Elucidating Design Rules toward Enhanced Solid-State Charge Transport in Oligoether-Functionalized Dioxythiophene-Based Alternating Copolymers

This study investigates the solid-state charge transport properties of the oxidized forms of dioxythiophene-based alternating copolymers consisting of an oligoether-functionalized 3,4-propylenedioxythiophene (ProDOT) copolymerized with different aryl groups, dimethyl ProDOT (DMP), 3,4-ethylenedioxythiophene (EDOT), and 3,4-phenylenedioxythiophene (PheDOT), respectively, to yield copolymers P(OE3)-D, P(OE3)-E, and P(OE3)-Ph. At a dopant concentration of 5 mM FeTos₃, the electrical conductivities of these copolymers vary significantly (ranging between 9 and 195 S cm^-1) with the EDOT copolymer, P(OE3)-E, achieving the highest electrical conductivity. UV-vis-NIR and X-ray spectroscopies show differences in both susceptibility to oxidative doping and extent of oxidation for the P(OE3) series, with P(OE3)-E being the most doped. Wide-angle X-ray scattering measurements indicate that P(OE3)-E generally demonstrates the lowest paracrystallinity values in the series, as well as relatively small π-π stacking distances. The significant (i.e., order of magnitude) increase in electrical conductivity of doped P(OE3)-E films versus doped P(OE3)-D or P(OE3)-Ph films can therefore be attributed to P(OE3)-E exhibiting both the highest carrier ratios in the P(OE3) series, along with good π-π overlap and local ordering (low paracrystallinity values). Furthermore, these trends in the extent of doping and paracrystallinity are consistent with the reduced Fermi energy level and transport function prefactor parameters calculated using the semilocalized transport (SLoT) model. Observed differences in carrier ratios at the transport edge (c_t) and reduced Fermi energies [η(c)] suggest a broader electronic band (better overlap and more delocalization) for the EDOT-incorporating P(OE3)-E polymer relative to P(OE3)-D and P(OE3)-Ph. Ultimately, we rationalize improvements in electrical conductivity due to microstructural and doping enhancements caused by EDOT incorporation, a structure-property relationship worth considering in the future design of highly electrically conductive systems.

Effects of film thickness on electrochemical properties of nanoscale polyethylenedioxythiophene (PEDOT) thin films grown by oxidative molecular layer deposition (oMLD)

Poly(3,4-ethylene dioxythiophene) (PEDOT) has a high theoretical charge storage capacity, making it of interest for electrochemical applications including energy storage and water desalination. Nanoscale thin films of PEDOT are particularly attractive for these applications to enable faster charging. Recent work has demonstrated that nanoscale thin films of PEDOT can be formed using sequential gas-phase exposures via oxidative molecular layer deposition, or oMLD, which provides advantages in conformality and uniformity on high aspect ratio substrates over other deposition techniques. But to date, the electrochemical properties of these oMLD PEDOT thin films have not been well-characterized. In this work, we examine the electrochemical properties of 5-100 nm thick PEDOT films formed using 20-175 oMLD deposition cycles. We find that film thickness of oMLD PEDOT films affects the orientation of ordered domains leading to a substantial change in charge storage capacity. Interestingly, we observe a minimum in charge storage capacity for an oMLD PEDOT film thickness of ∼30 nm (60 oMLD cycles at 150 °C), coinciding with the highest degree of face-on oriented PEDOT domains as measured using grazing incidence wide angle X-ray scattering (GIWAXS). Thinner and thicker oMLD PEDOT films exhibit higher fractions of oblique (off-angle) orientations and corresponding increases in charge capacity of up to 120 mA h g^-1. Electrochemical measurements suggest that higher charge capacity in films with mixed domain orientation arise from the facile transport of ions from the liquid electrolyte into the PEDOT layer. Greater exposure of the electrolyte to PEDOT domain edges is posited to facilitate faster ion transport in these mixed domain films. These insights will inform future design of PEDOT coated high-aspect ratio structures for electrochemical energy storage and water treatment.

Metal-like Charge Transport in PEDOT(OH) Films by Post-processing Side Chain Removal from a Soluble Precursor Polymer

Herein, a route to produce highly electrically conductive doped hydroxymethyl functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) films, termed PEDOT(OH) with metal-like charge transport properties using a fully solution processable precursor polymer is reported. This is achieved via an ester-functionalized PEDOT derivative [PEDOT(EHE)] that is soluble in a range of solvents with excellent film-forming ability. PEDOT(EHE) demonstrates moderate electrical conductivities of 20-60 S cm^-1 and hopping-like (i.e., thermally activated) transport when doped with ferric tosylate (FeTos₃ ). Upon basic hydrolysis of PEDOT(EHE) films, the electrically insulative side chains are cleaved and washed from the polymer film, leaving a densified film of PEDOT(OH). These films, when optimally doped, reach electrical conductivities of ≈1200 S cm^-1 and demonstrate metal-like (i.e., thermally deactivated and band-like) transport properties and high stability at comparable doping levels.

Iron(III) Dopant Counterions Affect the Charge-Transport Properties of Poly(Thiophene) and Poly(Dialkoxythiophene) Derivatives

This study investigates the charge-transport properties of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(ProDOT-alt-biEDOT) (PE₂) films doped with a set of iron(III)-based dopants and as a function of dopant concentration. X-ray photoelectron spectroscopy measurements show that doping P3HT with 12 mM iron(III) solutions leads to similar extents of oxidation, independent of the dopant anion; however, the electrical conductivities and Seebeck coefficients vary significantly (5 S cm^-1 and + 82 μV K^-1 with tosylate and 56 S cm^-1 and +31 μV K^-1 with perchlorate). In contrast, PE₂ thermoelectric transport properties vary less with respect to the iron(III) anion chemistry, which is attributed to PE₂ having a lower onset of oxidation than P3HT. Consequentially, PE₂ doped with 12 mM iron(III) perchlorate obtained an electrical conductivity of 315 S cm^-1 and a Seebeck coefficient of + 7 μV K^-1. Modeling these thermoelectric properties with the semilocalized transport (SLoT) model suggests that tosylate-doped P3HT remains mostly in the localized transport regime, attributed to more disorder in the microstructure. In contrast perchlorate-doped P3HT and PE₂ films exhibited thermally deactivated electrical conductivities and metal-like transport at high doping levels over limited temperature ranges. Finally, the SLoT model suggests that PE₂ has the potential to be more electrically conductive than P3HT due to PE₂'s ability to achieve higher extents of oxidation and larger shifts in the reduced Fermi energy levels.

Significant Enhancement of the Electrical Conductivity of Conjugated Polymers by Post-Processing Side Chain Removal

The processability and electronic properties of conjugated polymers (CPs) have become increasingly important due to the potential of these materials in redox and solid-state devices for a broad range of applications. To solubilize CPs, side chains are needed, but such side chains reduce the relative fraction of electroactive material in the film, potentially obstructing π-π intermolecular interactions, localizing charge carriers, and compromising desirable optoelectronic properties. To reduce the deleterious effects of side chains, we demonstrate that post-processing side chain removal, exemplified here via ester hydrolysis, significantly increases the electrical conductivity of chemically doped CP films. Beginning with a model system consisting of an ester functionalized ProDOT copolymerized with a dimethylProDOT, we used a variety of methods to assess the changes in polymer film volume and morphology upon hydrolysis and resulting active material densification. Via a combination of electrochemistry, X-ray photoelectron spectroscopy, and charge transport models, we demonstrate that this increase in electrical conductivity is not due to an increase in degree of doping but an increase in charge carrier density and reduction in carrier localization that occurs due to side chain removal. With this improved understanding of side chain hydrolysis, we then apply this method to high-performance ProDOT-alt-EDOT_x copolymers. After hydrolysis, these ProDOT-alt-EDOT_x copolymers yield exceptional electrical conductivities (∼700 S/cm), outperforming all previously reported oligoether-/glycol-based CP systems. Ultimately, this methodology advances the ability to solution process highly electrically conductive CP films.

Pulsed heating atomic layer deposition (PH-ALD) for epitaxial growth of zinc oxide thin films on c-plane sapphire

An in situ pulsed heating atomic layer deposition (PH-ALD) technique is used to grow heteroepitaxial ZnO thin films on c-plane sapphire with temperature-sensitive metalorganic precursors. During metalorganic precursor delivery, the substrate is maintained at a base temperature of 110 °C to prevent thermal decomposition of the precursors. After the substrate is sequentially exposed to the metalorganic precursor and water co-reactant at this low temperature, a high-power resistive heater is used to rapidly heat the substrate to between 400 and 900 °C to drive film crystallization. These in situ heat pulses enable epitaxial growth of (0001) ZnO films on c-plane sapphire. Rocking curves with FWHM of values as low as 0.53° are achieved. In contrast, films deposited entirely at 110 °C appear random polycrystalline and post-deposition annealing to 900 °C achieves only partial "epitaxial character" with a notably different in-plane orientation. Variations in heat pulse temperature and the number of deposition cycles between heat pulses are explored. Epitaxial growth persists up to 5 deposition cycles per heat pulse, with the 2θ-ω FWHM increasing to 1-2°. To further reduce process times, a templating approach is also explored in which a limited number of "template" layers are initially deposited with PH-ALD followed by low-temperature ALD at 110 °C. Epitaxial growth is encouraged with as few as 5 cycles of PH-ALD followed by 495 cycles of low-temperature ALD. Crystal quality further improves by using up to 50 template cycles, with a 2θ-ω FWHM of 1.3°. Epilayers also show enhanced photoluminescence (PL) at room temperature. These results demonstrate how in situ pulse-heating can be used to promote epitaxial film growth in ALD processes using temperature-sensitive metalorganic precursors.

Quantifying charge carrier localization in chemically doped semiconducting polymers

Charge transport in semiconducting polymers ranges from localized (hopping-like) to delocalized (metal-like), yet no quantitative model exists to fully capture this transport spectrum and its dependency on charge carrier density. In this study, using an archetypal polymer-dopant system, we measure the temperature-dependent electrical conductivity, Seebeck coefficient and extent of oxidation. We then use these measurements to develop a semi-localized transport (SLoT) model, which captures both localized and delocalized transport contributions. By applying the SLoT model to published data, we demonstrate its broad utility. We are able to determine system-dependent parameters such as the maximum localization energy of the system, how this localization energy changes with doping, the amount of dopant required to achieve metal-like conductivity and the conductivity a system could have in the absence of localization effects. This proposed SLoT model improves our ability to predict and tailor electronic properties of doped semiconducting polymers.

Single-Cycle Atomic Layer Deposition on Bulk Wood Lumber for Managing Moisture Content, Mold Growth, and Thermal Conductivity

Wood is a universal building material. While highly versatile, many of its critical properties vary with water content (e.g., dimensionality, mechanical strength, and thermal insulation). Treatments to control the water content in wood have many technological applications. This study investigates the use of single-cycle atomic layer deposition (1cy-ALD) to apply <1 nm Al₂O₃, ZnO, or TiO₂ coatings to various bulk lumber species (pine, cedar, and poplar) to alter their wettability, fungicidal, and thermal transport properties. Because the 1cy-ALD process only requires a single exposure to the precursors, it is potentially scalable for commodity product manufacturing. While all ALD chemistries are found to make the wood's surface hydrophobic, wood treated with TiO₂ (TiCl₄ + H₂O) shows the greatest bulk water repellency upon full immersion in water. In situ monitoring of the chamber reaction pressure suggests that the TiCl₄ + H₂O chemistry follows reaction-rate-limited processing kinetics that enables deeper diffusion of the precursors into the wood's fibrous structure. Consequently, in humid or moist environments, 1cy-ALD (TiCl₄ + H₂O) treated lumber shows a 4 times smaller increase in thermal conductivity and improved resistance to mold growth compared to untreated lumber.

Lenalidomide treatment and prognostic markers in relapsed or refractory chronic lymphocytic leukemia: data from the prospective, multicenter phase-II CLL-009 trial

Efficacy of lenalidomide was investigated in 103 patients with relapsed/refractory chronic lymphocytic leukemia (CLL) treated on the prospective, multicenter randomized phase-II CLL-009 trial. Interphase cytogenetic and mutational analyses identified TP53 mutations, unmutated IGHV, or del(17p) in 36/96 (37.5%), 68/88 (77.3%) or 22/92 (23.9%) patients. The overall response rate (ORR) was 40.4% (42/104). ORRs were similar irrespective of TP53 mutation (36.1% (13/36) vs 43.3% (26/60) for patients with vs without mutation) or IGHV mutation status (45.0% (9/20) vs 39.1% (27/68)); however, patients with del(17p) had lower ORRs than those without del(17p) (21.7% (5/22) vs 47.1% (33/70); P=0.049). No significant differences in progression-free survival and overall survival (OS) were observed when comparing subgroups defined by the presence or absence of high-risk genetic characteristics. In multivariate analyses, only multiple prior therapies (⩾3 lines) significantly impacted outcomes (median OS: 21.2 months vs not reached; P=0.019). This analysis indicates that lenalidomide is active in patients with relapsed/refractory CLL with unfavorable genetic profiles, including TP53 inactivation or unmutated IGHV. (ClinicalTrials.gov identifier: NCT00963105).

The Prognostic Significance of Resting Regional Left Ventricular Function in Patients With Varying Degrees of Myocardial Ischemia

Background

Our aim was to determine whether regional left ventricular (LV) function on a resting transthoracic echo (TTE) provides prognostic information in patients with varying degrees of ischemia on myocardial perfusion imaging.

Methods

Between 2004 - 2009, we identified 503 patients (mean age 69 (SD 11); 79% male) with reversible ischemia on a myocardial SPECT scan who had a TTE within 30 days. We evaluated the rate of subsequent revascularization and death for all patients.

Results

Following the SPECT scan and TTE, 246/503(49%) patients underwent revascularization, 64/503 (13%) patients died, 369 (73%) patients had a normal left ventricular ejection fraction (LVEF), 242 (48%) patients had a resting wall motion abnormality (WMA), 21/261 (8%) with no WMA died compared to 43/242 (18%) in patients with a WMA. In patients with a WMA (n = 242) there was no significant difference in mortality when comparing patients with small (< 6 segments) and large (> 6 segments) WMA (P = 0.44). In patients with moderate/severe ischemia, the presence of a resting WMA was associated with a higher mortality rate (18% v 7%; P = 0.005). In a multivariable model, LVEF (< 50%) was associated with a hazard ratio of 2.2 (P = 0.002, 95% CI 1.34 - 3.68) however, WMA and number of abnormal segments did not reach statistical significance.

Conclusion

A resting wall motion abnormality in patients with moderate/severe ischemia is associated with a higher mortality compared to patients with mild ischemia on myocardial perfusion imaging. Regional left ventricular dysfunction unlike LVEF was not an independent predictor of mortality.

A multicenter phase II study incorporating high-dose rituximab and liposomal doxorubicin into the CODOX-M/IVAC regimen for untreated Burkitt's lymphoma

BACKGROUND

Despite improvement with intensive multi-agent chemotherapy, 2-year progression-free survival (PFS) rates for adults with high-risk Burkitt's lymphoma (BL) remains <55%.

PATIENTS AND METHODS

We conducted a phase II trial for newly diagnosed classic BL utilizing liposomal doxorubicin (Adriamycin) in lieu of doxorubicin and incorporating intravenous rituximab (at 500 mg/m(2) twice/cycle) into the CODOX-M/IVAC regimen. Correlative analyses included paired serum and cerebrospinal fluid (CSF) rituximab levels and close examination of cardiac function.

RESULTS

Among 25 BL patients, the median age was 44 years (23-70) and 4 patients were HIV positive. There were 20 high-risk and 5 low-risk patients. At baseline, 40% of high-risk patients had bone marrow involvement, 35% had bulky disease and 15% had central nervous system involvement. The overall response rate was 100% (complete remission 92%). At 34-month median follow-up, the 2-year PFS and overall survival (OS) rates for all patients were 80% and 84%, respectively (low-risk: both 100%; high-risk: 76% and 81%, respectively). Furthermore, the 2-year PFS, OS, and disease-specific survival (DSS) rates for high-risk, HIV-negative patients were 84%, 89% and 100%, respectively. Adverse events (AEs) appeared to be consistent with prior CODOX-M/IVAC data, although there were several grade 3 cardiac events noted (all declined ejection fraction without clinical symptoms). The mean serum rituximab levels at 24 h after cycles 1 and 3 for patients without relapse were 258 and 306 μg/ml, respectively, versus 131 and 193 μg/ml, respectively, for patients with early progression (P = 0.002 and 0.002, respectively). The mean CSF rituximab levels for all patients were 0.11 and 0.24 μg/ml, respectively, at cycle 1 (24/72 h), which equated to serum:CSF ratios of 0.05% and 0.20%, respectively.

CONCLUSIONS

The integration of rituximab into CODOX-M/IVAC for adult BL was feasible and tolerable, while changes in cardiac function warrant continued examination. This regimen was associated with excellent survival rates for HIV-negative BL. Further investigation of the predictive value of serum rituximab is needed. Clinicaltrials.gov NCT00392990.

Improvement in structural and functional echocardiographic parameters during chronic heart failure therapy guided by natriuretic peptides: mechanistic insights from the ProBNP Outpatient Tailored Chronic Heart Failure (PROTECT) study

AIMS

We sought to determine if heart failure (HF) care with a goal to lower N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations, compared with standard of care (SOC) management, is associated with improvement in echocardiographic parameters of cardiac structure and function.

METHODS AND RESULTS

Of 151 subjects with HF due to left ventricular systolic dysfunction (LVSD) prospectively randomized to NT-proBNP-guided vs. SOC HF care, 116 had serial echocardiographic data. Endpoints in this echocardiographic study included the relationship between change in NT-proBNP and LV reverse remodelling, as well as associations between biomarker-guided therapy and measures of diastolic function, right ventricular (RV) size and function, estimates of LV filling pressure and RV systolic pressure (RVSP), and the degree of mitral regurgitation (MR). After a mean of 10 months of study procedures, in adjusted analyses, final NT-proBNP concentrations predicted risk of remodelling [hazard ratio (HR) ↑LV end-diastolic volume index = 1.43, 95% confidence interval (CI) 1.10-1.86, P = 0.007; HR ↑LV end-systolic volume index = 1.54, 95% CI 1.10-1.91, P = 0.01; HR ↓LV ejection fraction (LVEF) = 1.53, 905% CI 1.12-1.89, P = 0.02]. In addition to greater improvement in LVEF and reductions in LV volume, compared with SOC, NT-proBNP-guided patients showed significant decreases in the ratio of early transmitral peak velocity to early diastolic peak annular velocity (E/E'), pulmonary vein peak S velocity, RV fractional area change, RVSP, and MR severity.

CONCLUSION

NT-proBNP concentrations may serve as a non-invasive indicator of the state of cardiac structure and function in HF due to LVSD. Multiple, prognostically meaningful echocardiographic variables improved more significantly in patients treated with NT-proBNP-guided care vs. SOC.

Use of amino-terminal pro-B-type natriuretic peptide to guide outpatient therapy of patients with chronic left ventricular systolic dysfunction

OBJECTIVES

The aim of this study was to evaluate whether chronic heart failure (HF) therapy guided by concentrations of amino-terminal pro-B-type natriuretic peptide (NT-proBNP) is superior to standard of care (SOC) management.

BACKGROUND

It is unclear whether standard HF treatment plus a goal of reducing NT-proBNP concentrations improves outcomes compared with standard management alone.

METHODS

In a prospective single-center trial, 151 subjects with HF due to left ventricular (LV) systolic dysfunction were randomized to receive either standard HF care plus a goal to reduce NT-proBNP concentrations ≤1,000 pg/ml or SOC management. The primary endpoint was total cardiovascular events between groups compared using generalized estimating equations. Secondary endpoints included effects of NT-proBNP-guided care on patient quality of life as well as cardiac structure and function, assessed with echocardiography.

RESULTS

Through a mean follow-up period of 10 ± 3 months, a significant reduction in the primary endpoint of total cardiovascular events was seen in the NT-proBNP arm compared with SOC (58 events vs. 100 events, p = 0.009; logistic odds for events 0.44, p = 0.02); Kaplan-Meier curves demonstrated significant differences in time to first event, favoring NT-proBNP-guided care (p = 0.03). No age interaction was found, with elderly patients benefitting similarly from NT-proBNP-guided care as younger subjects. Compared with SOC, NT-proBNP-guided patients had greater improvements in quality of life, demonstrated greater relative improvements in LV ejection fraction, and had more significant improvements in both LV end-systolic and -diastolic volume indexes.

CONCLUSIONS

In patients with HF due to LV systolic dysfunction, NT-proBNP-guided therapy was superior to SOC, with reduced event rates, improved quality of life, and favorable effects on cardiac remodeling. (Use of NT-proBNP Testing to Guide Heart Failure Therapy in the Outpatient Setting; NCT00351390).

Delayed heart rate recovery after adenosine stress testing with supplemental arm exercise predicts mortality

BACKGROUND

Delayed heart rate (HR) recovery after treadmill exercise testing predicts mortality. Patients with suspected ischemic heart disease who cannot perform adequate treadmill exercise are typically evaluated with pharmacological stress myocardial perfusion imaging (MPI) studies, but little prognostic significance has been attributed to the hemodynamic response to vasodilator stress testing with low-level exercise. We hypothesized that a delay in HR recovery after adenosine stress testing with arm exercise is associated with increased mortality.

METHODS AND RESULTS

Technetium 99m-Sestamibi MPI was performed in 1,455 consecutive patients (70 +/- 12 years, 50.2% men) with adenosine stress and supplemental arm exercise. HRs were recorded at rest, continuously during infusion, and then 5 minutes post-infusion. Delayed HR recovery was defined as a decline of < or = 12 bpm from peak HR at 5 minutes after discontinuation of the infusion. Of 1,356 patients during 5 years of follow up, there were 135 deaths (10%). Delayed HR recovery was strongly predictive of all-cause mortality (16.5% vs 5.3% in those with normal HR recovery, P < .001) with an adjusted hazard ratio of 2.5 (95% CI, 1.7-3.6; P < .001).

CONCLUSION

Delayed HR recovery after adenosine stress testing with arm exercise is a readily available and powerful predictor of all-cause mortality.

NK resistance of tumor cells from multiple myeloma and chronic lymphocytic leukemia patients: implication of HLA-G

Exploiting the antitumor effect of natural killer (NK) cells has regained interest in light of data from preclinical and clinical work on the potential of alloreactive NK cells. Multiple myeloma (MM) and chronic lymphocytic leukemia (CLL) represent the two most prevalent adult hematological malignancies in the western hemisphere. To evaluate the role of NK cells in the immune surveillance and their therapeutic potential for CLL and MM, tumor cell susceptibility to NK-mediated killing was investigated. Results show relative resistance of tumor cells from CLL as well as MM (73 and 70% of the patients, respectively) to NK-mediated killing. To gain insight into molecular mechanisms of this resistance, the expression of the tolerogenic HLA-G molecule in CLL and MM and its relevance to susceptibility to NK-mediated killing were investigated. HLA-G transcript was found in tumor cells from 89% (n=19) of CLL and 100% (n=9) of MM patients examined. HLA-G1 surface expression was observed in CLL and was very low or undetectable in MM. Notably, blocking of HLA-G1 with specific antibody on CLL samples increased their susceptibility to NK-mediated killing, demonstrating that HLA-G participates in protecting CLL cells from NK-mediated killing and may thus contribute to their immune escape in vivo.

Analysis of Cardiac Dimensions, Mass and Function in Heart Transplant Recipients Using 64-slice Multi-detector Computed Tomography

BACKGROUND

Heart transplant recipients present a challenge to cardiac multi-detector computed tomography (MDCT) imaging due to high resting heart rates and body mass indices. Previous studies demonstrated the feasibility of coronary allograft vasculopathy detection by MDCT in heart transplant recipients. However, its performance in assessing cardiac structure and function in these patients has not been evaluated. The aim of this study was to compare 64-slice MDCT analysis of cardiac structure and function to 2-dimensional echocardiography in heart transplant recipients.

METHODS

Two independent observers used both semi-automated and automated software to measure chamber dimensions and left ventricular ejection fraction and mass in 20 heart transplant recipients by 64-slice MDCT. Inter-observer variability was determined. The results were compared with echocardiographic measurements provided by another blinded observer.

RESULTS

There was moderate agreement between MDCT and echocardiography for chamber dimension measurements, except for left atrial diameter. Ejection fraction by MDCT was slightly lower (mean difference: -2 +/- 9%, p = 0.29) than that obtained by echocardiography and the correlation was moderate (R = 0.49 to 0.54). Left ventricular mass measurements were significantly lower by MDCT (mean difference: -87 +/- 44 g, p < 0.001). Inter-observer agreement for MDCT analysis of left ventricular function (R = 0.90) and mass (R = 0.83) were excellent.

CONCLUSIONS

These findings demonstrate moderate agreement between 64-slice MDCT and echocardiography in the assessment of chamber dimensions as well as left ventricular mass and function in heart transplant recipients with low inter-observer variability. Also, the addition of cardiac structural and functional analysis to MDCT coronary angiography requires no additional scan time, contrast administration or radiation exposure.

Myocardial blood flow and oxygen consumption in patients with Friedreich's ataxia prior to the onset of cardiomyopathy

OBJECTIVES

We tested the hypothesis, in patients with Friedreich's ataxia and no overt structural heart disease, that impairment of cardiac oxidative metabolism may be compensated for either by increased rest myocardial blood flow or more efficient oxygen consumption in performance of external work.

BACKGROUND

Friedreich's ataxia is characterized by a mutant frataxin gene, which causes mitochondrial iron overload and impaired energy production. Further, it is frequently associated with cardiomyopathy. Studies using magnetic resonance spectroscopy, however, suggest impaired cardiac energetics even in the absence of structural heart disease.

METHODS

Positron emission tomography measured rest myocardial blood flow (N-13-ammonia method) and myocardial oxygen consumption (11-C-acetate, Kmono) in Friedreich's ataxia patients (n=8; 31+/-5 years, mean+/-SD, four women) and healthy controls (n=8; 30+/-7 years, five women) matched for stroke work index and age. Stroke work index and power were determined by electrocardiogram gated positron emission tomography N-13-ammonia using modified Simpson's rule to compute left ventricular volumes.

RESULTS

Neither stroke work index nor rest myocardial blood flow differed significantly between the groups. Although myocardial oxygen consumption was lower in Friedreich's ataxia (P<0.001), Kmono/rest myocardial blood flow, an index of myocardial oxygen extraction, did not differ between the groups. Power/Kmono, an index of the efficiency of myocardial oxygen consumption, was greater in Friedreich's ataxia (P<0.04). Rest myocardial blood flow normalized to rate pressure product was lower in Friedreich's ataxia (P<0.05).

CONCLUSIONS

Prior to the onset of cardiomyopathy, selected patients with Friedreich's ataxia may compensate for impaired cardiac energetics through more efficient oxygen consumption rather than increased rest myocardial blood flow. The data illustrate a more general mechanism pertaining to metabolic regulation of myocardial blood flow and myocardial oxygen consumption.

Comparison of sixty-four-slice multidetector computed tomographic coronary angiography to coronary angiography with intravascular ultrasound for the detection of transplant vasculopathy

Coronary allograft vasculopathy (CAV) is the most important limitation to long-term survival in adult heart transplant recipients and is difficult to detect without intravascular ultrasound (IVUS). We systematically evaluated the image quality of 64-slice multidetector computed tomographic (MDCT) coronary angiography in heart transplant recipients and tested the hypothesis that this modality is comparable to invasive coronary angiography with IVUS for the detection of CAV. Heart transplant recipients (n = 20) underwent invasive coronary angiography with IVUS and MDCT coronary angiography with a 64-slice scanner. Images were systematically analyzed for image quality and the presence of CAV. In addition, multidetector computed tomography and quantitative coronary angiography were used to measure lumen diameters at prespecified locations. Image quality analysis showed that, despite high mean heart rates (77 +/- 7 beats/min) and body mass index (29.5 +/- 5.3 kg/m(2)), 83% of coronary segments were graded as of excellent or good image quality. On average, 95 +/- 9% of the overall visualized length of the coronary arteries was imaged without motion artifacts, and the mean contrast-to-noise ratio was 11.3 +/- 4.6. Compared with IVUS, multidetector computed tomography had a sensitivity of 70%, specificity of 92%, positive predictive value of 89%, and negative predictive value of 77% for the detection of CAV. MDCT vessel diameter measurements correlated well with those obtained from quantitative coronary angiography (R(2) = 0.89). In conclusion, 64-slice multidetector computed tomography provides good to excellent image quality in heart transplant recipients and has moderate to excellent test characteristics for the detection of CAV. Further, MDCT measurements of lumen diameters correlated well with quantitative coronary angiography.

The evolving role of Alemtuzumab in management of patients with CLL

New insights into prognostic markers and the pathophysiology of chronic lymphocytic leukemia (CLL) are beginning to change the concept of CLL treatment. Alemtuzumab has evolved as a potent and effective therapeutic option for patients with CLL. Specifically, alemtuzumab has demonstrated substantial efficacy in fludarabine-refractory patients and has shown impressive responses when administered subcutaneously in first-line therapy. A group of experts gathered to discuss new data related to the use of alemtuzumab in CLL and to assess its place in the rapidly changing approach to treating patients with this disease. The main goals of this program were to update the management guidelines that were previously developed for alemtuzumab-treated patients and to provide community oncologists with guidance on the most effective way to integrate alemtuzumab into a CLL treatment plan.

Atrial endocarditis--the importance of the regurgitant jet lesion

The jet lesions of valvular regurgitation or intracardiac shunts have been hypothesized to play an important role in the pathogenesis of endocarditis for many years. We describe a case of mitral valve endocarditis that involved the left atrium along the path of a jet lesion. This resulted in atrial endocarditis and pericarditis, both of which complicated her presentation and hospital course. Using transesophageal echocardiography, we were able to directly visualize the path and full extent of infection prior to surgery. Special attention should be focused upon the path of eccentric jets in order to fully define the extent of endocarditis.

Chemotherapy dose intensity in non-Hodgkin's lymphoma: is dose intensity an emerging paradigm for better outcomes?

BACKGROUND

Higher chemotherapy dose intensity has been studied as a way of improving the clinical outcomes in various malignancies, including non-Hodgkin's lymphoma (NHL).

METHODS

We reviewed clinical trials that have studied the relation between dose and response in cancer chemotherapy, the theory behind dose-intense chemotherapy, and the clinical results with dose-escalated and dose-dense therapy in aggressive NHL.

RESULTS

Myeloablative high-dose chemotherapy with stem cell transplantation produces higher 5-year survival rates than standard salvage chemotherapy in relapsed aggressive lymphoma, but its role as initial therapy is not yet clear. Nonmyeloablative dose-escalated chemotherapy is feasible with granulocyte colony-stimulating factor (G-CSF) support, but this approach does not improve outcomes. Dose-dense (14-day) CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) with G-CSF support produces better results than 21-day CHOP in patients with previously untreated aggressive lymphoma, without additional toxicity. The addition of etoposide to dose-dense CHOP may provide further benefits in younger patients. The addition of rituximab to G-CSF-supported dose-dense CHOP is feasible. Preliminary data suggest the feasibility of dose-dense chemotherapy for NHL with the once-per-cycle G-CSF, pegfilgrastim.

CONCLUSION

Dose-dense chemotherapy with G-CSF support produced better clinical outcomes in both younger and older patients. Phase 3 trials of dose-dense CHOP plus rituximab with CSF support are warranted.

Infected Cardiac Myxoma

Infected cardiac myxomas are extremely rare with only forty cases described in the literature. We report a case of an infected cardiac myxoma that presented in a manner similar to bacterial endocarditis. Our case is the first to be diagnosed using previously defined criteria, and is unusual in that transesophageal echocardiography was required to make the diagnosis.

High remission rate in acute myeloblastic leukemia with only two days of chemotherapy

Twenty five patients with AML who had neither a history of toxic exposure or myelodysplasia were treated with a remission induction regimen consisting of two pulses of chemotherapy separated by 96 hrs. Each pulse consisted of cytarabine 2gm/m(2) (at t=0 and t=12 hrs) with mitoxantrone [30mg/m(2) ] administered immediately after the second cytarabine administration. Amifostine was administered three times a week [on Monday, Wednesday, and Friday] until the outcome of therapy was known. This regimen induced complete remissions in 15 of 17 patients less than 70 years of age and in 5 of 8 patients older than 70 years.

Mitoxantrone and fludarabine in the treatment of patients with non-Hodgkin's lymphoma failing primary therapy with a doxorubicinor mitoxantrone-containing regimen

Patients with recurrent lymphoma of any grade were treated with mitoxantrone (12 mg/m2 given intravenously (IV) over 15-30 minutes on day 1) followed by fludarabine at a dose of (25 mg/m 2 given IV over 30 minutes on days 1-3) every 28 days fludarabine at a dose of (25 mg/m2 given IV over 30 minutes on days 1-3) every 28 days. All patients had failed one prior chemotherapy regimen that contained either doxorubicin or mitoxantrone, total dose not exceeding 350 mg/m2 doxorubicin or 80 mg/m2 mitoxantrone. mitoxantrone. Thirty one patients (22 with intermediate- or high-grade and 9 with low-grade NHL) were enrolled. Median age was 63 years (range: 21 to 87). The objective response rate for patients with intermediate/high-grade NHL was 55% (27% with CR) and 89% (56% with CR) for patients with low-grade NHL. Median time to disease progression was 5.1 months for patients with intermediate/high-grade NHL and 10.8 months for patients with low-grade NHL. Median time to death for patients with intermediate/high-grade disease was 11.4 months. Median time to death for patients with low-grade NHL was not calculable as only one death (due to respiratory failure) occurred in this group 6.5 months after study start. The regimen was well tolerated. Grade 3/4 neutropenia was reported in 80% (24 of 30) of patients and Grade 3/4 thrombocytopenia in 19% (6 of 31) of patients. Nine hospitalizations for adverse events (primarily fever and neutropenia) occurred among eight patients, all with intermediate/high-grade NHL, during a total of 118 cycles of therapy. Further studies of this combination regimen in patients with intermediate/high-grade NHL and studies combined with monoclonal antibodies in low-grade NHL are warranted.

Effectiveness of interferon-alfa and mid-cycle chemotherapy added to an anthracycline-based regimen in the treatment of aggressive non-Hodgkin's lymphoma

Interferon-alfa in combination with cytotoxic chemotherapy has been shown to be effective in treating certain types of non-Hodgkin's lymphoma (NHL) (1). However, there is no published data on upfront induction treatment of aggressive NHL with IFN-alfa containing regimens. Studies have also shown that one can overcome regrowth resistance by administering mid-cycle agents which slow tumor proliferation between courses of cytotoxic therapy (2). Based on this, we treated 32 consecutive patients between 1/93 and 9/96 with a regimen containing cyclophosphamide 750 mg/m2, mitoxantrone 12 mg/m2, and teniposide 60 mg/m2 IV on day 1 with prednisone 100 mg PO given on days 1-5. On day 15, patients received vincristine 1.4 mg/m2 (2 mg max.) and bleomycin 10 units/m2 IV. Interferon-alfa-2b 5x10(6) units/m2 SQ was administered on days 22-26. The median age was 55 (range 26-83), M:F ratio was 2.5:1, and the median International Prognostic Index was 2. 38% of patients had stages I-II and 62% had stages III-IV disease. Fifty-nine percent of the patients achieved a complete response, 22% a partial response, and 19% had progressive disease. The overall survival (OS) was 81% and the progression free survival (PFS) was 56% at 4.3 years. There were no severe (grade IV) hematologic, flu-like, GI and infectious toxicities from IFN-alpha. Leukopenia was the main severe toxicity related to the chemotherapy regimen (days 1-15), but not IFN-alpha. Severe infection secondary to the chemotherapy regimen occurred in one patient. Interferon-alfa-2b and mid-cycle chemotherapy added to an anthracycline based regimen is effective induction treatment for patients with aggressive NHL. The OS and PFS using this regimen, based on regrowth resistance, appears to be at least as or more effective than CHOP therapy for this group of patients. Severe toxicities were rare.

Poor prognosis acute myelogenous leukemia: 1 - response to treatment with high dose cytarabine/mitoxantrone/ethyol @ (Amifostine)

Twenty patients with poor prognosis AML and four patients in the blastic phase of a myeloproliferative disorder were treated with two 'pulses' of therapy each consisting of two doses of high dose araC (separated by 12 h) followed by a single dose of mitoxantrone. The pulses were separated by 96 h. Amifostine was then administered tiw. The median age of the population was 68 years with 88% of patients having had either a prior MDS, MPD or toxic exposure. The acute leukemia of 58% of patients either entered a CR or reverted to preleukemic state. For patients under 70 years of age, treatment produced 62% CRs with a leukemia free decision marrow in 77%. For patients over 70 years the CR rate was 27% with 36% of patients having a leukemia free decision marrow.

Tumor necrosis factor modulates CD 20 expression on cells from chronic lymphocytic leukemia: a new role for TNF alpha?

Tumor necrosis factor alpha (TNF alpha) is a pleiotropic cytokine that is constitutively produced by leukemic cells in B Chronic Lymphocytic Leukemia (B-CLL). It has been shown to have autocrine and paracrine functions in normal B cells and in B lymphoproliferative diseases. This study was conducted to determine the effect of TNF alpha (in vitro) on CD20 expression on cells from patients with B-CLL. Currently, anti-CD20 monoclonal antibody therapy is becoming a second line treatment in the management of B cell disorders like low-grade non-Hodgkin's lymphoma (NHL) and B-CLL. Our results demonstrate amply that very low doses of TNF alpha (0. 0125 ng/ml) can be used to significantly increase CD20 expression on cells from patients of B-CLL as evidenced by increases in both percentage positivity and mean fluorescence intensity. The upregulation is evident as early as 24 hours and is maintained for up to 72 hours. We propose that the upregulation is a direct result of in vitro differentiation stimulated by TNF alpha. The results presented can be exploited in the designing of priming protocols prior to antibody therapy and this is discussed.

Effect of interferon-alpha on CD20 antigen expression of B-cell chronic lymphocytic leukemia

Chimeric CD20 monoclonal antibody as alternative therapy in relapsed low-grade non-Hodgkin's lymphoma (NHL) has produced responses in nearly 50% of patients. Augmenting CD20 expression on tumor cells and/or inducing its expression may increase the cell kill and effectiveness of antibody therapy. Peripheral blood lymphocytes from 19 patients with B-cell chronic lymphocytic leukemia (B-CLL) were incubated in vitro in the presence of interferon-alpha (IFN-alpha) (500 U/ml and 1,000 U/ml) for 24 and 72 hours. The effect on CD20 expression was studied by flow cytometry. The differences in the percentage positivity, the mean fluorescence intensity (MFI), and the product of percentage positivity and MFI were used to assess upregulation. There was a significant upregulation of CD20 expression on B cells seen at both concentrations after 24-hour priming (p < 0.01). B-CLL cells cultured for 72 hours in the presence of IFN-alpha also showed upregulation of CD20 expression; however, the degree of upregulation was much lower than that seen at 24 hours. There was no statistically significant increase in CD20 antigen expression on normal lymphocytes following cytokine exposure. These results suggest that IFN-alpha priming may augment the effectiveness of antibody therapy by directly upregulating CD20 antigen expression in addition to its indirect action through effector cells of the host.

Signal antonymy unique to myelodysplastic marrows correlates with altered expression of E2F1

Myelodysplastic syndromes (MDS) have previously been reported to show competitively high rates of apoptosis and proliferation in the bone marrow (BM). Using a double-labelling technique in the present study, we demonstrated that a significantly high number of S-phase cells were simultaneously apoptotic (signal antonymy; SA) in MDS (mean +/- s.e.m. 53.5 +/- 6.7%, n = 24, P < 0.001). In contrast, SA was negligible in all other specimens studied, including normal control BM (n = 13) from non-Hodgkin's lymphoma (NHL) patients, BM from patients with de novo acute myelogenous leukaemia (1'AML; n = 5), or secondary AML that had transformed from MDS (2'AML; n = 10), or the solid tumours from patients with NHL (n = 9) or head and neck squamous cell carcinoma (HNSCC; n = 10). Subsequently, the expression of a transcription factor, E2F1, was studied in density-separated BM aspirate mononuclear cells from MDS patients (n = 9) and a normal control. Two separate sets of primers were used that recognized the regulatory retinoblastoma (Rb) protein-binding region and the functional DNA-binding region of E2F1. Interestingly, although the latter manifested the expected band (280 bp) in all samples, the Rb-specific primers showed the expected band (380 bp) in the normal and in 4/9 MDS specimens. Two other MDS specimens also showed a smaller band ( approximately 325 bp), whereas 3/9 MDS patients showed exclusively the smaller band. The levels of SA were significantly higher in those MDS cases that showed the smaller Rb-specific band either alone or in addition to the expected band (median 19.5%, n = 4, P = 0.037) than in those showing exclusively the expected band (median 0.4%, n = 3). Our present studies show SA as a characteristic feature of MDS and, importantly, demonstrate its link with an altered expression of E2F1 in some MDS patients.

Effects of cytokines on CD20 antigen expression on tumor cells from patients with chronic lymphocytic leukemia

Anti-CD20 antibody is an established treatment for low-grade non-Hodgkin's lymphoma (NHL). Augmenting the expression of CD20 antigen on the tumor cells may increase the cell kill and therefore increase the effectiveness of the antibody. To study this, we incubated peripheral blood lymphocytes from CLL patients with the following cytokines: EPO, SCF, TNFalpha, TGFbeta, GMCSF, TPO, IL-1, IL-2, IL-3, IL-4, GCSF. CD20 expression was studied by flow cytometry at baseline, 24 and 72 h after exposure to these cytokines. Upregulation of CD20 antigen expression was observed with IL-4, TNFalpha and GMCSF.

Clinicopathological features of aggressive large granular lymphocyte leukaemia resemble Fas ligand transgenic mice

Fas ligand triggers cell death after interaction with its receptor Fas. Altered expression of Fas has been associated with lymphoproliferation and autoimmune disorders in both mice and man. Apoptosis of lung and liver tissue is seen in Fas ligand transgenic mice. It is not known whether constitutive expression of Fas ligand can cause a similar human disease. Four patients with aggressive large granular lymphocyte (LGL) leukaemia involving lung and liver were studied. All four patients were severely ill with pulmonary involvement. Two patients presented with hypoxia and were oxygen dependent; the other two patients had severe pulmonary hypertension. Lung biopsies showed interstitial infiltration by leukaemic LGL. The infiltrating lymphocytes expressed both Fas and Fas ligand, whereas normal pneumocytes expressed only Fas. Similar findings were observed in liver biopsies from these patients. Features mimicking the pathological changes of graft-versus-host disease were observed, including pneumocyte apoptosis. All four patients had high levels of circulating Fas ligand. Successful treatment with oral methotrexate or 2-chlorodeoxyadenosine was associated with disappearance or marked reduction of circulating Fas ligand. These results suggest that dysregulated expression of Fas ligand can lead to human disease with pathological features resembling graft-versus-host disease.

Suppression of telomerase activity and cytokine messenger RNA levels in acute myelogenous leukemia cells in vivo in patients by amifostine and interleukin 4

High levels of telomerase activity and high rates of cell proliferation are associated with a poor prognosis in acute myelogenous leukemia. Furthermore, cytokine production by leukemia cells is believed to play an important role in determining the proliferative characteristics of leukemia. The in vivo effects of two noncytotoxic agents on these parameters were determined in 33 acute myelogenous leukemia patients. Three daily doses of interleukin (IL) 4 or a single dose of amifostine reduced telomerase activity in the leukemia marrow cells in 7 of 9 and 11 of 13 patients, respectively. The administration of a single dose of amifostine resulted in a reduction in tumor necrosis factor alpha and IL-6 transcript levels in the marrow cells of 10 of 13 and 12 of 13 patients in which these transcripts were present. The administration of only three doses of IL-4 or a single dose of amifostine has a significant effect on leukemia cell parameters, which are believed to have a significant impact on the in vivo biology of the disease and on its response to remission induction therapy.

Spontaneous down-regulation of Fas-associated phosphatase-1 may contribute to excessive apoptosis in myelodysplastic marrows

In this study, we examined the role of Fas-signaling in the apoptotic pathway in myelodysplastic syndromes (MDS). Ficoll-separated mononuclear cells from 18 bone marrow aspirate specimens obtained from 17 MDS patients, 4 normal healthy donors, and 3 acute myeloid leukemia patients transformed from MDS (t-AML) were studied for mRNA expression of Fas-L, Fas, and the effectors of their signaling, Caspase 1 and Caspase 3, using reverse transcriptase polymerase chain reaction. Fas-L, Fas, and Caspase 1 were detectable in all of the samples in the three groups. Caspase 3 was detectable both in MDS and t-AML specimens but was negligible in normal cells. The apoptotic index (AI%) determined by in situ end labeling of fragmented DNA in 4-hour cultures of mononuclear cells was significantly higher in MDS cells compared to normal or t-AML cells (mean +/- SEM: 2.3% +/- 0.4% in MDS, n = 10 vs. 0.6% +/- 0.2%, n = 4, P = 0.014 in normal cells, and 0.2% +/- 0.2%, n = 3, P = 0.007 in t-AML cells). Treatment of MDS cells with anti-Fas-L antibody suppressed apoptosis (AI%: 2.1% +/- 0.6% in untreated vs. 1.37% +/- 0.5% in treated, n = 6, P = 0.02), indicating functional participation of Fas-signaling in MDS. Further, it was found that Fas-L, Fas, and Caspase 1 mRNA expression remained unchanged in 4 hours. Caspase 3 expression appeared in normal cells after 4 hours and was present at both 0 and 4 hours in MDS and t-AML cells. In contrast to persistent expression in normal and t-AML cells, cells from the 5 MDS patients studied consistently showed significantly lowered or undetectable expression of a negative regulator of Fas, called Fas-associated phosphatase-1 (Fap-1) after 4 hours. Thus, the high AI% in MDS corresponds to a rapid decline in Fap-1. Furthermore, in tumor necrosis factor alpha (TNF-alpha) treated HL60 promyelocytic cells, a definite periodicity in the expression of different mRNAs was observed with upregulation of TNF-alpha itself at 30 minutes, increased expression of Fas and the appearance of Fas-L after 2 hours, and a decrease in Fap-1 expression after 8 hours. These results suggest that TNF-alpha not only induces the effectors of Fas-signaling but also may downregulate the inhibitor. We conclude that a spontaneous and rapid down-regulation of Fap-1, possibly induced by TNF-alpha, a cytokine shown to be present in excess in MDS marrows, may underlie the increased apoptotic death of hematopoietic cells in these patients. Interference with Fap-1 turnover may provide a new therapeutic modality for MDS.

Correlation of tumor necrosis factor alpha (TNF alpha) with high Caspase 3-like activity in myelodysplastic syndromes

Increased intramedullary apoptotic death of hematopoietic cells is thought to contribute to the ineffective hematopoiesis in myelodysplastic syndromes (MDS). Furthermore, high amounts of tumor necrosis factor alpha (TNF alpha) have previously been correlated with apoptosis in MDS marrows. The present studies were undertaken to examine the status of two key downstream effectors of TNF alpha signaling, i.e. Caspase 1 and Caspase 3 enzymes, using a fluorometric assay in the bone marrow aspirate mononuclear cells (BMMNC) in relation to apoptotic DNA fragmentation detected by in situ end-labeling (ISEL) of DNA and with localization of TNF alpha in the corresponding biopsies from 14 MDS patients. Both Caspase 1 and 3 were detectable in freshly harvested BMMNC, albeit median Caspase 3 levels (47.5 units/mg protein) being almost 10 times higher than Caspase 1 (4.0 units/mg protein). Upon short-term culture for 4 h in a serum-supplemented medium in vitro a significant increase was seen in Caspase 3 activity (58.8 +/- 13.9 at 0 h vs. 177.8 +/- 55.2 units/mg protein at 4 h, n = 14, P = 0.017) and in percent cells labeled by ISEL (apoptotic index or AI%: 0.76% +/- 0.25% vs. 3.99% +/- 1.1%, n = 14, P = 0.004, respectively). Caspase 1 activity increased after 15 min in culture. Interestingly, TNF alpha levels measured by immunohistochemistry correlated with the net increase in Caspase 3 activity after 4 h (p = 0.517, n = 13, P = 0.07) and the starting levels of Caspase 1 at 0 h correlated with the Caspase 3 levels attained at 4 h (p = 0.593, n = 13, P = 0.033). Additionally when TNF alpha-positive bone marrows (8/14) were compared with the negative marrows (6/14) the Caspase 3 levels were significantly higher in the TNF alpha-positive marrows (189.6 +/- 66.2 vs. 25.0 +/- 14.6 units/mg protein, respectively, P = 0.043). The increase in AI%, though not statistically significant, was also higher in the TNF alpha-positive marrows. Finally in HL60 cells the effects of different Caspase inhibitors and pentoxifylline (PTX) (interferes with lipid signaling of cytokines) on TNF alpha-induced apoptosis were evaluated. TNF alpha treatment significantly increased AI% (P < 0.003) as compared to the untreated controls. A co-treatment with three Caspase inhibitors, zVAD.FMK (inhibitor of Caspases 1 and 3, 10 microM/l), Ac.YVAD.FMK (Caspase 1 inhibitor, 1 microM/l), Ac.DEVD.FMK (Caspase 3 inhibitor, 10 microM/l) as well as PTX (250 microM/l) significantly curtailed the AI% induced by TNF alpha. The present studies thus identify the downstream effectors of TNF alpha-inducible apoptosis in MDS and so also the suppressors of TNF alpha apoptotic signaling. These results may have significant clinical implications in the therapy of MDS in the future.

The relative extent and propensity of CD34+ vs. CD34- cells to undergo apoptosis in myelodysplastic marrows

The paradox of peripheral cytopenias despite cellular bone marrow (BM) observed in myelodysplastic syndromes (MDS) has been associated with excessive intramedullary apoptosis of hematopoietic cells. Since MDS is regarded as a stem cell disorder, the present studies were undertaken to examine the relative susceptibility and propensity of early progenitor CD34+ cells to undergo apoptosis as compared to more maturing/matured CD34- cells. Five serial studies were performed on 4 independent groups of 36 newly diagnosed MDS patients. First, in 2 separate groups of 16 and 8 patients each, measurement of the extent of apoptosis in CD34+ and CD34- fractions of the BM aspirate mononuclear cells was carried out using independent biparametric flow cytometry methods, CD34 labeling/terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) (n = 16), and CD34 labeling/reduced uptake of nucleic acid staining dye LDS751 (n = 8). The difference in the median degrees of apoptosis in CD34+ vs. CD34- cells was not statistically significant by either technique (P = 0.583 and P = 0.674 for TUNEL and LDS751, respectively). In the next group of 4 MDS patients, a double-labeling was performed on plastic embedded marrow biopsy sections, to detect CD34 antigen with specific monoclonal antibody and apoptosis by in situ end labeling (ISEL) of fragmented DNA. Despite high overall apoptosis (56.2% +/- 18.4%), only an occasional CD34+ cell was found to be simultaneously labeled with ISEL. Finally, in the last group of 8 MDS patients, CD34+ cells were separated from CD34- cells on affinity column and cultured in serum containing medium for 4 hours. At 0- and 4-hour time points, ISEL was carried out to label apoptotic cells. In addition, a fluorometric assay was employed to estimate the activity of a proapoptotic enzyme, Caspase 3. Both the net increase in % ISEL labeled cells (apoptotic index or AI) and Caspase-3 activity were significantly lower in CD34+ cells as compared to CD34- cells (AI, 0.87% +/- 0.5% vs. 3.97% +/- 1.4%, n = 6, P = 0.028 and Caspase-3 Units/mg protein, 46.9 +/- 25.0 vs. 71.7 +/- 23.03, n = 5, P = 0.042, respectively). We conclude that when estimated in a total population of mononuclear cells, CD34+ cells and CD34- cells show comparable degrees of apoptosis. However, once separated the CD34+ fraction demonstrates lower propensity to undergo apoptosis, thereby suggesting the CD34- fraction as being a possible source for proapoptotic signaling.

Imbalanced expression of the glucocorticoid receptor isoforms in cultured lymphocytes from a patient with systemic glucocorticoid resistance and chronic lymphocytic leukemia

The human glucocorticoid receptor (GR) is expressed as two alternatively spliced isoforms, GRalpha and GRbeta. Whereas GRalpha is a hormone-activated transcription factor, GRbeta does not bind glucocorticoids (GCs), is transcriptionally inactive, and is a potential inhibitor of activated GRalpha. Differential expression of GR isoforms may play a role in generalized or tissue-specific GC resistance. GCs induce apoptosis in neoplastic lymphoid cells; and, defective apoptosis is implicated in the genesis of chronic lymphocytic leukemia (CLL). We studied a patient with generalized GC resistance and CLL. GR number in the patient's transformed lymphocytes was approximately one half that of control cells with a approximately 10-fold reduction in binding affinity for dexamethasone. In vitro apoptosis induction in CLL cells was delayed in response to GCs, but not to other apoptosis inducers. Sequencing of the GR cDNA and gene including the 2.3-kb coding region, the intron/exon junctions, the known 5'-regulatory region, and approximately 300 bp of the 3'-region revealed no alterations. Western blot with an N-terminal antibody showed normal levels of immunoreactive GR, but quantitative analysis with isoform-specific C-terminal antibodies revealed a markedly reduced GRalpha expression, and high GRbeta expression. These findings indicate that imbalanced expression of the GR isoforms may be a mechanism of GC resistance, and may have implications for tumorigenesis by enhancing cell survival.

Evidence for involvement of tumor necrosis factor-alpha in apoptotic death of bone marrow cells in myelodysplastic syndromes

We previously reported excessive apoptosis and high levels of tumor necrosis factor-alpha (TNF-alpha) in the bone marrows of patients with myelodysplastic syndromes (MDS), using histochemical techniques. The present studies provide further circumstantial evidence for the involvement of TNF-alpha in apoptotic death of the marrow cells in MDS. Using our newly developed in situ double-labeling technique that sequentially employs DNA polymerase (DNA Pol) followed by terminal deoxynucleotidyl transferase (TdT) to label cells undergoing apoptosis, we have characterized DNA fragmentation patterns during spontaneous apoptosis in MDS bone marrow and in HL60 cells treated with TNF-alpha or etoposide (VP16). Clear DNA laddering detected by gel electrophoresis in MDS samples confirmed the unique length of apoptotic DNA fragments (180-200 bp). Surprisingly, however, phenotypically heterogeneous population of MDS cells as well as the homogenous population of HL60 cells showed three distinct labeling patterns after double labeling--only DNA-Pol reaction, only TdT reaction, and a combined DNA Pol + TdT reaction, albeit in different cohorts of cells. Each labeling pattern was found at all morphological stages of apoptosis. MDS mononuclear cells, during spontaneous apoptosis in 4 hr cultures, showed highest increase in double-labeled cells (DNA Pol + TdT reaction). Interestingly, this was paralleled by TNF-alpha-induced apoptosis in HL60 cells. In contrast, VP16 treatment of HL60 cells led to increased apoptosis in cells showing only TdT reaction. The double-labeling technique was applied to normal bone marrow and peripheral blood mononuclear cells after treatment with known endonucleases that specifically cause 3' recessed (BamHI), 5' recessed (PstI), or blunt ended (DraI) double-stranded DNA breaks. It was found that the DNA-Pol reaction in MDS and HL60 cells corresponds to 3' recessed DNA fragments, the TdT reaction to 5' recessed and/or blunt ended fragments, and a combined "DNA Pol + TdT reaction" corresponds to a copresence of 3' recessed with 5' recessed and/or blunt ended fragments. Clearly, therefore, apoptotic DNA fragments, in spite of a unique length, may have differently staggered ends that could be cell (or tissue) specific and be selectively triggered by different inducers of apoptosis. The presence of TNF-alpha-inducible apoptotic DNA fragmentation pattern in MDS supports its involvement in these disorders and suggests that anti-TNF-alpha (or anticytokine) therapy may be of special benefit to MDS patients, where no definitive treatment is yet available.

Excessive proliferation matched by excessive apoptosis in myelodysplastic syndromes: the cause-effect relationship

The paradox of pancytopenia despite cellular bone marrows (BM) was investigated in 120 patients with myelodysplastic syndromes (MDS). Detailed cell cycle kinetics were examined following in vivo infusions of iodo--and/or bromodeoxyuridine (IUdR/BrdU), while the incidence of apoptosis was measured by in situ end labeling (ISEL) of fragmented DNA. Results showed that MDS are highly proliferative disorders with an equally high incidence of apoptotic intramedullary cell death accounting for the paradox of cellularity/cytopenia. By double-labeling BM biopsy sections for ISEL/BrdU we found the peculiar situation of "signal antonymy" where S-phase cells were frequently apoptotic, a phenomenon so far only seen in MDS biopsies. The cause-effect relationship of this excessive proliferation/apoptosis is discussed at length.