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Biomedical subjects

S S Han

Publications and source records attributed to S S Han.

At least 37 records · Page 2Linked to original sources
PubMed2001

A 10-year experience of liver transplantation for hepatitis C: analysis of factors determining outcome in over 500 patients.

OBJECTIVE: To determine the factors affecting the outcome of orthotopic liver transplantation (OLT) for end-stage liver disease caused by hepatitis C virus (HCV) and to identify models that predict patient and graft survival. SUMMARY BACKGROUND DATA: The national epidemic of HCV infection has become the leading cause of hepatic failure that requires OLT. Rapidly increasing demands for OLT and depleted donor organ pools mandate appropriate selection of patients and donors. Such selection should be guided by a better understanding of the factors that influence the outcome of OLT. METHODS: The authors conducted a retrospective review of 510 patients who underwent OLT for HCV during the past decade. Seven donor, 10 recipient, and 2 operative variables that may affect outcome were dichotomized at the median for univariate screening. Factors that achieved a probability value less than 0.2 or that were thought to be relevant were entered into a stepdown Cox proportional hazard regression model. RESULTS: Overall patient and graft survival rates at 1, 5, and 10 years were 84%, 68%, and 60% and 73%, 56%, and 49%, respectively. Overall median time to HCV recurrence was 34 months after transplantation. Neither HCV recurrence nor HCV-positive donor status significantly decreased patient and graft survival rates by Kaplan-Meier analysis. However, use of HCV-positive donors reduced the median time of recurrence to 22.9 months compared with 35.7 months after transplantation of HCV-negative livers. Stratification of patients into five subgroups, based on time of recurrence, revealed that early HCV recurrence was associated with significantly increased rates of patient death and graft loss. Donor, recipient, and operative variables that may affect OLT outcome were analyzed. On univariate analysis, recipient age, serum creatinine, donor length of hospital stay, donor female gender, United Network for Organ Sharing (UNOS) status of recipient, and presence of hepatocellular cancer affected the outcome of OLT. Elevation of pretransplant HCV RNA was associated with an increased risk of graft loss. Of 15 variables considered by multivariate Cox regression analysis, recipient age, UNOS status, donor gender, and log creatinine were simultaneous significant predictors for patient survival. Simultaneously significant factors for graft failure included log creatinine, log alanine transaminase, log aspartate transaminase, UNOS status, donor gender, and warm ischemia time. These variables were therefore entered into prognostic models for patient and graft survival. CONCLUSION: The earlier the recurrence of HCV, the greater the impact on patient and graft survival. The use of HCV-positive donors may accelerate HCV recurrence, and they should be used judiciously. Patient survival at the time of transplantation is predicted by donor gender, UNOS status, serum creatinine, and recipient age. Graft survival is affected by donor gender, warm ischemia time, and pretransplant patient condition. The authors' current survival prognostic models require further multicenter validation.

Adult↗
PubMed2001

Dyspnea and palpitation during pregnancy.

OBJECTIVES: Dyspnea and palpitation are common features of pregnancy. While several theories have been put forward to explain the etiology of gestational dyspnea and palpitation, there have been few systemic studies of its incidence, severity and time-course in a group of normal women. METHODS: We interviewed postpartum women, within 3 days after delivery, about dyspnea and palpitation. Separately from this interview, we performed 24-hour ECG monitoring for obstetric patients with palpitation before delivery. RESULTS: The subjects interviewed were 261 women, of whom 37.5 percent and 11.5 percent experienced dyspnea and palpitation, respectively. These symptoms had tendency to increase to term. The presence of arrhythmias could be documented in only 22% of patients having 24-hour Holter monitoring. CONCLUSION: Dyspnea and palpitation were common among normal pregnant women and had a tendency to increase to term.

Adult↗
PubMed2001

The effect of methyl methanesulfonate (MMS)-induced excision repair on p53-dependent apoptosis in human lymphoid cells.

The tumor suppressor p53 product has been shown to play an important role in preventing carcinogenesis by at least two different mechanisms, by evoking cell cycle arrest and eliciting DNA repair on one hand, or by eliminating damaged cells by induction of apoptosis on the other hand. As a first step toward understanding the relationship between protective responses and apoptosis after genotoxic stress, we examined the effect of DNA strand breaks generated from repair processes in respect to acute cellular responses against DNA damage, and on p53-dependent apoptosis in human lymphoid cells. We used two isogenic cell lines, TK6 harboring wild-type p53, and WI-L2-NS, which carries a mutant p53. A significant difference in sensitivity was observed at 50 microg/ml methyl methane-sulfonate (MMS) between the two cell lines used. In addition, a clear p53-mediated contribution to apoptosis in MMS-induced cell death was observed. However, we did not observe any differences in repair of MMS-lesions, as determined by comet assay, between the two cell lines. These data suggest that the differences in apoptosis induction in the two lines are not a reflection of differences in strand-break frequency or repair capacity.

Alkylation↗
PubMed2000

Immunotoxicity of ethyl carbamate in female BALB/c mice: role of esterase and cytochrome P450.

Ethyl carbamate, a potent carcinogen, has been characterized to be metabolized by cytochrome P450 (P450) and esterase. It has recently been demonstrated that P450 may activate ethyl carbamate to immunotoxic metabolites. To investigate the role of esterase in ethyl carbamate-induced immunosuppression, mice were pretreated intraperitoneally with an esterase inhibitor, diazinon, at 20 mg/kg 30 min prior to the administration of ethyl carbamate intraperitoneally at 100 and 400 mg/kg for 7 consecutive days. Pretreatment with diazinon completely blocked the serum esterase activity. Histopathologically splenic and thymic atrophy was observed when mice were treated with ethyl carbamate, which was potentiated by the pretreatment with diazinon. In spleen, lymphocytes in the periarteriolar lymphoid sheath and the marginal zone appeared to be depleted in the white pulps. In thymus, ethyl carbamate caused a marked depletion of cells in cortex. The antibody response to sheep red blood cells (SRBCs) was more suppressed by ethyl carbamate in diazinon-pretreated groups than in corn oil-pretreated groups. These results suggest that the metabolism of ethyl carbamate by esterase may be an inactivation pathway in ethyl carbamate-induced immunosuppression. In addition, ethyl N-hydroxycarbamate, a P450 metabolite, suppressed the lymphoproliferative response induced by lipopolysaccharide and concanavalin A in splenocyte cultures. These results indicate that the metabolism of ethyl carbamate by P450 may be an activation pathway in immunosuppression by ethyl carbamate.

Animals↗
PubMed2000

Isolation of TC/AG repeat microsatellite sequences for fingerprinting rice blast fungus and their possible horizontal transfer to plant species.

Genome fingerprinting has been a major role in characterization of population structure and analysis of the variability in phytopathogenic fungi. In order to characterize Korean rice blast fungal isolates, the genomic DNAs were digested with AluI endonuclease and subsequent PCR amplifications using random decamer primers with combinations of microsatellite primers had been carried out. This Alu-Inter SSR technique revealed high polymorphism among the Korean blast fungal isolates. Then, fragments from the Alu-Inter SSR analysis were isolated to be used as probes in Southern hybridization, which also revealed high polymorphism between isolates to distinguish individuals. The sequences of the isolated fragments contained TC/AG tandem repeats interspersed with a 30 bp direct repeat. In gel blot analysis, the isolated TC/AG repeat microsatellite sequences were proved to be useful for characterizing the isolates in blast fungi in addition to the conventional MGR (Magnaporthe grisea repeat) probes. One interesting point was that the rice blast fungus derived TC/AG repeat microsatellite sequences were abundant in non-rice blast fungi and plant species, but not in other fungi and yeasts. A discussion on the possible horizontal gene transfer between phytopathogenic fungi and host plants is presented.

Base Sequence↗
PubMed2000

Role of metabolic activation by cytochrome P450 in thioacetamide-induced suppression of antibody response in male BALB/c mice.

Effects of thioacetamide on antibody response to sheep red blood cells were investigated in male BALB/c mice. When mice were treated intraperitoneally with thioacetamide once, the antibody response was significantly suppressed at 200 mg/kg with hepatotoxicity. When mice were treated intraperitoneally with thioacetamide for 7 consecutive days, the antibody response was suppressed at 50 mg/kg without hepatotoxicity. To determine the possible role of metabolic activation by cytochrome P450 in thioacetamide-induced suppression of antibody response, mice were pretreated with phenobarbital intraperitoneally for 3 days, followed by intraperitoneal administration of 100 mg/kg of thioacetamide for 3 days. The elevated activities of serum aspartate aminotransferase and alanine aminotransferase by thioacetamide were potentiated by phenobarbital pretreatment. The suppression of antibody response by thioacetamide was potentiated by phenobarbital. In liver microsomes, the activities of P450 2B-specific enzymes were induced by phenobarbital. Our present results suggest that thioacetamide may require metabolic activation by P450 to its immunosuppressive form(s).

Alanine Transaminase↗
PubMed2000

Inhibitory effects of curcumin and capsaicin on phorbol ester-induced activation of eukaryotic transcription factors, NF-kappaB and AP-1.

Recently, considerable attention has been focused on identifying dietary and medicinal phytochemicals that can inhibit, retard or reverse the multi-stage carcinogenesis. Spices and herbs contain phenolic substances with potent antioxidative and chemopreventive properties. Curcumin, a yellow colouring agent from turmeric and capsaicin, a pungent principle of red pepper exhibit profound anticarcinogenic and antimutagenic activities. Two well-defined eukaryotic transcription factors, nuclear factor-kappa B (NF-kappaB) and activator protein 1 (AP-1) have been implicated in pathogenesis of many human diseases including cancer. These transcription factors are known to be activated by a wide array of external stimuli, such as tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), tumor necrosis factor, reactive oxygen species, bacterial lipopolysaccharide, and ultraviolet. In the present study, we found that topical application of TPA onto dorsal skin of female ICR mice resulted in marked activation of epidermal NF-kappaB and AP-1. Curcumin and capsaicin, when topically applied prior to TPA, significantly attenuated TPA-induced activation of each transcription factor in mouse skin. Likewise, both compounds inhibited NF-kappaB and AP-1 activation in cultured human promyelocytic leukemia (HL-60) cells stimulated with TPA. Based on these findings, it is likely that curcumin and capsaicin exert anti-tumor promotional effects through suppression of the tumor promoter-induced activation of transcription factors, NF-kappaB and AP-1.

Animals↗
PubMed2000

A mouse thymic stromal cell line producing macrophage-colony stimulating factor and interleukin-6.

A thymic stromal cell line, TFGD, was established from a thymic tumor mass developed spontaneously in p53 knock out mouse, and was found to produce cytokines that could induce bone marrow hematopoietic stem cells (HSCs) to differentiate into macrophages. The cytokines produced by the TFGD line were assessed by immunoassays. High level of macrophage-colony stimulating factor (M-CSF) and interleukin (IL)-6 was detected in the TFGD-culture supernatant, whereas granulocyte/macrophage-colony stimulating factor (GM-CSF), IL-3, IL-4, IL-5, IL-13, or interferon (IFN)-gamma was undetectable. Blocking experiments showed that anti-M-CSF monoclonal antibody could neutralize the differentiation-inducing activity shown by the TFGD-culture supernatant. Dot blot analysis of the total RNA isolated from the cultured fetal thymic stromal cells showed that M-CSF transcripts were expressed in the normal thymus. These observations, together with the earlier finding that M-CSF plus IL-6 is the optimal combination of cytokines for the induction of macrophage differentiation from HSCs in vitro, may indicate that thymic macrophages could be generated within the thymus by cytokines involving M-CSF.

Animals↗
PubMed2000

Embryo lethality and teratogenicity of a new fluoroquinolone antibacterial DW-116 in rats.

DW-116, 1-(5-fluoro-2-pyridyl)-6-fluoro-7-(4-methyl-l-piperazinyl)-1, 4-dihydro-4-oxoquinolone-3-carboxylic acid hydrochloride, is a newly developed fluoroquinolone antibacterial. The potential of DW-116 to induce developmental toxicity was, investigated in Sprague-Dawley rats. DW-116 was administered by gavage to pregnant rats from days 6 to 16 of gestation at dose levels of 0, 31.3, 125, and 500 mg/kg per day. All dams were subjected to caesarean section on day 20 of gestation and their fetuses were examined for external, visceral and skeletal abnormalities. At 500 mg/kg, toxic effects including clinical signs of toxicity, suppressed body weight and decreased food intake were found in dams. An increase in the resorption rate, a decrease in the litter size, a reduction in the fetal weight, and a decrease in the placental weight were also seen. In addition, various types of external, visceral, and skeletal malformations occurred at an incidence of 17.9, 74.2 and 8.3%, respectively. Characteristic malformations included oedema, cleft palate, dilated cerebral ventricle, hypoplasia of lung and ventricular septum defect. A dramatic increase in the incidence of skeletal variations (55.6%) and retardations (94.4%) and a decrease in the number of ossification centres of sternebra, metacarpals, metatarsals and sacrocaudal vertebra were also observed. At 125 mg/kg, a reduction in the placental weight and an increase in the incidence of skeletal variations were found. There were no signs of maternal toxicity or embryotoxicity at 31.3 mg/kg. These results indicate that the fluoroquinolone antibacterial DW-116 is embryotoxic and teratogenic at minimally maternally toxic dose and is minimally embryotoxic at nonmaternally toxic dose in rats.

Abnormalities, Drug-Induced↗
PubMed2000

Antiherpetic activities of acidic protein bound polysacchride isolated from Ganoderma lucidum alone and in combinations with acyclovir and vidarabine.

To investigate antiherpetic activity, an acidic protein bound polysaccharide (APBP) was isolated from carpophores of Ganoderma lucidum. This brownish APBP was isolated from water soluble substances of the carpophores by activity-guided isolation method. APBP was tested for its antiviral activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) by plaque reduction assay in tissue culture. APBP showed potent antiviral activity against HSV-1 and HSV-2 in Vero cells at its 50% effective concentration (EC(50)) of 300 and 440 microg/ml, respectively. APBP had no cytotoxicity on Vero cells at a concentration of 1 x 10(4) microg/ml. APBP exhibited a potent antiviral activity with selectivity index (SI) of more than 22.73. The combined antiherpetic effects of APBP with nucleoside antiherpetic agents, acyclovir (ACV) and vidarabine (ara-A), were examined on the multiplication of these two strains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. CI values were in the range 0.47-0.51 for a combination of APBP with ACV, and in the range of 1.02-1.18 for a combination of APBP with ara-A. The combinations of APBP with ACV on HSV-1 and HSV-2 showed potent synergistic effects, and these results suggest that the possibility of developing APBP as a new antiherpetic agent.

Acyclovir↗
PubMed2000

Antiherpetic activities of acidic protein bound polysacchride isolated from Ganoderma lucidum alone and in combinations with interferons.

To investigate antiherpetic activity, an acidic protein bound polysaccharide (APBP) was isolated from carpophores of Ganoderma lucidum. This brownish APBP was isolated from water soluble substances of the carpophores by activity-guided isolation method. APBP was tested for its antiviral activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) by plaque reduction assay in tissue culture. APBP showed potent antiviral activity against HSV-1 and HSV-2 in Vero cells at its 50% effective concentration (EC(50)) of 300 and 440 microg/ml, respectively. APBP had no cytotoxicity on Vero cells at a concentration of 1x10(4) microg/ml. APBP exhibited a potent antiviral activity with selectivity index (SI) of more than 22.73. The combined antiherpetic effects of APBP with protein antiviral agents, interferon alpha (IFN alpha) and interferon gamma (IFN gamma), were examined on the multiplication of these two strains of herpesviruses in Vero cells by the combination assay. The results of combination assay were evaluated by the combination index (CI) that was calculated by the multiple drug effect analysis. The combinations of APBP with IFN alpha on HSV-1 and HSV-2 showed more potent synergistic effects with CI values of 0.30-0.62 for 50-90% effective levels than those of APBP with IFN gamma with CI values of 0.65-1.10. These results suggest the possibility of developing APBP as a new antiherpetic agent.

Animals↗
PubMed2000

Possible mode of antiviral activity of acidic protein bound polysaccharide isolated from Ganoderma lucidum on herpes simplex viruses.

Two protein bound polysaccharides, a neutral protein bound polysaccharide (NPBP) and an acidic protein bound polysaccharide (APBP), were isolated from water soluble substances of Ganoderma lucidum by EtOH precipitation and DEAE-cellulose column chromatography. Their antiviral activities against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) were then investigated by plaque reduction assay. APBP exhibited more potent HSV-1 and HSV-2 antiviral activity than NPBP with 50% effective concentration (EC(50)) of 300-520 microg/ml. In order to examine the possible mode of the antiviral activity of APBP its virucidal effect, antiviral activity in preincubation, attachment and penetration assay were tested with HSV-1 and HSV-2. APBP was found to have a direct virucidal effect on HSV-1 and HSV-2. APBP did not induce IFN or IFN-like materials in vitro and is not expected to induce a change from a normal state to an antiviral state. APBP in concentrations of 100 and 90 microg/ml inhibited up to 50% of the attachment of HSV-1 and HSV-2 to Vero cells and was also found to prevent penetration of both types of HSV into Vero cells. These results show that the antiherpetic activity of APBP seems to be related to its binding with HSV-specific glycoproteins responsible for the attachment and penetration, and APBP impedes the complex interactions of viruses with cell plasma membranes.

Animals↗
PubMed2000

Selective involvement of reactive oxygen intermediates in platelet-activating factor-mediated activation of NF-kappaB.

Although it has been suggested that some biological activities of platelet-activating factor (PAF) are mediated by, at least in part, reactive oxygen intermediates (ROI), the precise mechanisms underlying the interaction between the two remains to be elucidated. Antioxidants, such as alpha-tocopherol acid succinate, N-acetyl-L-Cysteine, pyrrolidinedithiocarbamate failed to inhibit PAF-induced immediate systemic reactions such as lethality, symptoms of disseminated intravascular coagulation, and histological changes such as pulmonary edema and hemorrhage in renal medullae 10 min following PAF injection. In contrast. antioxidants significantly inhibited both the in vivo and in vitro PAF-induced NF-kappaB activation and NF-kappaB-dependent TNF-alpha expression. The effects of the antioxidants were due to their inhibition of PAF-induced degradation of IkappaBalpha, a protein responsible for keeping NF-kappaB in an inactive form. A protein tyrosine kinase and N-tosyl-L-phenylalanine chloromethyl ketone sensitive serine protease were involved in both PAF- and H2O2-induced NF-kappaB activation. Collectively, these data indicate that the PAF-induced NF-kappaB activation is selectively mediated through the generation of ROI.

Acetylcysteine↗
PubMed2000

Establishment of a phagocytic cell line from Bombina orientalis.

Continuous serum-free culture of Bok-2 cells was generated from primary culture of the tail bud stage embryos of the toad, Bombina orientalis. Bok-2 cells can be maintained in modified L-15 serum-free medium prepared by mixing L-15 medium, lactalbumin enzymatic hydrolysate, sucrose and sodium bicarbonate. Bok-2 cells have an ameboid behavior and morphology. When Bok-2 and viable Candida albicans were co-cultured, Bok-2 cells showed an immune response characterized by chemotaxis, phagocytosis and partial clearing activity of Candida cells and colonies. And Bok-2 cells also showed phagocytosis of latex beads without serum treatment and displayed numerous pseudopodia, membrane evagination for phagocytosis and phagosome activity. On the basis of these results, Bok-2 cells were identified as professional phagocytes.

Animals↗
PubMed2000

A protocol of early spiral computed tomography for the detection of stones in patients with renal colic has reduced the time to diagnosis and overall management costs.

BACKGROUND: The recent use of spiral computed tomography (CT) without contrast for the diagnosis of acute flank pain has been shown to be highly sensitive and specific for the detection of urolithiasis. This method has not, however, been evaluated for its contribution to savings in management costs. The present study aims to evaluate the cost savings gained by instituting a protocol of early spiral CT to investigate these patients. METHODS: The records of 200 patients presenting to the Accident and Emergency Department (A&E) with acute flank pain during two periods were retrospectively reviewed. The first period was before the spiral CT protocol was instituted and the second was after. Cost analyses between the two periods were performed. RESULTS: After the spiral CT protocol, 72 versus 31 patients had a definitive diagnosis prior to discharge from hospital. The time taken to diagnosis was also significantly shorter after the protocol implementation (6.3 vs. 16.8 h). This resulted in a shorter time spent in the A&E, and hence bed cost savings. Radiological costs were reduced by 22%, but the major cost saving was made by a reduction in time spent in A&E (44%). CONCLUSIONS: The implementation of a protocol of early spiral CT for patients with suspected renal colic has led to earlier definitive diagnosis and shorter hospital stays. This is associated with a significant reduction in costs associated with managing this condition.

Adult↗
PubMed2000

Effects of flupyrazofos on liver microsomal cytochrome P450 in the male Fischer 344 rat.

1. The effects of flupyrazofos on liver microsomal cytochrome P450 were investigated in the male Fischer 344 rat. When rats were treated intraperitoneally with flupyrazofos for 3 consecutive days, the activities of ethoxyresorufin O-deethylase and testosterone 2 beta-hydroxylase were significantly reduced, whereas the activities of pentoxyresorufin beta-depentylase and testosterone 6beta- and 7 alpha-hydroxylases were induced in liver microsomes. 2. Within 24 h after treatment with 50 m kg(-1) flupyrazofos, most enzyme activities were decreased, indicating the interaction of flupyrazofos with cytochrome P450. 3. In Western immunoblotting, cytochrome P4502B1/2 proteins were clearly induced by treatment with flupyrazofos, whereas P4501A1/2 and 2C6 proteins were reduced in liver microsomes. 4. The present results indicate that flupyrazofos modulates the expression of cytochrome P450 in rat.

Animals↗
PubMed2000

An analysis and evaluation of student nurses' participation in ethical decision making.

This study analyses the types and frequencies of ethical dilemmas and the rationale of ethical decision making in student nurses; it also evaluates their decision making. One hundred senior student nurses who were enrolled in a two-credit course in nursing ethics were asked to provide an informal description of a dilemma that they had experienced during their clinical practice. The results were as follows. The ethical dilemmas identified fell into four categories and were of 27 types. Those most frequently experienced were 'family giving up on a patient because he or she could not be cured', and 'not telling the truth to the patient'. The Korean Nurses' Code of Ethics was applied, in particular the preamble, and the third, fourth, seventh and tenth clauses. The most common rule of ethics and principle applied in these nurses' ethical decision making were veracity and nonmaleficence. With regard to the moral reasoning process, the primary concern was the welfare of the patients. These students were equipped with the ability to exercise critical and reflective thought when they experienced ethical dilemmas.

Attitude of Health Personnel↗