The effect of timing of ondansetron administration on its efficacy, cost-effectiveness, and cost-benefit as a prophylactic antiemetic in the ambulatory setting

Although ondansetron (4 mg I.V.) is effective in the prevention and treatment of postoperative nausea and vomiting (PONV) after ambulatory surgery, the optimal timing of its administration, the cost-effectiveness, the cost-benefits, and the effect on the patient's quality of life after discharge have not been established. In this placebo-controlled, double-blind study, 164 healthy women undergoing outpatient gynecological laparoscopic procedures with a standardized anesthetic were randomized to receive placebo (Group A), ondansetron 2 mg at the start of and 2 mg after surgery (Group B), ondansetron 4 mg before induction (Group C), or ondansetron 4 mg after surgery (Group D). The effects of these regimens on the incidence, severity, and costs associated with PONV and discharge characteristics were determined, along with the patient's willingness to pay for antiemetics. Compared with ondansetron given before induction of anesthesia, the administration of ondansetron after surgery was associated with lower nausea scores, earlier intake of normal food, decreased incidence of frequent emesis (more than two episodes), and increased times until 25% of patients failed prophylactic antiemetic therapy (i.e., had an emetic episode or received rescue antiemetics for severe nausea) during the first 24 h postoperatively. This prophylactic regimen was also associated with the highest patient satisfaction and lowest cost-effectiveness ratios. Compared with the placebo group, ondansetron administered after surgery significantly reduced the incidence of PONV in the postanesthesia care unit and during the 24-h follow-up period and facilitated the recovery process by reducing the time to oral intake, ambulation, discharge readiness, resuming regular fluid intake and a normal diet. When ondansetron was given as a "split dose," its prophylactic antiemetic efficacy was not significantly different from that of the placebo group. In conclusion, the prophylactic administration of ondansetron after surgery, rather than before induction, may be associated with increased patient benefits.

IMPLICATIONS

Ondansetron 4 mg I.V. administered immediately before the end of surgery was the most efficacious in preventing postoperative nausea and vomiting, facilitating both early and late recovery, and improving patient satisfaction after outpatient laparoscopy.

Selection of a high tanshinone-producing crown gall strain and production of tanshinone in the strain

Crown galls were induced by direct infection of sterile seedlings of Salvia miltiorrhiza with Agrobacterium tumefaciens C58 and subcultured on a 67-V hormone-free medium by successively selecting red cell aggregates. A high tanshinone-producing crown gall strain C1 was obtained after 12 months in a subculture. It grows well and retains its high tanshinone-producing characteristic in liquid stationary cultures. It is obvious that the yeast extract and fermentation extract of Armillaria mellea as elicitors promote strain C1 to produce tanshinone. Tanshinone content of strain C1 cultures was over three times higher than that of the crude drugs. The results indicated that the crown gall tissue and elicitor technique could provide some new clues for the production of tanshinone under the condition of a liquid stationary culture.

[The design of a circuit for detecting respiration signal with impedance method]

A respiration signal detecting circuit with impedance method is introduced. In this circuit, a four electrode arrangement is used, which can reduce movement artifact in using two electrodes. In signal processing, a series of methods such as filtering and amplyfing are used to overcome the heart beat and bloodflow signals. The circuit has successfully been applied in the blocking physiological parameters monitor that we have developed.

Embolization of tumors and vascular lesions in the oral and maxillofacial regions

The embolization was used for the treatment of 10 patients with tumors and vascular lesions in the oral and maxillofacial region. The patients were diagnosed as having vascular deformity, hemangioma, hemangiofibroma and chemodectoma. The selective and superselective target artery embolization were conducted and the satisfactory results were achieved. The procedures, effects and precautions of the embolic therapy were also discussed.

CD4+ T-lymphocytopenia in long-term survivors following intensive chemotherapy in childhood cancers

BACKGROUND

It is generally believed the effects of short intensive courses of therapy are rapidly reversible in childhood cancers, and immunologic function following years of maintenance treatment with chemotherapy usually returns to normal by 6 months or less when treatment is terminated. However, we previously demonstrated that dysregulation of immunoglobulins, especially IgD, was observed in long-term survivors following intensive chemotherapy in cancer patients. With regard to cellular immunity, investigators reported that antineoplastic chemotherapy significantly reduces the number of CD4+ T-lymphocytes, and production of newly developing CD4+ T-lymphocytes was inversely related to the patients' age. However, the incidence of CD4+ lymphocytopenia in long-term survivors of childhood cancers is not known.

PROCEDURE

Here, we report the flow cytometric analysis of peripheral blood from long-term survivors who continue complete remission off chemotherapy for more than 5 years.

RESULTS

Six out of 74 long-term survivors (8.1%), showed low CD4+ T-lymphocyte count (<300/mm3). Three of six patients showed continued CD4+ T-lymphocytopenia over a year. In spite of the persistent low levels of CD4+ T cells, these three patients were not susceptible to severe infections.

COMMENT

Intriguingly, in patients with CD4+ T-lymphocytopenia there has been a tendency toward increased numbers of natural killer cells or gamma delta T cells that may be operating as a thymus-independent compensatory mechanism to defend the hosts.

Thymic B-cell non-Hodgkin's lymphoma in a child

A 13-year-old male developed thymic non-Hodgkin's lymphoma. Microscopically, the tumor was composed of large cells, resembling centroblasts. Immunohistochemically, the tumor demonstrated leukocyte common antigen+, L26 (B-cell)+, UCHL1 (T-cell)-, suggesting the B-cell phenotype. In contrast to the terminally differentiated phenotype (CD10-, surface immunoglobulin-) observed in adult cases, flow cytometric analysis showed that they were relatively immature: CD10+, CD19+, HLA-DR-, IgM+/-, kappa+. He was successfully treated with intensive chemotherapy. Since childhood thymic lymphomas are exclusively small non-cleaved cell lymphoma with T-cell phenotype, this case represents a unique entity in children.

[Effects of cytokines on multidrug-resistance in K562/A02 cells]

OBJECTIVE

To explore the effects of cytokines on human leukemic cell line K562/S and its multidrug-resistant counterpart K562/A02.

METHODS

The toxicities of cytokines and the IC50 (the concentration causing 50% inhibition of cell growth) of DNR were assayed by MTT method; intracellular drug concentration was measured by fluorometry; p-glycoprotein (p-gp) expression was detected by APAAP and mdr-1 mRNA was assayed by RT-PCR.

RESULTS

The IC50 of DNR for K562/A02 and K562/S cells were 45.08 microg/ml and 0.607 microg/ml, respectively. Pretreating K562/A02 cells with rhu IFN (500 U/ml) or rhu IL-2 (250 U/ml) for 24 hours partially restored the sensitivity of K562/A02 cells to DNR (IC50 were 16.39 and 11.96 microg/ml, respectively) but had not effect on K562/S cells, and it elevated the intracellular DNR accumulation in K562/A02 from 2151 ng/mg x protein to 2570 and 2503ng/mg x protein, respectively. p-gp and mdr-1 mRNA were not down regulated. By contrast, rhu G-CSF and rhu GM-CSF had no effect on either K562/A02 or K562/S.

CONCLUSION

rhu IFN or rhu IL-2 could partially restore the sensitivity of K562/A02 to DNR and elevate the intracellular DNR accumulation via a mechanism independent of p-gp or mdr-1 mRNA down-regulation.

[A digital filter method for the elimination of 50 Hz interference from the ECG]

The author uses improved Levkov method to remove 50 Hz interference from ECG signal so that filtered QRS wave can be exactly regarded as the mark identifying other physiological signals' characteristics points, and the paper presented the result of the cancelling.

Fibrin regulation of interleukin-8 gene expression in human vascular endothelial cells

Recent studies in our laboratory, as well as others, have suggested that fibrin can regulate cell function in vitro and likely control inflammation in vivo by acting as a potent cell activator. This has led us to hypothesize that during tissue and vascular injury, fibrin can enhance leukocyte recruitment by inducing vascular endothelial cell expression of leukocyte chemotactic factors. To begin to test this hypothesis, we developed an in vitro model of in situ fibrin polymerization on human umbilical vein endothelial cell culture (HUVEC) and determined the ability of fibrin to induce HUVEC expression of the potent leukocyte chemotactic factor interleukin-8 (IL-8). Our initial studies showed that fibrin induced IL-8 expression in a time- and dose-dependent fashion. Fibrin-induced IL-8 expression in HUVEC could be seen as early as 2 hours post-fibrin stimulation. Additionally, fibrin concentrations as low as 30 microg/mL stimulated a detectable level of IL-8 antigen expression from HUVEC. We also showed that this fibrin induced IL-8 had the identical molecular weight and similar antigenic identity as recombinant and monocyte derived IL-8. Northern blot analysis showed that the IL-8 antigen increase seen in fibrin treated HUVEC was due to fibrin induced elevation of steady state mRNA expression in HUVEC. These data clearly support our hypothesis that fibrin is a potent vascular endothelial cell (VEC) activator that can directly contribute to leukocyte recruitment and activation by inducing leukocyte chemotactic factor expression from VEC.

Eltanolone as an alternative to propofol for ambulatory anesthesia

The intravenous (i.v.) steroid anesthetic, eltanolone, compares favorably to propofol with respect to its induction characteristics. This double-blind investigation was designed to compare the induction and recovery profile of eltanolone (versus propofol) when it was used for both induction and maintenance of ambulatory anesthesia. Eighty-three consenting ASA physical status I-III outpatients undergoing minor gynecologic or urologic procedures lasting 10-40 min were randomly assigned to one of three anesthetic treatment groups. All patients received midazolam, 2 mg i.v., and fentanyl, 50 micrograms i.v., before induction of anesthesia. The control group (Group 1) was induced with propofol, 2.4 mg/kg i.v. (18-60 yr or ASA physical status I or II) or 1.6 mg/kg i.v. (61-80 yr and/or ASA physical status III), followed by intermittent bolus doses of 0.6 mg/kg i.v. in combination with N2O 67% for maintenance of anesthesia. In Group 2, anesthesia was induced with eltanolone, 0.75 mg/kg i.v., (18-60 yr and/or ASA physical status I or II) or 0.5 mg/kg i.v. (61-80 yr and/or ASA physical status III), and maintained with intermittent bolus injections of 0.2 mg/kg i.v. and N2O 67%. Group 3 received eltanolone, 1.0 mg/kg i.v. (18-60 yr and/or ASA physical status I or II), or 0.75 mg/kg i.v. (61-80 yr and/or ASA physical status III), followed by intermittent bolus injections of 0.2 mg/kg i.v. and N2O 67%. In addition to recording the induction and recovery times and side effects, psychomotor testing was performed before and at 30-min intervals after anesthesia. Induction times (57 +/- 23, 67 +/- 26, and 61 +/- 22s, respectively) were similar in all three groups. Although eltanolone produced no pain on injection (versus 52% in the propofol group), 10% of the eltanolone-treated patients (versus none in the propofol group) developed transient cutaneous (rash-like) reactions. The total dose of study medication used during the anesthetic period was 9.2 +/- 3.7 mg.kg-1.h-1 in the propofol group compared with 3.3 +/- 1.4 mg.kg-1.h-1 and 3.3 +/- 1.9 mg.kg-1.h-1 in Groups 2 and 3, respectively. Early recovery times were significantly shorter after propofol anesthesia. However, times to ambulation, micturition, and being judged "fit for discharge," as well as recovery of cognitive function, were similar in all three groups. Although ethanolone seems to be a safe and effective i.v. anesthetic, these data suggest that it is unlikely to replace propofol in the ambulatory setting.

IMPLICATIONS

Eltanolone is an investigational steroid anesthetic that causes less pain on injection and less cardiovascular depression than propofol (the most widely used intravenous anesthetic in the outpatient setting). Unfortunately, emergence from anesthesia after ambulatory surgery is slower with eltanolone compared with propofol. Therefore, it is unlikely that eltanolone will replace propofol for outpatient anesthesia.

Two cytotoxic pathways of natural killer cells in human cord blood: implications in cord blood transplantation

Using K562 cells as a target we investigated cord blood (CB)-natural killer (NK) cytolytic pathways. The cytotoxicity of fresh CB-NK cells was significantly lower than that of peripheral blood mononuclear cells (PB MNCs). When CB was incubated with IL-2, the level of CB-NK cytotoxicity was increased and boosted to the level observed in PB-NK cells. Fresh CB-NK cells induced apoptosis in target cells. Activated CB cells induced apoptosis and necrosis in target cells, at the same level as PB MNCs. CB stem cell transplantation may also induce graft-versus-host disease (GVHD)/graft-versus-leukaemia (GVL), similar to bone marrow transplantation.

[Effects of antisense oligodeoxynucleotides targeting multidrug resistance gene on resistant cell line K562/ AO2]

OBJECTIVE

To investigate the reversal effect of antisense oligodeoxynucleotide on human multidrug-resistant leukemic cell line K562/AO2.

METHODS

Antisense oligodeoxynucleotides (AOD) targeting-6 approximately 9 sites of exon 2 in human multidrug resistance gene(mdr-1), one of which is sequence-strict-complied and linked with polyethyleneglycol (PEG) at 5' end (AP, 15 mer), the other lacks nucleotide complied site-1 (AP', 14mer), were synthesized. AP, AP' and verapamil were simultaneously added to human mdr-1-mRNA positive leukemia cell line K562/AO2 and, mdr-1-mRNA and p170 were detected. AS' and AP'were labelled by FITC and designated as ASF' and APF', respectively. In addition, the intracellular concentration of them was detected by FACS.

RESULTS

AP' significantly enhanced the sensitivity of K562/AO2 to DOX, down-regulated the expression of mdr-1 and MRP-mRNA and p170, elevated the intracellular concentration of the two AOD, while AP had no effect. The uptake of APF' was significantly higher than that of ASF' in K562/AO2, and the fluorescence was observed in the plasma and nuclear of K562/AO2 cells.

CONCLUSION

(AOD targeting mdr-1 promoted the drug sensitivity of drug-resistant tumor cells. 2 AOD had no cytotoxicity to tumor cells. 5 Low molecule PEG enhanced significantly the uptake of AOD by tumor cells.

Fibrin induction of tissue factor expression in human vascular endothelial cells

BACKGROUND

For the present study, we hypothesized that fibrin is an inducer of tissue factor (TF) expression in vascular endothelial cells in vitro and in vivo.

METHODS AND RESULTS

To test the in vitro aspect of this hypothesis, human umbilical vein endothelial cells (HUVECs) were cocultured with physiologically relevant concentrations of fibrin (0.03 to 1.0 mg fibrin/mL) for various times (0.5 to 24 hours), and TF expression was compared with that in unstimulated HUVECs (media control). Results demonstrated that fibrin induced a time- and dose-dependent increase in TF antigen expression, functional TF procoagulant activity, and TF mRNA in HUVECs.

CONCLUSIONS

These studies demonstrate that fibrin can directly regulate TF expression in HUVECs in vitro.

Cytotoxic T-lymphocytes recognizing P-glycoprotein in murine multidrug-resistant leukemias

A multidrug-resistant murine lymphoid leukemia P388/ADR overexpresses P-glycoprotein (P-gp), an active transporter that pumps cytotoxic drugs out of cells and a product of mdr1 gene. Cytotoxic T lymphocytes (CTL) that showed cytotoxicity against P388/ADR were generated from mixed lymphocyte tumor cell culture. CTL do not kill drugsensitive parental P388 (P388/parent) that does not express P-gp. Monoclonal antibody against P-gp inhibited cytotoxic activity. Similar results were obtained in another multidrug-resistant cell line P388/VP-16. Cytotoxic activity was mediated by Thy1+ CD4- CD8+ T-cells. When P388/ADR was treated with murine IL-4, expression of P-gp was downregulated. Monoclonal antibody against interleukin-4 (IL-4) abrogated the IL-4-induced suppression of P-gp. Cytolytic activity of CTL against IL-4-treated P388/ADR was dose dependently inhibited. These results suggest that P-gp is immunogenic and can be a target of CTL in this murine leukemia model.

[Discovery of a novel reassortant H1N2 influenza virus]

Three strains of influenza A virus were isolated from patients suffering from influenza like disease in Railway Hygiene and Anti-epidemic Station of Taiyuan in January 1996. The identification results by serological method indicated that the isolates were different from H1N2 subtype of influenza A virus isolated from men in 1989 and 1992 and that their HA antigenicity was similar to that of A/RP/8/34 (H1N1) virus, but distinguishable from that of influenza A (H1N1) virus circulating in mans recently. The comparison of migration patterns of the RNA among the isolates, the A/PR//34 (H1N1) and the A/Wuhan/359/95 (H3N2) viruses revealed that the migration patterns of RNA 1-4 segments of the isolates were similar to those of A/PR/8/34 (H1N1) virus, but those of RNA 5-6 segments were indistinguishable from those of A/Wuhan/359/95 (H3N2) strain. However, the migration patterns of RNA 7-8 segments of the isolates were not only different from those of A/PR/8/34 (H1N1) virus, but also distingrasgable from those of A/Wuhan/359/95 (H3N2) strain. Therefore, it could be considered that the isolates were a novel reassortant H1N2 influenza A virus.

[The plant regeneration of Salvia miltiorrhiza Bge. transformed by Agrobacterium]

The hairy roots and crown galls of Salvia miltiorrhiza were obtained by infecting plant with A. rhizogenes (strain 15834, LBA 9402) and A. tumefaciens (strain C58). The transformed plants were regenerated light and transplanted form cultural medium into soil successfully. The plants transformed by A. rhizogenes have characteristics of short stems and develop hairy roots, those and trans formed by A. tumefaciens grow vigorously featuring, longer stems and well developed roots. Both biomass production and tanshenone content are higher than the original plant.

Pharmacokinetic study on acetaminophen: interaction with a Chinese medicine

To know the influences of a Chinese traditional medicine (KAKKONTO) on the metabolism of acetaminophen (APAP), we have carried out pharmacokinetic studies on APAP under KAKKONTO coadministration in humans and rats. In humans, the pharmacokinetic parameters were calculated from the blood APAP concentration-time curves of each volunteer. The parameters did not show any significant differences between the KAKKONTO-coadministration group (group K) and the APAP-administration group (group A). KAKKONTO, when given at two different doses, did not show any significant effects on blood APAP level. In rats, the blood APAP level was significantly higher than that of group A (p < 0.01) only in the 100 mg/kg of group K at 0.25 h after APAP administration. There were no other significant differences.

[In vitro reversal of homoharringtonine resistance by the combination of tamoxifen and verapamil]

OBJECTIVE

To investigate the reversal of homoharringtonine (HHT)-resistance by tamoxifen (TAM) or verapamil (VER) alone or in combination.

METHODS

The drug-sensitivity test was performed with semisolid agar culture.

RESULTS

The cytotoxicity of HHT to K562/S cells was not enhanced by TAM or VER alone or in combination,but HHT resistance in HHT resistant cells (K562/H20) was reversed by VER and TAM at nontoxic doses (4micromol/L or 8micromol/L). The IC50 of K562/H20 for HHT decreased from 446.8 +/- 0.08microg/L to 45.1 +/- 0.02microg/L in the presence of 4micromol/L of VER, to 22.4 +/- 0.03microg/L in 8micromol/L of VER, to 85.1 +/- 0.03microg/L in 4micromol/L of TAM and to 26.4 +/- 0.02microg/L in 8micromol/L of TAM. In the presence of combinations of 2micromol/L VER and 4micromol/L TAM and of 2micromol/L VER and 8micromol/L TAM, IC50 of K562/H20 decreased to 30.4 +/- 0.02microg/L and 4.3 +/- 0.04microg/L, respectively.

CONCLUSION

HHT-resistance could be reversed by VER or TAM alone, and the combination of the two drugs showed a synergistic effect.

Reciprocal regulation of the content of aromatic L-amino acid decarboxylase and tyrosine hydroxylase mRNA by NGF in PC12 cells

Aromatic L-amino acid decarboxylase (AADC) and tyrosine hydroxylase (TH) are involved in the synthesis of dopamine and other monoamine neurotransmitters, and their activities can be regulated by a number of physiological stimuli. An interesting finding has been that (-)-deprenyl and some other irreversible monoamine B oxidase inhibitors increase AADC gene expression and that these compounds can exert neuronal protection/rescue effects. In this study, we have investigated the effects of nerve growth factor (NGF), and of (-)-deprenyl on AADC and TH gene expression in PC12 cells. Cells were treated with different doses of NGF (0.2-50 ng/ml) for up to 3 days. Northern and blot hybridizations were performed to detect AADC and TH mRNA. The results show that NGF can down-regulate AADC gene expression while increasing TH gene expression in a time- and dose-dependent fashion. Treatment with (-)-deprenyl alone increases the gene expression of AADC, and (-)-deprenyl further counteracts the reductions induced by NGF. This study introduces novel results with regard to the regulation of the gene expression of AADC in PC12 cells, which is not paralleled by the other catecholamine biosynthetic enzymes. These findings support the existence of an interaction between NGF and AADC gene expression that may be associated with the process of neuronal degeneration or regeneration.

Fibrin induction of ICAM-1 expression in human vascular endothelial cells

In acute and chronic inflammatory processes, fibrin deposition, and leukocyte accumulation are classic histopathologic hallmarks. Previous studies have shown that fibrin and fibrin degradation products can have biologic effects on vascular endothelial cells and can induce the expression of several endothelial cell-derived factors that may be important in regulating inflammation and tissue repair. We now demonstrate that coculture of human vascular endothelial cells (EC) with fibrin results in the up-regulation of intercellular adhesion molecule-1 (ICAM-1), thus providing a first link between fibrin deposition and adhesion molecule expression, which may lead subsequently to leukocyte accumulation and extravasation. Increased ICAM-1 expression was demonstrated by ELISA, flow cytometry, and functional adhesion assays. EC ICAM-1 expression increased in a time and dose response fashion. Cell surface levels of ICAM-1 induced by fibrin were comparable to, or exceeded, levels induced by IL-1beta. ICAM-1 expression increased beginning at 4 h post-fibrin formation with sustained elevated expression at 48 h. Fibrin-stimulated EC also bound increased numbers of polymorphonuclear neutrophils in cellular adhesion assays. This increase in adhesion could be blocked by Ab to ICAM-1. Inhibition of fibrin polymerization also inhibited the up-regulation of ICAM-1. Culture medium from fibrin-stimulated EC contained elevated levels of soluble ICAM-1. These data suggest that fibrin deposition on vascular EC, in addition to other reported effects on EC metabolism, may also lead to leukocyte accumulation and extravasation through the induction of leukocyte adhesion molecules such as ICAM-1.

Fibrin induction of ICAM-1 expression in human vascular endothelial cells

In acute and chronic inflammatory processes, fibrin deposition, and leukocyte accumulation are classic histopathologic hallmarks. Previous studies have shown that fibrin and fibrin degradation products can have biologic effects on vascular endothelial cells and can induce the expression of several endothelial cell-derived factors that may be important in regulating inflammation and tissue repair. We now demonstrate that coculture of human vascular endothelial cells (EC) with fibrin results in the up-regulation of intercellular adhesion molecule-1 (ICAM-1), thus providing a first link between fibrin deposition and adhesion molecule expression, which may lead subsequently to leukocyte accumulation and extravasation. Increased ICAM-1 expression was demonstrated by ELISA, flow cytometry, and functional adhesion assays. EC ICAM-1 expression increased in a time and dose response fashion. Cell surface levels of ICAM-1 induced by fibrin were comparable to, or exceeded, levels induced by IL-1beta. ICAM-1 expression increased beginning at 4 h post-fibrin formation with sustained elevated expression at 48 h. Fibrin-stimulated EC also bound increased numbers of polymorphonuclear neutrophils in cellular adhesion assays. This increase in adhesion could be blocked by Ab to ICAM-1. Inhibition of fibrin polymerization also inhibited the up-regulation of ICAM-1. Culture medium from fibrin-stimulated EC contained elevated levels of soluble ICAM-1. These data suggest that fibrin deposition on vascular EC, in addition to other reported effects on EC metabolism, may also lead to leukocyte accumulation and extravasation through the induction of leukocyte adhesion molecules such as ICAM-1.

Approximate maximum likelihood hyperparameter estimation for Gibbs priors

The parameters of the prior, the hyperparameters, play an important role in Bayesian image estimation. Of particular importance for the case of Gibbs priors is the global hyperparameter, beta, which multiplies the Hamiltonian. Here we consider maximum likelihood (ML) estimation of beta from incomplete data, i.e., problems in which the image, which is drawn from a Gibbs prior, is observed indirectly through some degradation or blurring process. Important applications include image restoration and image reconstruction from projections. Exact ML estimation of beta from incomplete data is intractable for most image processing. Here we present an approximate ML estimator that is computed simultaneously with a maximum a posteriori (MAP) image estimate. The algorithm is based on a mean field approximation technique through which multidimensional Gibbs distributions are approximated by a separable function equal to a product of one-dimensional (1-D) densities. We show how this approach can be used to simplify the ML estimation problem. We also show how the Gibbs-Bogoliubov-Feynman (GBF) bound can be used to optimize the approximation for a restricted class of problems. We present the results of a Monte Carlo study that examines the bias and variance of this estimator when applied to image restoration.

[Establishment of human amnion cell mutagenesis system by using a shuttle vector pS189]

Using transient shuttle vector pS189, we established a subclone human amnion cell (FL) mutagenesis detection system, and we detected the mutation specificity of N-methy-N'-nitro-N-nitrosoguanidine (MNNG) in this system. The spontaneous mutant frequency of target gene supF was 1.7 x 10(-5) and MNNG-induced mutant frequency was increased with dosage. The results from 0.8% agarose gel electrophoresis, PCR, PCR-single strand conformation polymorphism (PCR-SSCP) analysis showed that MNNG-induced 89% mutants were point mutants. These results indicated that this system can be used to detect and study the mutagenesis mechanism of potential mutagens.