Effects of Naringin on Cardiomyocytes From a Rodent Model of Type 2 Diabetes.

Diabetic cardiomyopathy (DCM) is a primary disease in diabetic patients characterized by diastolic dysfunction leading to heart failure and death. Unfortunately, even tight glycemic control has not been effective in its prevention. We have found aberrant diastolic Ca2+ concentrations ([Ca2+]d), decreased glucose transport, elevated production of reactive oxygen species (ROS), and increased calpain activity in cardiomyocytes from a murine model (db/db) of type 2 diabetes (T2D). Cardiomyocytes from these mice demonstrate significant cell injury, increased levels of tumor necrosis factor-alpha and interleukin-6 and expression of the transcription nuclear factor-κB (NF-κB). Furthermore, decreased cell viability, and reduced expression of Kir6.2, SUR1, and SUR2 subunits of the ATP-sensitive potassium (KATP) channels. Treatment of T2D mice with the citrus fruit flavonoid naringin for 4 weeks protected cardiomyocytes by reducing diastolic Ca2+ overload, improving glucose transport, lowering reactive oxygen species production, and suppressed myocardial inflammation. In addition, naringin reduced calpain activity, decreased cardiac injury, increased cell viability, and restored the protein expression of Kir6.2, SUR1, and SUR2 subunits of the KATP channels. Administration of the KATP channel inhibitor glibenclamide caused a further increase in [Ca2+]d in T2D cardiomyocytes and abolished the naringin effect on [Ca2+]d. Nicorandil, a KATP channel opener, and nitric oxide donor drug mimic the naringin effect on [Ca2+]d in T2D cardiomyocyte; however, it aggravated the hyperglycemia in T2D mice. These data add new insights into the mechanisms underlying the beneficial effects of naringin in T2D cardiomyopathy, thus suggesting a novel approach to treating this cardiovascular complication.

Enhancing Endogenous Nitric Oxide by Whole Body Periodic Acceleration Elicits Neuroprotective Effects in Dystrophic Neurons.

We have previously shown that inadequate dystrophin in cortical neurons in mdx mice is associated with age-dependent dyshomeostasis of resting intracellular Ca2+ ([Ca2+]i) and Na+ ([Na+]i), elevated reactive oxygen species (ROS) production, increase in neuronal damage and cognitive deficit. In this study, we assessed the potential therapeutic properties of the whole body periodic acceleration (pGz) to ameliorate the pathology observed in cortical neurons from the mdx mouse. pGz adds small pulses to the circulation, thereby increasing pulsatile shear stress to the vascular endothelium, which in turn increases production of nitric oxide (NO). We found [Ca2+]i and [Na+]i overload along with reactive oxygen species (ROS) overproduction in mdx neurons and cognitive dysfunction. mdx neurons showed increased activity of superoxide dismutase, glutathione peroxidase, malondialdehyde, and calpain as well as decreased cell viability. mdx neurons were more susceptible to hypoxia-reoxygenation injury than WT. pGz ameliorated the [Ca2+]i, and [Na+]i elevation and ROS overproduction and further increased the activities of superoxide dismutase, glutathione peroxidase and reduced the malondialdehyde and calpains. pGz diminished cell damage and elevated [Ca2+]i during hypoxia-reoxygenation and improved cognitive function in mdx mice. Moreover, pGz upregulated the expression of utrophin, dystroglycan-ß and CAPON, constitutive nitric oxide synthases, prosaposin, brain-derived neurotrophic, and glial cell line-derived neurotrophic factors. The present study demonstrated that pGz is an effective therapeutic approach to improve mdx neurons function, including cognitive functions.

Compensatory Increase in Ovarian Aromatase in Older Regularly Cycling Women.

CONTEXT: Serum estradiol (E2) levels are preserved in older reproductive-aged women with regular menstrual cycles despite declining ovarian function. OBJECTIVE: The objective of the study was to determine whether increased granulosa cell aromatase expression and activity account for preservation of E2 levels in older, regularly cycling women. DESIGN: The protocol included daily blood sampling and dominant follicle aspirations at an academic medical center during a natural menstrual cycle. SUBJECTS: Healthy, regularly cycling older (36-45 y; n = 13) and younger (22-34 y; n = 14) women participated in the study. MAIN OUTCOME MEASURES: Hormone levels were measured in peripheral blood and follicular fluid aspirates and granulosa cell CYP19A1 (aromatase) and FSH-R mRNA expression were determined. RESULTS: Older women had higher FSH levels than younger women during the early follicular phase with similar E2 but lower inhibin B and antimullerian hormone levels. Late follicular phase serum E2 did not differ between the two groups. Follicular fluid E2 [older (O) = 960.0 [interquartile range (IQR) 765.0-1419.0]; younger (Y) = 994.5 [647.3-1426.5] ng/mL, P = 1.0], estrone (O = 39.6 [29.5-54.1]; Y = 28.8 [22.5-42.1] ng/mL, P = 0.3), and the E2 to testosterone (T) ratio (O = 109.0 ± 41.9; Y = 83.0 ± 18.6, P = .50) were preserved in older women. Granulosa cell CYP19A1 expression was increased 3-fold in older compared with younger women (P < .001), with no difference in FSH-R expression. CONCLUSIONS: Ovarian aromatase expression increases with age in regularly cycling women. Thus, up-regulation of aromatase activity appears to compensate for the known age-related decrease in granulosa cell number in the dominant follicle to maintain ovarian estrogen production in older premenopausal women.

The rationale for intensity-modulated proton therapy in geometrically challenging cases.

Intensity-modulated proton therapy (IMPT) delivered with beam scanning is currently available at a limited number of proton centers. However, a simplified form of IMPT, the technique of field 'patching', has long been a standard practice in proton therapy centers. In field patching, different parts of the target volume are treated from different directions, i.e., a part of the tumor gets either full dose from a radiation field, or almost no dose. Thus, patching represents a form of binary intensity modulation. This study explores the limitations of the standard binary field patching technique, and evaluates possible dosimetric advantages of continuous dose modulations in IMPT. Specifics of the beam delivery technology, i.e., pencil beam scanning versus passive scattering and modulation, are not investigated. We have identified two geometries of target volumes and organs at risk (OAR) in which the use of field patching is severely challenged. We focused our investigations on two patient cases that exhibit these geometries: a paraspinal tumor case and a skull-base case. For those cases we performed treatment planning comparisons of three-dimensional conformal proton therapy (3DCPT) with field patching versus IMPT, using commercial and in-house software, respectively. We also analyzed the robustness of the resulting plans with respect to systematic setup errors of ±1 mm and range errors of ±2.5 mm. IMPT is able to better spare OAR while providing superior dose coverage for the challenging cases identified above. Both 3DCPT and IMPT are sensitive to setup errors and range uncertainties, with IMPT showing the largest effect. Nevertheless, when delivery uncertainties are taken into account IMPT plans remain superior regarding target coverage and OAR sparing. On the other hand, some clinical goals, such as the maximum dose to OAR, are more likely to be unmet with IMPT under large range errors. IMPT can potentially improve target coverage and OAR sparing in challenging cases, even when compared with the relatively complicated and time consuming field patching technique. While IMPT plans tend to be more sensitive to delivery uncertainties, their dosimetric advantage generally holds. Robust treatment planning techniques may further reduce the sensitivity of IMPT plans.

Dose escalation with proton radiation therapy for high-grade meningiomas.

Purpose of this study was to determine the toxicity and treatment outcome after dose escalation with proton radiation therapy for patients with World Health Organization (WHO) grade II and grade III meningiomas. Between 1997 and 1999, 6 patients with newly diagnosed or recurrent grade II or III meningioma were treated on a Phase I/II dose escalation trial with combined proton-photon radiotherapy at the Harvard Cyclotron Laboratory/Massachusetts General Hospital. The median age was 46. The sites were sphenoid wing in 2 patients, parasagittal/falcine in 2, parasellar in 1, and olfactory groove in 1. The median gross total volume (GTV) at the time of radiation was 13.3 cc (range: 4.0-129.5). The total dose to the GTV for the grade II and III meningiomas was 68.4 and 72.0 Gy (RBE) in 1.8 Gy (RBE), respectively. The median percentage of proton was 80%. All patients tolerated radiation treatment without any treatment break. None of the patients required steroids or hospitalization during radiation. There was no acute grade 3 to 5 toxicity. With a median follow-up period of 145 months for all surviving patients, one patient developed local recurrence. For the 5 patients with tumor controlled at the primary sites, 3 patients developed new meningioma(s) distantly from the primary sites at a median time of 25 months (range, 9-79). The median survival for grade II and grade III tumors was 145 months and 28 months, respectively. One patient developed late grade 1 dry eye. Two patients developed late grade 2 hypothyroidism and two developed grade 2 hypogonadism. There was no late grade 3-5 toxicity. Dose escalation with proton radiation therapy resulted in low toxicity and high local control rate in patients with high-grade meningiomas. Development of distant meningioma(s) intracranially was the main pattern of failure. Larger prospective studies are necessary to confirm our results.

Filtering Data Based on Human-Inspired Forgetting.

Robots are frequently presented with vast arrays of diverse data. Unfortunately, perfect memory and recall provides a mixed blessing. While flawless recollection of episodic data allows increased reasoning, photographic memory can hinder a robot's ability to operate in real-time dynamic environments. Human-inspired forgetting methods may enable robotic systems to rid themselves of out-dated, irrelevant, and erroneous data. This paper presents the use of human-inspired forgetting to act as a filter, removing unnecessary, erroneous, and out-of-date information. The novel ActSimple forgetting algorithm has been developed specifically to provide effective forgetting capabilities to robotic systems. This paper presents the ActSimple algorithm and how it was optimized and tested in a WiFi signal strength estimation task. The results generated by real-world testing suggest that human-inspired forgetting is an effective means of improving the ability of mobile robots to move and operate within complex and dynamic environments.

Maternal alcohol consumption increases sphingosine levels in the brains of progeny mice.

The effect of 'binge' alcohol upon sphingolipid metabolism in the fetal alcohol syndrome (FAS) was examined in pregnant mice (C57BL/6J) by administering a single dose of alcohol during the third trimester (gestational day 15-16). The control mice were administered a sucrose solution of equal caloric value. Brains from progeny at postnatal days 5, 15, 21 and 30 were dissected into three regions, and sphingolipid concentrations of the brain regions were determined including assay of monoglycosylceramide, ceramide, sphingosine and sphingomyelin. We found that a single dose of ethanol induces an elevation of sphingosine (2-3.5-fold) in the brain of progeny. The level of brain ceramide at a dose of 1.5 g/kg was significantly higher than control. Alcohol consumption during pregnancy induces neuronal loss in progeny brains. Our result suggests that the elevation of sphingosine in progeny brain induced by maternal alcohol consumption may be responsible for observed neuronal loss in FAS.

Effect of gemtuzumab ozogamicin on acute myeloid leukemia blast cells in vitro, as a single agent and combined with other cytotoxic cells.

The effect of gemtuzumab ozogamicin (GO) alone, or combined with low-dose cytarabine or etoposide, on the proliferation of acute myeloid leukaemia blast cells in vitro was investigated. GO alone induced a dose-dependent inhibition of proliferation although an increase in apoptosis was only seen in a minority of patients. A correlation was found between PgP function and GO sensitivity but not between CD33 or PgP expression and GO. Combinations of GO with varying concentrations of cytarabine or etoposide were additive in inhibiting proliferation, reducing cell viability and increasing apoptosis.

Advantage of protons compared to conventional X-ray or IMRT in the treatment of a pediatric patient with medulloblastoma.

PURPOSE: To compare treatment plans from standard photon therapy to intensity modulated X-rays (IMRT) and protons for craniospinal axis irradiation and posterior fossa boost in a patient with medulloblastoma. METHODS: Proton planning was accomplished using an in-house 3D planning system. IMRT plans were developed using the KonRad treatment planning system with 6-MV photons. RESULTS: Substantial normal-tissue dose sparing was realized with IMRT and proton treatment of the posterior fossa and spinal column. For example, the dose to 90% of the cochlea was reduced from 101.2% of the prescribed posterior fossa boost dose from conventional X-rays to 33.4% and 2.4% from IMRT and protons, respectively. Dose to 50% of the heart volume was reduced from 72.2% for conventional X-rays to 29.5% for IMRT and 0.5% for protons. Long-term toxicity with emphasis on hearing and endocrine and cardiac function should be substantially improved secondary to nontarget tissue sparing achieved with protons. CONCLUSION: The present study clearly demonstrates the advantage of conformal radiation methods for the treatment of posterior fossa and spinal column in children with medulloblastoma, when compared to conventional X-rays. Of the two conformal treatment methods evaluated, protons were found to be superior to IMRT.

Normal studies are essential for objective medical evaluations of children who may have been sexually abused.

UNLABELLED: The findings of carefully conducted research studies of non-abused children should be used in medical evaluations for suspected sexual abuse if they are to be legally defensible. These studies have shown that a "wide" hymenal opening and a "narrow" rim of hymen should not be used as markers of abuse. CONCLUSION: The study by Myhre and associates is another addition to a growing collection of good science in a field of medicine where objectivity is essential.

Adolescent sexual assault: documentation of acute injuries using photo-colposcopy.

OBJECTIVE: To document the frequency and types of genital injuries in adolescent women examined acutely following a sexual assault, and determine any historical correlates of injury. DESIGN: Retrospective chart review. SETTING: Sexual Assault Response Team services at a community hospital in an urban setting. PATIENTS: All female patients aged 14-19 yr who were referred by law enforcement for an acute sexual assault examination and were examined between May 1994 and May 1999. OUTCOME MEASURES: The frequency of signs of genital trauma at various anal and genital sites, as recorded by the examining clinician. RESULTS: Charts of 214 female subjects (mean age 16.3 yr) were reviewed. The most common findings were posterior fourchette tear (36%); erythema of the labia minora, hymen, cervix, or posterior fourchette (18%-32%); and swelling of the hymen (19%). Time to examination was highly correlated with the degree of injury noted (P =.000). The incidence of hymenal tears in self-described virgins was higher than in nonvirgins (19% vs. 3%, P =.008); however, the total number or severity of other injuries was not significantly higher in virgins. Victims reporting anal penetration had a higher frequency of anal injuries than those who denied such contact (14/31, 61% vs. 2/150, 1%; P =.000). CONCLUSIONS: Tears of the posterior fourchette or fossa were the most common findings (40%). Hymenal tears were uncommon, even in self-described virginal girls. Timely examination of adolescent victims is important to document injuries; however, many victims will still not have signs of bruising, abrasions, or tears.

Comparison of megakaryopoiesis in vitro of paired peripheral blood progenitor cells and bone marrow harvested during remission in patients with acute myeloid leukaemia.

We have studied paired peripheral blood progenitor cells (PBPC) and bone marrow (BM) samples from 12 acute myeloid leukaemia (AML) patients following intensive chemotherapy, and assessed direct granulocyte-macrophage colony-forming units (CFU-GM), erythroid burst-forming units (BFU-E), megakaryocyte CFU (CFU-Mk) numbers and the production of CD61+ (platelet glycoprotein IIIa) cells in suspension culture in response to various haemopoietic growth factor combinations. We found that CFU-GM and BFU-E numbers per 105 mononuclear cells were similar in both AML PBPC and BM harvests; CFU-Mk numbers, however, were significantly higher in PBPC than BM. In addition, the higher total white cell count of the PBPC harvests meant that PBPC have much higher numbers of total progenitors per collection. CD61+ cell numbers in suspension cultures of AML PBPC and BM were lower than those of harvested normal marrow. However, response to pegylated recombinant human megakaryocyte growth and development factor (PEGrHuMGDF) both alone and in combination with other growth factors was qualitatively similar to that of normal BM. As with normal BM, response to PEGrHuMGDF alone did not increase further with addition of granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage CSF (GM-CSF), interleukin 6 (IL-6) or erythropoietin (EPO) in the AML PBPC and BM. Further responses over PEGrHuMGDF alone were seen when added with stem cell factor (SCF) or with a combination of SCF + IL-3 + EPO in both AML PBPC and BM cultures; however, the magnitude of the response was greater in the PBPC cultures. Response to PEGrHuMGDF + IL-3 was seen in the PBPC cultures but not in the AML BM. These data suggest that, in AML patients, there are proportionally more megakaryocyte progenitor cells in the mobilized PBPC than in the BM harvests, which would explain the more rapid platelet recovery following PBPC autografts.

Novel CPR with periodic Gz acceleration.

The effects of periodic Gz acceleration (pGz) on cardiovascular function and hemodynamics were determined in a pig model of acute cardiopulmonary resuscitation (CPR). The application of pGz (horizontal head-to-foot oscillations) at 2 Hz increased cardiac output in fibrillated animals proportional to the amplitude of the applied acceleration force that plateaued at 0.7 G. Cardiac output in fibrillating animals was restored to 20% of the values obtained before fibrillation with pGz-CPR and arterial blood gas values were normal during this period. The central vascular pressure gradient driving blood flow was only about 6 mmHg, suggesting low vascular resistance during pGz-CPR. In another study, capillary blood flow was determined before and after pGz-CPR using colored microspheres. Capillary perfusion was detected in all tissue beds studied during pGz-CPR. Significant capillary blood flow was detected in the endocardium and brain stem during pGz-CPR that represented 39 and 197% of control values before fibrillation, respectively. Thus, the cardiac output during pGz-CPR was preferentially distributed to the myocardial and brain tissues. In a final group, animals were successfully resuscitated with return of spontaneous circulation (ROSC) after pGz-CPR for 15 min following cardiac fibrillation with a 3-min non-intervention period. Following ROSC, blood pressure was maintained at pre-arrest values for 2 h without any pharmacological or mechanical support. Arterial blood gases during the pGz-CPR and the ROSC periods were normal and not different from values obtained before fibrillation. None of the control animals (18 min of fibrillation without pGz-CPR) survived the experimental protocol and only two of these six animals briefly returned to spontaneous circulation (<20 min). In conclusion, experimental pGz-CPR produces cardiac output, capillary blood flow, and ventilation sufficient to maintain fibrillating animals for 18 min with ROSC for 2 h without support.

Regional blood flow during periodic acceleration.

OBJECTIVE: To determine whether a motion platform that imparts noninvasive periodic acceleration (pGz) forces to the body causes systemic vasodilation and changes local organ blood flow. DESIGN: Prospective paired blocked design. SETTING: Medical center research laboratory. SUBJECTS: Juvenile Yorkshire pigs. INTERVENTIONS: Juvenile pigs (12 kg) were anesthetized, paralyzed, and placed on a motion platform that oscillated at a frequency of 4 Hz and a force of approximately 0.4 G. MEASUREMENTS AND MAIN RESULTS: Regional blood flows, as assessed by colored microspheres, increased during pGz relative to values obtained before pGz. Blood flow (mL.min-1.100 g-1) significantly increased to the epicardium (71%), endocardium (93%), cerebrum (183%), brain stem (177%), renal cortex (53%), ileal mucosa (69%), gastric antral mucosa (72%), and liver (86%). Spleen and skeletal muscle blood flow increased without statistical significance, 38% and 158% with pGz, relative to paired control values. Regional blood flows returned to baseline 10 mins after discontinuation of pGz, except in the myocardial layers, where blood flow remained significantly elevated. There was no difference compared with baseline in heart rate, arterial blood gases, and blood pressure, but serum nitrite concentration was significantly higher (58%) during pGz. In another series of animals, pGz increased pulmonary artery blood flow directly proportional to the magnitude of the applied acceleration force with frequency held constant. CONCLUSIONS: Periodic sinusoidal inertial forces in the spinal axis increase blood flow to tissues. The increased blood flow is reversible and may be caused by vasodilation secondary to local mediator release. These effects may be desirable in clinical conditions of low tissue oxygen delivery and perfusion.

Nucleotide release and associated conformational changes regulate function in the COOH-terminal Src kinase, Csk.

The COOH-terminal Src kinase (Csk) regulates a broad array of cellular processes via the specific phosphorylation and downregulation of Src family protein kinases. While Csk has been a topic for steady-state kinetic studies, the individual steps associated with substrate phosphorylation have not been investigated. To understand active-site phenomena, pre-steady-state and transient-state kinetic methods were applied to develop a catalytic pathway for substrate processing. Rapid quench flow techniques show that the phosphorylation of a substrate peptide, generated from a random library, occurs in two kinetic phases: a rapid, exponential "burst" phase followed by a slow, linear phase. The amplitude of the burst phase increases as a function of enzyme concentration, indicating that the biphasic kinetics are not the result of product inhibition. Analysis of the burst rate as a function of substrate concentration indicates that the phosphoryl transfer step is fast (k3 > or = 140 s(-1) and highly favorable (k3/k-3 > or = 6). The apparent dissociation rate constant for ADP (0.6 s(-1), measured using stopped-flow kinetic methods and a fluorescent trapping agent, mant-ATP, is close to kcat. Since the substrate dissociation constant is high, the release of phosphopeptide is not likely to limit turnover. These findings indicate that Csk rapidly delivers the gamma-phosphate of ATP to the substrate and rapidly releases the phosphoproduct. Overall rate limitation in the steady state is then attributed to the slow, net dissociation of ADP. Viscosometric studies suggest that this final event in the catalytic cycle is coupled with slow conformational changes.

Electrostatic environment surrounding the activation loop phosphotyrosine in the oncoprotein v-Fps.

Autophosphorylation of Tyr-1073 in the activation loop of the oncoprotein v-Fps enhances the phosphoryl transfer reaction without influencing substrate, ATP, or metal ion binding affinities [Saylor, P., et al. (1998) Biochemistry 37, 17875-17881]. A structural model of v-Fps, generated from the insulin receptor, indicates that pTyr-1073 chelates two arginines. Mutation of these residues to alanine (R1042A and R1066A) results in weakly phosphorylated enzymes, indicating that one electropositive center is insufficient for attaining maximum loop phosphorylation and concomitant high catalytic activity. While the turnover rate for R1066A is similar to that for a mutant lacking a phosphorylatable residue in the activation loop, the rate for R1042A is 50-fold slower. While solvent perturbation studies suggest that the former is due to a slow phosphoryl transfer step, the latter effect results from a slow conformational change in the mutant, potentially linked to motions in the catalytic loop. Binding of a stoichiometric quantity of Mg(2+) is essential for ATP binding and catalysis, while binding of an additional Mg(2+) ion activates further the wild-type enzyme. The affinity of the R1066A enzyme for the second Mg(2+) ion is 23-fold higher than that of the phosphorylated or unphosphorylated form of wild-type v-Fps, with substrate binding unaffected. Conversely, the affinity of R1066A for a substrate mimic lacking a phosphorylation site is 12-fold higher than that for the phosphorylated or unphosphorylated form of wild-type v-Fps, with binding of the second Mg(2+) ion unaffected. A comparison of these enzyme-independent parameters indicates that Arg-1042 and Arg-1066 induce strain in the active site in the repressed form of the enzyme. While this strain is not relieved in the phosphorylated form, the improvements in catalysis in activated v-Fps compensate for reduced metal and substrate binding affinities.

Induction of BIM, a proapoptotic BH3-only BCL-2 family member, is critical for neuronal apoptosis.

Sympathetic neuronal death induced by nerve growth factor (NGF) deprivation requires the macromolecular synthesis-dependent translocation of BAX from the cytosol to mitochondria and its subsequent integration into the mitochondrial outer membrane, followed by BAX-mediated cytochrome c (cyt c) release. The gene products triggering this process remain unknown. Here, we report that BIM, a member of the BH3-only proapoptotic subfamily of the BCL-2 protein family, is one such molecule. NGF withdrawal induced expression of BIM(EL), an integral mitochondrial membrane protein that functions upstream of (or in parallel with) the BAX/BCL-2 and caspase checkpoints. Bim deletion conferred protection against developmental and induced neuronal apoptosis in both central and peripheral populations, but only transiently, suggesting that BIM--and perhaps other BH3-only proteins--serve partially redundant functions upstream of BAX-mediated cyt c release.

Stimulation of autologous proliferative and cytotoxic T-cell responses by "leukemic dendritic cells" derived from blast cells in acute myeloid leukemia.

Effective presentation of tumor antigens is fundamental to strategies aimed at enrolling the immune system in eradication of residual disease after conventional treatments. Myeloid malignancies provide a unique opportunity to derive dendritic cells (DCs), functioning antigen-presenting cells, from the malignant cells themselves. These may then co-express leukemic antigens together with appropriate secondary signals and be used to generate a specific, antileukemic immune response. In this study, blasts from 40 patients with acute myeloid leukemia (AML) were cultured with combinations of granulocyte-macrophage colony-stimulating factor, interleukin 4, and tumor necrosis factor alpha, and development to DCs was assessed. After culture, cells from 24 samples exhibited morphological and immunophenotypic features of DCs, including expression of major histocompatibility complex class II, CD1a, CD83, and CD86, and were potent stimulators in an allogeneic mixed lymphocyte reaction (MLR). Stimulation of autologous T-cell responses was assessed by the proliferative response of autologous T cells to the leukemic DCs and by demonstration of the induction of specific, autologous, antileukemic cytotoxicity. Of 17 samples, 11 were effective stimulators in the autologous MLR, and low, but consistent, autologous, antileukemic cytotoxicity was induced in 8 of 11 cases (mean, 27%; range, 17%-37%). This study indicates that cells with enhanced antigen-presenting ability can be generated from AML blasts, that these cells can effectively prime autologous cytotoxic T cells in vitro, and that they may be used as potential vaccines in the immunotherapy of AML.