Transglycosylation and reverse hydrolysis reactions of endoglycoceramidase from the jellyfish, Cyanea nozakii

Endoglycoceramidase (EGCase: EC 3.2.1.123) is an enzyme capable of cleaving the glycosidic linkage between oligosaccharides and ceramides in various glycosphingolipids. We report here transglycosylation and reverse hydrolysis reactions of EGCase from the jellyfish Cynaea nozakii. Various alkyl-GM1 oligosaccharides (alkyl-II(3)NeuAcGgOse4) were synthesized when GM1 ganglioside was treated with the EGCase in the presence of 1-alkanols. Among various 1-alkanols tested, methanol was found to be the most preferential acceptor, followed by 1-hexanol and 1-pentanol. GM1 was the best donor, followed by GD1b and GT1b, when methanol was used as an acceptor. However, neither globoside nor glucosylceramide was utilized by the enzyme as a donor substrate. The enzyme transferred oligosaccharides from various glycosphingolipids to NBD-ceramide, a fluorescent ceramide, producing NBD-labeled glycosphingolipids. In addition to the transglycosylation reaction, the enzyme catalyzed the reverse hydrolysis reaction; lactose was condensed to ceramide to generate lactosylceramide in the presence of the enzyme. These results indicate that the jellyfish enzyme will facilitate the synthesis of various neoglycoconjugates and glycosphingolipids.

Disappearance of aortic intramural hematoma and its significance to the prognosis

BACKGROUND

An aortic intramural hematoma (IMH) is a form of aortic dissection (AD). IMHs regress with time or completely disappear in some patients, whereas they progress to overt AD in other patients. The purpose of the present study was to investigate how IMHs change serially during a follow-up period.

METHODS AND RESULTS

We analyzed 44 consecutive medically treated patients with IMHs, in whom transesophageal echocardiography (TEE) was performed serially at both 1 and 6 months after the onset. After TEE, the patients were followed with interviews (mean follow-up 1552+/-539 days). IMHs disappeared at 6 months in 21 patients (48%) (disappearance group), whereas IMHs were still demonstrated at 6 months in 20 patients (45%) (persistent group); in the disappearance group, IMHs disappeared at 1 month in 8 patients (18%). In 3 patients (7%) in whom an IMH was demonstrated at 1 month, overt AD occurred until 6 months. The disappearance group was younger than the persistent group (64+/-11 versus 72+/-8 years, P:<0.01), and the maximum diameter of the aorta was smaller in the disappearance group than in the persistent group (33+/-5 versus 42+/-7 mm, P:<0.01). During the long-term follow-up, overt AD occurred at 7 and 11 months in 2 patients, and progressive aortic dilatation that required surgical treatment occurred at 12 and 24 months in 2 of the persistent group patients, whereas neither overt AD nor progressive aortic dilatation occurred in the disappearance group. In the patients in whom overt AD occurred, the maximal aortic diameter was >45 mm and an IMH was demonstrated at 1 month. On the other hand, those with a maximal aortic diameter of <45 mm or a disappeared IMH did not have overt AD.

CONCLUSIONS

IMHs disappeared until 1 month in 18% and until 6 months in 48% of patients with IMHs. The disappearance of IMHs was related to the maximum diameter of the aorta and age. Both a disappeared IMH and a maximal aortic diameter of <45 mm suggest a good prognosis.

Purification, characterization, and cDNA cloning of a novel acidic endoglycoceramidase from the jellyfish, Cyanea nozakii

Endoglycoceramidase (EC ) is an enzyme capable of cleaving the glycosidic linkage between oligosaccharides and ceramides in various glycosphingolipids. We report here the purification, characterization, and cDNA cloning of a novel endoglycoceramidase from the jellyfish, Cyanea nozakii. The purified enzyme showed a single protein band estimated to be 51 kDa on SDS-polyacrylamide gel electrophoresis. The enzyme showed a pH optimum of 3.0 and was activated by Triton X-100 and Lubrol PX but not by sodium taurodeoxycholate. This enzyme preferentially hydrolyzed gangliosides, especially GT1b and GQ1b, whereas neutral glycosphingolipids were somewhat resistant to hydrolysis by the enzyme. A full-length cDNA encoding the enzyme was cloned by 5'- and 3'-rapid amplification of cDNA ends using a partial amino acid sequence of the purified enzyme. The open reading frame of 1509 nucleotides encoded a polypeptide of 503 amino acids including a signal sequence of 25 residues and six potential N-glycosylation sites. Interestingly, the Asn-Glu-Pro sequence, which is the putative active site of Rhodococcus endoglycoceramidase, was conserved in the deduced amino acid sequences. This is the first report of the cloning of an endoglycoceramidase from a eukaryote.

Prediction of progression or regression of type A aortic intramural hematoma by computed tomography

BACKGROUND

It has been reported that early surgery should be required for patients with type A aortic intramural hematoma (IMH) because it tends to develop classic aortic dissection or rupture. However, the anatomic features of type A IMH that develops dissection or rupture are unknown. The purpose of this study was to investigate the predictors of progression or regression of type A IMH by computed tomography (CT).

METHODS AND RESULTS

Twenty-two consecutive patients with type A IMH were studied by serial CT images. Aortic diameter and aortic wall thickness of the ascending aorta were estimated in CT images at 3 levels on admission and at follow-up (mean 37 days). We defined patients who showed increased maximum aortic wall thickness in the follow-up CT (n=9) or died of rupture (n=1) as the progression group (n=10). The other 12 patients, who all showed decreased maximum wall thickness, were categorized as the regression group. In the progression group, the maximum aortic diameter in the initial CT was significantly greater than that in the regression group (55+/-6 vs 47+/-3 mm, P=0.001). A Cox regression analysis revealed that the maximum aortic diameter was the strongest predictor for progression of type A IMH. We considered the optimal cutoff value to be 50 mm for the maximum aortic diameter to predict progression (positive predictive value 83%, negative predictive value 100%).

CONCLUSIONS

Maximum aortic diameter estimated by the initial CT images is predictive for progression of type A IMH.

[Usefulness and safety of the early rehabilitation program for patients with acute aortic dissection]

The usefulness and safety of the early rehabilitation program (2- and 3-week courses) were validated for patients with acute aortic dissection. This program undergone by 42 consecutive patients between 1996 and 1997 was compared to the conventional program undergone by 66 patients between 1993 and 1995, using the prognosis and complications for elderly patients. Mortality rate and morbidity rate were not significantly different between the early and conventional programs. The incidence of intensive care unit (ICU) syndrome in elderly patients was 16% (3 of 19 cases) vs 50% (15 of 30 cases), respectively (p < 0.05). The duration of hospital stays was 26 +/- 7 vs 37 +/- 13 days, respectively (p < 0.05). The early rehabilitation program for patients with acute aortic dissection was safe and useful to prevent complications in elderly patients, and was cost effective.