Advanced biomatrix designs for regenerative therapy of periodontal tissues

Periodontitis is an inflammatory disease that causes loss of the tooth-supporting apparatus, including periodontal ligament, cementum, and alveolar bone. A broad range of treatment options is currently available to restore the structure and function of the periodontal tissues. A regenerative approach, among others, is now considered the most promising paradigm for this purpose, harnessing the unique properties of stem cells. How to make full use of the body's innate regenerative capacity is thus a key issue. While stem cells and bioactive factors are essential components in the regenerative processes, matrices play pivotal roles in recapitulating stem cell functions and potentiating therapeutic actions of bioactive molecules. Moreover, the positions of appropriate bioactive matrices relative to the injury site may stimulate the innate regenerative stem cell populations, removing the need to deliver cells that have been manipulated outside of the body. In this topical review, we update views on advanced designs of biomatrices-including mimicking of the native extracellular matrix, providing mechanical stimulation, activating cell-driven matrices, and delivering bioactive factors in a controllable manner-which are ultimately useful for the regenerative therapy of periodontal tissues.

Characterization and optimization of vascular endothelial growth factor(165) (rhVEGF(165)) expression in Escherichia coli

Vascular endothelial growth factors(165) (VEGF(165)) is the most potent and widely used pro-angiogenic factor. Here we determined optimal culture condition of recombinant human VEGF(165) (rhVEGF(165)) in Escherichia coli (E. coli). rhVEGF(165) expression was the highest in 0.25% of L-arabinose induction concentration, at 20 °C induction temperature, and for 5 h induction time under the control of araBAD promoter using pBADHisA vector. In biological activity test, rhVEGF(165) significantly increased the proliferative activity of CPAE cells (p<0.001) and upregulated the expressions of endothelial cell growth-related genes, such as platelet endothelial cell adhesion molecule (PECAM-1), endothelial-specific receptor tyrosine kinase (TEK), kinase insert domain protein receptor (KDR), and tyrosine kinase with immunoglobulin-like and EGF-like domains 1 (TIE1) in calf pulmonary artery endothelial (CPAE) cells.

Aberrant ventral striatal responses during incentive processing in unmedicated patients with obsessive-compulsive disorder

OBJECTIVE

Obsessive-compulsive disorder (OCD) is characterized by the dysfunction of control and reward mechanisms. However, only few neuroimaging studies of OCD have examined the reward processing. We examined the neural responses during incentive processing in OCD.

METHOD

  Twenty unmedicated patients with OCD and 20 age-, sex-, and IQ-matched healthy controls underwent functional magnetic resonance imaging while performing a modified monetary incentive delay task.

RESULTS

Compared with controls, patients with OCD showed increased ventral striatal activation in the no-loss minus loss outcome contrast and a significant positive correlation between the ventral striatal activation and compulsion symptom severity. In addition, patients with OCD showed increased activations in the frontostriatal regions in the gain minus no-gain outcomes contrast. During loss anticipation, patients with OCD showed less activations in the lateral prefrontal and inferior parietal cortices. However, during gain anticipation, patients with OCD and healthy controls did not differ in the ventral striatal activation.

CONCLUSION

These findings provide neural evidence for altered incentive processing in unmedicated patients with OCD, suggesting an elevated sensitivity to negatively affect stimuli as well as dysfunction of the ventral striatum.

Abstract P3-10-25: The Prognosis of Metaplastic Breast Cancer Patients Compare to Triple-Negative Breast Cancer Patients

Background: Metaplastic breeast cancer (MBC) is a rare, heterogenous cancer characterized by admixture of adenocarcinoma with metaplastic elements, low hormone receptor expression and poor outcome. This study was planned to assess the clinicopathological chacteristics and immunohistochemical findings of MBC compared to invasive ductal carcinoma (IDC) including the triple-negative subtype (TN-IDC). Material and Methods: We retrospectively reviewed the medical records of 47 MBC and 1,346 IDC patients. Two hundred eighteen TN-IDC patients were included in the 1,346 IDC patients. Between 2005 and 2009, these patients were undergone surgical treatment at the Samsung Medical Center. Patients were reviewed clinicopathologic factors, immunohistochemistry of biologic factors such as ER, PR, HER-2, p53, Ki67, cytokeratine (CK) 5/6, epidermal growth factor receptor (EGFR), and treatment modalities (type of operation, use of chemotherapy, radiotherapy and hormone therapy). Result: The MBC patients presented with a larger tumor size (&gt;T1, 66.0% vs. 44.3.%, P = 0.008), lower lymph node involvement (N0, 73.3% vs. 55.6%, P = 0.03), higher histologic (HG) and nuclear grade (NG) (HG3, 70.0% vs. 41.5%, P = 0.001; NG3,82.6% vs. 46.9%, P &lt; 0.001), fewer estrogen receptor (ER), progesterone receptor (PR) and HER2 positivity (ER+, 4.3% vs. 69.2%, P &lt; 0.001; PR+, 6.4% vs. 63.5%, P &lt; 0.001; HER2+, 0% vs. 27.6%, P &lt; 0.001), higher p53, CK5/6 and EGFR expression (p53+, 63.8% vs.38.8%, P &lt; 0.001; CK5/6+, 71.9% vs.21.5%, P &lt; 0.001; EGFR+, 93.9% vs.21.6%, P &lt;0.001) and more TN subtypes (93.6% vs. 16.2%, P &lt; 0.001) compared to the IDC group. There was no significant difference in clinicopathological characteristics with MBC and TN-IDC except EGFR over expression (EGFR+, 93.9% vs.69.0%, P = 0.017). In follow-up duration (median 30 months, range 2-56 months), seven (14.9%) MBC patients and 98 (7.2%) IDC patients recurred. The 3-year disease-free survival (DFS) rate was 78.1% in the MBC group and 91.1% in IDC group (P &lt;0.001). The 3-year DFS rate was not significantly difference between MBC group and TN-IDC group (78.1% vs. 84.9%, P = 0.114). However, in patients with lymph node metastasis who underwent adjuvant chemotherapy, the 3-year DFS rate was 44.4% in MBC group and 72.5% in TN-IDC group (P = 0.025).

Discussion: In our result, MBC show poorer clinical outcome than IDC. It is not shown significant difference between MBC and TN-IDC. However, MBC patients with nodal metastasis have poorer prognosis than TN-IDC patients with metastasis despite adjuvant chemotherapy.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-10-25.

Design and construction of a compact microwave proton source for a proton linac

A 100 MeV, 20 mA proton linear accelerator is being developed by the Proton Engineering Frontier Project at the Korea Atomic Energy Research Institute. 20 MeV acceleration system using radio frequency quadrupole and drift tube linac was already developed and has been tested. To operate this acceleration system with a long time, more reliable proton source is needed. A compact microwave proton source was proposed and has been designed and constructed as a prototype ion source for the 100 MeV proton linear accelerator. The design of microwave power injection system is based on the microwave proton injector at LANL and CEA. The wave power from a 2.45 GHz, 2 kW magnetron source is introduced into a compact plasma chamber with 7 cm diameter and 5 cm length through a standard tapered, double-ridged waveguide (WRD250) and a quartz window. The microwave power supply is installed on high voltage platform. Axial magnetic fields up to 1 kG can be provided with a water-cooled solenoid coil. A single-hole three electrode extraction system is designed for an extraction current up to 30 mA at a 50 kV extraction voltage. The design and initial operations of the proton source are presented.

Decreased phosphorylation of STAT-1, STAT-4 and cytokine release in MDR-TB patients with primary resistance

SETTING

We recently showed that treatment failure rate was higher among multidrug-resistant tuberculosis (MDR-TB) patients without a previous history of tuberculosis (TB) treatment, or so-called 'primary resistance'.

OBJECTIVE

To investigate the phosphorylation levels of signal transducers and activators of transcription-1 (STAT-1) and STAT-4 and the subsequent cytokine release as a possible cause of a poor prognosis in MDR-TB patients with primary resistance.

DESIGN

Ten patients with successfully treated pulmonary TB without resistance, 12 MDR-TB patients with acquired resistance and 10 MDR-TB patients with primary resistance were enrolled. After 24 h stimulation of peripheral blood mononuclear cells (PBMC) with interferon-gamma (IFN-gamma), interleukin-12 (IL-12), purified protein derivative (PPD), or lysate of Mycobacterium tuberculosis, flow cytometric analysis of intracellular pSTAT-1 and pSTAT-4 were performed and secretion of IFN-gamma, IL-12p40 and tumour necrosis factor-alpha (TNF-alpha) was measured in culture supernatant.

RESULTS

The mean fluorescent intensities of pSTAT-1 and pSTAT-4 in PBMC of MDR-TB patients with primary resistance decreased on stimulation of IFN-gamma, PPD or lysate of M. tuberculosis when compared with patients with acquired resistance. In addition, secretion of IFN-gamma, IL-12p40 and TNF-alpha in these patients decreased on various stimuli.

CONCLUSION

Decreased phosphorylation of STAT-1, STAT-4, and of subsequent cytokine release, might be associated with a poor prognosis in MDR-TB patients with primary resistance.

Characterization of time-related changes after experimental bile duct ligation

BACKGROUND

Although bile duct ligation (BDL) in mice is used to study cholestasis, a detailed description of this animal model is lacking. The aim of this study was to define specific phases of acute and chronic injury and repair in the different cellular compartments of the liver.

METHODS

C57BL/6 mice underwent BDL or sham laparotomy, and serum and liver tissue were analysed between 8 h and 6 weeks later.

RESULTS

Biliary infarcts and alanine aminotransferase levels revealed acute hepatocellular injury peaking at days 2-3, paralleled by enhanced transcription of pro-proliferative mediators and followed by a distinct peak of hepatocellular proliferation at day 5. Cholangiocellular proliferation occurred in large bile ducts on days 2-3 and in small bile ducts on day 5. Neutrophil infiltration occurred within 8 h, with neutrophils remaining the predominant immune cell type until day 3. Acute injury was followed by continuous tissue repair, lymphocyte and Kupffer cell infiltration, and accumulation of collagen during the second week. Thereafter, the number of alpha-smooth muscle actin-positive cells and the expression of transforming growth factor beta1, tissue inhibitor of metalloproteinases 1 and procollagen (I) decreased, and liver fibrosis stabilized.

CONCLUSION

BDL elicits dynamic changes in mouse liver. The chronological dissection and quantification of these events identified specific phases of acute and chronic cholestatic liver injury.

White matter abnormalities in drug-naïve patients with obsessive-compulsive disorder: a diffusion tensor study before and after citalopram treatment

OBJECTIVE

The aim was to investigate the white matter abnormalities of drug-naïve patients with obsessive-compulsive disorder (OCD) using diffusion tensor-imaging and the white matter changes in the patients after pharmacotherapy.

METHOD

Thirteen drug-naïve OCD patients and 13 age- and sex-matched healthy comparison subjects were examined using diffusion tensor-imaging and structural magnetic resonance imaging. Measurements were made in OCD patients before and after 12 weeks of citalopram treatment.

RESULTS

Compared with controls, the drug-naïve OCD patients showed significant increases in fractional anisotropy (FA) in the corpus callosum, the internal capsule and white matter in the area superolateral to the right caudate. The increases in FA were mostly no longer observed in patients after 12 weeks of treatment compared with controls.

CONCLUSION

Our findings suggest that white matter alterations are associated with the pathophysiology of OCD, and the abnormalities may be partly reversible with pharmacotherapy.

Characteristics of indicator microorganisms in paddy rice plots after reclaimed water irrigation

A study was performed to examine the effects of reclaimed-water irrigation on microorganism concentration in the ponded-water of paddy rice plots. Several treatments were used and each one was triplicated to evaluate the change of indicator microorganisms (total coliforms (TC), faecal coliforms (FC), and E. coli) concentrations in 2003 and 2004 growing seasons. Their concentrations increased significantly after irrigation, but decreased by approximately 45% in 24 h. It implies that agricultural activities such as ploughing and fertilising need to be practiced one or two days after irrigation, considering health risks. Treatments with UV-disinfected water irrigation, demonstrated significantly lower concentrations than others, including control plots where natural water was irrigated. The monitoring result from actual paddy rice fields and experimental paddy plots showed that concentrations of indicator microorganisms ranged from 10(2) to 10(5) MPN/100 mL. The field scale water reuse research project is in progress and national guidelines for reclaimed-water irrigation are under preparation in Korea. A comprehensive assessment of existing agricultural practices and a thorough monitoring in the fields as well as treatment plots are recommended to make national guidelines more representative.

Integrated modelling under uncertainty in watershed-level assessment and management

Uncertainty in water quality model predictions is inevitably high due to natural stochasticity, model uncertainty, and parameter uncertainty. An integrated modelling system (modified-BASINS) under uncertainty is described and demonstrated for use in receiving-water quality prediction and watershed management. A Monte Carlo simulation was used to investigate the effect of various uncertainty types on output prediction. Without pollution control measures in the watershed, the concentrations of total nitrogen (T-N) and total phosphorus (T-P) in the Hwaong Reservoir, considering three uncertainty types, would be less than about 4.4 and 0.23 mg L(-1), respectively, in 2012, with 90% confidence. The effects of two watershed management practices, wastewater treatment plants (WWTP) and constructed wetlands (WETLAND), were evaluated. The combined scenario (WWTP + WETLAND) was the most effective at improving reservoir water quality, bringing concentrations of T-N and T-P in the Hwaong Reservoir to less than 3.4 and 0.14 mg L(-1), 24 and 41% improvements, respectively, with 90% confidence. Overall, the Monte Carlo simulation in the integrated modelling system was practical for estimating uncertainty and reliable in water quality prediction. The approach described here may allow decisions to be made based on the probability and level of risk, and its application is recommended.

Acute-phase response alters the disposition kinetics of cefepime following intravenous administration to rabbits

The effect of experimentally induced fever on the pharmacokinetics of cefepime administered intravenously at a dose of 75 mg/kg bw was studied in six healthy rabbits. The study was conducted in two consecutive phases, separated by a washout period of 2 weeks. Infection was induced by the intravenous inoculation of 5 x 10(8) cfu of Escherichia coli 24 h before the pharmacokinetic investigation was carried out. Serial blood samples for cefepime concentration determination were obtained for 48 h following drug administration. The concentrations of cefepime in the plasma were determined by a quantitative microbiological assay using an agar-gel diffusion method employing Bacillus subtilis ATCC 6633 as the test organism, with a level of detectability of approximately 0.10 microg/ml. Cefepime plasma concentrations versus time were evaluated by non-compartmental methods using WinNonLin. Cefepime was well tolerated and no serious adverse events were observed. Rectal temperature increased 1 degree C 24 h post injection in infected animals. Highly significant differences in the blood plasma concentrations of cefepime were observed between febrile and healthy animals at all the sampling times. This could explain the greater area under the plasma level-time curve of the drug in febrile compared with healthy animals. The results from pharmacokinetic calculations showed that both the distribution volume at steady state (V (dss)) and body clearance (CL(tot)) were affected in febrile as compared to healthy animals. The mean values of V (dss) and CL(tot) of cefepime in healthy rabbits were 1.168 L/kg and 0.303 L/kg/h, respectively. As compared with healthy animals, the mean estimates of V (dss) (0.917 L/kg) and CL(tot) (0.205 L/kg per h) of cefepime were significantly lower, whereas t (1/2lambda), MRT and AUMC were significantly higher in febrile rabbits. It is concluded that, although experimental infection had an effect on the disposition kinetics of cefepime in healthy and febrile rabbits, this was not sufficiently pronounced to require alteration of the dosage during disease.

Low loss high mesa optical waveguides based on InGaAsP/InP heterostructures

Low loss high mesa optical waveguides were fabricated on InGaAsP/InP heterostructures by utilizing inductively-coupled-plasma reactive ion etching (ICP-RIE) and electron beam lithography technique. The fabrication process was optimized by measuring sidewall roughness of deep-etched waveguides. Atomic force microscope loaded with carbon nanotude was used to obtain three-dimensional image of the etched sidewall of waveguides. The obtained statistical information such as rms roughness and correlation length was used to theoretically calculate scattering loss of waveguides. Several waveguides with different number of sharp bends and the length were fabricated and their propagation losses were measured by modified Fabry-Perot method. The measured propagation losses were compared with theoretically calculated losses.

Concurrent chemoradiotherapy in patients with nasopharyngeal cancer: prognostic significance of low expression of bax

A randomized trial has demonstrated that concurrent chemoradiotherapy (CRT) is superior to radiotherapy (RT) alone in locally advanced nasopharyngeal cancer (NPC). Our study comprise 35 patients with locally advanced NPC (stage I: 1, II: 12, III: 7, IV: 15) with 1 cycle of induction chemotherapy (5-fluorouracil 1,000 mg/m(2)/day and cisplatin 20 mg/m(2)/day, days 1- 4) followed by concurrent CRT starting on day 22. Concurrent CRT consisted of RT (70 Gy/35 fractions for 7 weeks) with cisplatin 20 mg/m(2)/day for 4 days on weeks 1, 4, 7 of RT. Complete response (CR) was achieved in 33 patients (94%). Four-year progression-free survival (PFS) and overall survival (OS) of all patients were 57% and 65%, respectively. In analysis of prognostic factors, low expression of bax was the most significant independent predictor of poor prognosis in both PFS (p=0.002) and OS (p=0.008). In conclusion, the outcome of patients treated with this combined therapeutical modality appears to be comparable with that of Intergroup 0099 trial with high CR rate. Low expression of bax was significantly associated with poor PFS and OS.

Effects of high concentrations of energy sources and metabolites on suspension culture of Chinese hamster ovary cells producing tissue plasminogen activator

A high-concentration medium was developed for the high-density cultivation of Chinese hamster ovary (CHO) cells to produce tissue plasminogen activator (tPA). First, the effects of the concentrations of several medium components on the growth and metabolism of CHO cells were studied particularly in relation to the serum concentration, in order to develop a suitable concentrated medium. High concentrations of serum, glucose, lactate, and glutamine and a low ammonia concentration increased the specific growth rate and decreased the specific tPA production rate. Among these components, the effect of the serum concentration was the most significant. There was an inverse correlation between the specific rates of cell growth and tPA production. Using a medium containing glutamine at twice the concentration of the original medium (F-12) allowed the medium volume to be reduced to seven-ninths that of the original, without any reduction in tPA productivity. When the F-12 medium was supplemented five-fold with amino acids and vitamins, the total amount of tPA produced, specific rate of tPA production, and yield of tPA per unit volume of medium employed were respectively enhanced 1.7, 1.5, and 3.6 times. As a consequence, the frequency of medium exchange could be reduced. The results strongly indicate that the supplementation of nutrient amino acids and vitamins to a medium with a low concentration of serum are the most critical factors for cost-effective tPA production in high-density cell cultivation.

Enhancement of styrene removal by Pseudomonas sp. SR-5 in mixed culture with a benzoic acid-degrading bacterium in biofilter

The growth of a styrene-degrading bacterium, Pseudomonas sp. SR-5, was inhibited by benzoic acid (BA), one of the styrene degradation intermediates, in liquid culture. A benzoic acid-degrading microorganism, Raoultella sp. strain A, was isolated from a peat biofilter inoculated with a wastewater. The styrene removal efficiencies of the two laboratory-scale biofilters inoculated with only strain SR-5 and a mixed culture of strains SR-5 and A were compared using a mixed packing material of peat and ceramic (1:1) for 45 days. The biofilter with the mixed culture showed a higher removal efficiency than that with a single culture of SR-5. The maximum elimination capacities of the biofilters with the mixed culture and the single culture were 141 g m(-3)h(-1) and 106 g m(-3)h(-1), respectively. In the biofilter with the single culture, 136 g of benzoic acid (m3 of dry packing material)(-1) was accumulated at the end of the experiment. However, no accumulation of benzoic acid was observed in the biofilter with the mixed culture.

Peripheral glutamate receptors contribute to mechanical hyperalgesia in a neuropathic pain model of the rat

We hypothesized that glutamate (Glu) released from the peripheral terminals of primary afferents contributes to the generation of mechanical hyperalgesia following peripheral nerve injury. Nerve injury was performed on rats with a lumbar 5 spinal nerve lesion (L5 SNL), which was preceded by L5 dorsal rhizotomy (L5 DR) to avoid the potential central effects induced by L5 SNL through the L5 dorsal root. Mechanical hyperalgesia, as evidenced by a reduction in paw withdrawal threshold (PWT), was short-lasting (<6 days) after L5 DR, but persistent (>42 days) after L5 SNL preceded by L5 DR. When an intraplantar injection into the affected hind paw was given immediately before L5 SNL, non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist MK-801 (20 nmol), group-I metabotropic Glu (mGlu) receptor antagonist DL-amino-3-phosphonopropionic acid (DL-AP3; 70 nmol), and selective group-II mGlu receptor agonist 4-aminopyrrolidine-2,4-dicarboxylate (APDC; 20 nmol) delayed the onset of PWT reduction for 1-4 days. However, this onset was not affected by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid/kainate receptor antagonist 2,3-dioxo-6-nitro-1,2,3,4,-tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX; 100 nmol). When the same injection was given after L5 SNL-induced mechanical hyperalgesia had been established, MK-801 reversed the PWT reduction for 30-75 min, whereas NBQX, DL-AP3, or APDC had no effect. These results suggest that the manipulation of the peripheral Glu receptors reduces neuropathic pain, by blocking NMDA and group-I mGlu receptors and by stimulating group-II mGlu receptor during the induction phase of neuropathic pain, but only by blocking the NMDA receptor during its maintenance phase.

Ion channels of Fasciola hepatica incorporated into planar lipid bilayers

Ion channels are important target sites of anthelmintics, but little is known about those in Fasciola hepatica. In this work, we applied a planar lipid bilayer technique to characterize the properties of single ion channels in F. hepatica. Under a 200/40 mM KCl gradient, a large conductance channel of 251 pS was observed in 18% of the membranes studied. The channel was selective to K(+) over Cl(-) with a permeability ratio of K(+) to Cl(-) (PK/PCl) of 4.9. Open state probability (Po) of the channel was less than 0.5 and dependent on voltage (-60 to approximately +40 mV) and Ca(2+) (approximately 100 microM). The other two types of single channels observed in 11 and 5% of membranes, respectively, were a K(+)-permeable channel of 80 pS (PK/PCl=4.6) and a Cl(-)-permeable channel of 64 pS (PK/PCl=0.058). Open state probability of both channels showed little voltage dependence. The results indicate that distinct single channels of 60 to approximately 251 pS are present in relative abundance and, in addition, that the planar lipid bilayer technique can be a useful tool for the study of single ion channels in F. hepatica.

Styrene degradation by Pseudomonas sp. SR-5 in biofilters with organic and inorganic packing materials

Pseudomonas sp. SR-5 was isolated as a styrene-degrading bacterium. In liquid culture containing 1% (v/v) styrene, more than 90% styrene was degraded in 53 h and the doubling time of SR-5 was 2 h. The removal of styrene gas was investigated in biofilters for 31 days using an organic packing material of peat and an inorganic packing material of ceramic inoculated with SR-5. The maximum-styrene-elimination capacities for peat and ceramic packing materials were 236 and 81 g m(-3) h(-1), respectively. The percentage of styrene converted to low molecular weight compounds including CO(2) in the peat and ceramic biofilters during a 10-day operation were estimated to be 90.4 and 36.7%, respectively. As the pressure drop in the peat bioflter at the end of experiment was significantly higher than that in ceramic biofilter, a biofilter using a mixture of peat and ceramic was tested. We determined that the maximum elimination capacity was 170 g m(-3) h(-1) and the production of low molecular weight compounds was 95% at a low pressure drop for this mixed packing material filter.

Motility restriction after resection of an extraocular muscle

Restriction of eye movement after surgery is an unusual but troublesome complication. A patient presented with a limitation of abduction after a 5 mm resection of medial rectus muscle and an 8 mm recession of lateral rectus muscle. Since the forced duction test was positive, restrictive factors were suggested to be implicated. A reparative operation was performed at the postoperative 9 month, and the forced duction test was negative after releasing the resected medial rectus muscle. The patient showed an improved abduction after recessing the resected muscle. Even after an uneventful surgery, resection of an extraocular muscle may cause restriction of ocular rotation caused by muscle scarring to the sclera or by an increased tightness of the muscle.

Idarubicin, cytarabine, and topotecan in patients with refractory or relapsed acute myelogenous leukemia and high-risk myelodysplastic syndrome

In an effort to develop more effective therapy for patients with refractory or relapsed acute myelogenous leukemia (AML) and high-risk myelodysplastic syndrome (MDS), we investigated the efficacy of a combination chemotherapy consisting of idarubicin, cytarabine, and topotecan. Twenty-seven patients were treated: four with primary refractory AML, nine with AML in first relapse, four with AML in second relapse, and 10 with MDS-RAEB/RAEBT. Patients received as salvage therapy a single course of idarubicin 12 mg/m(2) IV bolus on days 1-3, cytarabine 1 g/m(2) over two hours q 12 hr on days 1-5, and topotecan 1.25 mg/m(2) over 24 hr on days 1-5. Median age was 42 years (range 17-65 years). All patients were evaluable for response: 14 (51.9%) achieved complete remission, 10 with AML (59%) and four with MDS (40%), respectively. Thirteen AML patients (excluding four relapsed after autologous stem cell transplantation) were grouped into four categories to stratify the probability of achieving complete remission (CR): group 1, first CR duration > or = 2 years and receiving first salvage treatment (S1); group 2, first CR duration 1-2 years and receiving S1; group 3, first CR duration 0-1 years and receiving S1; and group 4, first CR duration 0-1 years and receiving S2, S3, or S4 after failing S1. The response rate of each group was as follows: group 1, one of two (50%); group 2, one of one (100%); group 3, four of four (100%); group 4, two of six (33.3%). The median remission duration and survival of patients with AML were six and 12 months, respectively. Median duration of survival in 10 MDS patients was 15 months, and all four MDS patients achieving a CR maintained continuous CR with a median follow-up of 11 months. Severe myelosuppression was observed in all patients, resulting in fever or documented infections in 89% of patients. Median time to recovery of neutrophils > or =0.5 x 10(9)/l was 22 days (11-34) and for platelets > 20 x 10(9)/l 35 days (11-58). Reversible grade 3-4 toxicities included diarrhea (two patients) and mucositis (seven patients). We conclude that combination chemotherapy with intermediate dose cytarabine, idarubicin, and topotecan has significant antileukemic activity and acceptable toxicity in salvage AML and high-risk MDS.