Biomedical subjects

Y Yoon

Publications and source records attributed to Y Yoon.

At least 37 records · Page 2Linked to original sources

PubMed2000

New antiepileptic drugs and preparations.

Epilepsy affects 1.2% to 4.4% of the general population. Given the clinical profile of the newer antiepileptic agents, it is likely their usage will increase in the coming years, thus increasing the emergency physician's exposure to these medications and their side effects. Several of these side effects can have high morbidity, such as the aplastic anemia and hepatotoxicity caused by felbamate, and the Stevens-Johnson syndrome associated with lamotrigine. Overdoses of these medications also could increase, as will our knowledge of recognizing and managing them. The clinical spectrum of the newer medications is the treatment of partial seizures. None of the newer medications can be orally loaded nor are they available in an i.v. preparation. Serum drug levels are not available in most institutions and are not routinely measured in the ED. The new preparations of phenytoin, diazepam, and valporic acid add increased efficiency in drug administration, providing a new method for prehospital treatment of seizures and a more tolerable means of administration in the ED.

Acetates↗

PubMed2000

The dynamin family of mechanoenzymes: pinching in new places.

The large GTPase dynamin is a mechanoenzyme that mediates the liberation of nascent clathrin-coated pits from the plasma membrane during endocytosis. Recently, this enzyme has been demonstrated to comprise an extensive family of related proteins that have been implicated in a large variety of vesicle trafficking events during endocytosis, secretion and even maintenance of mitochondrial form. The potential contributions by the dynamin family to these diverse but related functions are discussed.

Actins↗

PubMed2000

Treatment of prostatic abscess: value of transrectal ultrasonographically guided needle aspiration.

The purpose of this study was to assess the effectiveness of transrectal ultrasonographically guided needle aspiration in the treatment of prostatic abscess. Fourteen patients with prostatic abscess were evaluated with this technique and treated with sonographically guided needle aspiration. Using this technique, all cases (100%) had one or more hypoechoic areas within the prostate that contained inhomogeneous materials; in 10 patients (71.0%), the lesion showed internal septa or solid portion. The margins of the hypoechoic area were well defined and thick in 11 patients (79.0%) and poorly defined in 3 patients (21.0%). The estimated volume of the prostatic abscess ranged between 2 and 28 ml (mean, 12.0 ml). The presence of a pus collection within the prostate was confirmed by transrectal ultrasonographically guided aspiration in all patients. However, successful treatment of prostatic abscess with transrectal needle aspiration was done in 12 (86.0%) of 14 patients; the treatment failed in 2 (14.0%) of 14 patients. One patient was treated with perineal incision and drainage and the other with transurethral resection. The amount of pus drained ranged between 1 and 39 ml (mean, 12.0 ml). On follow-up transrectal ultrasonographic examination, no remaining abscess pocket was found within the prostate in any of the cases. One year later, the prostatic abscess recurred in one case. In conclusion, transrectal ultrasonographic guidance is useful in the diagnosis of prostatic abscess as well as in the guidance for aspiration and the drainage of such abscesses. Transrectal ultrasonographically guided needle aspiration could be an effective method for treating prostatic abscess.

Abscess↗

PubMed2000

Plasma nitric oxide concentrations and nitric oxide synthase gene polymorphisms in coronary artery disease.

BACKGROUND: Plasma NOx (nitrate and nitrite) is a stable end product of the vasodilator NO. Several polymorphisms in the endothelial constitutive NO synthase (ecNOS) gene have been reported, including the 4a/4b VNTR polymorphism in intron 4, the E298D mutation in exon 7, and the G10-T polymorphism in intron 23. The aims of this study were to examine plasma NOx in patients with coronary artery disease (CAD) and to assess the association between plasma NOx concentrations and the three ecNOS gene polymorphisms. METHODS: Plasma NOx was measured in samples from 128 healthy controls and from 110 CAD patients at least 2 months after myocardial infarction. Three genetic polymorphisms that are known or have been suggested to be associated with plasma NOx concentration were also analyzed by PCR-restriction fragment length polymorphism. RESULTS: Median plasma NOx was significantly higher (P <0.001) in CAD patients (95.9 micromol/L) than in controls (73.8 micromol/L). Furthermore, the median plasma NOx was significantly higher (P <0.001) in hypertensive CAD patients (116.0 micromol/L) than in controls and normotensive CAD patients (86.0 micromol/L). The G-allele frequency of the G10-T polymorphism in intron 23 was significantly higher in CAD patients than in controls. Other polymorphisms showed no differences in allelic frequencies among the control and CAD groups. In controls, individuals with the E298D mutation in exon 7 (136.1 micromol/L) showed significantly higher (P = 0.001) median plasma NOx than those without this mutation (64.5 micromol/L). CONCLUSIONS: Plasma NOx was higher in hypertensive CAD patients than in normotensive CAD patients and controls. The E298D polymorphism of the ecNOS gene was associated with increased plasma NOx. Further study is needed to understand the gene expression and enzyme activity of ecNOS and their association with genotypes.

Aged↗

PubMed2000

Expression of molecular messages for angiogenesis by fibroblasts from aneurysmal abdominal aorta versus dermal fibroblasts.

BACKGROUND: The molecular messages which drive angiogenesis in the adventitia of an aneurysmal aorta are uncertain. The emergence of molecular phenotyping by cDNA expression arrays provides a simple and rapid method for a preliminary approach to the analysis of molecular messengers for neovascularization in cultured cells. In the present experiment, fibroblasts cultured from the aorta of a patient with abdominal aortic aneurysm (AAA) were compared with normal dermal fibroblasts, on an array that evaluates several mRNAs with known roles in angiogenesis. METHODS: RNA was isolated from fibroblasts and purified. Labelled cDNA probes were generated from a mixture of RNA and CDS primers. Atlas Array membranes (Clontech) were prehybridized by ExpressHyb buffer. The cDNA probes were then added to the membranes, which were exposed to Phospholmage Screen (Molecular Dynamics) and analysed by a dedicated computer program. RESULTS: The most significantly upregulated mRNAs in AAA (by comparison to dermal fibroblasts) were: MCAF, MDNCF, EGR-1, VEGF, FGF-7, Mal protein, Mac Marcks, Transducin, Interleukin-9 receptor, and TNF. CONCLUSION: VEGF and TNF were upregulated, as expected. However, the upregulation of monocyte chemotactic and activating factor (MCAF) and monocyte-derived neutrophil chemotactic factor (MDNCF) suggest that the fibroblast may be more significantly involved in driving the inflammatory response that leads to AAA than previously realized.

Aortic Aneurysm, Abdominal↗

PubMed1999

Tanshinone IIA, an ingredient of Salvia miltiorrhiza BUNGE, induces apoptosis in human leukemia cell lines through the activation of caspase-3.

Tanshinone II-A is a derivative of phenanthrene-quinone isolated from Salvia miltiorrhiza BUNGE, a traditional herbal medicine that is known to induce antiinflammatory, anti-oxidative and cytotoxic activity. We have examined cellular effects of Tanshione II-A on HL60 human promyelocytic leukemic cells and K562 human erythroleukemic cells. Tanshione II-A induced a dose- and time-dependent DNA fragmentation into the multiples of 180 bp and specific proteolytic cleavage of poly(ADP-ribose) polymerase in both cell lines. PI-staining and flow cytometry analysis of K562 cells following Tanshione II-A treatment showed an increase of the cells possessing hypodiploid DNA indicative of apoptotic state of cells. Caspase-3 activity was significantly increased during Tanshinone II-A treatment of both HL60 and K562 cells, whereas caspase-1 activity was not changed. These results suggest that Tanshione II-A induced HL60 and K562 cellular apoptosis that may be associated with the selective members of caspase family.

Abietanes↗

PubMed1999

Usefulness of cilostazol versus ticlopidine in coronary artery stenting.

A combination of ticlopidine and aspirin has been accepted as the standard antithrombotic regimen after coronary stenting. However, ticlopidine poses serious side effects such as neutropenia or thrombocytopenia. Cilostazol, a cyclic adenosine monophosphate phosphodiesterase inhibitor, is a novel antiplatelet agent with vasodilatory properties. We compared the efficacy and safety of cilostazol plus aspirin (C+A) with ticlopidine plus aspirin (T+A) in elective coronary stenting. Three hundred patients were randomly assigned to receive C+A or T+A 2 days before stenting. The primary end point was a composite of angiographic stent thrombosis, or major cardiac events (death, myocardial infarction, bypass surgery, repeat intervention) at 30 days. The secondary end points were bleeding vascular complications, neutropenia, thrombocytopenia, or side effects requiring discontinuation of the drugs at 30 days. The primary end point was reached in 1.4% in the C+A group and 2.0% in the T+A group (p = 1.0). The rate of bleeding vascular complications was 1.4% in the C+A group and 2.0% in the T+A group (p = 1.0). The rate of drug-related side effects was not statistically different between the 2 groups but slightly higher in the T+A group than in the C+A group (2.7% vs 0.7%, p = 0.37). However, neutropenia was seen in 2 patients only in the T+A group. As a poststenting antithrombotic, C+A is as effective as T+A in preventing major cardiac events including stent thrombosis, and safer in that it does not cause neutropenia despite the fact that there is no statistical difference in the incidence of adverse effects and complications.

Adult↗

PubMed1999

Tanshinone IIA isolated from Salvia miltiorrhiza BUNGE induced apoptosis in HL60 human premyelocytic leukemia cell line.

Apoptosis is a new therapeutic target of cancer research. Tanshinone IIA isolated from Salvia miltiorrhiza BUNGE, a traditional oriental medical herb, was observed to induce apoptosis in HL60 human premyelocytic leukemia cell line. Tanshinone IIA induced DNA fragmentation into the multiples of 180 bp and increased the percentage of hypodiploid cells in flow cytometry after propidium iodide (PI) staining. Tanshinone IIA-induced apoptosis is accompanied by the specific proteolytic cleavage of poly(ADP-ribose) polymerase (PARP) and the activation of caspase-3, a major component in apoptotic cell death mechanism.

Abietanes↗

PubMed1999

Murine Siva-1 and Siva-2, alternate splice forms of the mouse Siva gene, both bind to CD27 but differentially transduce apoptosis.

CD27, a member of the TNFR family known to provide essential co-stimulatory signals for T cell growth and B cell Ig synthesis, can also mediate cell death. Using the CD27 cytoplasmic tail as the bait in yeast two hybrid assay, we previously cloned human Siva, a pro-apoptotic molecule. Here we report the characterization of the mouse Siva gene as a 4 kb sequence containing 4 exons and 3 introns. RT-PCR has revealed the presence of two forms of mouse Siva mRNA, the longer full length form Siva-1 and the shorter Siva-2 lacking the sequence coded by exon 2. Immunoblotting with anti-Siva (human) antibodies clearly demonstrate the presence of both Siva-1 and Siva-2. Cotransfection experiments in 293T cells reveal that mouse CD27 receptor can interact with both forms of Siva. Although mouse Siva-1 can trigger apoptosis in Rat-1 cells and in some of the mouse cell lines in transient transfection experiments, similar to the observation made with human Siva, intriguingly its alternate splice form, Siva-2 appears to be much less toxic. It is therefore likely that Siva-2 could regulate the function of Siva-1.

3T3 Cells↗

PubMed1999

Shikonin, an ingredient of Lithospermum erythrorhizon induced apoptosis in HL60 human premyelocytic leukemia cell line.

Apoptosis is a new therapeutic target of cancer research. Shikonin isolated from Lithospermum erythrorhizon, a traditional oriental medicinal herb, was observed to induce apoptosis in HL60 human premyelocytic leukemia cell line. Shikonin induced DNA fragmentation into the multiples of 180 bp and increased the percentage of hypodiploid cells in flow cytometry after propidium iodide staining. The increase of apoptotic cells was preceded by the activation of caspase-3, which was reported to play a central role in apoptotic process. The DNA fragmentation induced by shikonin was completely inhibited by the pretreatment of z-VAD-fmk, a specific inhibitor of caspase, clearly showing that the mode of cell death is apoptotic.

Antineoplastic Agents, Phytogenic↗

PubMed1999

The dynamin-like protein DLP1 is essential for normal distribution and morphology of the endoplasmic reticulum and mitochondria in mammalian cells.

The dynamin family of large GTPases has been implicated in vesicle formation from both the plasma membrane and various intracellular membrane compartments. The dynamin-like protein DLP1, recently identified in mammalian tissues, has been shown to be more closely related to the yeast dynamin proteins Vps1p and Dnm1p (42%) than to the mammalian dynamins (37%). Furthermore, DLP1 has been shown to associate with punctate vesicles that are in intimate contact with microtubules and the endoplasmic reticulum (ER) in mammalian cells. To define the function of DLP1, we have transiently expressed both wild-type and two mutant DLP1 proteins, tagged with green fluorescent protein, in cultured mammalian cells. Point mutations in the GTP-binding domain of DLP1 (K38A and D231N) dramatically changed its intracellular distribution from punctate vesicular structures to either an aggregated or a diffuse pattern. Strikingly, cells expressing DLP1 mutants or microinjected with DLP1 antibodies showed a marked reduction in ER fluorescence and a significant aggregation and tubulation of mitochondria by immunofluorescence microscopy. Consistent with these observations, electron microscopy of DLP1 mutant cells revealed a striking and quantitative change in the distribution and morphology of mitochondria and the ER. These data support very recent studies by other authors implicating DLP1 in the maintenance of mitochondrial morphology in both yeast and mammalian cells. Furthermore, this study provides the first evidence that a dynamin family member participates in the maintenance and distribution of the ER. How DLP1 might participate in the biogenesis of two presumably distinct organelle systems is discussed.

Animals↗

PubMed1998

A novel dynamin-like protein associates with cytoplasmic vesicles and tubules of the endoplasmic reticulum in mammalian cells.

Dynamins are 100-kilodalton guanosine triphosphatases that participate in the formation of nascent vesicles during endocytosis. Here, we have tested if novel dynamin-like proteins are expressed in mammalian cells to support vesicle trafficking processes at cytoplasmic sites distinct from the plasma membrane. Immunological and molecular biological methods were used to isolate a cDNA clone encoding an 80-kilodalton novel dynamin-like protein, DLP1, that shares up to 42% homology with other dynamin-related proteins. DLP1 is expressed in all tissues examined and contains two alternatively spliced regions that are differentially expressed in a tissue-specific manner. DLP1 is enriched in subcellular membrane fractions of cytoplasmic vesicles and endoplasmic reticulum. Morphological studies of DLP1 in cultured cells using either a specific antibody or an expressed green fluorescent protein (GFP)- DLP1 fusion protein revealed that DLP1 associates with punctate cytoplasmic vesicles that do not colocalize with conventional dynamin, clathrin, or endocytic ligands. Remarkably, DLP1-positive structures coalign with microtubules and, most strikingly, with endoplasmic reticulum tubules as verified by double labeling with antibodies to calnexin and Rab1 as well as by immunoelectron microscopy. These observations provide the first evidence that a novel dynamin-like protein is expressed in mammalian cells where it associates with a secretory, rather than endocytic membrane compartment.

Alternative Splicing↗

PubMed1998

Ethanol-induced alterations of the microtubule cytoskeleton in hepatocytes.

Ethanol has been predicted to alter vesicle-based protein traffic in hepatocytes, in part, via a disruption of the microtubule (MT) cytoskeleton. However, information on the effects of chronic ethanol exposure on MT function in vivo is sparse. Therefore the goal of this study was to test for ethanol-induced changes in rat liver tubulin expression, assembly, and cellular organization, using molecular, biochemical and morphological methods. The results of this study showed that tubulin mRNA and protein levels were not altered by ethanol. Tubulin, isolated from control and ethanol-fed rats, showed similar polymerization characteristics as assessed by calculation of the critical concentration for assembly and morphological structure. In contrast, the total amount of assembly-competent tubulin was reduced in livers from ethanol-fed rats compared with control rats when assessed by quantitative immunoblot analysis using a tubulin antibody. In addition, we observed that MT regrowth and organization in cultured hepatocytes treated with cold and nocodazole was markedly impaired by chronic ethanol exposure. In summary, these results indicate that tubulin levels in liver are not reduced by ethanol exposure. While there is a substantial amount of tubulin protein capable of assembling into functional MTs in ethanol-damaged livers, a marked portion of this tubulin is polymerization incompetent. This may explain why these hepatocytes exhibit a reduced number of MTs with an altered organization.

Animals↗

PubMed1997

Insulin has a limited effect on the cell cycle progression in 3T3 L1 fibroblasts.

Insulin has pleiotropic effects on the regulation of cellular growth, differentiation, and metabolism. The biochemical events ultimately leading to cell proliferation after insulin treatment have been demonstrated in detail by numerous research groups. However, depending on cell types, it has been shown that insulin has various effects on cell proliferation. Therefore, we attempted to more critically evaluate the effect of insulin on cell proliferation in 3T3 L1 fibroblasts. In this study, we investigated insulin's effect on cell proliferation by using [3H]thymidine incorporation, flow cytometry, and cell counting. In 3T3 L1 fibroblasts studied in 0.5% serum, insulin induced a two-fold increase in [3H]thymidine incorporation over at 48 h, and the maximal rate of DNA synthesis was observed during 8-12 h incubation. The flow cytometric analysis also showed that insulin increased the cell population in the S phase. After insulin treatment for 48 h, cell numbers increased approximately 45% in comparison with 0.5% serum control. Cell division was found to occur only once in 60 h after staining 3T3 L1 fibroblasts with carboxyfluorescein diacetate succinimidyl ester (CFSE). Taken together, this data indicates that insulin stimulated the transit from the G0/G1 to S phase, progressed the cell cycle through the G2/M phase, and increased the cell number. However, under our experimental conditions, cells divided only once in 60 h in the presence of insulin.

3T3 Cells↗

PubMed1997

CD27, a member of the tumor necrosis factor receptor family, induces apoptosis and binds to Siva, a proapoptotic protein.

Members of the tumor necrosis factor receptor (TNFR) superfamily are important for cell growth and survival. In addition to providing costimulatory signals for cell proliferation, ligation of both TNFR1 and Fas can result in programmed cell death or apoptosis. The underlying mechanism requires an intact 80-aa stretch present in the cytoplasmic tails of both TNFR1 and Fas, termed the death domain (DD). Here we show that CD27, a member of the TNFR family, expressed on discrete subpopulations of T and B cells and known to provide costimulatory signals for T and B cell proliferation and B cell Ig production, can also induce apoptosis. Co-crosslinking of surface Ig receptors along with ligation of CD27 augments CD27-mediated apoptosis. Unlike TNFR1 and Fas, the cytoplasmic tail of CD27 is relatively short and lacks the DD. Using the yeast two-hybrid system, we have cloned a novel protein (Siva) that binds to the CD27 cytoplasmic tail. It has a DD homology region, a box-B-like ring finger, and a zinc finger-like domain. Overexpression of Siva in various cell lines induces apoptosis, suggesting an important role for Siva in the CD27-transduced apoptotic pathway.

Amino Acid Sequence↗

PubMed1997

Primers determine the sensitivity of PCR-mediated hepatitis B virus DNA detection and pretreatment of PCR mixture with 8-methoxypsoralen eliminates false-positive results.

Most methods for the diagnosis of hepatitis B virus (HBV) infection largely depend on viral DNA detection by polymerase chain reaction (PCR) or radioimmunological assay of viral antigens or antibodies. The quality assurance program recently established in Europe reported that PCR-mediated HBV DNA detection methods used in many laboratories produced a high rate of false-positive and false-negative results. Thus, we attempted to improve the conditions of current PCR methods for detection of HBV DNA. In the present study, we applied a recently developed method of releasing HBV DNA from virion by NaOH treatment of patient serum. Using four different primer sets specific to the HBV core region, we found that the sensitivity of first-round PCR can be improved by more than two orders of magnitude depending on the primers. The second round of PCR using nested primers was sensitive enough to detect up to 10(-6) pg of the HBV DNA, which is equivalent to approximately 3 copies of the HBV genome. Among the approximately 800 HBV-infected patient sera investigated in our laboratory, more than 60% of the tested samples gave positive results in the first-round PCR. The rate of positive results obtained using our experimental conditions is very high in comparison with other reports. The reamplification of the first-round PCR reaction mixture with the nested primers produced practically 100% positive results. For diagnosis of HBV infection, we routinely used 1 microliter of patient serum, which was found to be optimum in our laboratory. Surprisingly, from 20% of our positive results, even serum diluted to 1/100 (0.01 microliter) produced a stronger signal than 1 microliter. This observation suggests that direct PCR amplification of HBV DNA released from serum by NaOH treatment has to be compensated by other DNA detection methods for correct quantitation. In order to eliminate the false positive signal resulting from the carry-over due to massive screening of a large number of samples, PCR reaction mixture containing 8-methoxypsoralen was exposed to ultraviolet light prior to thermal cycle amplification. This exercise did not decrease the sensitivity of the detection method, but almost completely removed the false positive results caused by contaminated templates. We are in the process of improving PCR-mediated HBV DNA detection methods to attain more reliable and easily applicable methods.

Base Sequence↗

PubMed1997

Characterization of gamma-tubulin complexes in Aspergillus nidulans and detection of putative gamma-tubulin interacting proteins.

gamma-Tubulin is central to the nucleation of microtubule assembly in vivo. Although it is most obviously located at microtubule organizing centers, it is also found in soluble cytoplasmic complexes. Characterizing these complexes and identifying proteins that interact with gamma-tubulin in vivo will be necessary if gamma-tubulin function is to be understood fully. We have begun to investigate soluble complexes of gamma-tubulin in Aspergillus nidulans, the organism in which gamma-tubulin was discovered and in which a great deal of genetic and molecular genetic analysis of gamma-tubulin has been carried out. We find that approximately 32% of the gamma-tubulin in A. nidulans is soluble. Sucrose density gradients revealed that the soluble gamma-tubulin is in 8-20S complexes with little or no monomeric gamma-tubulin present. In the presence of 0.5 M KCl the average size of the complexes decreased and a peak was present between 4S and 11S. Cross-linking experiments with a zero-length cross-linker suggest that gamma-tubulin in isolated nuclei and in intact hyphae interacts physically with three proteins with molecular weights of approximately 105, 95, and 80 kDa.

Aspergillus nidulans↗

PubMed1996

Intravenous opioids stimulate norepinephrine and acetylcholine release in spinal cord dorsal horn. Systematic studies in sheep and an observation in a human.

BACKGROUND: Opioids produce analgesia by direct effects as well as by activating neural pathways that release nonopioid transmitters. This study tested whether systematically administered opioids activate descending spinal noradrenergic and cholinergic pathways. METHODS: The effect of intravenous morphine on cerebrospinal fluid and dorsal horn microdialysate concentrations of norepinephrine and acetylcholine was examined in 20 sheep. Animals received either intravenous morphine or fentanyl alone, or morphine plus intravenous naloxone or intrathecal idazoxan. RESULTS: Intravenous morphine (0, 0.5, 1 mg/kg, intravenous) produced dose-dependent increases in cerebrospinal fluid norepinephrine and acetylcholine, but not epinephrine or dopamine. Morphine's effect was blocked by intravenous naloxone and by intrathecal idazoxan. In microdialysis experiments, intravenous morphine increased the concentration of norepinephrine and acetylcholine, but not epinephrine or dopamine, in the dorsal horn. In contrast, intravenous morphine exerted no effect on any of these monoamines in the ventral horn. Intravenous naloxone and cervical cord transection each blocked morphine's effect on dorsal horn norepinephrine. CONCLUSIONS: These results support functional studies that indicate that systematically administered opioids cause spinal norepinephrine and acetylcholine release by a naloxone-sensitive mechanism. Idazoxan blockade of morphine's effects on cerebrospinal fluid norepinephrine was unexpected, and suggests that both norepinephrine and acetylcholine release in the spinal cord may be regulated by alpha 2-adrenoceptors. Microdialysis experiments suggest increased norepinephrine and acetylcholine levels in cerebrospinal fluid resulted from intravenous morphine-induced activation of bulbospinal pathways.

Acetylcholine↗