Biomedical subjects

J S Han

Publications and source records attributed to J S Han.

At least 91 records · Page 5Linked to original sources

PubMed1999

Interaction of SeqA and Dam methylase on the hemimethylated origin of Escherichia coli chromosomal DNA replication.

Preferential binding of SeqA protein to hemimethylated oriC, the origin of Escherichia coli chromosomal replication, delays methylation by Dam methylase. Because the SeqA-oriC interaction appears to be essential in timing of chromosomal replication initiation, the biochemical functions of SeqA protein and Dam methylase at the 13-mer L, M, and R region containing 4 GATC sequences at the left end of oriC were examined. We found that SeqA protein preferentially bound hemimethylated 13-mers but not fully nor unmethylated 13-mers. Regardless of strand methylation, the binding of SeqA protein to the hemimethylated GATC sequence of 13-mer L was followed by additional binding to other hemimethylated GATC sequences of 13-mer M and R. On the other hand, Dam methylase did not discriminate binding of 13-mers in different methylation patterns and was not specific to GATC sequences. The binding specificity and higher affinity of SeqA protein over Dam methylase to the hemimethylated 13-mers along with the reported cellular abundance of this protein explains the dominant action of SeqA protein over Dam methylase to the newly replicated oriC for the sequestration of chromosomal replication. Furthermore, SeqA protein bound to hemimethylated 13-mers was not dissociated by Dam methylase, and most SeqA protein spontaneously dissociated 10 min after binding. Also, SeqA protein delayed the in vitro methylation of hemimethylated 13-mers by Dam methylase. These in vitro results suggest that the intrinsic binding instability of SeqA protein results in release of sequestrated hemimethylated oriC.

Bacterial Outer Membrane Proteins↗

PubMed1999

Acute intermittent morphine increases preprodynorphin and kappa opioid receptor mRNA levels in the rat brain.

We determined the effects of morphine on mRNA levels for the opioid ligands preprodynorphin (PPD) and preproenkephalin (PPE) and the kappa opioid receptor (KOR). Rats received six injections of morphine (6.25 mg/kg/injection) every 2 h, and were sacrificed 30 min later. mRNA levels were measured in brain tissue after removal of the cortex, cerebellum and brainstem. There were increases in PPD and KOR mRNA levels (P<0.05 and P<0.005, respectively), with no alteration of PPE. These alterations in the kappa/dynorphin system may counter morphine-induced effects on the brain.

Animals↗

PubMed1999

Nocistatin reverses the effect of orphanin FQ/nociceptin in antagonizing morphine analgesia.

Nocistatin is a recently characterized neuropeptide derived from the preprohormone containing nociceptin (Orphanin FQ, OFQ). Nocistatin was reported to antagonize OFQ induced allodynia, hyperalgesia and prostaglandin E2-elicited pain responses. The aim of the present study was to determine whether nocistatin, injected intracerebroventricularly (i.c.v.), would reverse the anti-morphine effect of OFQ in rats using the tail-flick latency (TFL) as the nociceptive index. I.c.v. injection of nocistatin at doses of 0.005, 0.05, 0.5, 5, 50, and 500 ng produced no significant changes in the basal TFL, nor did it affect morphine analgesia. However, it significantly reversed the antagonistic effect of OFQ on morphine analgesia when co-injected i.c.v. at doses of 0.05, 0.5, 5, 50 and 500 ng per rat with OFQ. The dose-response curve was bell-shaped and the most effective dose was 0.5 ng. The results suggest that nocistatin can reverse the anti-morphine effect of OFQ in rat brain.

Analgesia↗

PubMed1999

Hippocampal lesions interfere with Pavlovian negative occasion setting.

Rats were trained with either a serial feature positive (L-->T1+ T-) or a serial feature negative (L-->T1-, T1+) discrimination, intermixed with training on another, nonconditional discrimination (T2+, N-), using a Pavlovian appetitive conditioning preparation with multiple response measures. Among rats trained with the serial feature positive discrimination, neurotoxic lesions of the hippocampus produced a transient impairment in the acquisition of that discrimination, but did not affect acquisition of the nonconditional discrimination. In contrast, among rats that received serial feature negative discrimination training, hippocampal lesions produced enduring deficits in the acquisition of both discriminations. The results of transfer tests indicated that both lesioned and control rats used a conditional learning strategy (occasion setting) to solve the feature positive and feature negative discriminations. Furthermore, lesioned rats, especially those that received training with the feature negative discrimination, displayed increasingly higher levels of general activity as training progressed. The results suggest that hippocampal lesions particularly interfere with inhibitory learning (negative occasion setting) about both explicit and contextual cues.

Animals↗

PubMed1999

PhoB-dependent transcriptional activation of the iciA gene during starvation for phosphate in Escherichia coli.

The IciA protein from Escherichia coli has been shown specifically to inhibit the in vitro initiation of chromosomal DNA replication. However, the in vivo role of IciA has not yet been established. In order to investigate the in vivo function of this protein, expression of the iciA gene was studied by monitoring the beta-galactosidase activity specified by an iciA promoter-lacZ fusion inserted into the chromosome. Among the conditions tested (carbon starvation, the stringent response, phosphate starvation, and the SOS response), only phosphate depletion increased iciA expression. Supplementation of phosphate-depleted cultures with inorganic phosphate reduced the beta-galactosidase activity to basal levels. Enhanced expression of iciA-lacZ was dependent upon the PhoB protein. PhoB is known to be a transcriptional activator of the Pho regulon, expression of which is activated during phosphate starvation. It was also found that the iciA promoter contains a PhoB protein-binding sequence, termed the Pho box, which is necessary for the activation of genes of the Pho regulon. These results suggest that the iciA gene is a member of the Pho regulon.

Bacterial Proteins↗

PubMed1999

Disconnection of the amygdala central nucleus and substantia innominata/nucleus basalis disrupts increments in conditioned stimulus processing in rats.

Rats with a neurotoxic lesion of the amygdala central nucleus (CN) in one hemisphere and a 192 immunoglobulin G (192IgG)-saporin lesion of cholinergic neurons in the contralateral substantia innominata/nucleus basalis (SI/nBM) failed to show the enhanced attentional processing of a conditioned stimulus (CS) observed in sham-operated rats when that CS's predictive value was altered. Performance of these asymmetrically lesioned rats was poorer than that of rats with a unilateral lesion of either structure or with a symmetrical lesion of both structures in the same hemisphere. These results implicate connections between the CN and SI/nBM in the incremental attentional processing of CSs, extending previous research that has shown similar effects of bilateral lesions of either the CN or the SI/nBM.

Amygdala↗

PubMed1999

A novel gene delivery system targeting cells expressing VEGF receptors.

Two ligand oligopeptides GV1 and GV2 were designed according to the putative binding region of VEGF to its receptors. GV1, GV2 and endosome releasing oligopeptide HA20 were conjugated with poly-L-lysine or protamine and the resulting conjugates could interact with DNA in a noncovalent bond to form a complex. Using pSV2-beta-galactosidase as a reporter gene, it has been demonstrated that exogenous gene was transferred into bovine aortic arch-derived endothelial cells (ABAE) and human malignant melanoma cell lines (A375) in vitro. In vivo experiments, exogenous gene was transferred into tumor vascular endothelial cells and tumor cells of subcutaneously transplanted human colon cancer LOVO, human malignant melanoma A375 and human hepatoma graft in nude mice. This system could also target gene to intrahepatically transplanted human hepatoma injected via portal vein in nude mice. These results are correlated with the relevant receptors (flt-1, flk-1/KDR) expression on the targeted cells and tissues.

Amino Acid Sequence↗

PubMed1999

Biochemical and morphological identification of ceramide-induced cell cycle arrest and apoptosis in cultured granulosa cells.

We have investigated the effects of ceramide on the progression of cell cycle and on apoptotic cell death in ovarian cultured granulosa cells. Rates of cellular proliferation were measured by immunocytochemical staining for proliferating cell nuclear antigen (PCNA) and flow cytometric cell cycle analysis. We also examined for morphological and biochemical signs of apoptosis. The PCNA expression was downregulated in a dose-dependent manner after treatment with C6-ceramide. Flow cytometric analysis demonstrated that the exposure of granulosa cells to C6-ceramide markedly decreased the population associated with G0/G1 DNA content and the reduction of cell numbers in G0/G1 phase was accompanied by the elevation of the A0 phase. The exposure of granulosa cells to exogenous C6-ceramide induced drastic morphological changes including cytoplasmic- or nuclear condensation and typical apoptotic DNA degradation. We also observed that phorbol 12-myristate 13-acetate, a protein kinase C (PKC) activator, significantly inhibited the ceramide-induced apoptosis. These results suggested that ceramide might block the progression of cell cycle at G0/G1 phase and as a consequence, granulosa cells would be committed to apoptosis. Our findings also indicated that down-regulation of the PKC activity might be involved in the ceramide-induced apoptosis in cultured granulosa cells.

Analysis of Variance↗

PubMed1999

Effects of ceramide, the Fas signal intermediate, on apoptosis and phospholipase D activity in mouse ovarian granulosa cells in vitro.

Although recent studies have demonstrated that ovarian follicular atresia occurs by apoptosis of granulosa cells, the intracellular signaling pathways involved in apoptotic cell death are still poorly characterized. We examined the role of ceramide as a candidate intracellular mediator of Fas-mediated signaling in cultured granulosa cells. Expression of Fas antigen was demonstrated by Western blot of granulosa cell lysates and immunostaining of cultured granulosa cells. Exposure of granulosa cells to anti-Fas monoclonal antibody (anti-Fas mAb) resulted in significant sphingomyelin hydrolysis, which was accompanied by a progressive increase in endogenous levels of ceramide. The addition of exogenous C6-ceramide induced drastic morphological change, including nuclear fragmentation and typical apoptotic DNA degradation. Furthermore, both anti-Fas mAb and C6-ceramide decreased phospholipase D (PLD) activity and diacylglycerol (DAG) concentrations in a time- or a dose-dependent manner. In addition, treatment with phorbol 12-myristate 13-acetate completely attenuated the ceramide-induced inhibition of PLD activity and partially suppressed ceramide-induced apoptosis. These results indicate that the Fas/ceramide signaling pathway might play a role in granulosa cell apoptosis and suggest that the PLD/DAG pathway might be cross-linked to the Fas/ceramide pathway in apoptotic processes of granulosa cells.

Animals↗

PubMed1999

Unilateral renal cystic disease in adults.

Unilateral renal cystic disease (URCD) is morphologically indistinguishable from autosomal dominant polycystic kidney disease (ADPKD) except for its unilaterality. Unlike ADPKD, URCD patients show neither a genetic background nor progressive deterioration in renal function; thus, the differential diagnosis of URCD from ADPKD is important. Only a few cases of URCD have been reported. This study reports two cases of URCD in adults together with a literature review. We identified these two cases using abdominal computerized tomography and family screening with renal ultrasonography.

Adult↗

PubMed1999

Hypothalamic-pituitary-adrenal activity and pro-opiomelanocortin mRNA levels in the hypothalamus and pituitary of the rat are differentially modulated by acute intermittent morphine with or without water restriction stress.

Acute administration of morphine stimulates the secretion of hypothalamic-pituitary-adrenal (HPA) hormones, ACTH, beta-endorphin and corticosterone in the rat. In this study we investigated the effects of repeated multiple-dose morphine on HPA activity under two different conditions: without or with water restriction stress. Rats received six intermittent injections of morphine (6.25 mg/kg per injection, s.c.) every 2 h and were killed 30 min after the last injection. The results were as follows. (1) Morphine significantly elevated plasma ACTH and corticosterone levels; water restriction also significantly increased ACTH secretion, but with no significant increase of plasma corticosterone levels. In contrast, rats treated with morphine under the water restriction condition failed to show any increases of either ACTH or corticosterone levels. (2) Morphine did not change pro-opiomelanocortin (POMC) mRNA levels in the anterior pituitary; whereas water restriction significantly increased the POMC mRNA levels. The water restriction-induced increases of POMC mRNA in the anterior pituitary were absent in the rats which received morphine. (3) Morphine significantly increased POMC mRNA levels in the hypothalamus; water restriction had no effect. The morphine-induced increases in POMC mRNA in the hypothalamus were absent in the rat under the water restriction condition. These findings, that the effects of morphine on HPA activation or POMC mRNA expression depend on the presence of stress, suggest a counter-regulatory role of opiates on a stress response and opioid gene expression.

Adrenocorticotropic Hormone↗

PubMed1999

Laparoscopic splenectomy for immune thrombocytopenic purpura--long-term result of 40 laparoscopic splenectomies.

Laparoscopic surgery has recently extended its indications and it has also become an acceptable surgical approach for splenectomy. In the last five years, we have performed 40 laparoscopic splenectomies for immune thrombocytopenic purpura. Thirty-five patients were female and 5 patients were male. The mean age was 34, varying from 17 to 56. After learning to perform laparoscopic splenectomy with five ports, we are now usually using three or four ports in a right lateral kidney position. There was no case of conversion to exploratory laparotomy. The mean hospital stay was 7 days. There was no perioperative mortality; but in 2 cases we had postoperative subphrenic abscesses which were successfully managed by catheter drainage. Since undergoing laparoscopic splenectomy, 28 patients (70%) were weaned effectively from their steroid medications. Eight patients (20%) have been on small doses of steroid, and 4 patients (10%) have been on the same doses of steroid with no response. The patient group with rapidly increasing platelet count after splenectomy showed a statistically significant relation with the complete response group (p < 0.001). Laparoscopic splenectomy is a safe and reasonable operative procedure for patients with immune thrombocytopenic purpura.

Adolescent↗

PubMed1999

Prognostic factors of diffuse proliferative lupus nephritis.

BACKGROUND: Diffuse proliferative lupus nephritis (DPLN) is the most severe form in lupus nephritis. PATIENTS AND METHODS: We retrospectively analyzed 90 DPLN patients who were confirmed by kidney biopsy and treated at least for 12 months to compare the effectiveness of treatment modalities and to investigate the prognostic factors of DPLN. The patients were categorized to intravenous cyclophosphamide pulse (CY) group and oral corticosteroid (with/without cytotoxic drug, PO) group. RESULTS: When the CY group (69 patients) and PO group (21 patients) were compared, there were no differences between two groups in sex, age, histologic chronicity index (CI, 4.55 vs 3.76; CY vs PO, respectively), mortality rate (4.3% vs 0%), remission rate of nephritis (at 3-year 59. 1 % vs 75.5%), renal survival rate (at 5-year 88.0% vs 91.7%) and complications of treatment, but significant differences in the frequency of nephrotic syndrome (66.7% vs 33.3%) and initial azotemia (30.4% vs 0%). histologic activity index (7.14 vs 4.33) and relapse rate (2.9% vs 42.9%). When the remission group (49 patients) and non-remission group (41 patients) were compared, CI, initial renal insufficiency, male sex and the duration of nephritis were the prognostic factors for remission in univariate analysis, and male sex (OR 10.99) and CI (OR 9.89) in multivariate analysis. When the remission group (35 patients) and non-remission (34 patients) group were compared in the CY group, CI was the prognostic factor in univariate analysis, and CI (OR 8.63) and male sex (OR 5.54) in multivariate analysis. The initial renal insufficiency (OR 12.74) and male sex (OR 7.99) were the prognostic factors for renal survival. The renal survival rate was 100% in remission-induced patients. CONCLUSION: We conclude that CI, male sex, initial renal insufficiency were the prognostic factors of DPLN, and treatment with oral corticosteroid could induce remission in patients who had mild histologic and clinical features. Therefore it would be necessary to evaluate the prognostic factors before the selection of treatment modality.

Adult↗

PubMed1999

[A method for preparation of carbon fiber electrode].

Carbon fiber electrode (CFE) can be used in detection of exocytosis of single neuron or endocrine cell. A simplified method for preparation of CFE, as described in the present paper, greatly ensures the coordination and success of the preparation. Such CFEs have a low noise level. Exocytosis of rat adrenal chromaffin cells was investigated in the clarification of the effect of MPP+ on transmitter release. It is found that exocytosis was not stimulated by MPP+ and the high K+ induced secretion was not changed by MPP+. These observations suggest that the previously reported elevation of dopamine content in the surrounding histosolution of DA neuron is probably resulted from blockage of the re-uptake of DA by MPP+.

1-Methyl-4-phenylpyridinium↗

PubMed1999

[Increased release of orphanin FQ (OFQ) in brain of chronic morphine tolerant rats].

The changes in OFQ-immunoreactivity (OFQ-ir) content and release of cerebroventricular perfusate, periaqueductal gray (PAG) and amygadala of chronic morphine tolerant rats were measured with radioimmunoassay (RIA). The results indicate: (1) chronic morphine tolerance was achieved in rats by injecting increasing doses of morphine (10, 20, 40, 50, 60 mg/kg, s.c., tid). The content of OFQ-ir in cerebroventricular perfusate in the rats of normal saline (NS) group remained at a steady level during the injections from d 1 to d 5, while in the morphine-treated group of rats the content of OFQ-ir showed 25% increase (P < 0.05 vs NS) and 52% increase (P < 0.01 vs NS) after 3 and 5 days' morphine injection respectively. (2) The content of OFQ-ir in PAG of rats receiving morphine injection for 1, 3 and 5 days showed respectively increases of 17% (P < 0.05), 48% (P < 0.05) and 80% (P < 0.01) against the NS group. (3) The content of OFQ-ir in rat amygdala receiving 1 day injection of morphine showed a 8% decrease, which was not significantly different from NS group. However, there was a 36% and 55% (P < 0.05) increase respectively after injection for 3 and 5 days. It is suggested that in the later stage of chronic morphine treatment, large amount of OFQ was released from rat brain to antagonize the effect of opioids, which may play an important role in the development of morphine tolerance.

Amygdala↗

PubMed1998

Partial purification of protein farnesyl cysteine carboxyl methyltransferase from bovine brain.

C-terminal farnesyl cysteine carboxyl methylation has been known to be the last step in the post-translational modification processes of several important signal transduction proteins in eukaryotes including ras related GTP binding proteins and the gamma-subunit of heterotrimeric G proteins. Protein farnesyl cysteine carboxyl methyltransferase (PFCCMT; EC, 2.1.1.100) catalyzing the reaction is well characterized as being stimulated by guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and suppressed by N-acetyl-S-farnesyl-L-cysteine (AFC). As an initial step to understand the physiological significance of the process, we attempted to purify the enzyme, which was partially purified 130-fold (specific activity, 143 pmol of methyl group transferred/min/mg of protein) with yield of 1.8% after purification by fast protein liquid chromatography (FPLC) on a Superdex 75 column. The enzyme was further purified with non denaturing polyacrylamide gel electrophoresis (ND-PAGE) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weight of PFCCMT was determined to be about 30 kDa based on Superdex 75 FPLC as well as photoaffinity labelling with S-adenosyl-L-[methyl-3H] methionine ([methyl-3H]SAM). The partially purified enzyme (Superdex 75 eluate) was found to be characteristically affected by GTP gamma S, being activated about 40-fold in 2 mM, in contrast to ATP which did not show any effect on enzyme activity. Meanwhile, the enzyme was found to be markedly inhibited by AFC, reaching 0 activity in 2 mM. These observations strongly suggested that the partially purified enzyme was PFCCMT.

Acetylcysteine↗

PubMed1998

Electroacupuncture: mechanisms and clinical application.

Acupuncture is an ancient Chinese method to treat diseases and relieve pain. We have conducted a series of studies to examine the mechanisms of this ancient method for pain relief. This article reviews some of our major findings. Our studies showed that acupuncture produces analgesic effect and that electroacupuncture (EA) is more effective than manual acupuncture. Furthermore, electrical stimulation via skin patch electrodes is as effective as EA. The induction and recovering profiles of acupuncture analgesia suggest the involvement of humoral factors. This notion was supported by cross-perfusion experiments in which acupuncture-induced analgesic effect was transferred from the donor rabbit to the recipient rabbit when the cerebrospinal fluid (CSF) was transferred. The prevention of EA-induced analgesia by naloxone and by antiserum against endorphins suggests that endorphins are involved. More recent work demonstrated the release of endorphins into CSF following EA. In addition, low frequency (2 Hz) and high frequency (100 Hz) of EA selectively induces the release of enkephalins and dynorphins in both experimental animals and humans. Clinical studies suggesting its effectiveness for the treatment of various types of pain, depression, anxiety, spinally induced muscle spasm, stroke, gastrointestinal disorders, and drug addiction were also discussed.

Acupuncture Analgesia↗

PubMed1998

OFQ reverses the kappa-opioid receptor-mediated depression of calcium current in rat dorsal root ganglion neurons.

Since the characterization of orphanin FQ (OFQ), the endogenous ligand of ORL1 receptor, much work has focused on its physiological functions. OFQ was reported to antagonize the effect of opioid-induced antinociception, although its mechanism remains obscure. In the present study, whole-cell patch clamp recording technique was used to observe if OFQ can reverse the inhibition of calcium current produced by the kappa-opioid agonist U50,488H (U50) in acutely dissociated rat DRG neurons. The concentrations of OFQ and U50 were 50 nM and 10 microM, respectively. Among 49 cells recorded, the calcium channel currents of 37 (75.5%) cells were inhibited by U50, of which 30 (81.1%) cells could be reversed by OFQ. It was interesting to note the similarity between OFQ and the well characterized anti-opioid peptide CCK-8 in that it reversed kappa-opioid receptor agonist induced suppression on calcium channel current, while by itself showed a calcium channel suppressive effect. Thus OFQ may be regarded as another anti-opioid peptide.

Animals↗