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Biomedical subjects

Y T Li

Publications and source records attributed to Y T Li.

At least 109 records · Page 6Linked to original sources
PubMed1992

[Transcervical resection of endometrium and submucous myomas].

Transcervical resection of the endometrium and submucous myomas using an unmodified urologic resectoscope has recently been developed as a treatment for menorrhagia and/or infertility when conservative management proves unsatisfactory but the patient desires to preserve the fertility or wishes to avoid hysterectomy. Through June 1990, 7 patients were treated with this procedure including one for endometrial ablation and six for transcervical myomectomy alone. No significant complication was seen and the results were relatively satisfactory in an average 7 1/2 months follow up. This approach seems a safe, effective surgical procedure and represents an attractive alternative to hysterectomy or abdominal myomectomy.

Adult↗
PubMed1992

[Uterine lipoleiomyoma with calcification: report of a case].

Uterine lipoleiomyoma is uncommon and has received little attention from gynecologists. We report a case of uterine lipoleiomyoma with subsequent pelvic abscess after rupture of the appendix. Its clinical picture mimicked uterine malignancy. The patient was a 60-year-old woman, who presented with a 2-week period of lower abdominal pain which was exacerbated 10 days later. After admission, gynecologic examination revealed a large pelvic mass of firm consistency. On a plain film of the abdomen, there was a large calcified mass in the pelvis. Pelvic ultrasound demonstrated a 15 yen 12 yen 12 cm mass with strong echogenicity in the margin, but the central component of the mass was attenuating and revealed a poorly defined echogenic mass. A computed tomography scan of the pelvis demonstrated a well-encapsulated mass that was predominantly the density of fat (-65 Hounsfield unit) in the central part, with calcification present in the peripheral layer of the mass. There was also a cystic lesion measuring 3 yen 2.5 yen 1.5 cm in the right adnexal area. A preoperative diagnosis of uterine lipoleiomyoma with necrosis, liposarcoma of the uterus or teratocarcinoma of the ovary was made by the CT scan. A diagnostic dilatation and curettage (D&C) revealed a uterine cavity length of 12 cm by sounding, and the specimen showed no malignant tissue. Therefore, the preoperative suspicion of ovarian teratocarcinoma could be excluded. The patient underwent an exploratory laparotomy, multiple pockets of pelvic abscess, enlargement of the uterus and induration of omentum surrounding the appendix were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcinosis↗
PubMed1991

Synthesis of neoglycoconjugates using oligosaccharide transferring activity of ceramide glycanase.

Ceramide glycanase (CGase) isolated from the leech Macrobdella decora was found to transfer the oligosaccharide en bloc from various glycosphingolipids to suitable acceptors. For example, CGase transferred the intact II3NeuAcGgOse4 from GM1 to 4-phenyl-1-butanol, 1,8-octanediol and various 1-alkanols having a chain length of six or more carbons. Among various 1-alkanols, 1-octanol was found to be the best acceptor. In an incubation mixture of 50 microliters containing 30 nmol of GM1, 50 micrograms of sodium cholate, 20 microliters of 1-octanol, and 0.1 unit of CGase, the ratio between hydrolysis and transglycosylation was approximately 3:1. Negative fast atom bombardment-mass spectral analysis of the enzymatically synthesized octyl-II3NeuAcGgOse4 showed a mass ion at m/z 1109.7 for the parent ion, consistent with its expected mass. NMR analysis of the enzymatically synthesized octyl-II3NeuAcGgOse4 showed that the Glc residue is linked to the octanol through a beta-linkage. Vicinal coupling constants of the ring protons of the sugar residues indicate that their pyranose ring geometries are not affected by the transferase activity. CGase also transferred the oligosaccharide from GM1 to CF3CO-NH(CH2)5CH2OH, (CH3)3CO-CO-NH(CH2)5CH2OH, (HOCH2)3C-NHCO-(CH2)4-COOMe, CH2 = CH-(CH2)7CH2OH and 1,2:3,4-di-O-isopropylidene-D-galactopyranose. The oligosaccharide transferring reaction carried out by CGase should become useful for the synthesis of neoglycoconjugates to study the biological functions expressed by glycan chains in glycosphingolipids.

Animals↗
PubMed1991

[Control of cisplatin-induced delayed emesis].

Despite excellent control of acute-stage emesis, some patients are still bothered by delayed emesis occurring more than 24 hours after cisplatin administration. We report 19 patients with 61 courses of cisplatin-based chemotherapy. They all received high-dose metoclopramide, dexamethasone and lorazepam on the day of cisplatin treatment. After 24 hours, they were treated with intravenous dexamethasone 8 mg once and metoclopramide 50 mg twice on day 2, and oral metoclopramide 10 mg qid on days 3-5. Delayed vomiting and nausea were noted in 27.9% and 39.4% respectively, as compared with 69.8% of delayed emesis and 79.4% of delayed nausea in 63 courses of 15 patients without receiving any antiemetics on days 2-5. The statistics showed significant difference (both P less than 0.001). Side effects were mild and acceptable. Therefore, this regimen is highly effective in preventing delayed vomiting and nausea.

Cisplatin↗
PubMed1991

[Improved control of cisplatin-induced emesis with high-dose metoclopramide, dexamethasone and lorazepam].

Despite treatment, emesis remains a major problem with cisplatin chemotherapy. Three potent antiemetics, metoclopramide, dexamethasone and lorazepam, were combined in prophylaxis of 18 patients receiving cisplatin based combination chemotherapy. In 75 courses of chemotherapy, 57% experienced complete protection from vomiting and 89% of treatment courses had two or fewer vomiting episodes. Complete protection and mild episodes from nausea was 47% and 53% respectively. Toxicities were mild and infrequent. It was concluded that combination of high-dose metoclopramide, dexamethasone and lorazepam was highly efficacious in preventing nausea and vomiting in moderate or high-dose cisplatin chemotherapy with little side effects.

Cisplatin↗
PubMed1991

Study of the identification of enterotoxigenic Escherichia coli by LT-DNA gene hybridization.

Reference strains of enterotoxigenic Escherichia coli (ETEC), non-ETEC, and other enteropathogenic bacteria were used to prove the reliability of LT-DNA gene hybridization. In the test, LT-DNA gene hybridization was compared with plate immunohemolytic test (PIHT) in identifying LT-ETEC. The results obtained by both methods showed no significant differences. 791 strains of E. coli isolated from 1,875 children with acute diarrhea in Taiyuan Children's Hospital were examined for LT-ETEC by LT-DNA gene hybridization and PIHT. 289 strains examined by LT-DNA gene hybridization were LT positive, while 205 strains examined by PIHT were LT positive. Three different assays were done: colony hybridization, PIHT and fecal direct blot hybridization on each of 74 fecal specimens from children with acute diarrhea. It was found that identification of LT-ETEC using fecal direct blot hybridization is a simple, sensitive and more practical method.

Bacterial Toxins↗
PubMed1991

Comparative evaluation of nine different methods for detecting enterotoxin of Escherichia coli.

Nine different methods for detecting enterotoxin of Escherichia coli were studied and compared. We found rabbit ileal-loop test and suckling mouse assay were both quite accurate and reliable for detecting heat labile toxin (LT) and heat stable toxin (ST) of enterotoxigenic Escherichia coli (ETEC). Mouse ileal-loop test was simple, but its sensitivity and specificity were comparatively low. CHO cell-culture assay might be more sensitive and specific. LT-DNA probe was the most sensitive and specific method. In practical application, PIHT (plate immunohemolytic test), Biken's, SPA-CoA and ELISA methods are recognized as simple, rapid, sensitive and specific methods for detecting ETEC-LT. These methods can be selected for use in clinical laboratory.

Animals↗
PubMed1990

A novel sialidase which releases 2,7-anhydro-alpha-N-acetylneuraminic acid from sialoglycoconjugates.

The leech (Macrobdella decora) was found to contain two sialic acid-cleaving enzymes: an ordinary sialidase and a novel sialic acid-cleaving enzyme. This novel enzyme released 2,7-anhydro-alpha-N-acetylneuraminic acid (Neu2,7-anhydro5Ac) instead of alpha-N-acetylneuraminic acid (Neu5Ac) from 4-methylumbelliferyl-Neu5Ac, glycoproteins, and gangliosides. We have partially purified this novel sialidase from M. decora. We have also isolated Neu2,7-anhydro5Ac released from 4-methylumelliferyl-Neu5Ac and whale nasal keratan sulfate in pure form. The novel sialidase produced Neu2,7-anhydro5Ac only from sialoglycoconjugates, but not from free Neu5Ac. The structure of Neu2,7-anhydro5Ac produced by the novel sialidase was established by chemical analysis, mass spectrometry, and NMR spectroscopy. NMR analysis showed that instead of the original 2C5 conformation, the pyranose ring of Neu2,7-anhydro5Ac was in the 5C2 conformation, which makes the formation of the 2,7-anhydro bridge possible.

Animals↗
PubMed1990

Gangliosides and sialoglycoproteins carrying a rare blood group antigen determinant, Cad, associated with human cancers as detected by specific monoclonal antibodies.

Two murine monoclonal antibodies, 2A3D2 and 2D11E2 (both IgM), which are directed to the gangliosides and sialoglycoproteins related to a rare blood group antigen, Cad, were obtained by using a ganglioside mixture prepared from human hepatocellular carcinoma cells (PLC/PRF/5) as the immunogen. These two monoclonal antibodies detected multiple ganglioside antigens present in the PLC/PRF/5 cells, and the major antigenic ganglioside was characterized as IV4GalNAc beta-GD1a, which has the carbohydrate structure GalNAc beta 1----4(NeuAc alpha 2----3)Gal beta 1----3GalNAc beta 1---- 4(NeuAc alpha 2----3)Gal beta 1----Cer. The two antibodies also reacted with GM2 (GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4Glc beta 1----Cer) and a Cad-active lactoseries ganglioside (IV4GalNAc beta-sialosylparagloboside, GalNAc beta 1----4[NeuAc alpha 2----3]Gal beta 1----4GlcNAc beta 1---- 3Gal beta 1----4Glc beta 1----Cer), which have carbohydrate structures related to IV4GalNAc beta-GD1a. Beside gangliosides, both antibodies recognized the carbohydrate determinant carried by glycophorin A on very rare Cad-positive human RBC; the structure of which is GalNAc beta 1----4(NeuAc alpha 2----3)Gal beta 1----3(NeuAc alpha 2---- 6)GalNAc alpha 1----Ser/Thr. From these findings, it is clear that monoclonal antibodies 2A3D2 and 2D11E2 both recognize the nonreduced carbohydrate terminus composed of three sugar residues, GalNac beta 1----4(NeuAc alpha 2----3)Gal beta 1----R, and are useful for detecting the Cad-related antigen in cells and tissues. By using these monoclonal antibodies, it was revealed that many cultured human hepatocellular carcinoma cell lines and cancer tissues taken from patients with hepatocellular carcinoma contain both Cad-active glycoprotein antigens and related gangliosides, while normal liver tissues contain no appreciable amount of either species of antigen. The Cad-active glycoprotein antigens in cultured human hepatocellular carcinoma cells appeared as triplet bands having molecular weights of 92,000, 75,000, and 61,000, under either reducing or nonreducing conditions in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Essentially the same triplet proteins were observed in as many as 4 of 9 cases (44%) of cancer tissue from patients with hepatocellular carcinoma, but not in neighboring cirrhotic tissues or normal livers tissues. These results suggest that the rare blood group antigen Cad is associated with human cancers, especially hepatocellular carcinoma.

Animals↗
PubMed1990

[Quantitative determination of 7 proteins in csf of patients with Guillain Barre syndrome].

Quantitative determinations were done for seven protein components namely albumin, IgG, transferrin, alpha-2 macroglobulin, IgA, IgM and ceruloplasmin in the CSF and sera from patients with Guillain Barré syndrome. The results showed that each of the protein significantly increased. All of these correlated remarkably with the increased values of total proteins in CSF. It seemed that the concentrations of the protein in CSF were influenced by those of the proteins in serum and the size of the corresponding protein molecule.

Adolescent↗
PubMed1990

[Infantile myofibromatosis].

Eight cases of infantile myofibromatosis, 5 male and 3 female, are reported. The ages ranged from 8 days to 3 years at diagnosis. The tumor was detected in 6 cases at birth and in 2 at the age of 3 and 11 months. The tumor occurred mostly in extremities, trunk, orbit, nose, soft tissue and bone. Spontaneous regression of all the tumor nodules was observed in 1 case of the multicentric type without evidence of visceral involvement within 3 years. Recurrence developed in 2/7 cases of solitary type 2 and 3 years after excision. Histologically, the tumor nodules were composed of myofibroblasts; blood vessel was abundant in a pericytoma-like pattern; and prominent necrosis or calcification was seen. By immunohistochemical stain for desmin, diffuse weak reactivity was shown in the tumor cells and granular cytoplasmic positivity in the actively proliferating tumor foci, suggesting the existence of muscle-specific intermediate filaments in the tumor cells.

Child, Preschool↗
PubMed1990

[The causes of death of early endometrial cancer].

This is an analysis of 136 patients with clinical stage I and II endometrial carcinoma treated with primarily surgery at the Columbia Presbyterian Hospital between 1978 and 1985. There was a minimum three years follow up. Of 136 patients, 28 (21%) died with recurrent cancer. Tumor upstaging, histology, grade, depth of myometrial invasion, peritoneal cytology were of important factors in prognosis. Therefore, a clinically sophisticated study during initial operation and a deliberate planning of adjuvant treatment should further improve the survival rate of early endometrial cancer.

Aged↗
PubMed1990

[Chlamydia trachomatis infection in women with ectopic pregnancy].

Chlamydia trachomatis infection, presumably sexually transmitted, has been implicated in the spread of tubal infertility and ectopic pregnancy. In searching evidence of Chlamydia trachomatis infection as a possible cause of tubal ectopic pregnancy, we enrolled 40 consecutive pathologically proven tubal ectopic women and 37 normal early intrauterine pregnant women from our OPD and ward from Jan. 1989 to July 1989. All cases underwent a structured interview giving particular attention to past reproductive history, contraception history and past history of STD. The levels of serum antibody IgG to Chlamydia trachomatis in all cases were determined. Seven ectopic women with wearing IUD in situ (group A) and 33 ectopic women with no identical factor (group B) were compared with 37 normal early intrauterine pregnant women (control group). The result showed group B more often had IgG antibody to Chlamydia trachomatis than control group (P = 0.001). Group A had higher antibody to Chlamydia trachomatis than control group but the difference was not statistically significant (P greater than 0.05). We concluded that the above findings add to the evidence that Chlamydia trachomatis infection is a major cause of tubal ectopic pregnancy.

Adult↗
PubMed1989

Characterization of glycosphingolipid mixtures with up to ten sugars by gas chromatography and gas chromatography-mass spectrometry as permethylated oligosaccharides and ceramides released by ceramide glycanase.

A novel, effective method for structural characterization of glycosphingolipids has been devised. It employs ceramide glycanase to release intact oligosaccharides followed by analysis using high-mass gas chromatography-mass spectrometry. The oligosaccharides and ceramides released by the glycanase were permethylated and analyzed. The capillary gas chromatography gave excellent resolution and separated, for example, two isomeric 10-sugar oligosaccharides with a molecular mass of 2150 daltons differing only by a Gal1-3GlcNAc and a Gal1-4GlcNAc linkage. The oligosaccharides released from sialic acid containing glycosphingolipids (gangliosides) were also analyzed for monosialo compounds. This analytical approach is simple, is quick, and can readily allow quantitation of individual glycosphingolipids.

Ceramides↗
PubMed1989

Isolation and characterization of ceramide glycanase from the leech, Macrobdella decora.

We have devised a simple method for achieving 890-fold purification of ceramide glycanase with 17% recovery from a North American leech, Macrobdella decora. The method includes water extraction, ammonium sulfate fractionation, and chromatography on octyl-Sepharose, Matrex gel blue A, and Bio-Gel A-0.5m columns. The final preparation showed one major protein band at 54 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By using Bio-Gel A-0.5m filtration, the native enzyme was found to have a molecular mass of 330 kDa. With GM1 as substrate, the optimum pH of this enzyme was determined to be 5.0; the enzyme was stable between pH 4.5 and 8.5. Zn2+ at 5 mM and Cu2+, Ag+, and Hg2+ at 1 mM strongly inhibited the hydrolysis of GM1 by ceramide glycanase. The ceramide glycanase released the intact glycan chain from various glycosphingolipids in which the glycan chain is linked to the ceramide through a beta-glucosyl linkage. This enzyme also cleaved lyso-glycosphingolipids such as lyso-GM1 and lyso-LacCer and synthetic alkyl beta-lactosides. Among seven alkyl beta-lactosides tested, the enzyme only hydrolyzed the ones with an alkyl chain length of four or more carbons. The enzyme also hydrolyzed 2-(octadecylthio)ethyl O-beta-lactoside and 2-(2-carbomethoxyethylthio)ethyl O-beta-lactoside. p-Nitrophenyl, benzyl, and phytyl beta-lactosides, on the other hand, were not hydrolyzed. These results suggest that the enzyme can recognize the hydrophobic portion of glycolipid substrates. The fact that 2-(2-carbomethoxyethylthio)ethyl O-beta-N-acetyllactosaminide and DiGalCer were refractory to the enzyme indicated that in the substrate the first sugar attached to the hydrophobic chain cannot be N-acetylglucosamine and galactose. Furthermore, dodecyl maltoside, Gal alpha 1----6Glc beta Cer, and the LacCer in which the --CH2OH of the galactose was converted into --CHO were also resistant to the enzyme, and Man beta 1----4 Glc beta Cer was hydrolyzed at a much slower rate than LacCer. These results indicate that the nature and the linkage of the sugar attached to the glucose have a profound effect on the action of this enzyme. The hydrolysis of glycosphingolipids by ceramide glycanase is stimulated by bile salts. Among various bile salts tested, sodium cholate at a concentration of 1 microgram/microliter was found to be most effective in stimulating the hydrolysis of various glycosphingolipids with the exception of LacCer. For LacCer, sodium taurodeoxycholate at a concentration of 2-3 micrograms/microliters was most effective. Tween 20, Nonidet P-40, and Triton X-100 did not stimulate the hydrolysis of GM1.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

Isolation and characterization of an activator protein for the hydrolysis of ganglioside GM2 from the roe of striped mullet (Mugil cephalus).

After the revelation of the presence of ganglioside GM2 as the major ganglioside in the roe of striped mullet, Mugil cephalus [Li, Hirabayashi, DeGasperi, Yu, Ariga, Koerner & Li (1984) J. Biol. Chem. 259, 8980-8985], we have continued to investigate the catabolism of GM2 in this tissue. We have found that mullet roe contains a specific activator protein which stimulates the hydrolysis of GM2 carried out by the beta-hexosaminidase isolated from the same tissue. This activator has been purified by using conventional procedures including ammonium sulphate fractionation and chromatography on Sepharose 6B, DEAE-Sephadex A-50, octyl-Sepharose and Matrex Gel Blue A columns. This activator protein is also able to stimulate the hydrolysis of GM2 carried out by human beta-hexosaminidase A. Unlike human GM2-activator, the roe activator protein does not stimulate the hydrolysis of GgOse3Cer or GbOse4Cer. The molecular mass (18 kDa) of the roe activator protein was found to be similar to that of human GM2-activator; however, the pI (pH 4.1) was found to be lower than that of human GM2-activator. This is the first report on the presence of a GM2-activator protein in a source other than mammalian tissues.

Animals↗
PubMed1989

Presence of two endo-beta-N-acetylglucosaminidases in human kidney.

We have isolated for the first time two kinds of endo-beta-N-acetylglucosaminidases (E-beta-GNases) simultaneously from human kidney. E-beta-GNase 1 was purified by water extraction, ammonium sulfate fractionation, and chromatography on Sephadex-G-200, DEAE-Sephadex, concanavalin A-Sepharose and Hypatite C columns. After the DEAE-Sephadex step, 107 units of E-beta-GNase 1 with a specific activity of 0.53 units/mg was obtained and after hydroxyapatite column, the enzyme recovery was 26 units with a specific activity of 10.4 units/mg. This enzyme hydrolyzed the high mannose-type asparaginylglycopeptide efficiently and had little activity toward the complex-type glycopeptide. This enzyme had an pH optimum at about 4.5 and was not inhibited by acetate ion. The Asn residue in a glycopeptide appeared not to be an important recognition site for E-beta-GNase 1 to express its activity because the acetylation or the dansylation of Asn residues as well as the elimination of Asn residue from the glycopeptide did not change the susceptibility of the oligosaccharide to E-beta-GNase 1. E-beta-GNase 2 was purified by water extraction, ammonium sulfate fractionation, and chromatography on Sephadex G-200, DEAE-Sephadex, concanavalin A-Sepharose, and Mono S columns. This enzyme was purified about 110-fold with 6.6% recovery. E-beta-GNase 2 was found to be a novel type of E-beta-GNase that hydrolyzed both the high mannose-type and the complex-type oligosaccharide with chitobiosyl group at the reducing end and without the Asn. E-beta-GNase 2 activity was found to be dependent on a L-aspartamido-beta-D-N-acetylglucosamine amidohydrolase (Asn-GNase) for the hydrolysis of asparaginylglycopeptide. Asn-GNase cleaved off the Asn residue from the glycopeptide, and the resulting oligosaccharide was hydrolyzed by E-beta-GNase 2. Because the acetylation or the dansylation of Asn residue in a glycopeptide rendered the glycopeptide resistant to Asn-GNase, the use of the modified asparaginylglycopeptide could not reveal the existence of E-beta-GNase 2 activity. The pH optimum of E-beta-GNase was found to be about 3.5. Like beta-hexosaminidases, this enzyme was inhibited by acetate ion, suggesting the recognition of GlcNAc moiety by this enzyme.

Acetylglucosaminidase↗