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Biomedical subjects

S C Li

Publications and source records attributed to S C Li.

At least 163 records · Page 9Linked to original sources
PubMed1987

Structure of a new hexasaccharide from the coaggregation polysaccharide of Streptococcus sanguis 34.

The major constituent of a coaggregation polysaccharide from Streptococcus sanguis 34 is a hexasaccharide, isolated as the alditol. The proposed structure is alpha-D-GalpNAc-(1----3)-beta-L-Rhap-(1----4)-beta-D-Glcp-(1----6) -beta-D-Galf- (1----6)-beta-D-GalpNAc-(1----3)-D-Galol, based upon g.l.c.-m.s. of alditol acetates and partially methylated alditol acetates, f.a.b.-m.s., 1H-n.m.r. spectroscopy, g.l.c.-m.s. of trimethylsilylated (+)- and (-)-2-butyl glycosides, and cleavage by alpha-N-acetylgalactosaminidase. The structural deduction was facilitated by cleavage of the hexasaccharide at the furanoside linkage by 48% hydrogen fluoride, and reduction of the product, to yield alpha-D-GalpNAc-(1----3)-beta-L-Rhap-(1----4)-beta-D-Glcp-(1----6) -D-Galol.

Carbohydrate Conformation↗
PubMed1987

Biochemical basis of type AB GM2 gangliosidosis in a Japanese spaniel.

The biochemical basis of a case of GM2 gangliosidosis in a Japanese Spaniel was studied. This dog had a massive accumulation of GM2 ganglioside in the brain. The beta-hexosaminidase activity in this affected dog brain was approximately 12 times higher than that of normal brain. However, the activity toward p-nitrophenyl-6-sulfo-2-acetamido-2-deoxyglucopyranoside was only four times higher in the affected brain than in normal brain. The GM2 activator preparation obtained from the normal dog brain could stimulate the hydrolysis of GM2 ganglioside by beta-hexosaminidase isolated from the affected dog. However, the corresponding activator fraction from the affected dog could not stimulate such a reaction. It was concluded that the biochemical basis of the GM2 gangliosidosis in this Japanese Spaniel was due to the attenuation in the stimulatory activity of GM2 activator. This case represents the first animal form similar to the activator deficiency (or defect) of Type AB GM2 gangliosidosis in humans.

Animals↗
PubMed1986

Accumulation of globotriaosylceramide in a case of leiomyosarcoma.

Analysis of the glycosphingolipid composition in one case of uterine leiomyosarcoma metastasized to the liver showed an accumulation of globotriaosylceramide as compared with normal liver and uterus from which the tumour originated. The structure and the amount of glycosphingolipids were established by using specific glycosidases, permethylation analysis and h.p.l.c. The reason for the accumulation of globotriaosylceramide in leiomyosarcoma remains to be answered.

Chromatography, High Pressure Liquid↗
PubMed1986

A unique glycosphingolipid-splitting enzyme (ceramide-glycanase from leech) cleaves the linkage between the oligosaccharide and the ceramide.

A novel type of enzyme which hydrolyzes the linkage between the ceramide and the sugar chain in various glycosphingolipids has been found in the leech, Hirudo medicinalis. This enzyme releases the intact oligosaccharide from LacCer, GbOse3Cer, GbOse4Cer, GbOse5Cer, nLcOse4Cer, GM3, GM2, GM1, GD1a and GT1 with the concurrent release of ceramides. By using tritium-labeled GM1 as substrate we found the optimum pH of this enzyme to be between pH 4 and 5. Since the enzyme cleaves the linkage between the ceramide and the sugar chain in various glycosphingolipids with no apparent preference toward the sugar chain, we propose to call this enzyme ceramide-glycanase.

Animals↗
PubMed1986

Urinary endo-beta-galactosidase capable of depolymerizing polylactosaminoglycans.

Human urine was found to contain an endo-beta-galactosidase capable of depolymerizing sulfated and non-sulfated polylactosaminoglycans. Using 0.05 M sodium phosphate buffer, pH 7.0, this enzyme was not retained by DEAE-Sephadex A-50 or concanavalin A-Sepharose. The urinary endo-beta-galactosidase liberated a disaccharide with chromatographic mobility identical to 6-O-sulfo-GlcNAc beta 1----3Gal as one of the major products from keratan sulfates isolated from whale nasal cartilage, bovine cornea, and human costal cartilage. It also liberated GlcNAc beta 1----3 Gal as one of the major oligosaccharides from erythroglycan. The oligosaccharide profiles produced from various keratan sulfates and erythroglycan by the action of urinary endo-beta-galactosidase are quite similar to those produced by Escherichia freundii endo-beta-galactosidase (Nakagawa, H., Yamada, T., Chien, J.-L., Gardas, A., Kitamikado, M., Li, S.-C., and Li, Y.-T. (1980) J. Biol. Chem. 255, 5955-5959). The presence of urinary endo-beta-galactosidase indicates the existence of a new catabolic pathway for polylactosaminoglycans. This pathway involves the cleavage of internal beta-galactosyl linkages of the glycan chain.

Galactosidases↗
PubMed1986

Brain injury due to head trauma. Epidemiology in urban areas of the People's Republic of China.

A door-to-door survey was carried out in six cities of the People's Republic of China during 1983 in a well-defined population of 63,195 to determine the prevalence of frequently occurring neurologic disorders, including brain injury. In the survey, trained health workers conducted a complete census and administered a questionnaire that had been pretested to assure a high level of sensitivity in identifying individuals suffering from brain injury due to head trauma. All those with responses suggesting brain injury were examined by senior neurosurgeons who used uniform diagnostic criteria and reviewed available medical records to establish a diagnosis. There was 100% cooperation with the screening and diagnostic phases of the survey. Based on this investigation, the age-adjusted (to the 1960 US population) prevalence ratio for brain injury due to head trauma is seven per 1,000, and the incidence rate is 56 per 100,000 per year. The ratios and rates are higher in male than female subjects. The main cause of brain injury due to head trauma in the People's Republic of China is bicycle accidents.

Adolescent↗
PubMed1986

Presence of glycoproteins containing the polylactosamine structure in brain and liver of GM1 gangliosidosis patients. Comparative study between clinical types I and II, using endo-beta-galactosidase enzyme.

The material derived from defective degradation of glycoproteins, which accumulates in brain and liver of a patient with GM1 gangliosidosis type I, was investigated, and the structure of the main storage compounds determined. For comparison, brain and liver of a patient with GM1 gangliosidosis type II were also analyzed. Analysis of the glycopeptides obtained after pronase digestion of the defatted residue indicates the storage of glycoprotein-like material in type I, but not in type II. Treatment with endo-beta-galactosidase showed that the stored material contained N-acetyllactosamine repeating units. Two major oligosaccharides, OS I and OS II, were isolated after the enzyme treatment, whose structures are: GlcNAc beta 1----3 Gal (OS I) and Gal beta l----4GlcNAc beta 1----3 Gal (OS II). Treatment with exo-beta-galactosidase transformed the trisaccharide OS II into the disaccharide OS I, indicating that the deficiency of beta-galactosidase in GM1 gangliosidosis type I, but not in type II, also affects glycoprotein catabolism, leading to the accumulation of glycopeptides containing terminal beta-galactosyl residues and N-acetyllactosamine repeating units. These results indicate the severe impairment in the catabolism of glycoconjugates with beta-linked galactose in type I, although this impairment is not as pronounced in type II.

Brain Chemistry↗
PubMed1986

A prevalence survey of 'incapacitating headache' in the People's Republic of China.

Two Chinese populations over age 15 were surveyed as to the point prevalence of "incapacitating" headaches in an urban population of 1,525 persons and a rural one of 1,203. Personal interviews were carried out by a team of instructed interviewers; there was 100% cooperation. In both populations, prevalence in women was twice that in men except in the urban population in the youngest age group. Prevalence in the urban was almost exactly twice that of the rural population, with the highest figure occurring in traders.

Adolescent↗
PubMed1986

Ganglioside patterns in normal and lepromatous armadillo tissues.

Gangliosides derived from tissues of normal and lepromatous armadillos were examined by thin-layer chromatography. The ganglioside patterns produced by the Mycobacterium leprae-infected tissues varied from that of the normal tissue. Although increased levels of several gangliosides were observed in the infected tissues, there was an apparent preferential increase in GM3 gangliosides as determined by column chromatography and enzymatic hydrolysis.

Animals↗
PubMed1986

Clinical studies on neurophysiological and biochemical basis of acupuncture analgesia.

From November 1965 to December 1978, about 10,635 cranio-cerebral operations were performed under acupuncture anesthesia in 24 neurosurgical departments in China. The extensive clinical practices have proved that acupuncture surely has analgesic effect. So far most researches upon the mechanism for analgesia by acupuncture were based on animal experiments, but not confirmed or evidenced in human beings. For this reason, a series of clinical studies upon the neurophysiological and biochemical basis for acupuncture analgesia has been made utilizing the facilities of a neurologic clinic provided that the patient's condition is not adversely affected and therapeutic efficiency is enhanced. The results are summarized as follows.

Acupuncture Therapy↗
PubMed1985

Preparation and enzymatic degradation of monosulfogangliotriaosylceramide.

Gangliotriaosylceramide 3'-sulfate (GgOse3Cer-II3-sulfate) contains the sugar sequence similar to that of GM2 ganglioside except that the NeuAc in GM2 is replaced by a sulfate group. Due to this structural similarity, we have studied the in vitro synthesis of GgOse3Cer-II3-sulfate using the system for GM2. Our results showed that GgOse3Cer-II3-sulfate could be synthesized from lactosylceramide 3'-sulfate and UDP-GalNAc catalyzed by N-acetylgalactosaminyltransferase prepared from rat brain (Dicesare, J. L., and Dain, J. A. (1971) Biochim. Biophys. Acta 231, 385-393). As in the case of GM2, the GgOse3Cer-II3-sulfate biosynthesized in vitro or isolated from rat kidney could also be cleaved by human beta-hexosaminidase A in the presence of GM2-activator (Li, S.-C., Hirabayashi, Y., and Li, Y.-T. (1981) J. Biol. Chem. 256, 6234-6240). The fact that the GM2-activator could stimulate beta-hexosaminidase A to hydrolyze both GM2 and Gg-Ose3Cer-II3-sulfate indicates that these two glycolipids may be catabolyzed by the same mechanism.

Animals↗
PubMed1985

Glycosphingolipids in insects. Chemical structures of ceramide tetra-, penta-, hexa-, and heptasaccharides from Calliphora vicina pupae (Insecta: Diptera).

Four neutal fraction glycosphingolipids, designated components 4-7, were purified from the pupae of Calliphora vicina and isolated by the use of high performance liquid chromatography. Their chemical structures were determined to be: GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer; GalNAc(alpha 1-4)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer and Gal(alpha 1-3)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer; Gal(beta 1-3)GalNAc(alpha 1-4)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer; and GlcNAC(beta 1-3)Gal(beta 1-3)GalNAc(alpha 1-4)GalNAc(beta 1-4)GlcNAc(beta 1-3)Man(beta 1-4)Glc(beta 1-1)Cer. By the use of specific exoglycosidases, it was possible to assign anomeric configurations to all the sugar residues present. Analysis of the ceramide moiety by electron-impact mass spectrometry revealed the dominant fatty acid and sphingoid to be arachidic acid (C20:0) and tetradecasphing-4-enine, respectively.

Carbohydrates↗