Search PubMed⌕ Search

Biomedical subjects

Y H Jin

Publications and source records attributed to Y H Jin.

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

Characterization of electrogenic Na/K pump in rat neostriatal neurons.

The electrogenic Na/K pump current (Ip) was studied in the dissociated neostriatal neurons of the rat by using the nystatin-perforated patch recording mode. The Ip was activated by external K+ in a concentration-dependent manner with an EC50 of 0.7 mM at a holding potential (VH) of -40 mV. Other monovalent cations also caused Ip and the order of potency was Tl+>K+, Rb+>NH4+, Cs+>>>Li+. The Ip decreased with membrane hyperpolarization in an external solution containing 150 mM Na+, while the Ip did not show such voltage dependency without external Na+. Ouabain showed a steady-state inhibition of Ip in a concentration- and temperature-dependent manner at a VH of -40 mV. The IC50 values at 20 and 30 degrees C were 7.1 x 10(-6) and 1.3 x 10(-6) M, respectively. The decay of Ip after adding ouabain well fitted with a single exponential function. At a VH of -40 Mv, the association (k+1) and dissociation (k-1) rate constants estimated from the time constant of the current decay at 20 degrees C were 4.0 x10(2) s-1 M-1 and 6.3 x 10(-3) s-1, respectively. At 30 degrees C, k+1 increased to 2.8 x 10(3) s-1 M-1 while k-1 showed no such change with a value of 1.8 x 10(-3) s-1. A continuous Na+ influx was demonstrated by both the Na+-dependent leakage current and tetrodotoxin-sensitive Na+ current, which resulted in the continuous activation of the Na/K pump. It was thus concluded that the Na/K pump activity was well-maintained in the dissociated rat neostriatal neurons with distinct functional properties and that the activity of the pump was tightly connected with Na+ influxes.

Animals↗
PubMed1998

Developmental changes of GABA(A) receptor-chloride channels in rat Meynert neurons.

The developmental changes of GABA(A) receptors were investigated in Meynert neurons freshly dissociated from day 0, 2 week-, and 6 month-old rats using both nystatin and gramicidin perforated patch recording modes under voltage-clamp conditions. The age-related changes in the current amplitude and threshold concentration in the concentration-response relationships for GABA indicated the developmental alteration of the GABA(A) receptor subunits and the channel density. The GABA-induced E(Cl-) measured by the gramicidin perforated patch mode shifted to more negative with development. The decay time constant of GABAergic inhibitory postsynaptic spontaneous currents (sIPSCs) in the synaptic active zone accelerated with aging. The GABA-induced currents were potentiated in a concentration dependent manner in the presence of benzodiazepine (BZP) agonists, diazepam (DZP) and zolpidem (ZPM). The potentiation rate of DZP on the GABA(A) response decreased with aging, but not in the case of ZPM, which demonstrated a stronger action in the aging rat neurons. These results suggested that the GABA(A) receptor x Cl- channel complexes may thus change both the assembly and interaction of subunits as well as their functional roles with aging.

Animals↗
PubMed1998

Isolation and characterization of hrp1+, a new member of the SNF2/SWI2 gene family from the fission yeast Schizosaccharomyces pombe.

The SNF2/SWI2 ATPase/helicase family comprises proteins from a variety of species, which serve a number of functions, such as transcriptional regulation, maintenance of chromosome stability during mitosis, and various types of DNA repair. Several proteins with unknown functions are also included in this family. The number of genes that belong to this family is rapidly expanding, which makes it easier to analyze the common biological functions of the family members. This study was designed to clone the SNF2/SWI2 helicase-related genes from the fission yeast Schizosaccharomyces pombe in the hope that this would help to elucidate the common functions of the proteins in this family. The hrp1+ (helicase-related gene from S. pombe) gene was initially cloned by PCR amplification using degenerate primers based on conserved SNF2 motifs within the ERCC6 gene, which encodes a protein involved in DNA excision repair. The hrp1+ ORF codes for an 1373-amino acid polypeptide with a molecular mass of 159 kDa. Like other SNF2/SWI2 family proteins, the deduced amino acid sequence of Hrp1 contains DNA-dependent ATPase/7 helicase domains, as well as a chromodomain and a DNA-binding domain. This configuration is similar to that of mCHD1 (mouse chromo-ATPase/helicase-DNA-binding protein 1), suggesting that Hrp1 is a S. pombe homolog of mCHD1, which is thought to function in altering the chromatin structure to facilitate gene expression. Northern blot analysis showed that the hrp1+ gene produces a 4.6-kb transcript, which reaches its maximal level just before the cells enter the exponential growth phase, and then decreases gradually. DNA-damaging agents, such as MMS, MNNG and UV, decrease the rate of transcription of hrp1+. Deletion of the hrp1+ gene resulted in accelerated cell growth. On the other hand, overexpression of Hrp1 caused a reduction in growth rate. These results indicate that hrp1+ may act as a negative regulator of cellular growth.

Adenosine Triphosphatases↗
PubMed1998

Tandospirone-induced K+ current in acutely dissociated rat dorsal raphe neurones.

1. The effects of tandospirone (TDS) on dissociated rat dorsal raphe neurones were investigated using the patch-clamp method. 2. Under current-clamp conditions, TDS hyperpolarized the cell membrane, resulting in the reduction of firing rates. 3. Under voltage-clamp conditions, TDS induced an inward rectifying K+ current in a concentration-dependent manner. 4. The TDS-induced K+ currents (I(TDS)) were mimicked by 8-OH-DPAT, a 5-HT1A agonist. The I(TDS) was blocked by spiperone, a 5-HT1A receptor antagonist, in a concentration-dependent manner. 5. N-Ethylmaleimide, an agent which uncouples between the receptor and the G-protein, irreversibly blocked the I(TDS). 6. In neurones perfused intracellularly with a pipette-solution containing GTP using the conventional whole-cell patch recording, the I(TDS) showed a gradual rundown. When the neurones were perfused with GTPgammaS, TDS activated the inwardly rectifying K+ current in an irreversible manner. 7. In the inside-out patch recording mode, TDS-activated single K+ channel currents (i(TDS)) which also showed an inward rectification. When the GDP in cytosolic side was completely replaced with GTP, the open probability of i(TDS) significantly increased. 8. These results indicate that the activation of 5-HT1A receptors by TDS directly opens the inward rectifying K+ channels via a G-protein mediated process.

Animals↗
PubMed1998

Inhibitory effects of procainamide on rabbit platelet aggregation and thromboxane B2 production in vitro.

AIM: To study the influences of procainamide (PA) on thrombin-induced rabbit platelet aggregation and thromboxane B2 (TXB2) production in vitro. METHODS: Turbidimetry and radioimmunoassay were used. RESULTS: PA 8.5, 34, 136, and 544 mumol.L-1 inhibited thrombin-induced platelet aggregation and TXB2 production, and the inhibitory rates were 45% +/- 37%, 48% +/- 32%, 88% +/- 23%, 92% +/- 15% and 53% +/- 24%, 65% +/- 26%, 90% +/- 6%, 95% +/- 6%, respectively. There was positive correlation between PA concentration and efficiency of inhibition of platelet aggregation and TXB2 production, and also between the inhibition % of platelet aggregation and that of production of TXB2. The three linear equations and main parameters were Y = 0.2075X-4.9157, r = 0.9985; Y = 0.9546X-34.6724, r = 0.9921; Y = 0.8202X + 19.7062, r = 0.9921. CONCLUSION: PA inhibited thrombin-induced platelet aggregation and TXB2 production in rabbits.

Animals↗
PubMed1997

Effects of benzodiazepine receptor agonists in neurones acutely dissociated from the rat neostriatum.

To understand the properties of benzodiazepine receptor in the neostriatum, we examined the potentiating effects of diazepam, triazolam and brotizolam on the GABA(A) receptor-mediated Cl- current in dissociated rat neostriatal neurones using the nystatin-perforated patch recording configuration. Neurones were classified into large and small neurones, on their somatic size. In the large neurones, which are putative cholinergic interneurones, all the benzodiazepine receptor agonists recognized a single effective site. However, in the small neurones, which are mostly considered to be projecting neurones, the effect of brotizolam was best described when two effective sites were assumed. Therefore, the properties of benzodiazepine receptor differed among large and small neurones while at least two kinds of functional binding sites were also found to exist in small neurones.

Animals↗
PubMed1997

A new mouse gene, SRG3, related to the SWI3 of Saccharomyces cerevisiae, is required for apoptosis induced by glucocorticoids in a thymoma cell line.

We isolated a new mouse gene that is highly expressed in thymocytes, testis, and brain. This gene, SRG3, showed a significant sequence homology to SWI3, a yeast transcriptional activator, and its human homolog BAF155. SRG3 encodes 1,100 amino acids and has 33-47% identity with SWI3 protein over three regions. The SRG3 protein contains an acidic NH2 terminus, a myb-like DNA binding domain, a leucine-zipper motif, and a proline- and glutamine-rich region at its COOH terminus. Rabbit antiserum raised against a COOH-terminal polypeptide of the SRG3 recognized a protein with an apparent molecular mass of 155 kD. The serum also detected a 170-kD protein that seems to be a mouse homologue of human BAF170. Immunoprecipitation of cell extract with the antiserum against the mouse SRG3 also brought down a 195-kD protein that could be recognized by an antiserum raised against human SWI2 protein. The results suggest that the SRG3 protein associates with a mouse SWI2. The SRG3 protein is expressed about three times higher in thymocytes than in peripheral lymphocytes. The expression of anti-sense RNA to SRG3 mRNA in a thymoma cell line, S49.1, reduced the expression level of the SRG3 protein, and decreased the apoptotic cell death induced by glucocorticoids. These results suggest that the SRG3 protein is involved in the glucocorticoid-induced apoptosis in the thymoma cell line. This implicates that the SRG3 may play an important regulatory role during T cell development in thymus.

Amino Acid Sequence↗
PubMed1997

Identification and expression of uvi31+, a UV-inducible gene from Schizosaccharomyces pombe.

The Schizosaccharomyces pombe uvi31+ gene has been previously isolated as a UV-inducible gene [Lee JK et al. (1994) Biochem Biophys Res Commun 202:1113-1119]. This gene encodes a protein of about 12 kDa with 57% amino acid sequence similarity to Escherichia coli BolA protein which is known to be involved in switching between the cell elongation and septation systems during the cell division cycle. The putative Mlul cell cycle box (MCB), SWI4/6-dependent cell cycle box (SCB), and gear-box elements are found in the upstream region of uvi31+ gene, suggesting that this gene shows the cell cycle-regulated and growth phase-dependent expression. Interestingly, the level of uvi31+ transcript varies throughout the cell cycle, peaking in G1 phase before septation, and also shows the growth phase-dependent pattern during cellular growth, increasing maximally at the diauxic shift phase just before stationary phase. Furthermore, the transcript level of this gene is raised after S phase arrest, and is also increased maximally at 4 hr after UV irradiation of 240 J/m2. These results suggest that the delayed induction of uvi31+ gene after UV irradiation may be caused by cell cycle control of this gene after DNA replication checkpoint arrest. Thus, the uvi31+ gene may play a role in controlling the progress of the cell cycle after DNA damage (UV irradiation).

Amino Acid Sequence↗
PubMed1997

Pleomorphic adenoma of the trachea.

A case of salivary gland type pleomorphic adenoma of the trachea in a 48-year-old woman is presented. Pleomorphic adenoma is extremely rare in the trachea. The behavior of this tumor in the trachea appears to be similar to its counterpart in other sites and distinctly different from the more frequently encountered epithelial tumors.

Adenoma, Pleomorphic↗
PubMed1996

Identification of the DNA damage-responsive elements of the rhp51+ gene, a recA and RAD51 homolog from the fission yeast Schizosaccharomyces pombe.

The Schizosaccharomyces pombe rhp51+ gene encodes a recombinational repair protein that shares significant sequence identities with the bacterial RecA and the Saccharomyces cerevisiae RAD51 protein. Levels of rhp51+ mRNA increase following several types of DNA damage or inhibition of DNA synthesis. An rhp51::ura4 fusion gene was used to identify the cis-acting promoter elements involved in regulating rhp51+ expression in response to DNA damage. Two elements, designated DRE1 and DRE2 (for damage-responsive element), match a decamer consensus URS (upstream repressing sequence) found in the promoters of many other DNA repair and metabolism genes from S. cerevisiae. However, our results show that DRE1 and DRE2 each function as a UAS (upstream activating sequence) rather than a URS and are also required for DNA-damage inducibility of the gene. A 20-bp fragment located downstream of both DRE1 and DRE2 is responsible for URS function. The DRE1 and DRE2 elements cross-competed for binding to two proteins of 45 and 59 kDa. DNase I footprint analysis suggests that DRE1 and DRE2 bind to the same DNA-binding proteins. These results suggest that the DRE-binding proteins may play an important role in the DNA-damage inducibility of rhp51+ expression.

Base Sequence↗
PubMed1996

Differential expression of the rhp51+ gene, a recA and RAD51 homolog from the fission yeast Schizosaccharomyces pombe.

The rhp51+ gene encodes three transcripts of 1.9, 1.6 and 1.3 kb which have at least six polyadenylation sites. Primer-extension analysis revealed that two transcription start points (tsp) at - 166 and - 136 were responsible for the DNA damage inducibility of this gene. Northern blot analyses showed that the three transcripts were expressed differentially in response to a variety of DNA damage. During the mitotic cell cycle, only the largest transcript exhibited periodic expression, reaching the maximal level in front of the cdc22+ transcript which peaks at the G1/S boundary. Unexpectedly, the steady-state levels of the three transcripts were differentially regulated during the growth cycle. The largest and smallest transcripts accumulated in large quantity at the diauxic shift and during the entry into stationary phase, respectively. To localize the regions responsible for the differential expression of rhp51+, we constructed rhp51::ura4 and ura4::rhp51 hybrid genes, and analyzed their expression patterns in response to methyl methanesulfonate (MMS)-induced DNA damage. The results showed that the promoter region and 5' half of rhp51+ are sufficient to confer damage-responsiveness while the 3' end of the gene alone can direct the formation of multiple, discrete 3' ends of the transcripts. From these results, we conclude that this novel one gene-multiple product system is possible through the cooperation of both the promoter and 3' terminal regions.

Amino Acid Sequence↗
PubMed1996

Nonsurgical placement of a nasolacrimal polyurethane stent: long-term effectiveness.

PURPOSE: To evaluate the long-term effectiveness of a polyurethane stent in the treatment of obstruction of the lacrimal sac and the nasolacrimal duct. MATERIALS AND METHODS: Fluoroscopically guided placement of a polyurethane nasolacrimal stent was evaluated in 283 obstructed lacrimal systems of 236 patients, with a follow-up period of more than 1 year (range, 52-134 weeks). The obstruction was at the junction between the lacrimal sac and the nasolacrimal duct in 192 systems, at the lacrimal sac in 52, and at the nasolacrimal duct in 39. The causes of obstruction were traumatic in 34 and idiopathic in 249 systems. RESULTS: Stent placement was technically successful in 270 systems (95%). At 7 days after stent placement, 235 (87%) of the 270 systems with successful placement demonstrated complete resolution of epiphora, 27 (10%) had partial resolution, and the remaining eight (3%) had no resolution. There was recurrence in 81 systems due to obstruction of the stent (n = 77) or obstruction of the common canaliculus (n = 4). The recurrence rate was much higher in the systems with obstruction at the lacrimal sac (64%) than in the systems with obstruction at the junction (26%) between the lacrimal sac and nasolacrimal duct or at the nasolacrimal duct (15%). CONCLUSION: Stent placement in the obstructed lacrimal system below the junction between the lacrimal sac and the nasolacrimal duct is valuable as an initial therapy.

Adolescent↗
PubMed1995

Characterization of SFP2, a putative sulfate permease gene of Saccharomyces cerevisiae.

The SFP2 gene of Saccharomyces cerevisiae has been characterized. The deduced amino acid sequence contained twelve highly hydrophobic domains and showed 50, 47, 44 and 48% homologies to Neurospora crassa sulfate permease II (CYS14), soybean GMAK170 nodulin, human colon mucosa protein (DRA) and a putative open reading frame (ORF) downstream of Escherichia coli prs (phosphoribosyl pyrophosphatate synthetase) gene, respectively, in the aligned regions. Cells lacking SFP2 were viable and displayed no obvious decrease in their growth rate. Southern blot analysis revealed that SFP2 exists as a single copy in haploid genome. Northern blot analysis showed that SFP2 produced a 2.8-kb transcript which was highly expressed under sulfur derepressing condition. SFP2 mRNA was found to turn over with a half-life of approximately 15 min, which may contribute to the regulation of sulfate permease function, and reached its maximal level in about 22 h after depression.

Amino Acid Sequence↗
PubMed1995

Nonsurgical placement of a nasolacrimal polyurethane stent.

PURPOSE: To describe the placement of a nasolacrimal polyurethane stent with a new introducer set and hook. MATERIALS AND METHODS: The authors designed a soft polyurethane stent, an introducer that does not require balloon dilation, and a hook that can remove a ball-tipped guide wire from the inferior nasal meatus under fluoroscopic guidance. The stent was placed in 51 lacrimal systems in 44 outpatients who had complete obstruction of the lacrimal sac or nasolacrimal duct. RESULTS: Stent placement was technically successful and well tolerated in 50 of 51 nasolacrimal systems. The procedure lasted an average of 16 minutes (range, 10-33 minutes). After stent placement, 47 of 50 eyes showed complete resolution of epiphora, and the other three showed partial resolution. During follow-up, no stents migrated, and one stent became blocked. The stent was reopened by means of forceful irrigation of saline solution through the superior punctum. CONCLUSION: Placing a polyurethane nasolacrimal stent by use of the new introducer and hook simplifies the technique, shortens operating time, reduces cost, and makes the procedure well tolerated by patients.

Adolescent↗
PubMed1995

Purification and characterization of beta-glucuronidase from Escherichia coli HGU-3, a human intestinal bacterium.

beta-Glucuronidase was purified 360-fold from Escherichia coli HGU-3, an human intestinal bacterium. The specific activity of the purified enzyme was 17.78 units/mg protein. The enzyme (M.W. 290000) is composed of four subunits (M.W. 72000) with a pI and optimal pH of 4.8 and 6-7, respectively. The apparent Km for p-nitrophenyl-beta-D-glucuronide was found to be 0.22 mM. The enzyme was inhibited by saccharic acid 1,4-lactone, glycyrrhizin, N-ethylmaleimide (NEM) and p-chloromercuriphenylsulfonic acid (PCMS). Using the bile containing bilirubin diglucuronide as a substrate, the purified beta-glucuronidase was able to hydrolyze it to bilirubin. This hydrolyzed bilirubin formed calcium bilirubinate with a reaction mixture containing CaCl2.

Bilirubin↗
PubMed1995

Evidences for possible involvement of Rhp51 protein in mitotic events including chromosome segregation.

To understand the role of the Rhp51 protein in Schizosaccharomyces pombe, we examined the phenotypes of the null mutant for the rhp51+ gene. Unlike Saccharomyces cerevisiae rad51 mutants, S. pombe rhp51 mutants (rhp51delta cells) displayed slow growth and heterogeneity in cell size, indicating perturbation of the cell cycle. Furthermore, many aberrant nuclear structures found in 4',6'-diamidino-2-phenylindole (DAPI)-stained rhp51delta cells and the caffeine hypersensitivity of the mutant cells suggested an involvement of the Rhp51 protein in normal chromosome segregation. These data suggested that the Rhp51 proteins were required for normal cell growth as well as a DNA repair pathway. Moreover, rhp51delta mutants showed a considerable sensitivity to ultraviolet (UV) light-irradiation as well as methyl methanesulfonate (MMS) treatment, indicating that the Rhp51 proteins are involved in both the active excision mechanism of UV-induced DNA damage and recombinational repair in S. pombe. Taken together, we suggest that the role(s) of the Rhp51 protein in S. pombe may be different from those of Rad51 in S. cerevisiae.

DNA Damage↗