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Y Jang

Publications and source records attributed to Y Jang.

72 records · Page 4Linked to original sources
PubMed1996

Characterization of an SAV organism and proposal of Mycobacterium triplex sp. nov.

Polyphasic taxonomic methods were employed to characterize a new species of slowly growing, nonpigmented mycobacteria. We propose the name Mycobacterium triplex sp. nov. for this new taxon. Conventional identification testing demonstrated a group of similar organisms that were geographically widespread in the United States. Commercially available nucleic-acid probes specific for the Mycobacterium avium complex were unreactive for these strains. High-performance liquid chromatography analysis of the mycolic acids revealed mycolate profiles that closely resembled Mycobacterium simiae. Comparative 16S rRNA sequence data confirmed the phylogenetic relationship of the strains with the slowly growing mycobacteria. Representative-type strains have been deposited in the American Type Culture Collection as strain ATCC 700071 [corrected].

Bacterial Typing Techniques↗
PubMed1996

Real-time determination of left ventricular ejection fraction by automatic boundary detection in patients with dilated cardiomyopathy: a comparison with radionuclide ventriculography.

Echocardiographic automatic boundary detection (ABD) is a new on-line technique which automatically outlines the left ventricular endocardial border and instantly calculates the left ventricular area and volume from two dimensional echocardiographic images. To determine if left ventricular ejection fraction (LVEF) can be derived using the ABD method, 25 consecutive patients with dilated cardiomyopathy, aged 52.1 +/- 15.2 (range 14 approximately 75), underwent complete echocardiographic examination with both the ABD method and radionuclide ventriculography (RVG). End-diastolic and end-systolic left ventricular areas were obtained on-line from the apical four chamber view. Left ventricular length was also measured from an apical view. Left ventricular volumes and ejection fraction were calculated using the single plane area-length method. ABD measurements could be obtained in all patients. Linear regression analysis compared ejection fraction derived by ABD and RVG. The mean radionuclide LVEF was 20.9 +/- 6.8% and mean ABD-derived LVEF was 22.7 +/- 5.8%. Linear regression analysis revealed that the ABD-derived LVEF is closely correlated with the RVG-derived LVEF (r = 0.87, p < 0.001). In conclusion, ABD echocardiography is a new on-line technique which may be used to accurately calculate LVEF in patients with dilated cardiomyopathy.

Adolescent↗
PubMed1996

Influence of 17- alpha-estradiol on catecholamine secretion from the perfused rat adrenal gland.

OBJECTIVES: It has been known that adrenal corticosteroids influence the expression of adrenomedullary catecholamine-synthetizing enzymes and also suppress the emission of axonal-like processes in cultured chromaffin cells. In the present study, it was attempted to investigate the effect of 17-alpha-estradiol on catecholamine (CA) secretion evoked by acetylcholine (ACh). DMPP. McN-A-343, excess K+ and Bay-K-8644 from the isolated perfused rat adrenal gland. METHODS: Mature male Sprague-Dawley rats were anesthetized with ether. The adrenal gland was isolated by the method of WaKade. A cannula used for perfusion of the adrenal gland was inserted into the distal end of the renal vein. The adrenal gland, along with ligated blood vessels and the cannula, was carefully removed from the animal and placed on a platform of a leucite chamber. RESULTS: The perfusion of 17-alpha-estradiol (1-100 uM) into an adrenal vein for 20 min produced relatively dose-dependent inhibition in CA secretion evoked by ACh (5.32 mM). DMPP (100 uM for 2 min). McN-A-343 (100 uM for 2 min) and Bay-K-8644 (10 uM for 4 min), while it did not affect the CA secretory effect of high K+ (56 mM). Also, in the presence of 17-beta-estradiol. CA secretion of ACh. DMPP and McN-A-343, without any effect on excess K(+)-evoked CA sectretion was depressed. However, in adrenal glands pre-loaded with 17-alpha-estradiol (10 uM) plus tamoxifen (2 uM), which is known to be a selective antagonist of estrogen receptors (for 20 min). CA secretory responses evoked by ACh. DMPP and McN-A-343 were condiderably recovered as compared to that of 17-alpha-estradiol only, but excess K(+)-induced CA secretion was not affected. However, pre-treatment with 17-alpha-estradiol in the presence of meclopramide (dopaminergic antagonist) did not affect the secretory effect of CA evoked by ACh. DMPP, McN-A-343 and high potassium. CONCLUSIONS: These results suggest that 17-alpha-estradiol causes the marked inhibition of CA secretion evoked by cholinergic receptor stimulation, but not that by excess K+, indicating strongly that this effect may be mediated by inhibiting the influx of extracellular calcium into the rat adrenomedullary chromaffin cells through the activation of inhibitory estrogen receptors, and it also plays a modulatory role in regulating CA secretion.

Adrenal Glands↗
PubMed1995

Influence of blockade at specific levels of the coagulation cascade on restenosis in a rabbit atherosclerotic femoral artery injury model.

BACKGROUND: The relation among the coagulation cascade, its individual proteins, and the response to vascular injury is largely undefined. We have evaluated the effect of four probes that block specific levels of coagulation cascade on neointimal hyperplasia in the atherosclerotic rabbit arterial injury model. METHODS AND RESULTS: Focal femoral atherosclerosis was induced by air-desiccation injury and hypercholesterolemic diet in 48 New Zealand White rabbits, followed by balloon angioplasty. Active-site inactivated factor VIIa (DEGR-VIIa), which blocks the binding of factor VIIa to tissue factor, was administered (n = 12 arteries) by intravenous bolus (1 mg/kg) at the time of balloon angioplasty and followed by infusion of 50 micrograms.kg-1.h-1 for 3 days; for the control (n = 13 arteries), 150 U heparin was injected as bolus and followed by infusion of saline at 50 microL.kg-1.min-1. Recombinant tissue factor pathway inhibitor (TFPI), which binds factor Xa and inhibits the tissue factor-factor VIIa complex and factor Xa, was given as a 1 mg/kg bolus followed by 15 micrograms.kg-1.min-1 infusion for 3 days (n = 17 arteries). Recombinant tick anticoagulant peptide (TAP; n = 15 arteries) and hirudin (n = 14 arteries), which block factor Xa and thrombin, respectively, were administered as a 1 mg/kg bolus followed by 5 micrograms.kg-1.min-1 infusion for 3 days. These three groups had their own controls (n = 14 arteries). There were no differences among treatment groups in preangioplasty and postangioplasty minimal luminal diameter (MLD) by angiography. The mean MLD 21 days after balloon angioplasty was significantly different between control and DEGR-VIIa-treated groups (0.74 +/- 0.25 and 1.24 +/- 0.27 mm, respectively; P = .0001) and between the TFPI-treated group and others (0.88 +/- 0.21 mm for control, 0.97 +/- 0.22 mm for hirudin-treated, 0.98 +/- 0.14 mm for TAP-treated, and 1.32 +/- 0.21 mm for TFPI-treated arteries; P = .0001 by ANOVA). By quantitative histological analysis, the ratio of neointimal cross-sectional area compared with the area of internal elastic lamina in the DEGR-VIIa-treated group was significantly less than control (0.48 +/- 0.12 versus 0.67 +/- 0.12, P = .0001), and the ratio of neointimal cross-sectional area to the area demarcated by the internal elastic lamina of the TFPI-treated group was significantly reduced compared with the other groups (0.46 +/- 0.20 for TFPI-treated, 0.67 +/- 0.15 for hirudin-treated, 0.61 +/- 0.15 for TAP-treated, and 0.64 +/- 0.13 for control groups; P = .003). CONCLUSIONS: Treatment with DEGR-VIIa or TFPI for 3 days in this rabbit atherosclerotic injury model reduced angiographic restenosis and decreased neointimal hyperplasia compared with controls. These findings highlight the importance of early initiators of the extrinsic coagulation pathway, especially factor VII and tissue factor, in the response to arterial injury.

Angioplasty, Balloon↗
PubMed1994

Cell adhesion molecules in coronary artery disease.

To date, six families of cell adhesion molecules are known. These are cell surface receptors that mediate adhesion of cells to each other or to components of the extracellular matrix and include integrins, selectins, the immunoglobulin superfamily, cadherins, proteoglycans and mucins. These cell adhesion molecules play a key role in cell-cell interaction (such as among endothelium, monocytes, smooth muscle cells and platelets) and cell-extracellular matrix interaction (such as between leukocytes, platelets or fibroblasts and the extracellular matrix). The importance of these interactions has recently been demonstrated in clinical trials with the use of an antibody fragment directed against the platelet alpha IIb beta IIIa integrin, with reduction of arterial thrombosis and restenosis after percutaneous coronary interventions. A fundamental role for cell adhesion molecules has been suggested for several other relevant disease processes, including atherosclerosis, acute coronary syndromes, reperfusion injury and allograft vasculopathy. This review focuses on providing the clinically relevant biology of these families of adhesion molecules, setting the foundation for delineation of their emerging role in cardiovascular therapeutics.

Animals↗
PubMed1993

Curvilinear-gradient high-performance liquid chromatography for identification of mycobacteria.

Over a 1-year period, 502 mycobacterial cultures submitted to the Microbial Diseases Laboratory were identified by high-performance liquid chromatography (HPLC) in parallel with standard biochemical methods. Identification by HPLC using a curvilinear gradient was achieved by comparing the chromatograms of the unknown cultures to chromatograms for known reference strains, together with calculation of peak height or peak area ratios, as necessary. The overall agreement between HPLC and biochemical identification was 97.2%. In addition, 7 of 12 cultures of Mycobacterium bovis were identified by HPLC as the BCG strain. Of 111 cultures biochemically identified as members of the M. avium complex (MAC), 108 were confirmed as MAC by DNA probe and 106 were confirmed by HPLC. Of the latter 106, 58 probe-positive strains were identified as M. avium, 38 were identified as M. intracellulare, and 10 were identified as Mycobacterium sp. strain "X" by HPLC. Of the remaining five nonchromogenic cultures, four had MAC-like chromatograms that did not match any in our library sufficiently to permit definitive identification. Of the latter four, two were confirmed as MAC strains by DNA probe and two were not. The last of the cultures biochemically identified as MAC (1 of 111) was a mixture of MAC and non-MAC strains. Overall, only 2 of 502 cultures yielded results by HPLC that differed from those obtained by standard biochemical methods. The HPLC result was confirmed in both cases by an independent national reference laboratory. In the 12 instances in which HPLC did not provide identification, the chromatograms were either uninterpretable or did not match available reference chromatograms. These findings show that the identification obtained by HPLC concurs well with that obtained by both the standard biochemical methods and the DNA probes. Thus, identification by HPLC provides mycobacteriology laboratories with a reproducible and specific method for accurate and timely identification of most medically important mycobacteria.

Bacterial Typing Techniques↗
PubMed1993

Influence of arachidonic acid on catecholamine secretion in the perfused rat adrenal medulla.

The present study was conducted to investigate the influence of arachidonic acid, which is known to be an important unsaturated fatty acid component of membrane phospholipids and to be liberated by phospholipase A2 action, on secretion of catecholamines (CA) from the isolated perfused rat adrenal glands and to clarify the mechanism of its action. Arachidonic acid (10 uM) perfused into an adrenal gland of the rat for 20 min caused a significant inhibition of CA secretion evoked by ACh (5.32 x 10(-3) M), DMPP (10(-4) M) and muscarine (10(-4) M) while it did not affect that induced by excess K+ (5.6 x 10(-2) M). Arachidonic acid, in the presence of ouabain (100 uM), an inhibitor of Na+, K(+) -ATPase, also produced a marked inhibitory effect of CA secretion evoked by ACh, DMPP and muscarine but did not modify the secretory effect of excess K+. The perfusion of arachidonic acid along with indomethacin (30 uM), which is an inhibitor of cyclooxygenase, for 20 min attenuated markedly CA secretory effect evoked by ACh, DMPP and muscarine while it did not influence that by excess K+. Prostaglandin F2 alpha perfused in a retrograde direction for 20 min inhibited greatly the CA secretion evoked by DMPP but did not affect the effect evoked by excess K+. All of arachidonic acid, ouabain, indomethacin and prostaglandin F2 alpha used in the present study did not affect the spontaneous basal release of CA in the perfused rat adrenal glands. Taken together, these experimental results suggest that arachidonic acid, as well as prostaglandin F2 alpha, cause the inhibitory action of CA secretion evoked by cholinergic receptor-mediated stimulation, but not by membrane depolarization, and also play a modulatory role in regulating CA secretion from the rat adrenal medulla.

Adrenal Medulla↗
PubMed1993

A hybrid system for diagnosing multiple disorders.

This paper investigates the advantages of introducing feedback between the processes of automated medical diagnosis and automated diagnostic-knowledge acquisition. Experimental results show that a diagnostic system with such feedback is capable of an efficiency/accuracy trade-off when applied to the problem of diagnosing multiple disorders. A primary feature of this work is a new mechanism, called the "diagnostic-unit" representation, for remembering results of previous diagnoses. The diagnostic-unit representation is explicitly tailored to capture the most likely relationships between disorders and clusters of findings. Unlike typical bipartite "If-Then" representations, the diagnostic-unit representation uses a general graph representation to efficiently represent complex causal relationships between disorders and clusters of findings. In addition to the basic diagnostic-unit concept, this paper presents experience-based strategies for incrementally deriving and updating diagnostic units and the various relationships between them. Techniques for selecting diagnostic units relevant to a given problem and then combining them to generate solutions are also described.

Artificial Intelligence↗
PubMed1991

Simultaneous analysis of flunixin, naproxen, ethacrynic acid, indomethacin, phenylbutazone, mefenamic acid and thiosalicylic acid in plasma and urine by high-performance liquid chromatography and gas chromatography-mass spectrometry.

Simple and reproducible high-performance liquid chromatographic (HPLC) and gas chromatographic-mass spectrometric (GC-MS) methods have been developed for the simultaneous analysis of several acidic drugs in horse plasma and urine. Although the capillary GC-MS column provided better separation of the drugs than the reversed-phase C8 (3 microns, 75 mm) HPLC column, the total analysis time with HPLC was shorter than the total analysis time with GC-MS. The HPLC system equipped with a diode-array detector provided simultaneous screening (limit of detection 100-500 ng/ml) and confirmation (limit 1.0 micrograms/ml) of the drugs. The HPLC system equipped with fixed-wavelength ultraviolet and fluorescence detectors provided a relatively sensitive screening [limit of detection 50-150 ng/ml for ultraviolet and 10 ng/ml for fluorescence (naproxen only) detectors] of the drugs. However, the positive samples had to be confirmed by using either the diode-array detector or the GC-MS system. The GC-MS system provided simultaneous screening and confirmation of the drugs at very low concentrations (20-50 ng/ml).

Analgesics↗
PubMed1991

Evaluation of receptor mechanism mediating fentanyl analgesia and toxicity.

In the present study the antagonism of fentanyl pharmacodynamics was studied in the mouse and the receptor populations mediating the analgesic and lethal effects of fentanyl were examined. Both 1 and 8 days following implantation (s.c.) of a 15 mg naltrexone pellet there was a significant shift to the right of the fentanyl dose-response curves for analgesia and lethality. The analgesia dose-response curves were shifted significantly more (80- to 264-fold) than the lethality curves (13- to 16-fold) in the presence of naltrexone. In addition, acute naloxone (0.1 mg/kg s.c.), antagonized fentanyl analgesia more than lethality. Consequently, the relative safety ratio of fentanyl (LD50/ED50) was decreased in the presence of opioid antagonists. Pretreatment with naloxonazine (35 mg/kg s.c.) 24 h prior to testing effectively inhibited fentanyl-induced analgesia, but not fentanyl-induced lethality. However, pretreatment with beta-funaltrexamine (beta-FNA) (20 mg/kg, s.c.) 24 h prior to testing inhibited both fentanyl-induced analgesia and lethality. Implantation (s.c.) of a 75 mg morphine pellet for 72 h resulted in cross-tolerance to both fentanyl analgesia and lethality. However, the degree of the cross-tolerance was 1.8-fold for analgesia and 4.5-fold for lethality. Displacement studies of [3H]naltrexone by fentanyl in mouse brain homogenate indicated two populations of binding sites. Taken together, the pharmacodynamic studies and the binding studies suggest that fentanyl exerts its analgesic and lethal effects through different receptor populations.

Analgesics↗
PubMed1991

Modification of morphine-induced analgesia and toxicity by pertussis toxin.

The present study evaluates the effect of pertussis toxin (PTX) on morphine-induced analgesia and lethality. Mice were injected with 0.2 microgram PTX intracerebroventricularly (i.c.v.) and 0.2 micrograms PTX intrathecally (i.t.) or saline. Mice were tested for morphine-induced analgesia (tail flick) and lethality 16 days later; mice were also examined for pentobarbital-induced mortality. Morphine analgesic potency was decreased by approximately 4-fold in PTX-treated mice compared to controls. Conversely, the lethal potency of morphine was increased by 10-fold in PTX-treated mice compared to controls. PTX treatment did not alter the lethal potency of pentobarbital. Morphine-induced analgesia and lethality were dose-dependently antagonized by naloxone in both PTX and saline-treated groups. The results of this study suggest that morphine analgesia is mediated through PTX-sensitive G proteins. On the other hand, morphine-induced lethality appears to be limited by PTX-sensitive factor(s) since PTX treatment enhanced morphine's lethal potency. The increase in lethal potency of morphine may be due to unmasking of an excitatory opioid receptor mediated effect by PTX.

Analgesia↗
PubMed1984

Myelin development in infant brain.

Myelin was isolated from subcortical areas of ten human brains, with ages ranging from 24 days to 350 days-of-age; samples were subsequently analyzed for lipid composition. Eight infants were victims of Sudden Infant Death Syndrome, and two infants were accident cases. Gray and white matter samples from each brain were also dissected and analyzed. Galactolipids were only 12% of the total lipids in white matter from brains of infants that were 24 days-of-age, a time when myelination was just starting in the subcortical areas. At 175 and 350 days of age, myelination was well underway and galactolipids measured 22% of the total lipids. Total phospholipids decreased (65% to 54%) in white matter during development, with the decrease mostly in phosphatidylcholine (23% to 15%). Even though there was little white matter present at early ages, myelin could be isolated. Surprisingly, the lipid composition of myelin from the 24-day-infant brain was similar to that from adult brain. Galactolipids were 22% of the total lipids, cholesterol, 23%, and phospholipids, 52%. These results suggest that only subtle remodeling of myelin occurs in humans once myelination commences. All four major gangliosides were present in myelin during this first year of development. Interestingly, the yield of myelin from the 350-day-old infant subcortical white matter was similar to that from an adult. Thus major tracts in this area may have acquired most of the myelin by one year-after-birth. Since the control samples blend quite well into the developmental pattern obtained, it is believed there are no abnormalities in myelin lipids from SIDS infants.

Brain↗
PubMed1983

Comparison of lipids and lipid metabolism in a human glioma cell line, its clone, and oligodendroglia.

The human glioma cell line D-54 MG and one of its single-cell-derived clones exhibit some properties of oligodendroglia, including surface antigens, enzymatic activity, and absence of markers for astrocytes. The glioma cells were further examined for glycolipids characteristic of oligodendroglia. The glioma cells had only about 2% of the total lipids as galactolipids while oligodendroglia have 10%. Incorporation studies showed only 25% of the incorporation of galactose into galactolipids as found in oligodendroglia. Sphingomyelin and phosphatidylinositol appeared to be increased. Several phospholipids exhibited high levels of incorporation of substrates, e.g., phosphatidylcholine and phosphatidylinositol. The ganglioside patterns were much less complex for the glioma cells. Thus, the glioma cells have greatly decreased amounts of glycolipids when compared to oligodendroglia. This finding is consistent with the theory that the loss of glycolipids on the cell surface may lead to the loss of regulation of contact inhibition.

Acetates↗
PubMed1982

Biochemical studies of the late infantile form of metachromatic leukodystrophy.

Biochemical studies from a patient with the late infantile form of metachromatic leukodystrophy are presented. Since the autopsy was performed soon after death, viable cells were isolated from brain. The purified cells had altered densities and unusual appearances. The cells when placed in culture were able to incorporate radiolabeled substrates into cerebrosides, indicating that some of the cells were of oligodendroglial origin. Myelin was isolated using several different methods, and the degree of abnormality appeared to be dependent upon the method of isolation. Nonetheless, MLD myelin, while still retaining its characteristic-morphology, had increased levels of sulfatides (two to four times that normally found). Other membrane subfractions were isolated that were not present in control tissue and that were more abnormal in composition than myelin. Finally, the glycoproteins in MLD tissue also appeared to be altered. There were losses in MLD myelin glycoproteins that bind to Concanavalin A (Con A) and additional prominent glycoproteins that bind to wheat germ agglutinin.

Autopsy↗
PubMedDate not supplied

123I-MIBG myocardial scintigraphy as a noninvasive screen for the diagnosis of coronary artery spasm.

BACKGROUND: It has been suggested that the sympathetic nervous system might play an important role in the development of coronary artery spasm. However, no cardiac imaging modality has been able to demonstrate abnormal sympathetic innervation in patients with coronary artery spasm. The purpose of this study was to assess the presence and location of abnormal sympathetic innervation using iodine 123-metaiodobenzylguanidine (123I-MIBG) single photon emission computed tomography (SPECT) and to evaluate the clinical efficacy of 123I-MIBG SPECT as a noninvasive screening test in patients with coronary artery spasm. METHODS AND RESULTS: Coronary arteriography and a provocative test with intravenous administration of ergonovine maleate were performed in 26 patients (20 men, 6 women, mean age 48.2+/-12.0 years, range 20 to 67 years) who were suspected of having a coronary artery spasm. The subjects were divided into 2 groups: group 1 (n = 18) comprised subjects with a positive provocative test result, and group 2 (n = 8) comprised subjects with negative provocative test results. Ten healthy subjects served as controls. No abnormal MIBG uptake was observed in the control subjects. Abnormal sympathetic nervous innervation using 123I-MIBG SPECT was observed either as a reduced uptake or a defective pattern in the perfused areas in 13 of the 18 regions supplied by vessels of ergonovine-induced vasospasm. Normal sympathetic innervation, as evidenced by normal 123I-MIBG uptake, was noted in all of the 60 segments of normal vessel territories. Reduced uptake of 123I-MIBG was not detected in the perfused areas of 5 vasospasm-induced vessels (perfusion territory of left anterior descending coronary artery [LAD] and the right coronary artery [RCA] in 2 and 3 patients, respectively). The sensitivity and specificity of 123I-MIBG for detection of coronary artery spasm were 72.2% (95% confidence interval [CI] 55% to 89%) and 100%, respectively. The positive predictive and negative predictive values were 100% and 92.3% (95% CI 91% to 93%), respectively. CONCLUSION: 123I-MIBG SPECT is a feasible method to evaluate noninvasively and localize the territories of coronary arteries with spasm. Invasive diagnostic coronary arteriography with ergonovine provocation test may be unnecessary for diagnosis of coronary artery spasm in patients with typical resting pain, negative exercise test or normal thallium perfusion scan results, but showing abnormalities in 123I-MIBG SPECT.

3-Iodobenzylguanidine↗