and mice by dominant negative Mastermind-like1 (DNMAML1), a genetic pan-Notch inhibitor. DNMAML1 mice were subjected to 4-Nitroquinoline 1-oxide-induced oral-esophageal carcinogenesis. Highly invasive characteristics of primary human ESCC were recapitulated in OTC as well as DNMAML1 mice. In OTC, cyclin D1 overexpression induced squamous hyperplasia. Concurrent EGFR overexpression and mutant p53 resulted in transformation and invasive growth. Interestingly, cell proliferation appeared to be regulated differentially between those committed to squamous-cell differentiation and those invading into the stroma. Invasive cells exhibited Notch-independent activation of cyclin D1 and Wnt signaling. Within the oral-esophageal squamous epithelia, Notch signaling regulated squamous-cell differentiation to maintain epithelial integrity, and thus may act as a tumor suppressor by preventing the development of a tumor-promoting inflammatory microenvironment.

Risk factors for recurrence after transarterial chemoembolization for early-stage hepatocellular carcinoma

BACKGROUND

Radiofrequency ablation (RFA) is a standard therapy for the treatment of hepatocellular carcinoma (HCC) with 3 or fewer tumors of up to 3 cm (early-stage HCC); when RFA is unsuccessful or unfeasible, transcatheter arterial chemoembolization (TACE) has often been performed. However, little information about the outcome of TACE for early-stage HCC has been reported and it is hard to decide whether to perform additional treatment following TACE in these difficult conditions. The aim of this study was to determine the risk factors for local or intrahepatic distant recurrence after TACE in early-stage HCC.

METHODS

Among 1,560 newly diagnosed HCC patients who were admitted to Okayama University Hospital, 43 patients with early-stage HCC who received only TACE in at least one nodule were enrolled in this study. We analyzed the risk factors for local and distant recurrence by the Cox proportional hazard model.

RESULTS

The local recurrence rates and intrahepatic distant recurrence rates at 3 months, 6 months, and 1 year were 18.6, 33.4, and 61.8%, and 2.8, 2.8, and 34.3%, [corrected] respectively.Among 12 parameters examined as possible risk factors for recurrence, heterogeneous Lipiodol uptake (risk ratio 3.38; 95% confidence interval 1.14-10.60) and high serum des-gamma-carboxy prothrombin (DCP) (2.58; 1.03-7.14) were significantly correlated with local recurrence, and the presence of multiple tumors (10.64; 1.76-93.75) was significantly correlated with intrahepatic distant recurrence.

CONCLUSIONS

Heterogeneous Lipiodol uptake, high serum DCP, and multiple tumors are risk factors for recurrence in patients with early-stage HCC who have undergone palliative TACE.

Hepatocellular carcinoma occurring in hepatobiliary fibropolycystic disease

Congenital hepatic fibrosis (CHF) and bile duct hamartomas (von Meyenburg complexes) are hepatobiliary fibropolycystic diseases. There have been several reports of liver neoplasias arising in hepatobiliary fibropolycystic diseases. However, most of them were cholangiocarcinomas and cases involving hepatocellular carcinoma (HCC) are rare. A 51-year-old woman was found to have multiple hepatic tumors by ultrasonography and enhanced computed tomography (CT) during a regular work-up for the recurrence of lung cancer and thyroid cancer, which had been surgically removed 4 and 3 years ago, respectively. Nodules were observed at S3, S5, and S6 (2 cm in diameter). All of the nodules were hyperattenuated at the early arterial phase, and the main tumor at S5 showed hypoattenuation at the delayed phase on dynamic CT and magnetic resonance imaging (MRI). HCC was suspected from these findings. She also suffered from multiple small cystic lesions in the liver. The surgically removed liver showed HCC arising in CHF, which is a rare histological finding.

Delayed onset of systemic lupus erythematosus in a child with endothelial tubuloreticular inclusion

We report here on an 11-year-old Japanese girl who was found to have proteinuria by routine mass screening urinalysis for school children, and who developed systemic lupus erythematosus (SLE) 21 months later. The initial renal biopsy, performed 3 months after the first visit to Tokyo Medical University Kasumigaura Hospital (TMUKH), revealed membranous glomerulonephritis. In an immunofluorescent study, IgG was the only positive immunoglobulin found. A "full-house" immunofluorescence glomerulopathy, well known as a predictive finding for lupus nephritis, was not detected. Endothelial tubuloreticular inclusions (ETI) were found by electron microscopy. Because the diagnosis of SLE was not established clinically and serologically, the patient was followed every 3 months without drugs. Her urinary findings returned to normal within 18 months. Three months after the last visit, she was sent to Tsukuba University Hospital (TUH) for fever, arthralgia, dyspnea and butterfly rash. She was diagnosed as having SLE, pleuritis, and pericarditis. Although she was treated with methylpredonisolone and oral prednisolone, she developed cardiac tamponade on the 12th day of admission during the course of pneumococcal septicemia. Finally, she was treated successfully with surgical procedures, antibiotics and oral prednisolone and was discharged. We conclude that ETI is a more significant early sign of SLE than "full-house" immmunofluorescence glomerulopathy, especially in pediatric cases.

Steroid-sensitive nephrotic syndrome associated with Kimura disease

We report an 11-year-old Japanese boy with Kimura disease and associated nephrotic syndrome. Before the diagnosis of Kimura disease was established, the patient had three episodes of swelling on the left cheek with subsequent nephrotic syndrome. Steroids were effective for both conditions. However, both conditions recurred within months of discontinuation of steroids. For the fourth episode of swelling on the left cheek, cyclosporine (CsA) was used. The subcutaneous tumor responded to CsA and disappeared within a few days. There has been no subsequent relapse of the nephrotic syndrome to date.

Sensitivity analyses of heart rate variability variables by an incremental, passive head-up tilt

We analyzed the sensitivity of heart rate variability (HRV) variables as an index of autonomic nervous activity by an incremental, passive head-up tilt (HUT). Twelve healthy male volunteers, mean age 20.5 years +/- 2.1 SD, were subjected, after a horizontal (0 degrees) supine posture period, to an incremental, passive HUT of 14.5, 30, 48.6, 61 and 90 degrees. The tested HRV variables were: heart rate (HR), standard deviation of the RR interval (SD(RR)), coefficient of variance of the RR interval (CV(RR)), low-frequency band [0.04-0.15 Hz] power spectrum (P(LF)), high-frequency band [0.15-0.4 Hz] power spectrum (P(HF)), the ratio of P(LF) to P(HF) (P(LF)/P(HF)), coefficients of low-frequency and high-frequency component variance (C-CV(LF), C-CV(HF)), percentages of P(LF) and P(HF) in total power spectrum (%LF, %HF), and normalized units of low frequency and high frequency band power spectra (NU(LF), NU(HF)). The SD(RR), CV(RR), P(LF) and C-CV(LF) were not sensitive to the sine of the tilt angles, i.e., the body-axis component of gravity (+Gz), in the incremental HUT. Therefore, these variables may be less suitable as indices of autonomic nervous activity. The P(LF)/P(HF), NU(LF), and NU(HF) appear to be useful as indices of sympathovagal balance. Both the NU(LF) and NU(HF) (both are equivalent and inversely related) are suitable for the comparison of sympathovagal balance between subjects of different ages and levels of physical fitness because they are not significantly influenced by age and physical fitness. The HR and HRV variables represent quite different characteristics of autonomic nervous activity, according to the Rosenblueth Simeone model. Therefore, the HR appears to be effective for combined assessment of sympathovagal balance. These results provide information useful in the selection of HRV variables while estimating autonomic nervous activity from short-term HRV.

Effects of skin surface cooling and heating on autonomic nervous activity and baroreflex sensitivity in humans

The influence of skin surface cooling and heating on heart rate variability (HRV), blood pressure variability (BPV), and baroreflex sensitivity (BRS) were studied in 11 healthy supine volunteers in air temperatures of 18 degrees C (cool), 24 degrees C (mild), 48 degrees C (warm), and 60 degrees C (hot) in a styrene foam chamber. The high-frequency component of HRV (HFRR) decreased and the ratio of low- to high-frequency components, LFRR/HFRR, increased with skin surface heating. Therefore, a suppression of cardiac vagal nervous activity and an enhancement of cardiac sympathetic nervous activity can be caused by skin surface heating. The low-frequency component of BPV (LFSBP), i.e. the fluctuations of the Mayer waves, increased with skin surface heating. The responses between the very low-frequency components of HRV (VLFRR) and systolic BPV (VLFSBP) to thermal skin stimulation were different, although these variables both were considered to be indicators of the thermoregulatory vasomotor control or renin-angiotensin system. Baroreflex sensitivity (BRS) did not increase with skin surface heating, at least in humans.

The sulphated carbohydrate-protein linkage region isolated from chondroitin 4-sulphate chains of inter-alpha-trypsin inhibitor in human plasma

Inter-alpha-trypsin inhibitor (ITI) in human plasma has a unique structural architecture composed of three polypeptide chains (H1, H2 and L chains), which are linked to each other through a chondroitin 4-sulphate chain. The structure of the carbohydrate-protein linkage region of the chondroitin 4-sulphate chain attached to the L chain was investigated. The peptide-chondroitin sulphate fraction was isolated by anion-exchange chromatography after exhaustive digestion with lysyl endopeptidase and then V8 protease. The chondroitin 4-sulphate chain was released from the peptides by beta-elimination using NaB3H4 and then digested with chondroitinase ABC. These treatments resulted in a single 3H-labelled hexasaccharide alditol fraction derived from the linkage region which had been associated with the L chain. Chemical and enzymatic analyses as well as fast-atom bombardment-mass spectrometry (FAB-MS) analysis revealed that the 3H-labelled hexasaccharide alditol had the following structure: delta HexA-alpha 1-3GalNAc(4-sulphate)beta 1-4GlcA beta 1-3Gal(4-sulphate)beta 1-3Gal beta 1-4Xyl-ol (where delta HexA is 4-deoxy-alpha-L-threo-hex-4-enepyranosyluronic acid and Xyl-ol is xylitol). The structure contained the novel 4-sulphated Gal residue, which was previously demonstrated in a linkage hexasaccharide isolated from chondroitin 4-sulphate of rat chondrosarcoma (Sugahara et al., J. Biol. Chem., 263, 10168-10174, 1988) and of whale cartilage (Sugahara et al., Eur. J. Biochem., 202, 805-811, 1991). The above disulphated hexasaccharide alditol was the only component detected in the linkage region fraction of the chondroitin 4-sulphate chain of ITI, which implies some biological significance of this novel structure.

Transfer reaction catalyzed by exo-beta-1,4-galactanase from Bacillus subtilis

A transfer reaction catalyzed by an exo-beta-1,4-galactanase from Bacillus subtilis was studied. The enzyme had a broad acceptor specificity and transferred galactobiosyl residues to acceptors such as various alcohols, including hydroxy benzenes and saccharides. Transfer products of glycerol formed by the enzyme were compared with those formed by Escherichia coli beta-galactosidase and by Penicillium citrinum endo-galactanase. E. coli enzyme transferred 90% of galactose residues to the primary hydroxyl groups of glycerol and P. citrinum endo-enzyme transferred 80% of saccharide residues to the secondary hydroxyl group. The B. subtilis exo-galactanase was less specific than the other two enzymes and formed two products (1-DG and 2-DG) with a 2-DG/1-DG ratio of about 2. The structures of the saccharides were examined by 13C-nuclear magnetic resonance analysis and by enzymatic hydrolysis. 1-DG and 2-DG were elucidated to be O-beta-D-galactosyl-(1----4)-O-beta-D-galactosyl-(1----1)-glycerol and O-beta-D-galactosyl-(1----4)-O-beta-D-galactosyl-(1----2)-glycerol, respectively. The efficiency of the transfer reaction was measured at various concentrations of glycerol using galactotriose as a donor. About 40-75% of galactobiosyl residues were transferred at an acceptor concentration range of 20-100 mg/ml.

Purification and characterization of an exo-1,4-beta-galactanase from a strain of Bacillus subtilis

An arabinogalactan 4-beta-D-galactanohydrolase was purified to a homogeneous state from the culture filtrate of a strain of Bacillus subtilis. The enzyme have a molecular mass of 36 kDa and an isoelectric point of pH 7.9. The enzyme is most active at around pH 6.5-7 and at 60 degrees C, and is stable between pH 6-10 and below 55 degrees C. Hg2+ and Cu2+ inhibit the activity. The enzyme hydrolyze soybean arabinogalactan which contains beta-1,4-galactosidic linkages in its main chain structure, but not other polysaccharides with beta-1,3-galactosidic linkages. The hydrolysis products from soybean arabinogalactan are predominantly galactobiose with a small amount of galactotetraose. The enzyme is an exo-enzyme and the ability to transfer galactobiose to other galactobiose molecules is indicated by the formation of galactotetraose.