Phase I clinical trial: pharmacokinetics of a novel anthracycline, DA-125 and metabolites. Single dose study

Single dose of DA-125, 20 (n = 3), 40 (n = 3), 60 (n = 3), 80 (n = 6), or 100 (n = 6) mg/m2 body surface area, was administered intravenously in 5 min to 21 patients with various types of cancer as phase I clinical trial. The main side-effects of DA-125 were nausea, vomiting, leukopenia (especially neutropenia), and thrombocytopenia. Among those, hematological side-effects increased with increased doses of DA-125. No patient developed side-effects equal to or higher than grade III up to DA-125 dose of 60 mg/m2. However, at DA-125 dose of 80 mg/m2, 1 out of 3 patients developed grade III leukopenia and grade IV neutropenia. Therefore, 3 additional patients participated taking the dose of 80 mg/m2; no patient developed side-effects equal to or higher than grade III. Hence, DA-125 dose increased to 100 mg/m2. At DA-125 dose of 100 mg/m2, 2 out of 3 patients developed side-effects equal to or higher than grade III and, therefore, 3 additional patients participated taking this dose. Among the 3 additional patients, 1 patient developed both grade III leukopenia and neutropenia. Therefore, further accrual was stopped at this dose (100 mg/m2). The maximally tolerated dose (MTD) of DA-125 was determined to be 100 mg/m2, and the dose-limiting factor for DA-125 was bone marrow suppression. DA-125 dose of 80 mg/m2, 80% of MTD of DA-125, was recommended as the dose for phase II clinical trial. Cardiotoxicity was not observed in any of the 21 patients according to the ECG and RVG. Neither fever, stomatitis, diarrhea, and renal and nervous system toxicity, nor abnormality in blood coagulation was observed in any of the patients, and death or life-threatening side-effects due to DA-125 were also not observed. Antitumor effects of DA-125 were evaluated from the 21 patients; 6 progressive disease, 14 stable disease, and 1 partial response. Pharmacokinetic parameters of M1, such as AUC, t1/2, CL, VSS, and MRT, seemed to be independent of i.v. doses of DA- 125, 20-100 mg/m2 and less than 0.75% of M1 were excreted in 96 h urine when expressed in terms of DA-125 i.v. dose. M2 was the main metabolite of DA-125 among M1-M4 excreted in urine; 10.1 approximately 22.3% of M2 was excreted in 96 h urine when expressed in terms of DA-125 i.v. dose. Bile was collected via the T-tube in 1 additional patient at the dose of 100 mg/m2. Biliary excretion of M1 and M2 was negligible; less than 0.320 and 4.76% of M1 and M2, respectively, were excreted in 96 h bile when expressed in terms of DA-125 i.v. dose.

Impact of tumor necrosis factor alpha on mouse embryonic stem cells

Previous studies have shown the adverse impact of the cytokine tumor necrosis factor alpha (TNFalpha) on the development of the inner cell mass in mouse blastocysts. In the present study, two embryonic stem (ES) cell lines were used to further investigate the action of TNFalpha. The expression of TNFalpha receptors in ES cells was tested by reverse transcription-polymerase chain reaction and Northern blot analysis. Transcripts encoding the two distinct receptor isoforms were detected in these cells. Using different approaches, our data showed a TNFalpha dose-dependent decrease in the number of ES cells after 24 h of exposure. Simultaneous blocking of the two receptors with antagonist antibodies was needed to completely abrogate the inhibitory effect of the cytokine. Extensive DNA nicks (visualized by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling [TUNEL] method), but not nuclear fragmentation, was found with a higher incidence in ES cells exposed to TNFalpha. The possibility that TNFalpha may stimulate ES cell differentiation was investigated with a test based on the expression of alkaline phosphatase. The results indicated that TNFalpha cannot over-ride the negative control exerted by leukemia inhibitory factor on differentiation. The opposite possibility, that TNFalpha blocks differentiation, was tested in suspended medium drops. In this system, TNFalpha was found to decrease the ability of ES cells to differentiate into embryoid bodies. In addition, expression of Rex-1, a marker gene for undifferentiated ES cells, was increased in ES cells exposed to TNFalpha. Thus our data support the hypothesis that TNFalpha is a significant (negative) effector of proliferation and differentiation in inner cell mass-derived ES cells.

All-trans retinoic acid induced differentiation of rat mammary epithelial cells cultured in serum-free medium

Retinoids are applied to not only cancer prevention but also cancer chemotherapy by stimulating differentiation of cells. We studied differentiation inducing effect of all-trans retinoic acid (ATRA) by studying proportion of high dense fractions of stem-like cells and the size of S phase fraction in cell cycle. From mammary organoids obtained from 7- to 8-week old F344 female rat mammary gland, we cultured rat mammary epithelial cells (RMEC) and treated physiological doses of 10(-6), 10(-7), and 10(-8) M ATRA from the first day and then cultured for 4, 7, and 14 days. After that, immunostaining was performed using peanut agglutinin (PNA) and anti-Thy-1.1 monoclonal antibody (Thy-1.1) that can be used as markers of differentiation. We separated four different cell subpopulations by flow cytometry: cells negative to both reagents (B-), PNA-positive cells (PNA+), Thy-1.1-positive cells (Thy-1.1+), and cells positive to both reagents (B+). We observed continuous decreases of high dense fractions of stem-like cells (PNA+ subpopulations) for 14 days and as much decreases as high doses of ATRA, which were thought to be proportional to doses of ATRA. We labeled RMEC with bromodeoxyuridine and investigated cell cycle fractions that went through S phase. We observed a tendency of decrease of S phase fraction with time in culture, which is thought to be related to continuous decreases of PNA+ subpopulations and inhibitory role of ATRA on cell cycle. These results suggest that physiological doses of ATRA could stimulate differentiation of RMEC and convert stem-like RMEC to differentiated cells in SFM for a relatively long period of 14 days.

Localization of transferrin binding protein in relation to iron, ferritin, and transferrin receptors in the chicken cerebellum

We have demonstrated that transferrin binding protein (TfBP), ferritin, and iron, are specifically localized in Bergmann glia, while the transferrin receptor is confined to Purkinje cells in the chicken cerebellum. The results of this study suggest that Bergmann glia have previously undescribed functions related to iron regulation such as sequestration of iron and the maintenance of iron homeostasis in the cerebellum.

Antitumor agents. 185. Synthesis and biological evaluation of tridemethylthiocolchicine analogues as novel topoisomerase II inhibitors

Several 1,2,3-tridemethyldeacetylthiocolchicine derivatives have been synthesized and evaluated for cytotoxic activity against various human tumor cell lines and for their inhibitory effects on DNA topoisomerases in vitro. Exhaustive demethylation of thiocolchicine analogues completely changes their biological profiles. Instead of displaying antitubulin activity, most target compounds inhibited topoisomerase II activity. Only compounds with a larger side chain, such as 15a, 23a, and 24a, did not interfere with topoisomerase II enzymatic functions. The cytotoxicity of target compounds was reduced by 3 orders of magnitude compared to that of colchicine in most cell lines. The hydrophilicity of phenolic compounds might prevent drug passage through the cell plasma membrane and, thus, be responsible for the relatively weak cytotoxicity. To test this hypothesis, 27-30 were prepared from 16a by protecting all hydroxy groups with esters with an aim to facilitate drug transportation. In vitro cytotoxicity assays indicated that 27 was more potent than its parent compound in all tested tumor cell lines and showed tissue selective cytotoxicity with a significant inhibitory effect against KB cells (IC50 = 2.7 microg/mL). Therefore, we propose that 27 acts as a prodrug, liberating 16a to exert its antitopoisomerase activity and, finally, to cause cell death.

Anti-AIDS agents. 32. Synthesis and anti-HIV activity of betulin derivatives

Eleven betulin derivatives were prepared and evaluated for anti-HIV activity in H9 lymphocytes. Compound 4 was found to be the most active with EC50 and TI values of 0.00066 microM and 21,515, respectively.

Survival after cardiopulmonary resuscitation in the general wards--the results of a dedicated "code" team

We describe our experience with a dedicated cardiopulmonary resuscitation team over 13 months for adults out-of-intensive care unit cardiopulmonary arrests. There were 137 recorded arrests with the majority (69%) happening "out-of-office-hours". The ages of patients ranged from 27 to 95 years, with 42% of patients > or = 70 years old. Spontaneous circulation was established in 38% with transfers to the intensive care unit. However, only 27% of these patients eventually survived to hospital discharge. Thus, there was an overall 10% hospital survival for all adult arrests in the general wards. Those that had return of spontaneous circulation were significantly younger than the nonsurvivors. Patients less than 70 years old had a higher hospital survival rate than those > or = 70 years old (16.5% vs 8.6%, chi 2 < 0.0001).

A retrospective study of near-drowning victims admitted to the intensive care unit

A retrospective study was conducted to evaluate the outcome of near-drowning patients admitted to the intensive care unit (ICU) comparing seawater and freshwater drownings. A chart review was used to identify near-drowning patients admitted to ICU from 1 April 1989 to 1 May 1996 for biodata, physiological data and outcome. Seventeen near-drowning patients were admitted to ICU over a period of nearly 7 years. There were 3 deaths (17.6%) and 8 patients (47%) required cardiopulmonary resuscitation. Freshwater near-drowning occurred in 8 patients and saltwater near-drowning occurred in 9 patients. Nearly all (94%) the patients had a PaO2/FiO2 ratio < 300 mm Hg. Pulmonary oedema was present on the chest radiographs of all patients. Mechanical ventilation was required for 8 patients (47%), and nearly all (94%) received prophylactic antibiotics. None of the patients developed pneumonia. Serum electrolytes and haemoglobin concentration were not grossly abnormal although, those with saltwater near-drowning had a significantly higher level of haemoglobin, sodium and urea compared to those with freshwater near-drowning. Patients that survived to hospital discharge had full neurological recovery and stayed an average of 4.5 days. We concluded that near-drowning victims that survive to be admitted to ICU have significant oxygenation defect with nearly half requiring ventilatory support. Mortality is appreciable, but those that survive to hospital discharge had full neurological recovery.

Natural killer cell activity depression in peripheral blood and ascites from gastric cancer patients with high TGF-beta 1 expression

Transforming growth factor beta 1 (TGF-beta 1) has been shown to inhibit the function of various types of cells in vitro such as natural killer (NK) cells. However, this activity has not been well characterized in vivo. Therefore, twenty three patients with advanced gastric adenocarcinoma (AGC), with cytologically-proven malignant ascites, were evaluated in this study. We determined whether the NK activities of their lymphocytes from either peripheral blood or ascites were suppressed by tumor cell TGF-beta 1 expression. We also examined whether NK activity was more suppressed in peripheral blood versus in ascites where tumor cell-derived TGF-beta 1 is potentially more locally concentrated. The expression of TGF-beta 1 mRNA was examined in the tumor cells from the ascitic fluid of the AGC patients. The NK activities of lymphocytes in peripheral blood and ascites were measured by the 4-hour 51Cr-release assay. We determined that eleven of twenty three patients had tumor cells expressing high levels of TGF-beta 1 mRNA. The NK activity in these eleven patients was significantly lower than the NK activity in peripheral blood and ascites from twelve patients with low TGF-beta 1 expression. In addition, the NK activity in malignant ascites was significantly lower than the activity in peripheral blood in these high TGF-beta 1-expressing cancer patients (p < 0.05). We also monitored survival time in these advanced gastric cancer patients. However, the patients with high expression of TGF-beta 1 showed a trend towards reduced survival although this was not statistically significant. The data in this study are consistent with observations in the previous experiments that showed inhibitory effects of TGF-beta 1 on NK activities in vitro, we reported the same phenomenon in patients with advanced gastric cancer.

Ventilatory strategies for acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a severe condition that has a high mortality. Mechanical ventilation is required and concepts have evolved over the last few decades as to the methods and principles guiding such ventilatory support. In particular, volutrauma as a feature of ventilator-associated lung injury has been well documented, leading to pressure-limited strategies with consequent permissive hypercapnia. Such an approach is in direct contrast to traditional ventilatory teaching of high tidal volumes and normal PaCO2. Current strategies therefore emphasis lower tidal volumes, adequate positive end-expiratory pressure (PEEP), minimum FiO2, and the use of pressure-control modes (plus or minus inverse-ratio ventilation). Hypercapnia is allowed to develop, and adjunctive methods are employed to improve oxygenation in order to minimise the "pressure-cost" of maintaining adequate oxygenation. With such an approach, overall mortality is reported to be around 40%.

Modulation of ventricular function through gene transfer in vivo

We used a catheter-based technique to achieve generalized cardiac gene transfer in vivo and to alter cardiac function by overexpressing phospholamban (PL) which regulates the activity of the sarcoplasmic reticulum Ca2+ ATPase (SERCA2a). By using this approach, rat hearts were transduced in vivo with 5 x 10(9) pfu of recombinant adenoviral vectors carrying cDNA for either PL, beta-galactosidase (beta-gal), or modified green fluorescent protein (EGFP). Western blot analysis of ventricles obtained from rats transduced by Ad.PL showed a 2.8-fold increase in PL compared with hearts transduced by Ad.betagal. Two days after infection, rat hearts transduced with Ad.PL had lower peak left ventricular pressure (58.3 +/- 12.9 mmHg, n = 8) compared with uninfected hearts (92.5 +/- 3.5 mmHg, n = 6) or hearts infected with Ad.betagal (92.6 +/- 5.9 mmHg, n = 6). Both peak rate of pressure rise and pressure fall (+3, 210 +/- 298 mmHg/s, -2, 117 +/- 178 mmHg/s, n = 8) were decreased in hearts overexpressing PL compared with uninfected hearts (+5, 225 +/- 136 mmHg/s, -3, 805 +/- 97 mmHg/s, n = 6) or hearts infected with Ad.betagal (+5, 108 +/- 167 mmHg/s, -3, 765 +/- 121 mmHg/s, n = 6). The time constant of left ventricular relaxation increased significantly in hearts overexpressing PL (33.4 +/- 3.2 ms, n = 8) compared with uninfected hearts (18.5 +/- 1.0 ms, n = 6) or hearts infected with Ad.betagal (20.8 +/- 2.1 ms, n = 6). These differences in ventricular function were maintained 7 days after infection. These studies open the prospect of using somatic gene transfer to modulate overall cardiac function in vivo for either experimental or therapeutic applications.

Prolyl endopeptidase inhibitors from caryophylli flos

Three prolyl endopeptidase inhibitors were isolated and identified as luteolin, quercetin and beta-sitosterol-3-O-beta-D-glucopyranoside with IC50 of 0.17, 0.19 and 27.5 ppm, respectively. The inhibition of two flavonoids were non-competitive with substrate. Twenty authentic flavonoids were tested in order to investigate structure-activity relationship. No significant relationship was found in them, however, catechol moiety of B-ring and 7-OH group in flavonoid skeleton were seemed to be responsible for the stronger activity.

Bioactive kaurane diterpenoids from Annona glabra

Phytochemical analysis of the fruits of Annona glabra yielded two new kaurane diterpenoids, annoglabasin A (methyl-16 beta-acetoxy-19-al-ent-kauran-17-oate)(1) and annoglabasin B (16 alpha-hydro-19-acetoxy-ent-kauran-17-oic acid)(2), along with 11 known kaurane derivatives (3-13). The structures of the new compounds were established by spectral and chemical evidence. Among these, methyl-16 alpha-hydro-19-al-ent-kauran-17-oate (11) exhibited mild activity against HIV replication in H9 lymphocyte cells, and 16 alpha-17-dihydroxy-ent-kauran-19-oic acid (4) showed significant inhibition of HIV-reverse transcriptase.

Prophylactic effect of Korean mistletoe (Viscum album coloratum) extract on tumor metastasis is mediated by enhancement of NK cell activity

We here demonstrated the prophylactic effect of an extract (KM-110) from Viscum album coloratum, a Korean mistletoe, on tumor metastasis produced by highly metastatic tumor cells, colon 26-M3.1 carcinoma, B16-BL6 melanoma and L5178Y-ML25 lymphoma cells, using experimental models in mice. Intravenous (i.v.) administration of KM-110 (100 microg/mouse) 2 days before tumor inoculation significantly inhibited lung metastasis of B16-BL6 and colon 26-M3.1 cells, and liver and spleen metastasis of L5178Y-ML25 cells. The prophylactic effect of KM-110 on tumor metastasis was evident with various administration routes, i.e. subcutaneous, oral, intranasal as well as i.v., and was dependent upon the dose of KM-110 administered. Furthermore, mice given KM-110 (100 microg) 2 days before tumor inoculation showed significantly prolonged survival rates compared with the untreated mice. In a time course analysis of NK activity, i.v. administration of KM-110 (100 microg) significantly augmented NK cytotoxicity to Yac-a tumor cells from 1 to 3 days after KM-110 treatment. Furthermore, depletion NK cells by injection of rabbit anti-asialo GM1 serum completely abolished the inhibitory effect of KM-110 on lung metastasis of colon 26-M3.1 cells. These results suggest that KM-110 possesses immunopotentiating activity which enhances the host defense system against tumors, and that its prophylactic effect on tumor metastasis is mediated by NK cell activation.

Acute occlusion of the middle cerebral artery: early evaluation with triphasic helical CT--preliminary results

PURPOSE

To evaluate use of triphasic helical computed tomography (CT) for early diagnosis of occlusion and assessment of ischemia in cases of acute middle cerebral arterial occlusion.

MATERIALS AND METHODS

Thirty-five patients with acute ischemia underwent triphasic helical CT within 6 hours after symptom onset. Early arterial, perfusion, and delayed phase CT scans were obtained 18, 30, and 80 seconds, respectively, after contrast material administration. Eighteen patients had proximal middle cerebral arterial occlusion diagnosed at magnetic resonance (MR) or digital subtraction angiography. Follow-up CT or MR imaging was performed in all patients. Two independent observers interpreted images for signs of arterial occlusion, collateral vessels, and the ischemic zone.

RESULTS

One observer found at least one of three signs in 17 of the 18 patients with occlusion, and the other found at least one sign in all 18: Early decreased arterial contrast enhancement was seen by both observers in 11 patients (kappa = 0.77), a nonenhancing arterial segment was seen by the two observers in 12 and 14 (kappa = 0.73), and delayed asymmetric arterial enhancement was seen in 13 and 16 (kappa = 0.49). Triphasic CT findings of the ischemic zone were consistent with follow-up CT or MR imaging findings in seven of 12 patients.

CONCLUSION

Triphasic helical CT is useful for early diagnosis of acute proximal middle cerebral arterial occlusion and assessment of the ischemic zone.

Antitumor agents. 181. Synthesis and biological evaluation of 6,7,2',3',4'-substituted-1,2,3,4-tetrahydro-2-phenyl-4-quinolones as a new class of antimitotic antitumor agents

A novel series of 6,7,2',3',4'-substituted-1,2,3,4-tetrahydro-2-phenyl- 4-quinolones were synthesized and evaluated for interactions with tubulin and for cytotoxic activity against a panel of human tumor cell lines, including ileocecal carcinoma (HCT-8), breast cancer (MCF-7), lung carcinoma (A-549), epidermoid carcinoma of the nasopharynx (KB), renal cancer (CAKI-1), and melanoma cancer (SKMEL-2). Most compounds (18, 20, 22-27) showed potent cytotoxic and antitubulin effects. The most active compounds (23, 26, 27) demonstrated strong cytotoxic effects with ED50 values in the nanomolar or subnanomolar range in almost all tumor cell lines. Three active racemates (20, 22, 25) were separated into the enantiomers, and generally, the optically pure (-)-isomers (20a, 22a, 25a) exhibited greater biological activity than the racemates or (+)-isomers. Cytotoxicity and antitubulin activity were closely correlated, with the most active compounds (23, 26, 27) having effects comparable to those of colchicine, podophyllotoxin, and combretastatin A-4.

Muscle sympathetic nerve activity during cold pressor test in patients with cerebrovascular accidents

BACKGROUND AND PURPOSE

Autonomic dysfunction is frequently present in patients with cerebrovascular accidents (CVA). However, the pathophysiological mechanisms of these disorders are not clear. The purpose of the study was to assess the effects of CVA on the autonomic nervous system.

METHODS

In eight male patients with a history of CVA with damage of the cortical or subcortical structures, we measured the cold pressor response during recording of muscle sympathetic nerve activity (MSNA) from the peroneal nerve on the hemiplegic side. We also studied 10 age-matched male control subjects. Tests were performed before, during, and after immersion of the nonhemiplegic hand in ice water for a period of 3 minutes in each phase. We also recorded changes in heart rate (HR), arterial blood pressure, skin temperature of the middle finger, and perception of pain using the Borg's score.

RESULTS

During the control period, the mean burst count of MSNA in CVA (57.2 +/- 3.9 beats/100 HR) was higher than in control subjects (36.3 +/- 3.2 beats/100 HR) (P<.05). Total MSNA (the mean burst amplitude per minute times burst rate) increased significantly in CVA and control during the immersion period by 79.9 +/- 18.4% and 133.1 +/- 25.6%, respectively. The percent change in total MSNA in CVA was attenuated during immersion compared with control subjects. The HR and skin temperature responses as well as the Borg's score were similar in both groups during control, hand immersion, and recovery periods.

CONCLUSIONS

The present results suggest that increased MSNA in CVA may be due to damage of cortical or subcortical structures or stroke-related changes in other areas or nonspecific changes that cause continuous increase in basal MSNA.

Effects of Ascorbic Acid on the Light-Induced Riboflavin Degradation and Color Changes in Milks

Effects of ascorbic acid (0.025, 0.05, and 0.1%, w/v) on the light-induced riboflavin degradation and color changes in whole and skim milks were studied during 10 h fluorescent light illumination at 7 +/- 2 degrees C. As the time of light illumination increased, the riboflavin content in milks greatly decreased, resulting in 30.1 and 59.1% reduction of riboflavin in whole milk and skim milk after 10 h exposure to fluorescent light, respectively. The ascorbic acid treatment effectively protected the photodegradation of riboflavin in both whole milk and skim milk, and its effectiveness is concentration dependent. The 0.1% ascorbic acid treatments resulted in 50.0 and 25.5% inhibition of riboflavin reduction in whole milk and skim milk after 10 h fluorescent light illumination, respectively. The color parameters of lightness (L), greenness (-a), and yellowness (b) in both whole milk and skim milk decreased after light illumination. Ascorbic acid treatment also protected effectively the changes in greenness and yellowness in both milks during the light illumination.

Effect of bile acids on the growth and differentiation of cultured human keratinocytes

Sixteen bile acids were tested at a concentration of 50 microM for their effect on growth of preconfluent cultures of proliferating keratinocytes. Monohydroxy bile acids (3-beta-hydroxy-delta 5-cholenate and lithocholate) stopped the accumulation of protein, dramatically decreased DNA content and led to a 90% loss of cell viability. Deoxycholate (DOC) and chenodeoxycholate inhibited protein accumulation and blocked increases in DNA content, without affecting cell viability. DOC had measurable growth-retarding effects at concentrations as low as 15 microM, and lithocholate at 2 microM. The glycine and taurine conjugates of bile acids were significantly less effective inhibitors of growth, as was the sulfate conjugate of lithocholic acid. DOC and chenodeoxycholate at 25-50 microM enhanced the differentiation-specific increase in particulate transglutaminase activity by as much as 80% over 6 days. Lithocholate had a similar effect at 5 microM. Glycine and taurine conjugates of DOC had a similar effect but were less potent; tauroursodeoxycholate had no effect. The data indicate that bile acids, at levels seen in obstructive biliary disease, can lead to a down-regulation of keratinocyte growth and an up-regulation of differentiation.

Cloning and phylogenetic analysis of chitin synthase genes from the insect pathogenic fungus, Metarhizium anisopliae var. anisopliae

Degenerated PCR primers were used to amplify chitin synthase genes from genomic DNA of Metarhizium anisopliae var. anisopliae. Through cloning and sequencing of approximately 600-bp fragments amplified by PCR, we found three genes encoding different types of chitin synthases, designated MaCHS1, MaCHS2, and MaCHS3. Southern blot analysis performed on genomic DNA showed that each of the chitin synthases MaCHS1, MaCHS2, and MaCHS3 is encoded by a single copy gene. Alignment of their deduced amino acid sequences with those of other euascomycetes separated the sequences into three distinct classes. MaCHS1 was identified as a gene for class I chitin synthase, MaCHS2 for class II, and MaCHS3 for class III. The UPGMA dendrogram and phylogenetic tree of the deduced amino acid sequences revealed the taxonomic and evolutionary position of Metarhizium anisopliae var. anisopliae.

Liver transplant in Singapore--coming of age

BACKGROUND/AIM OF STUDY

Liver transplantation was first performed in 1967, and has become an accepted form of treatment worldwide for chronic liver diseases, acute liver failure and certain metabolic diseases. We document our experience in Singapore over the last 7 years since the first transplant was performed in 1990.

METHOD

Retrospective study at National University Hospital, Singapore.

RESULTS

Twenty-two operations (10 paediatric and 12 adults) have been performed with the last 17 having been performed in the last 17 months. Currently, there are 15 survivors (68%) since 1990, and percentage survival is even better if one considers the cases from the last 17 months when the majority of cases (17 transplants-77%) were performed (77% survival). The most common indication for transplant was biliary atresia for the paediatric group, while the adults were transplanted for hepatitis B and C cirrhosis, primary biliary cirrhosis, and fulminant liver failure. Tacrolimus is the main immunosuppression (10 patients), with the remaining 5 patients on cyclosporine. Various surgical techniques (living donor, graft reduction) have been employed successfully to provide a complete transplant service. Hospital and ICU stays are within normal limits and the hospital charges range from a low of S$30,000 to S$141,000.

CONCLUSION

Liver transplantation has become a reality in Singapore with outcomes comparable to other transplant centres. The shortage of donors remains the greatest stumbling block for further expansion.

Antimicrobial activity and conformation of gaegurin-6 amide and its analogs

A function of the intra-disulfide bridge located at the C-terminal of Rana peptides has not been extensively studied. To investigate the function of the disulfide bridge related to the activity and the structure, we chose Gaegurin-6, isolated from Rana rugosa as a model peptide and synthesized linear analogs. The reduction of the disulfide bridge resulted in the complete loss of antimicrobial activity while replacements of cysteines by serines retained antimicrobial activity. Circular dichroism spectra from a titration of the peptides in sodium dodecyl sulfate indicated that the disulfide bridge of Gaegurin-6 might stabilize the induction of an alpha helical structure in lipid membranes and the alpha helical forming propensity of the peptides correlated with antimicrobial activity.

Use of recombinant poxviruses to stimulate anti-melanoma T cell reactivity

BACKGROUND

Dendritic cells (DC) are potent professional antigen-presenting cells that can activate naive T lymphocytes and initiate cellular immune responses. As adjuvants, DC may be useful for enhancing immunogenicity and mediating tumor regression. Endogenous expression of antigen by DC could offer the potential advantage of allowing prolonged constitutive presentation of endogenously processed epitopes and exploitation of multiple restriction elements for the presentation of the same antigen.

METHODS

DC were prepared from the peripheral blood of HLA A*0201 patients with metastatic melanoma in the presence of IL-4 (1000 IU/mL) and GMCSF (1000 IU/mL). Recombinant vaccinia and fowlpox viruses encoding the hMART-1 gene were constructed and used to infect DC. The efficiency of infection and expression of the MART-1 antigen were assessed by immunohistochemistry and intracellular FACS analyses. Cytotoxic lymphocytes (CTL) were generated by the stimulation of CD8+ T cells, with DC expressing the recombinant gene. Reactivity of the CTL was determined at weeks 1 and 2 by the amount of IFN-gamma released.

RESULTS

DC were infected with recombinant poxviruses and demonstrated specific melanoma antigen expression by immunohistochemistry, immunofluorescence, and intracellular FACS analysis. The expression by DC of MART-1 MAA after viral infection was sufficient to generate CD8+ T lymphocytes that recognized naturally processed epitopes on tumor cells in 10 of 11 patients.

CONCLUSIONS

Human DC are receptive to infection by recombinant poxviruses encoding MAA genes and are capable of efficiently processing and presenting these MAA to cytotoxic T cells. The potential advantage of this approach is the ability to present specific antigen independent of the identification of the epitope or the MHC restriction element. This strategy may be useful for the identification of relevant epitopes for a diverse number of HLA alleles and for active immunization in patients.