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Biomedical subjects

J S Yang

Publications and source records attributed to J S Yang.

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

Quantitative determination of styrene in blood and mandelic acid in urine of the occupationally styrene-exposed workers.

The concentration of styrene in blood of the occupationally styrene-exposed workers was checked by gas chromatographic headspace analysis. Mandelic acd in urine, that is a major metabolite of styrene, and hippuric acid were also analyzed by high performance liquid chromatography. For the biological monitoring of styrene-exposed workers, the routine method of the quantitative determination of styrene and its metabolites in the biological samples were studied.

Chromatography, Gas↗
PubMed1994

Characterization of two novel filamentous phages of Xanthomonas.

Two filamentous phages of Xanthomonas campestris pv. vesicatoria and Xanthomonas oryzae pv. oryzae were isolated and designated phi Xv and phi Xo, respectively. They were similar to other filamentous phages of Xanthomonas in (i) shape, (ii) restrictive host specificity, (iii) high stability, (iv) an ssDNA genome, (v) a dsDNA as the replicative form (RF), (vi) propagation without lysis of host cells and (vii) ability to integrate into the host chromosome. These phages showed sequence homology to filamentous phage phi Lf of X. c. pv. campestris. phi Xv was inactivated by antisera against phi Xv, phi Xo and phi Lf, whereas phi Xo and phi Lf were inactivated only by their respective antisera and the anti-phi Xv serum. Both the single-stranded phage DNAs and the RF DNAs of phi Xv, phi Xo and phi Lf were able to transfect X. c. pv. vesicatoria, X. o. pv. oryzae and X. c. pv. campestris. Physical maps of phi Xv and phi Xo were constructed for the RF DNAs. Genome sizes were estimated, based on mapping data, to be 6.8 kb for phi Xv and 7.6 kb for phi Xo, larger than that of the phi Lf genome (6.0 kb). The difference in genome sizes appeared to result from insertions of large DNA fragments. These fragments and the regions mediating integration were localized in the physical maps.

Bacteriophages↗
PubMed1994

[Effect of xylazine on acetylcholine content of the hippocampal CA1 region in urethane anesthetized rats].

By using acetylcholine selective microelectrode technique, a biphasic effect of xylazine on acetylcholine content of the hippocampal CA1 region in urethane anesthetized rats was observed as evidenced by the fact that small doses of xylazine (2.0 and 6.0 mg.kg-1) significantly increased, while higher dose (10.0 mg.kg-1) decreased the acetylcholine content. Though idazoxan (0.6 mg.kg-1) significantly antagonized the effect of xylazine when used in combination, the acetylcholine content in the hippocampal CA1 region of urethane anesthetized rats was still much lower than that of the control group. In rats whose nucleus locus coeruleus was chemically lesioned, xylazine (2.0 and 6.0 mg.kg-1) significantly decreased the acetylcholine content, and idazoxan (0.6 mg.kg-1), which increased the acetylcholine content in the hippocampal CA1 region when used alone, completely antagonized the effect of xylazine. These results suggest that the biphasic effect of xylazine and the lower than normal acetylcholine content observed when idazoxan was used to antagonize xylazine induced changes in acetylcholine content of the hippocampal CA1 region in urethane anesthetized rats might be related to the effects of xylazine and idazoxan on the central noradrenergic neurotransmitter system.

Acetylcholine↗
PubMed1994

[Compounds from Caesalpinia sappan L].

Two compounds were isolated from the stem of Caesalpinia sappan. Their structures were elucidated on the basis of physical and spectral analysis. They were named as tetraacetylbrazilin and protosappanin A respectively.

Benzopyrans↗
PubMed1993

Interaction of peptide fragment 828-848 of the envelope glycoprotein of human immunodeficiency virus type I with lipid bilayers.

The interaction of the peptide fragment 828-848, called P828, from the carboxy-terminal region of the envelope glycoprotein gp41 of HIV-I with model membranes composed of phosphatidylcholine (PC) and phosphatidylglycerol (PG) was investigated using microelectrophoretic mobility of liposomes, fluorescence polarization of labeled lipids, NMR, and differential scanning calorimetry. The peptide binds to negatively charged lipid surfaces. No interaction between P828 and neutral PC surfaces is observed. The interaction between the peptide and the lipid is exclusively electrostatic with the six positively charged arginines of P828 acting as binding sites for PG. Circular dichroism measurements of P828 indicate that the peptide undergoes a transition from a random coil to an ordered conformation upon binding to negatively charged PG bilayers or SDS micelles, but not in the presence of neutral PC bilayers. The ordered structure has an apparent helical content of 60%. IN DOPG/DOPC mixtures containing 20 mol % DOPG, the peptide causes the formation of lipid domains enriched in DOPG, as assessed by measurement of fluorescence energy transfer between labeled PG and PC. The formation of these domains requires energy and therefore reduces the strength of peptide binding to the lipid matrix. Our data support and quantitate the results from antibody binding studies [Haffar, O.K., Dowbenko, D. J., & Berman, P. W. (1988) J. Cell Biol. 107, 1677-1687] that the carboxy-terminal segment of the envelope glycoprotein gp41 interacts with microsomal membranes.

Amino Acid Sequence↗
PubMed1993

Endothelial potentiation of relaxation response to ascorbic acid in rat and guinea pig thoracic aorta.

The role of the endothelium was evaluated in the relaxation of rat and guinea pig aortic rings induced by ascorbic acid. Ascorbic acid relaxed rat and guinea pig aortic rings that were previously contracted with submaximal dose of phenylephrine (PE), in a concentration dependent manner. Removal of the endothelium significantly reduced the sensitivity but not the magnitude of the response to ascorbic acid. Methylene blue, but not propranolol, blocked the endothelial augmentation of vascular relaxation to ascorbic acid. Vessels precontracted with potassium chloride (high K+) were also relaxed by ascorbic acid. Methylene blue also inhibited the response to ascorbic acid in the intact vessels precontracted with high K+. A23187 and acetylcholine, but not ADP, variably caused endothelium dependent component relaxation in guinea pigs, whereas all of these three probes constantly caused it. In Ca(2+)-free medium, Ca(2+)-induced contraction of high K(+)-depolarized rat aorta was inhibited by the presence of ascorbate, which was more pronounced in endothelium intact rings than in endothelium denuded ones. PE-induced contraction in the presence of different concentrations of ascorbate reduced both the sensitivity and the maximal contractile force in rat aorta. Ascorbic acid (0.125-32 mM) did not change the pH in the medium. From these findings, it is speculated that 1) receptor- and potential-operated Ca2+ channels may be modulated by ascorbate, 2) endothelium has a significant role in promoting relaxation induced by ascorbic acid.

Animals↗
PubMed1993

Expression of the sodium channel beta 1 subunit in rat skeletal muscle is selectively associated with the tetrodotoxin-sensitive alpha subunit isoform.

Transcripts homologous to the rat brain sodium channel beta subunit (beta 1) are prominently expressed in both innervated and denervated adult skeletal muscle and in heart, but not in neonatal skeletal or cardiac muscle. Regulation of beta 1 mRNA expression closely parallels that of SkM1 alpha during development, after denervation in adult muscle, and in primary muscle culture, but does not follow SkM2 expression under any condition examined. In oocytes, beta 1 interacts functionally with SkM1 to modulate the abnormally slow inactivation kinetics observed with this alpha subunit expressed alone. We conclude that a common beta 1 subunit is expressed in skeletal muscle, heart, and brain and that in skeletal muscle, this subunit is specifically associated with the SkM1, rather than the SkM2, sodium channel isoform.

Animals↗
PubMed1993

Upper human hair follicle contains a subpopulation of keratinocytes with superior in vitro proliferative potential.

We and others have shown previously that corneal keratinocyte stem cells can proliferate in vitro better than their progeny cells. In this paper, we applied this approach to the identification of hair follicular stem cells. When human scalp hair follicles were placed in explant culture, the bulge area yielded best outgrowths. In another experiment, we isolated different subpopulations of human follicular keratinocytes by micro-dissection, dispersed them by trypsin/EDTA into single cells, and grew them in the presence of 3T3 feeder cells. The keratinocytes were then subcultured under identical conditions to compare their in vitro life span. Our results indicate that the life span of keratinocytes of the upper follicle (containing mainly the isthmus area) > sebaceous gland > lower follicle (between the bulge and bulb) > bulb (containing the matrix cells). The cultured upper follicular keratinocytes tend to be small and relatively uniform in size. The poor in vitro growth of matrix cells may reflect their non-stem cell nature and/or special growth requirement(s) satisfied in vivo by the neighboring dermal papilla cells. Unexpectedly, we found that the upper follicular keratinocytes grow even better than epidermal keratinocytes. The existence of a subpopulation of keratinocytes with an in vitro growth potential superior than other known keratinocytes of the skin supports the hypothesis that follicular stem cells reside in the upper follicle. Our data also raise the possibility that putative follicular stem cells are involved not only in forming the follicle, but also in the long-term maintenance of the epidermis. Finally, we discuss the possibility that keratinocyte stem cells, as defined by their in vivo slow-cycling nature, are absent in culture.

Cell Division↗
PubMed1993

[Study on lignans from Diphylleia sinensis].

A new lignan along with eight known lignans and a flavonoid were isolated from the rhizomes of Diphylleia sinensis Li.. Their structures were elucidated on the basis of chemical and spectral analysis. The new lignan, compound IX, was named as picropodophyllin-1-ethyl ether (IX). The eight known lignans were identified as podophyllotoxin (I), isopicropodophyllone (II), dehydropodophyllotoxin (III), diphyllin (IV), picropodophyllin (V), podophyllotoxone (VI), 4'-demethylpodophyllotoxin (VII) and picropodophyllin glucoside (VIII). Compounds II, VI, VII and VIII were found for the first time from the rhizome of this plant. The flavonoid was identified as kaempferol.

Antineoplastic Agents, Phytogenic↗
PubMed1993

[Determination of gelsemium alkaloids by RP-HPLC].

Gelsemium elegans Benth is a kind of traditional Chinese medicine, eight alkaloids have been isolated from this herb. In recent years, an HPLC method for the separation and determination of five of these alkaloids, ie. gelsemium A (G), koumine (F), kumantenidine (D), kumantenine (B) and kumantenmine (A) is described, dichroine being used as the internal standard. In this report a RP column of C18 and the mobile phase methanol--water--n-butylamine (78:22:0.1 V/V) were employed. The flow rate was 1.0 ml/min, the column temperature was 25 degrees C and the detection wavelength was 256 nm. The calibration curves showed good linearity over the range of 0.02-0.12 microgram, r = 0.9835-0.9977 and the recoveries were 95.01-99.70% for the five alkaloids. The method is simple, sensitive and reproducible and can be used for the quality control of Gelsemium preparations for clinical evaluation.

Alkaloids↗
PubMed1993

[Studies on the chemical constituents of Arctium lappa L].

Six compounds were isolated from the seeds of Arctium lappa L. One of them is a new lignan named neoarctin B(VI). The structure has been elucidated on the basis of spectral (UV, IR, 1H-NMR, 13C-NMR, DEPT, 2D-NMR and MS) analysis. The other five compounds were identified as daucosterol (I), arctigenin (II), arctiin (III), matairesinol (IV) and lappaol F (V).

Drugs, Chinese Herbal↗
PubMed1993

Report of a case of sympathetic ophthalmia with special regard to ultrastructural examination.

A case of sympathetic ophthalmia (SO) is reported. A long lasting stable result was obtained for this patient treated basically with traditional Chinese medicine. His exciting eye was investigated under light and transmission electron microscopes. Prominent granulomatous lesions in the choroid, Dalen-Fuchs nodules (DFNs) and disruption of outer and inner basement membrane of Bruch's membrane under DFNs are found, plasma cells are not few and melanocytes and retinal pigment epithelial cells are possibly the target cells. In various cells, nuclear bodies (NBs) are ubiquitous and sometimes multiple in an individual cell nucleus. Microtubule-like structures are present inside and outside the NBs and parallel lines composed of relatively uniform high electron dense granules as lattice-like structures can be seen. It was surmised that a virus induced autoimmune process might be involved in the pathogenesis of SO.

Adult↗
PubMed1993

[Antagonistic effects of cholinergic drugs on xylazine induced sedation].

Xylazine induced sedation in mice was observed as a kind of inhibition of exploratory activity. The reversible cholinesterase inhibitor cui xing ning (0.25-1.0 m.kg-1), the precursor of acetylcholine, choline bromide (100-300 mg.kg-1), and the M-receptor agonist arecoline (1.0-5.0 mg.kg-1) were shown to significantly antagonize xylazine (5.0 mg.kg-1) induced sedation. While cui xing ning (0.25 mg.kg-1) shifted the dose-response curve of xylazine induced sedation to the right, hemicholinum-3 (3 micrograms icv), which inhibits the synthesis of acetylcholine, shifted the dose-response curve to the left. These results suggest that the xylazine induced sedation may be partly due to a reduced central cholinergic function. Cui xing ning may have some value in the treatment of xylazine overdose and antagonize the anesthesia induced by anesthetics combined with xylazine.

Animals↗
PubMed1993

[Studies on the chemical constituents of Desmodium styracifolium (Osbeck) Merr].

A new alkaloid, named desmodimine, C12H15NO4, gum, and a new natural product, named desmodilactone, C8H13NO3, mp 84-85 degrees C have been isolated from the aerial parts of Desmodium styracifolium (Osbeck) Merr. belonging Leguminosae. On the basis of spectral analysis their structures were deduced as formula I and II. In addition, lupenone (III), lupeol (IV), tritriacontane (V), stearic acid (VI), eicosanoic acid eicosyl ester (VIII) and beta-sitosterol (VII) were isolated for the first time from this plant.

Drugs, Chinese Herbal↗
PubMed1992

Characterization of glycoprotein IIb/IIIa-positive cells in human umbilical cord blood: their potential usefulness as megakaryocyte progenitors.

A need for hematopoietic stem cells, particularly cells destined to enter the megakaryocyte (MK) series, prompted phenotypic analysis of mononuclear leukocytes in human cord blood. To this end, immunohistochemical, flow cytometric, and ultrastructural techniques were used. The immunogold silver enhancement method (IGS) for the detection of the MK-specific glycoprotein (GP) IIb/IIIa epitopes combined with a monocyte-specific stain for alpha-naphthyl butyrate esterase proved to be superior to flow cytometry (FACS) for precise quantitation of cell types in each sample. Immunoelectron microscopy afforded a description of distinctions between precursors bearing GPIIb/IIIa epitopes and other stem cells of the myeloid series. The number of presumed MK progenitors was surprisingly high, averaging 1.8% +/- 1.3% (range, 0.2% to 4.6%) by IGS and 4.1% +/- 3.0% (range, 0.2% to 9.3%) by FACS analysis. The occurrence of GPIIb/IIIa-positive denuded MK nuclei in cord blood was of interest, but was too small to affect these data. These observations should advocate a greater use of cord blood for restitution of MK/platelet-lineage-depleted patients as well as for experimental studies concerned with MK differentiation.

Antigens, CD↗
PubMed1992

The effects of probenecid on the excretion kinetics of stanozolol, an anabolic steroid, in rats.

The pharmacokinetic behaviour and the mechanism of renal excretion of stanozolol (STZ), as affected by co-treatment with probenecid, were studied in male Sprague-Dawley rats. Pharmacokinetic parameters following intravenous (i.v.) administration of STZ (20 mg kg-1 body wt.) were measured in both STZ-treated (control) and STZ plus probenecid-treated (treatment) groups. In order to assess the renal clearance of STZ, bolus doses of STZ and inulin (40 mg kg-1 body wt.) were injected i.v. either in the presence or absence of probenecid (40 mg kg-1 body wt.). The blood and urine concentrations of STZ were determined by capillary gas chromatography-mass spectrometry (GC-MS). In the probenecid treatment group, the area under the plasma disappearance and urinary excretion curves (AUC) of STZ were significantly decreased (P < 0.01) and the volume of distribution (Vd) and total clearance (CLt) were significantly increased statistically (P < 0.05 and P < 0.01, respectively). No remarkable differences in the urine flow rate, urine pH values, glomerular filtration rate (GFR) or renal clearance were observed in the treatment group. However, the clearance ratio in the treatment group was significantly increased from 11.72 to 17.27. From these results, it is suggested that the significant decrease of AUC, i.e. increase of disappearance of STZ in plasma by co-administration with probenecid, is due to the increase of the clearance ratio.

Animals↗
PubMed1992

Evaluation of finger blood flow with Tc-99m MDP (methylene diphosphonate).

BACKGROUND: A variety of methods were used to establish objective diagnostic criteria of Raynaud's phenomenon. We intended to introduce another method, using radionuclide (Tc-99m methylene diphosphonate) scintigraphy, which is more objective, simple and economical than the past methods. METHODS: The finger blood flow with radionuclide scintigraphy was evaluated in 10 patients of Raynaud's syndrome, 12 patients of connective disease without Raynaud's symptoms, and 20 normal persons. After immersing one hand in ice water (4 degrees C) for 30 seconds, the hand was exposed to 22 degrees C room air for 15 minutes, and then the patients received the intravenous (IV) bolus of 20 microCi of Tc-99m methylene diphosphonate (MDP). At the same time, scintigraphic image of both hands started with the region of interest, including the second, third, fourth and fifth fingers distal to the metacarpophalangeal (MCP) joints. Computer recording of the counts in the region of interest every 2 seconds for 310 seconds was started on IV bolus injection. RESULTS: The 310 seconds cumulative digital blood flow ratio of cold exposed hand to room air exposed hand was significantly lower in Raynaud's group (p < 0.001), and the ratio of initial slope of activity curve was also lower in the Raynaud's group (p < 0.001). Of the 8 patients showing Raynaud's syndrome, 4 patients of scleroderma and 1 patient of multiple myeloma showed no improvement of finger blood flow in the cold exposed hand after 2 weeks of pharmacological therapy, but 1 patient of mixed connective tissue disease, 1 patient of Behcet's syndrome and 1 patient of SLE showed much improved finger blood flow after combined administration of vasodilator, calcium channel blockers and antiplatelet drugs. CONCLUSIONS: The evaluation of finger blood flow with 99mTc-MDP could be considered to be one of the simple, economical and new methods that can be used in the follow-up, objective assessment of therapeutic effect, and giving an aid in the study of the pathophysiology of the Raynaud's phenomenon.

Adult↗