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Biomedical subjects

Y Yang

Publications and source records attributed to Y Yang.

At least 1,369 records · Page 76Linked to original sources
PubMed1991

Latent Semantic Indexing of medical diagnoses using UMLS semantic structures.

The relational files within the UMLS Metathesaurus contain rich semantic associations to main concepts. We invoked the technique of Latent Semantic Indexing to generate information matrices based on these relationships and created "semantic vectors" using singular value decomposition. Evaluations were made on the complete set and subsets of Metathesaurus main concepts with the semantic type "Disease or Syndrome." Real number matrices were created with main concepts, lexical variants, synonyms, and associated expressions. Ancestors, children, siblings, and related terms were added to alternative matrices, preserving the hierarchical direction of the relation as the imaginary component of a complex number. Preliminary evaluation suggests that this technique is robust. A major advantage is the exploitation of semantic features which derive from a statistical decomposition of UMLS structures, possibly reducing dependence on the tedious construction of semantic frames by humans.

Abstracting and Indexing↗
PubMed1991

A schematic analysis of the Unified Medical Language System.

The UMLS is a complex collection of medical terms and relationships derived from standard classifications. Appreciating the scope and layout of these relations from text descriptions of relational schema is difficult. The graphical technique of Logical Data Structure (LDS) representation was employed to illustrate the UMLS schema as a data abstraction, affording additional insights that might otherwise escape notice. An LDS representation of the Metathesaurus offers the following advantages: 1) the separation of a viewpoint from physical data structures enables a global outline of the contents; 2) the graphical map makes the interrelation of data visible; and 3) the logical entities explicitly reflect the decision-making which was implicit or ambiguous in the relational scheme.

Models, Theoretical↗
PubMed1991

[Study on thixotropic parameters of whole blood from healthy children].

With low shear-30 rheometer, the authors used a modified protocol to measure thixotropic parameters of whole blood from 200 healthy newborns and children, so as to suggest the normal range of blood thixotropic parameters in four age groups, namely, the newborns, 1 year- group, 5 year- and 10-15 year group. The results demonstrated that the thixotropic parameters in the newborn group were higher than those in other three groups. However, these thixotropic parameters in the group 1-10 years were lower than those in the 10-15 year group. No significant sex differences were noted among the fore three groups, but sex differences appeared obviously in the 10-15 year group. It implied that the changes relying on the age is consistent with children's growth, development and physiologic activities.

Adolescent↗
PubMed1991

[The transcatheter ablation of arrhythmias].

The introduction of transcatheter ablation techniques has opened a new era of the management of tachyarrhythmias. The rationale of these therapeutic procedures lies in the induction of an irreversible and limited damage to cardiac tissue involved in arrhythmias. In its original form, the technique involves the delivery of high energy DC discharges (fulguration) to the target area through a temporary catheter electrode. A primary drawback of fulguration, when used for ablation of AV node-His bundle, is the induction of a pacemaker-dependent state; the barotraumatic effect that results from high energy impulses constitutes the major limitation in the case of ablation of accessory pathways or arrhythmogenic areas. Recently, the efficiency of the procedure has been substantially improved by the use of low-power, high-frequency alternating current (radiofrequency), that allows to deliver graded amounts of disrupting energy to selected areas while avoiding undesirable biophysical effects to the surrounding tissue. Remarkable results, with a success rate close to 100%, are reported with radiofrequency ablation of AV node reentry tachycardia, as well as reciprocating tachycardia associated with the preexcitation syndrome, so that this technique can be considered the procedure of choice for both categories of patients. Catheter modification of AV conduction provides a therapeutic tool for treating atrial tachyarrhythmias with rapid ventricular responses. In such cases, however, the risk of AV block with the need for pacemaker implantation must be taken into account. Results of catheter ablation of ventricular tachycardia have been inconstant and generally disappointing, except for ventricular tachycardias due to reentry in the His-Purkinje system, for which a high success rate is reported. Experience with radiofrequency ablation in ventricular tachycardia is very limited, but localization of a critical segment of reentry could improve the efficiency of this technique.

Arrhythmias, Cardiac↗
PubMed1991

Discriminating binocular fusion from false fusion.

In a series of psychophysical experiments, observers discriminated between briefly flashed stimuli (cosine gratings, cosine plaids) that were either identical to the two eyes (dioptic) or differed between the two eyes (dichoptic). Although dioptic and dichoptic binocular stimuli were perceptually similar, they were distinguishable well above chance at exposure durations too brief for the onset of binocular rivalry. Random variations in display contrast did not alter this pattern of results. These results show that the neural events that signal false fusion of dissimilar monocular stimuli are not equivalent to those that underlie binocular fusion of matched monocular views.

Humans↗
PubMed1991

[Effect of acupuncture analgesia on synapses of paraventricular nucleus observed with transmission electron microscope].

In order to study the ultrastructural change of the paraventricular nucleus of hypothalamus during the electro-acupuncture, 13 healthy and adult rats were divided into control group and electro-acupuncture group. The results are as follows: 1. The synapses of the paraventricular nucleus mainly belong to the axodendricular asymmetrical synapses and contain a lot of round clear synaptic vesicles. 2. The round clear synaptic vesicles of the paraventricular nucleus in the electro-acupuncture group are much fewer than those in the control group. The difference is very significant (P less than 0.01). This suggests that the paraventricular nucleus is involved in the electroacupuncture analgesia.

Acupuncture Analgesia↗
PubMed1991

[Renal function of cations excretion in children predisposed to essential hypertension].

We studied the renal function of cations excretion in 86 normal children, aged 4-6 years old. 24-hour urinary excretion of sodium, potassium, calcium, magnesium, copper and zinc were measured before and after acute oral salt loading. The result showed that urinary sodium levels were significantly lower (101.88 mmol/24 h, 126.58 mmol/24 h, respectively, P less than 0.01) in children with family history of essential hypertension than in those without family history after salt loading. This suggests that the children with family history may have hereditary functional defect in the excretion of sodium before developing hypertension. We also found the renal excretions of potassium, calcium and zinc showed difference between children with and without family history of essential hypertension.

Calcium↗
PubMed1991

Immunological studies of osteoarthritis in bipedal rats.

Osteoarthritis (OA) models in bipedal rats were used to study the immune response, including the changes of IgG, antibody dependent cytotoxicity tests toward articular chondrocytes and the matrix. The results revealed significant difference between the bipedal and the quadruped rats. Immunological studies have proved that the OA model of bipedal rats is appropriate for the study of OA.

Animals↗
PubMed1990

Interactions of tazobactam and clavulanate with inducibly- and constitutively-expressed Class I beta-lactamases.

Clavulanate and tazobactam (YTR 830) were tested as inhibitors and inducers of the AmpC-type Class I beta-lactamases of Pseudomonas aeruginosa, Enterobacter cloacae, Citrobacter freundii, Serratia marcescens, Morganella morganii and the Ic beta-lactamase of Proteus vulgaris. Both clavulanate and tazobactam inhibited the Pr. vulgaris Class Ic beta-lactamase and potentiated ticarcillin and piperacillin against beta-lactamase derepressed variants of this species. Tazobactam, but not clavulanate, also had some ability to inhibit the AmpC Class I enzymes of M. morganii, C. freundii, Ps. aeruginosa, E. cloacae and S. marcescens. The piperacillin + tazobactam combination, unlike ticarcillin + clavulanate, showed some degree of synergy against most derepressed strains of these species. This behaviour partly depended upon the greater inhibitory activity of tazobactam for the enzymes, but also on piperacillin being easier to potentiate than ticarcillin. The synergy between piperacillin and tazobactam was greatest for M. morganii and C. freundii, least for Ps. aeruginosa and E. cloacae. Unfortunately, it is in the last two species that these enzymes pose the greatest resistance threat. Tazobactam caused little or no antagonism of piperacillin against beta-lactamase inducible species, whereas clavulanate antagonized ticarcillin against beta-lactamase inducible strains of E. cloacae and M. morganii (not other species). The antagonism of ticarcillin was attributable to beta-lactamase induction. The lack of antagonism with the tazobactam+piperacillin combination was related to tazobactam being a weaker inducer than clavulanate, not to piperacillin being less susceptible to antagonism than ticarcillin.

Bacteria↗
PubMed1990

Polysaccharide Fraction from Higher Plants which Strongly Interacts with the Cytosolic Phosphorylase Isozyme : I. Isolation and Characterization.

From leaves of Spinacia oleracea L. or from Pisum sativum L. and from cotyledons of germinating pea seeds a high molecular weight polysaccharide fraction was isolated. The apparent size of the fraction, as determined by gel filtration, was similar to that of dextran blue. Following acid hydrolysis the monomer content of the polysaccharide preparation was studied using high pressure liquid and thin layer chromatography. Glucose, galactose, arabinose, and ribose were the main monosaccharide compounds. The native polysaccharide preparation interacted strongly with the cytosolic isozyme of phosphorylase (EC 2.4.1.1). Interaction with the plastidic phosphorylase isozyme(s) was by far weaker. Interaction with the cytosolic isozyme was demonstrated by affinity electrophoresis, kinetic measurements, and by (14)C-labeling experiments in which the glucosyl transfer from [(14)C]glucose 1-phosphate to the polysaccharide preparation was monitored.

Journal Article↗
PubMed1990

[Relationship between hepatolithiasis and M phi, T cell subgroup reaction in the liver].

T Lymphocyte subpopulation and monocyte in the liver of 24 patients with hepatolithiasis were studied by ABC technique. It was found that there was a marked increase of the population of OKT8 and M phi positive cells in portal triads, and the ratio of OKT4 positive cells (helper/inducer T cells) to OKT8 positive cells (suppressor/cytotoxic T cells) was also higher than that in normal livers. T cells surrounding small bile ducts mainly had T4 phenotype, where as T8 cells seemed to predominate in small necrotic foci T8 cells in piecemeal necrotic foci were responsible for hepatocellular damage. These results suggest that in hepatolithiasis there was an enhancement of local cell immunoreaction and an imbalance of hepatic immunoregulatory T cells.

Antibodies, Monoclonal↗
PubMed1990

[A novel group of nucleolar organizer region associating proteins].

With the scleroderma autoantinucleolar antiserum which was discribed in our previous paper, we identified a novel group of nucleolar organizer associating proteins, ANOP. By means of immunoblotting, it was found that ANOP mainly consists of three polypeptides with molecular weights of 65, 76, and 78 KD respectively. Immunoelectron microscopy demonstrated that ANOP is localized in the shells of dense fibril components surrounding fibrillar centers of nucleolus. Moreover, indirect immunofluorescence studies on various cells of vertebrate animals indicated that ANOP is a group of highly conserved nucleolar antigens. The fibrillar centers of human, mouse, chinese hamster, chicken, frog and crucian carp cells can all be brightly stained by ANOP specific antiserum. However, it was found that in amphibian, the erythrocytes and the early embryo cells prior to gastrulation are devoid of ANOP. During gastrulation, ANOP begins to appear in the nuclei, and then, the content of ANOP in nucleoli apparently increases gradually. These phenomena suggest that ANOP may take a role in rRNA gene activity.

Animals↗