PubMed Health⌕ Search

Biomedical subjects

Y T Li

Publications and source records attributed to Y T Li.

At least 91 records · Page 5Linked to original sources
PubMed1994

Nefiracetam (DM-9384): effect on eyeblink classical conditioning in older rabbits.

The nootropic compound nefiracetam was evaluated in 88 older rabbits in a 750-ms delay paradigm of eyeblink classical conditioning (EBCC). Rabbits (mean age = 28.7 months) were assigned in groups of eight to one of six conditions in experiment 1: paired tone conditioned stimulus (CS)-corneal airpuff unconditioned stimulus (US) presentations and 1, 3, or 10 mg nefiracetam/kg or sterile saline vehicle; explicitly unpaired CS and US presentations and 3 mg nefiracetam/kg or sterile saline vehicle. Animals in the paired conditions received 10 daily sessions of 90 paired trials and animals in the unpaired conditions received 10 daily sessions of 180 unpaired CS and US presentations. The six conditions in experiment 2 were 5, 10, and 15 mg nefiracetam/kg and vehicle in 15 sessions of paired presentations; 10 mg nefiracetam/kg and vehicle in 15 sessions of unpaired conditioning. In both experiments 1 and 2, acquisition measured by trials to learning criterion was significantly faster at the 10 mg/kg dose of nefiracetam. In the repeated measures analyses comparing six doses in the paired conditions, all dependent measures [percentage conditioned responses (CRs), CR amplitude, and response latency] indicated significantly better conditioning in rabbits treated with 10 mg nefiracetam/kg, but this dose did not increase motor responding or responding in the unpaired condition. Nefiracetam facilitated acquisition of EBCC in older rabbits. EBCC is performed poorly by older humans and is seriously impaired in Alzheimer's disease. These preclinical data in an animal model with clear parallels in humans suggest that nefiracetam may prove effective as a cognition enhancer in clinical trials.

Acoustic Stimulation↗
PubMed1994

Nicotinic cholinergic system involvement in eyeblink classical conditioning in rabbits.

A nicotinic cholinergic antagonist, mecamylamine (MEC), was administered to rabbits tested on eyeblink classical conditioning (EBCC) in the 750-ms delay paradigm for 10 90-trial sessions. Nicotinic receptors were measured in 3 brain regions in 5 treatment groups: paired conditioned stimulus-unconditioned stimulus (CS-US) presentations with (a) vehicle, young; (b) vehicle, older; (c) 0.5 mg/kg MEC, young; unpaired CS-US with (d) 0.5 mg/kg MEC, young; and (e) vehicle, young. Daily MEC injections disrupted acquisition in young rabbits (769 trials to learning criterion vs. 323 trials for vehicle-treated young rabbits). MEC-treated young rabbits learned similarly to older rabbits. Brain nicotinic receptors were not affected by 10 daily MEC injections. To our knowledge, this experimental protocol, using a low MEC dose to selectively inhibit nicotinic cholinergic receptors, is the first to demonstrate a role for nicotinic cholinergic receptors in EBCC.

Animals↗
PubMed1994

[Clinical study on the use of multiglycosides of Tripterygium wilfordii after cadaveric kidney transplantation].

Based on the animal experiments, we first used the multiglycosides of Tripterygium wilfordii (GTW) as a main immunosuppressive agent to treat the patients with cadaveric kidney transplantation instead of Azathioprine (Aza) from 1990. By clinical observation and 3-year follow-up, the result showed the GTW having a satisfactory immunosuppressive effect. In this study, there were 85 cases in control group (Aza+CSA+Pred) and 87 cases in therapeutic group (GTW+CSA+Pred). The normalizing times of graft function after transplantation taked 18.17 +/- 1.61 days in control group and 10.9 +/- 0.18 days in therapeutic group respectively. The 1-, and 2-year graft survival rates were 89.3 +/- 0.3% and 87.0 +/- 0.3% in control group, 96.1 +/- 0.2% and 90.4 +/- 0.6% in therapeutic group respectively. The difference of the normalization times of graft function and graft survival rates between the two groups had statistically significant (P < 0.01). The incidence of complication such as infection, liver function damaging, etc, in therapeutic group was lower than in control group.

Adult↗
PubMed1994

[Cephradine delivery into the eye with domestic collagen shield].

The author reports that enhancement by the native made collagen-shield on the permeation of cephradine into the eye is 1.5 times and 1.3 times versus controls when the corneal epithelium is intact or defect, and is 10 times versus frequent eyedrops instillation. On the other hand, the enhancement of the collagen-shield is about the same as that of the soft contact lens impregnated with cephradine solution, but the drug concentration in aqueous humor is increased by collagen-shield 1-2 times than that by the wet soft contact lens. These results indicate that the collagen-shield can effectively increase the drug concentration in aqueous humor.

Animals↗
PubMed1994

Epidemiology of age-related dementia in China.

The results of these epidemiological studies suggest that the morbidity of age related moderate and severe dementia among the population of 65+ was 1.82%, when adjusted by 1984 US population ratio, it became 3.2%, as reported by US and European authors. Yet MID appears more common than PDD, which was more close to the data from Japan. The average annual incidence of moderate and severe dementia for persons aged 60+ was 0.3% (95% CI: 0.08%-0.52%). The incidence for those aged 70-79 (0.41%) was similar to that reported by US authors (Sluss), 0.58% among 70-74 years old, but lower than that observed by European authors (Hagnell, Magnusso) varied from 1.2% to 5.2% in the same age group. These great differences are likely to be partly due to differences in the age structure of samples, instruments for testing dementia, and diagnostic criteria. The course and outcome of dementia after 3-year follow-up indicated that the average survival time was 8 years, and the risk for death of dementia was 3 times higher than that of the whole cohort; the results were similar to those reported by westerners. The major risk factors for AD as identified in this study showed that family history both in first degree relatives of AD and psychosis were significantly associated with AD. The finding was consistent with the genetic hypothesis in western countries. In 7 risk factors that have been studied in US and European countries, 6 showed that the family history of dementia was significantly associated with AD.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Novel lacto-ganglio type gangliosides with GM2-epitope in bovine brain which react with IgM from a patient of the amyotrophic lateral sclerosis-like disorder.

A motor neuron disorder resembling that of amyotrophic lateral sclerosis was found in a patient who had received the intramuscular administration of a mixture of bovine brain gangliosides (Yuki, N., Sato, S., Miyatake, T., Sugiyama, K., Katagiri, T., and Sasaki, H. (1991) Lancet 337, 1109-1110). A very high titer of anti-GM2 IgM was detected in the patient's serum and the patient quickly recovered after plasmapheresis. The clinical course of the patient appeared to be different from amyotrophic lateral sclerosis and the anti-GM2 IgM was thought to be the culprit. The IgM reacted with GM2, GM1b-GalNAc, SPG(alpha 2-3)-GalNAc, and GD1a-GalNAc, but not with GA2 or GD2, meaning that the epitope recognized by the IgM was the GM2-like terminal structure, GalNAc beta 1-4(Neu-Ac alpha 2-3)Gal beta 1-. In this study, we found two novel GM2-epitope containing gangliosides, X1 and X2, in bovine brain gangliosides by TLC immunostaining using the patient's IgM. They were characterized as unique lacto-ganglio type gangliosides containing the following branching structures. [formula: see text] Their unusual structures may be immunogenic to humans to induce anti-GM2 antibody.

Aged↗
PubMed1993

Mass spectrometric investigations of drug-receptor interactions.

Mass spectrometric (MS) detection of biologically important noncovalent complexes is reviewed within the scope of on-going studies on this topic from this laboratory. The merits of ion spray MS and tandem MS are demonstrated in this area with examples that show systemic studies of several receptor-ligand, enzyme-substrate, and enzyme-product complexes associated with both an established well-characterized biological system (lysozyme hydrolysis of N-acetylglucosamine) and an important modern receptor-ligand complex (FKBP-FK-506 and FKBP-rapamycin). These examples and recent applications of negative ion MS and MS/MS with DNA adducts, heme-globin complexes, and antibiotic-binding proteins suggest an exciting new area of applications for MS that have not been previously available to investigators.

Animals↗
PubMed1993

[A clinicopathologic study of 15 cases of collecting duct carcinoma of the kidney].

Fifteen cases of papillary adenocarcinoma of the kidney are presented. The lesions were polycystic in gross appearance. Histologically, they were subdivided into three types: papillary cystadenocarcinoma, papillary oncocytic cystadenocarcinoma and papillary mucinous cystadenocarcinoma. Immunohistochemically, the tumor cells demonstrated positive reactivity for high molecular weight keratin and glandular lumina membrane positivity for EMA, which support a collecting duct origin for the tumor. Most of the tumors were large (average diameter 9.6 cm) and invasion of perinephric tissues was observed in 80% of the cases, an indication of its aggressive behavior. As most of the tumors occurred in the medulla and invaded the collecting ducts, the clinical manifestations were different from those of renal cell carcinomas.

Adolescent↗
PubMed1993

[Pulmonary edema in transcervical endometrial ablation: a case report].

The use of the transcervical resectoscope for endometrial ablation and/or resection of myomas is a relatively new technique in gynecologic surgery. Although complications are uncommon with this procedure, they can occasionally appear and lead to potential hazard. Here a patient presenting for endometrial ablation is described; 1.5% glycine was used as the irrigation solution to enhance visibility and to wash away blood and tissue particles. Unfortunately, a large amount of glycine was absorbed by the open vessels in the myometrium during operation, leading to pulmonary edema and dilutional hyponatremia. After administration of diuretics, sodium supplement and 100% oxygen, complications improved progressively. The patient was discharged on postoperative day 5 without any sequelae.

Adult↗
PubMed1993

[Combined pregnancy: a case report and literature review].

Combined or heterotopic pregnancy has been regarded as extremely rare in the past three decades. If it continues without diagnosis, a life-threatening situation may occur. A case of eight-week gestation is presented in which there was threatened abortion. The patient underwent exploratory laparotomy for internal bleeding. Upon operation, combined pregnancy, with a ruptured ectopic pregnancy, was diagnosed. Left salpingectomy was performed uneventfully. Neither chronic salpingitis nor administration of ovulation-induction agents was part of past history. A viable ongoing intrauterine pregnancy continued after operation, and a normal male was delivered by cesarean section after a 39-week gestation where labor progressed too slowly for normal delivery.

Adult↗
PubMed1993

[Twin pregnancy complicated by single intrauterine death. Report of six cases and literature review].

From 1982 to 1991, six twin pregnancies, in which one of the fetuses died in utero, have been encountered. The causes of antepartum death in twin gestation could be identified in four cases; one with abruptio placenta, one with twin-to-twin transfusion syndrome, one with twisting of cord and one with velamentous insertion of cord. All six surviving infants had no abnormality in the follow-up of two to seven years. Although a conclusion about the prognosis could not be drawn from such a small series, these good results may have resulted from 1) 2 cases having been dichorionic twins, and 2) the other 4 monochorionic twins of 31-36 gestation weeks were delivered 1 to 5 days after the diagnosis. Conservative treatment was usually suggested until the fetal lung was mature enough for induction of labor. One case was treated after the death of its counterpart with tocolytic agent for a further 15 days because of prematurity. Cesarean section was performed finally for fetal distress resulting from chronic abruption placenta. The other five cases were delivered through vaginal route. According to experience as well as literature review, to improve the prognosis, obstetricians should be familiar with the management of one fetal death in twin pregnancy, especially in those with monchorionic twins.

Adult↗
PubMed1992

Ceramide glycanase from the earthworm, Lumbricus terrestris.

Ceramide glycanase (CGase) is an enzyme that cleaves the linkage between the sugar chain and the ceramide. To make this enzyme readily available, we have developed a simple method for preparing it from the earthworm, Lumbricus terrestris. The method involves Bio-Gel A-0.5m, octyl-Sepharose and p-aminophenylthiogalactoside-agarose column chromatography. By gel filtration, the molecular mass of earthworm CGase was found to be 43.7 kDa. With ganglioside GM1 as substrate, the optimal pH of this enzyme was found to be between pH 3.5 and 4.0. Earthworm CGase hydrolyses glycolipids only in the presence of a detergent. Among various bile salts tested, sodium cholate was found to be the most effective in stimulating the hydrolysis of GM1 by this enzyme. Earthworm CGase released intact glycan chains from various glycosphingolipids in which the glycan chain is linked to the ceramide through a beta-glucosyl linkage. It also detached glycan chains from lactosyldialkylglycerol and alkyl-beta-lactosides.

Animals↗
PubMed1992

Evidence for two cDNA clones encoding human GM2-activator protein.

Two cDNAs encoding GM2 activator, pGM2A (648 bp) and GAP (1093 bp), were isolated from human placenta lambda gt11 libraries. The DNA sequence of pGM2A from 1 to 302 was almost identical with GAP, but diverged from 303-648. PCR was used to demonstrate the presence of both species of GM2 activator in placental RNA. Both cDNAs hybridized to mRNAs of approximately 2.3 kb and to identical single bands on genomic Southern blots.

Amino Acid Sequence↗
PubMed1992

Purification and characterization of a strictly specific beta-D-fucosidase from Aspergillus phoenicis.

Although beta-D-fucosidase (beta-D-fucohydrolase, EC 3.2.1.38) has been isolated from various sources, all those enzymes were associated with a high activity of beta-D-galactosidase and/or beta-D-glucosidase. We have purified a specific beta-D-fucosidase in electrophoretically homogeneous form from crude extracts of Aspergillus phoenicis by polyethyleneglycol 8000-phosphate buffer aqueous two-phase separation, and successive chromatography on DEAE-Sephadex A-50, hydroxyapatite, and Sephadex G-100 columns. The molecular weight of the enzyme was estimated to be 57,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 50,000 to 60,000 by gel filtration on Sephadex G-100. The enzyme showed optimum activity at pH 6.0 and 40 degrees C; it was stable in the pH range 5.5-6.5 and below 35 degrees C. The Km and the Vmax values for pNP-beta -D-fucoside were 2.4 mM, and 12.8 mumol.min-1.mg-1, respectively. The enzyme was strongly inhibited by sulfhydryl group reagents, p-chloromercuribenzoate, n-ethylmaleimide, and iodoacetate. It was also inhibited by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, diethyl pyrocarbonate, and N-bromosuccinimide. Thus, -SH and -COOH groups and histidyl and tryptophyl residues were essential for enzyme activity. The purified beta-D-fucosidase showed high specificity toward p-nitrophenyl-beta-D-fucoside. The enzyme was inhibited by D-fucose and D-fucono-gamma-lactone, but not by D-galactose, D-galactono-gamma-lactone, D-glucose, or D-glucono-gamma-lactone; the latter compounds are specific inhibitors of beta-D-galactosidase and beta-D-glucosidase, respectively. Thus, this enzyme is the most strictly specific beta-D-fucosidase when compared with those previously reported.

Aspergillus↗
PubMed1992

Thermostable, salt tolerant, wide pH range novel chitobiase from Vibrio parahemolyticus: isolation, characterization, molecular cloning, and expression.

A chitobiase gene from Vibrio parahemolyticus was cloned into plasmid pUC18 in Escherichia coli strain DH5 alpha. The plasmid construct, pC120, contained a 6.4 kb Vibrio DNA insert. The recombinant gene expressed chitobiase [EC 3.2.1.30] activity similar to that found in the native Vibrio. The enzyme was purified by ion exchange, hydroxylapatite and gel permeation chromatographies, and exhibited an apparent molecular weight of 80 kDa on SDS-polyacrylamide gel electrophoresis. Chitobiose and 6 more substrates, including beta-N-acetyl galactosamine glycosides, were hydrolyzed by the recombinant chitobiase, indicating its putative classification as an hexosaminidase [EC 3.2.1.52]. The enzyme was resistant to denaturation by 2 M NaCl, thermostable at 45 degrees C and active over a very unusual (for glycosyl hydrolases) pH range, from 4 to 10. The purified cloned chitobiase gave 4 closely focussed bands on an isoelectric focusing gel, at pH 4 to 6.5. The N-terminal 43 amino acid sequence shows no homology with other proteins in commercial databanks or in the literature, and from its N-terminal sequence, appears to be a novel protein, unrelated in sequence to chitobiases from other Vibrios reported and unrelated to hexosaminidases from other organisms.

Acetylglucosaminidase↗
PubMed1992

A case-control study of Alzheimer's disease in China.

We conducted a case-control study to assess possible factors associated with Alzheimer's disease (AD) with 70 clinically diagnosed AD patients and 140 age- and sex-matched nondemented neighborhood controls in China. Factors significantly associated with AD cases were family history of dementia in first-degree relatives, family history of psychotic disorders in first-degree relatives, and left-handedness/ambidexterity. A history of arthritis showed a significantly negative association with AD. Neither a family history for Down's syndrome, history of head trauma, nor other conditions that might support immune or viral hypotheses in AD were significantly associated with AD cases. These data support the role of familial/genetic factors in AD.

Aged↗
PubMed1992

Scrub typhus and pregnancy: a case report and literature review.

Scrub typhus is still prevalent on Penghu Islands. We herein report a case in a pregnant woman who had been to Yi-Lan County in Taiwan. The patient responded well to Minocycline (Minocin) therapy without complication. Her newborn baby was found not complicated with the disease. The relative literature is reviewed.

Adult↗