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Biomedical subjects

S M Yang

Publications and source records attributed to S M Yang.

At least 37 records · Page 2Linked to original sources
PubMed1998

A monoclonal antibody that recognizes a common carbohydrate epitope shared by various glycoproteins in human secretions.

A monoclonal antibody (mAb; a mouse IgM referred to as 1CF11) recognizing various human glycoproteins was obtained. While the immunoreaction of glycoproteins from human secretions including milk, saliva, and bronchus was demonstrated as a typical dose-responded S-shaped reaction curve on ELISA, no reaction was detected with milks and sera of animal origin as well as human serum. In the constituting polypeptides of the human milk secretory IgA molecule, only the secretory component was recognized by this mAb. Among various chemical treatments of the purified human milk lactoferrin (Lf), only either periodate or mild alkaline treatment abolished the immunoreactivity of the glycoprotein. A recombinant human Lf was not immunoreactive. Finally, the immunoreactive fragments were isolated from human milk Lf, which remained reactive with PAS reagent while lacking the previously reported N-glycans. These results strongly suggest that the mAb 1CF11 recognizes a new glycan O-glycosidically linked to glycoproteins in human secretions.

Animals↗
PubMed1998

Mediation by N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors in the expression of Fos protein at the nucleus tractus solitarii in response to baroreceptor activation in the rat.

We investigated the role of glutamatergic synapses in the expression of Fos protein at the nucleus tractus solitarii following baroreceptor activation in rats anaesthetized with pentobarbital sodium. Microinjection of L-glutamate (1 nmol) bilaterally into the nucleus tractus solitarii elicited significant hypotension and bradycardia. There was a concurrent increase, as determined immunohistochemically, in the expression of Fos protein at the commissural, medial and dorsomedial subnuclei of the caudal nucleus tractus solitarii. These effects were blunted when L-glutamate was co-administered with either the selective N-methyl-D-aspartate or non-N-methyl-D-aspartate glutamate receptor antagonist, dizocilpine maleate (200 pmol) or 6-cyano-7-nitroquinoxaline-2,3-dione (8 pmol), into the caudal nucleus tractus solitarii. Repeated and scheduled transient hypertension evoked by phenylephrine (2.5, 5.0 or 10.0 microg/kg, i.v.) also appreciably increased the number of Fos-immunoreactive neurons at the commissural, medial and dorsomedial subnuclei of the caudal nucleus tractus solitarii. The expression of Fos protein in this fashion was reduced, simultaneous with a discernible depression in baroreceptor reflex response, when baroreceptor activation was coupled with microinjection bilaterally of dizocilpine maleate (200 pmol) or 6-cyano-7-nitroquinoxaline-2,3-dione (8 pmol) into the nucleus tractus solitarii. Regression analysis showed that the depressive action on the baroreceptor reflex response by both glutamate receptor antagonists correlated positively to the reduction in Fos-immunoreactivity in the nucleus tractus solitarii after baroreceptor activation. Double immunohistochemical staining revealed that nucleus tractus solitarii neurons that showed Fos immunoreactivity were generally also immunoreactive to alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate receptor subunit 1. On the other hand, Fos immunoreactivity was usually absent from neurons in the nucleus tractus solitarii that were immunoreactive to N-methyl-D-aspartate receptor subunit 1. These results suggest that glutamatergic neurotransmission plays an active role, via comparable contributions from both N-methyl-D-aspartate and non-N-methyl-D-aspartate receptors, in the expression of Fos protein at the caudal nucleus tractus solitarii in response to baroreceptor activation.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1998

Optical recording of membrane potential on isolated spiral ganglion cells of newborn mice using a voltage-sensitive dye.

Optical imaging methods make monitoring of the membrane potential feasible. With this technique, one can observe different optical signals depending on optical properties, in response to membrane potential, using voltage-sensitive dyes. We used the multiple-site optical imaging system to investigate membrane potentials of the isolated, cultured spiral ganglion cells (SCGs) from newborn mice. We used a voltage-sensitive absorption dye. With high potassium (150 mM K+) exposure, the absorbency of SGCs stained with voltage-sensitive dye increased temporarily under a 700-nm interference filter at approximately 0.3%. This detection of the depolarization of SGCs using an optical recording technique with a voltage-sensitive dye is important because it shows that the simultaneous measurement of activity in a variety of regions is possible, as is the exploring of the intercellular signalling pathway.

Animals↗
PubMed1997

Probing subtle acid-induced conformational changes of ribonuclease A by electrospray mass spectrometry.

The newly developed technique, electrospray mass spectrometry, was used to probe subtle conformational changes of bovine pancreatic RNase A during acid denaturation. In a dilute acid solution of pH 2.6, RNase A lost nearly all of its activity, whereas its intrinsic fluorescence intensity at 304 nm and its ellipticity at 222 nm were fairly resistant to denaturation by acetic acid. The observed maximum charged state of the enzyme in electrospray mass spectra was increased from 11+ (at pH 3.3) to 14+ (at pH 2.6). This could result from exposure of the buried basic amino acid residues R-10, K-41, H-12 and perhaps H-48.

Animals↗
PubMed1995

[Preliminary observation on the destructive effect of chemical disinfectants in serum markers of hepatitis B and C].

Chloroform, 40% formaldehyde, 3% hydrogen peroxide solution and 75% alcohol were used to act on hepatitis B surface antigen (HBeAg), hepatitis B e antigen (HBaAg) and anti-hepatitis C virus antibody (Anti-HCV) positive serum for 5, 15, 30 and over 60 minutes. They were examined by enzyme-linked immunosorbent assay and observed for the effect. The destructive effect of chloroform on HBsAg and anti-HCV positive derum was marked. It was discovered that 40% formaldehyde solution destroyed HBsAg, HBeAg, and anti-HCV positive serm, while 75% alcohol also showed destructive effect on HBsAg, HBeAg and anti-HCV positive serum.

Chloroform↗
PubMed1994

[DMSO induced differentiation of human gastric adenocarcinoma cell line MGC 80-3].

The in vitro effects of dimethyl sulfoxide (DMSO) on MGC 80-3 cells were studied by light microscopy, transmission electron microscopy and biochemical methods. The results indicated that the inhibitory effects of DMSO on the growth of MGC 80-3 cells was concentration dependent and 1.5% DMSO was suitable in the present study. The growth rate, mitotic index, colony forming efficiency and Con A-aggregation of the cells treated with 1.5% DMSO in vitro for 7 days was reduced respectively by 35.15%, 18/1000, 90% and 55.8%. It was remarkable that the activity of membrane-associated alkaline phosphatase, which is not presented in normal human gastric mucosa, was decreased by 90% in the treated cells. There was a 75% decrease of the rate of tumorigenesis in the treated cells as compared with the tumorigenic rate of the untreated MGC 80-3 cells inoculated into nude mice. Gross morphological changes of MGC 80-3 cells treated with 1.5% DMSO were evident including enlargement and flatness of the cells, stumpy microvillies instead of long and rigid ones, and extremely well-developed Golgi apparatus and rough endoplasmic reticulum. This data indicated that DMSO was able to induce differentiation of MGC 80-3 cells and change their malignant phenotypes.

Adenocarcinoma↗
PubMed1994

[The relationship between stereoacuity and contracted visual field].

The stereoacuity (SA) was measured by means of the Titmus test, Random Dot E stereotest and Yan's stereoscopic test charts in 90 cases of glaucoma or retinitis pigmentosa with visual field contraction and 28 normal subjects. Significant reduction in SA was observed in all patients with contracted visual field, and markedly so (> 130") in cases with bilateral or unilateral tubular vision. The SA was reduced with visual field loss of over 30% and there was a positive correlation between the SA reduction and the area of visual field loss.

Adolescent↗
PubMed1993

Metallic expanding biliary stents in malignant obstruction. Cases with stent in stent.

We reviewed a total of 13 stent (Gianturco-Rosch biliary Z-stent) placements in 11 patients with biliary obstruction due to malignancy and report the cases treated with the stent-in-stent technique for treatment of stent occlusion due to tumor ingrowth. Causes of biliary obstruction included cholangiocarcinoma (four cases), hepatic hilar metastasis of gastrointestinal carcinoma (five cases), and pancreatic carcinoma (two cases). After transient percutaneous transhepatic biliary drainage (PTBD), the stents were successfully inserted by transhepatic route in all patients without any serious complication that needed further surgical intervention. Almost all patients were freed from the external PTBD tube about a week after stent placement and discharged from the hospital with improvement in quality of life as well as normal serum bilirubin levels. The technical advantages of stent placement include ease of insertion and the ability to drain both right and left biliary systems from a single transhepatic route by arranging the stents in a variety of configurations. Furthermore, it provides a second chance of stent placement when the previous stent has been occluded by tumor ingrowth.

Aged↗
PubMed1993

[Quantitative analysis of six lectin receptors and its application in differential diagnosis of astrogliomas and reactive hyperplasia of gliocytes].

The distribution of six lectin receptors (WGA, RCA-1, LCA, PSA, PNA, SBA) in 71 human astrogliomas, 8 human normal brain tissues and 11 reactive hyperplasia of gliocytes was examined by avidin-biotin-peroxidase technique and quantified with an image analysis. The results showed that WGA and RCA-1 may be used as good markers for distinguishing well differentiated astrocytomas from reactive hyperplasia of gliocytes. The quantities of LCA and PSA receptors of astrocytomas with different degree of differentiation were different. Expression of SBA and PNA receptors in normal brain tissues and different lesions was similar. The results suggest that glycoproteins and glycolipids with N-glucosidic bonds mainly changed in the process of histogenesis and differentiation of astrocytomas.

Astrocytes↗
PubMed1993

[Establishment of a model of human gastric cancer with liver metastasis in nude mice].

An animal model of liver metastasis was established by injection of suspending tumor cells into subcapsule of spleen in nude mice. With additional mechanic disaggregation, single-tumor cell suspension was prepared by enzymatic disaggregation, including trypsin-collagenase disaggregate medium treatment, from the subcutaneous MGC 80-3 xeno-transplanted tumor and filtered through filter holders with different pore size. To investigate the effect of liver damage by carbon tetrachloride (CCL4) on the metastatic potential of MGC 80-3 cells injected intrasplenically, the nude mice were divided into 2 groups: Group 1 received intrasplenic injection of 1.25 x 10(6) MGC 80-3 cells without CCL4 treatment; Group 2 received intrasplenic injection of equal cells with CCL4 treatment. The incidence of liver metastasis was 60% in Group 1, but 100% in Group 2. The mean numbers of metastatic nodules per liver were 1.80 in Group 1, but 4.85 in Group 2. It is obvious that the incidence and nodules of liver metastasis were increased in the mice treated with CCL4. This is a useful model to study antimetastatic agents and metastatic behaviors.

Adenocarcinoma, Mucinous↗
PubMed1991

The effects of atropine on pharmacokinetics of theophylline in rabbits.

The effects of atropine on serum concentrations and pharmacokinetics of theophylline were studied in six rabbits (2.07 +/- 0.11 kg). Theophylline serum concentration was determined by ultraviolet spectrophotometry. After i.v. administration of aminophylline 12.5 mg/kg, i.m. atropine 1 mg/kg decreased significantly the maximal serum concentration of theophylline from 23.6 +/- 1.1 to 19.6 +/- 1.1 mg/l, and increased that of theophylline at the time of 6 and 8 hours after injection. After i.v. aminophylline administration without or with atropine, the pharmacokinetic parameters of theophylline calculated using a one compartment open model were: K (elimination rate constant) = 0.23 +/- 0.03, 0.19 +/- 0.02/h; t1/2 (half life) = 3.04 +/- 0.40, 3.66 +/- 0.40 h; Cl (clearance) = 0.26 +/- 0.04, 0.23 +/- 0.03 l/kg/h, respectively (P less than 0.01). But there was no significant variation in modification of volume of distribution (Vd). The results suggested that there is a significant drug interaction between atropine and theophylline.

Animals↗
PubMed1990

Up-regulation of androgen receptor binding in male rat fat pad adipose precursor cells exposed to testosterone: study in a whole cell assay system.

Binding of androgens to adipocytes has previously been evaluated using cytosol fractions without taking into account nuclear binding, although the latter is suggested to be close to the physiological site of action. In the present study, performed in differentiated fat pad adipose precursor cells, we describe a simple, reliable and reproducible androgen binding assay in a system with intact cells. Tritiated and unlabeled methyltrienolone (R1881) were used to define specific and unspecific androgen binding. Triamcinolone acetonide was added to prevent the binding of R1881 to other types of receptors. Differentiated adipose precursor cells contain a homogeneous class of high affinity androgen binding sites, and binding is saturable and reversible. Binding apparently occurs at one site, with a Kd in the range of physiological androgen concentration (about 4 nM). Competition studies indicate that the receptor is specific for R1881, testosterone and dihydrotestosterone, which have approximately the same affinity, while progesterone, estradiol and dexamethasone show much lower affinity. Androgen binding was markedly enhanced after cellular exposure to R1881 and testosterone but not dihydrotestosterone, and this increase was dependent on protein synthesis, suggesting the formation of new receptors by these androgens. In conclusion, fully differentiated adipocytes contain a specific, high affinity receptor, the density of which is dependent on androgens.

Adipose Tissue↗
PubMed1990

Identification of cyclic metabolites of isopropylated phenyl phosphates in rabbit bile.

Some organophosphorous compounds, especially tri-o-cresylphosphate (TOCP), induce delay neuropathy. The cyclic saligenin phosphate (PSP) has been suggested to be the active metabolite of the protoxicant TOCP. The o-isopropylated triphenyl phosphates have been proven not to be neurotoxic. Studying the metabolism of these compounds we found the following cyclic metabolites: 2-phenyl-4H-4,4-dimethyl-1,1,3,2-benzodioxaphosphoran-2-oxide and 2-(o-isopropylphenyl)-4H-4,4-dimethyl-1,1,3,2-benzodioxaphospho ran-2-oxide. Additionally, monohydroxylated metabolites of the parent esters were detectable. The effect of glucuronidation on the formation of the cyclic metabolites is discussed in this paper.

Animals↗
PubMed1990

[Oblique muscle dysfunction and cyclotropia].

The disc-fovea angle was calculated from the fundus photo by measuring the distance of fovea to the geometric center of the disc and the distance of fovea to the horizontal meridian through the disc center. The authors found the average disc-fovea angle of 40 normal individuals to be extorsion 7.43 degrees; and the diagnosis of cyclotropia was made for patients with extorsion over 14.20 degrees or intorsion, and those in whom the disc-fovea angle difference between both eyes was 8 degrees or over. In 9 cases of AV syndrome, 86% (12/14) of the V pattern cases associated with inferior oblique overaction were excyclotropic, and 75% (3/4) of the A pattern cases were incyclotropic. In 5 cases of superior oblique paresis, 86% (6/7) of the diseased eyes were excyclotropic, whether the function of the antagonistic was normal. The authors concluded that fundus photos could serve as a basis for diagnosis of cyclotropia.

Anthropometry↗
PubMed1990

[The retinal visual acuity of amblyopia].

The authors studied the relationship between the retinal visual acuity (grating acuity) and recognition acuity (E acuity) in 94 normal eyes and 169 amblyopic eyes with the results that the RVA in 84% of the normal eyes was the same as E acuity, while in 66% of the amblyopic eyes, especially the strabismic category, RVA was better than E acuity. RVA was not affected by the orientation (0 degrees, 45 degrees, 90 degrees, or 135 degrees) of the grating or the size of the light field (1.5 degrees or 3.5 degrees). Factors which could contribute to the difference between the RVA and the E acuity and the difference between strabismic and refractive amblyopia were discussed. It was put forward that grating acuity was reliable in the diagnosis of amblyopia.

Adolescent↗
PubMed1990

[The relationship between corneal dellen and tearfilm breakup time].

In 51 patients (102 eyes) after strabismus operation, the incidence of corneal dellen was 22.54%. The average preoperative tearfilm breakup time was 28.75 sec, while the postoperative BUT in the dellen formation group was markedly reduced from the average 23.22 sec to 8.61 sec. The incidence of dellen after rectus resection (47.75%) was much higher than that after rectus recession (5.13%). It was believed that elevation of the bulbar conjunctiva after operation disturbed stability of the precorneal tearfilm to result in reduced BUT and local desiccation of the cornea, leading to dellen formation.

Adolescent↗
PubMed1989

A preliminary study on the use of enzyme-linked immunosorbent assay (ELISA) for detection of Trichinella spiralis infections in dogs.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect Trichinella spiralis infections in dogs using rabbit anti-canine IgG-horseradish peroxidase prepared according to the improved periodate method and an antigen purified from T. spiralis larvae by Sephadex G-200 chromatography. Sixty-six canine sera were tested for trichinosis by the ELISA and it showed a detection rate which was significantly higher than that by trichinoscopy. This antigen of T. spiralis appeared not to cross-react with the sera of dogs infected with Ancylostoma caninum or Taenia spp. A comparison of ortho-phenylenediamine and 5-amino-2-hydroxybenzoic acid as substrates in the ELISA did not reveal a significant difference. Pieces of filter paper saturated with a defined quantity of whole blood can be substituted for serum as a source material for the test. The relationship between worm burden and the absorbance value in ELISA is discussed.

Animals↗