Use of mechanical circulatory support in patients with non-ischemic cardiogenic shock

Background

The aim of this study was to evaluate mechanical circulatory support (MCS) for the treatment of non-ischemic cardiogenic shock (CS).

Methods

Data from 1,030 consecutive patients with non-ischemic CS treated with or without MCS at 16 tertiary-care centers were retrospectively collected. The association between MCS and 30-day mortality was assessed in a 1:1 propensity score matched cohort.

Results

MCS was used in 406 (39%) patients. MCS treated patients presented with more severe CS (lactate 5.4 vs. 4.1 mmol/l, systolic blood pressure 80 vs. 83 mmHg, higher SCAI class) and with more disease modifiers (prior cardiac arrest 42.4 vs. 36.1%, mechanical ventilation 78.4 vs. 56.5%). After matching, 272 patients treated with were compared vs. 272 patients treated without MCS. MCS was associated with a lower 30-day mortality (hazard ratio 0.77, 95% confidence interval 0.60–0.98, Figure 1). This finding was consistent through all tested sub-groups except when ejection fraction was considered, indicating an association especially in patients with an ejection fraction ≤20%. Complications occurred more frequently in patients with MCS; e.g. severe bleedings (21.8 vs. 9.2%) and access-site related ischemia (6.6 vs. 0%).

Conclusion

In patients with non-ischemic CS, MCS use was associated with lower 30-day mortality as compared to medical therapy only, particularly in patients with a lower ejection fraction. This provides rationale for randomized trials to validate these findings.

Funding Acknowledgement

Type of funding sources: None.

P5450Evening levels and circadian changes of salivary cortisol predict adverse events in heart failure patients with comorbid depression - a MOOD-HF substudy

Background

Depression is frequent in heart failure (HF) and associated with adverse clinical outcomes. The randomized MOOD-HF trial showed that in depressed patients with systolic heart failure (HF) the selective serotonin reuptake inhibitor escitalopram (E) improved neither survival nor depression compared to placebo (P). The hypothalamic-pituitary-adrenocortical axis is known to be altered in depression or HF. This MOOD-HF substudy aimed to clarify whether circadian salivary cortisol levels (SCL) were predictive of adverse events in depressed MOOD-HF participants and whether outcomes differed according to treatment with E.

Methods

MOOD-HF participants (all suffering from symptomatic systolic HF with left ventricular ejection fraction (LVEF) <45% and current major depression) were eligible for the present analysis if providing samples for SCL determination (luminescence immunoassay) at baseline visit (BL) and if not on oral glucocorticosteroid therapy. Depression severity was determined with the Montgomery–Åsberg Depression Rating Scale (MADRS) and LVEF measured by echocardiography.

Results

In the total study cohort (146 patients on E, 147 on P) median morning SCL at BL was 0.210 μg/dL (IQR 0.141–0.338 μg/dL) and median evening (pm) SCL 0.067 μg/dL (0.036–0.128 μg/dL, p<0.001). Median circadian change was 0.124 μg/dL (0.044–0.239 μg/dL). In patients with BL pm-SCL above the median MADRS-score was 21.7±9.1 and LVEF 33.7±8.4% respectively, in patients with pm-SCL below the median these values were 19.6±9.1 and 36.5±7.8% (p=0.048; p=0.004).

During 12 months follow-up the composite endpoint (all-cause death or rehospitalization) occurred least in E-treated patients with low pm-SCL and most often in E-treated patients with high pm-SCL (HR 2.02, 95% CI 1.12–3.65, p=0.010); patients on P had comparable event rates irrespective of BL pm-SCL (Figure A). Thus, numerically patients on E with low BL pm-SCL had lower event rates compared with corresponding P-treated patients (HR 0.76 (0.41–1.40, p=0.796)), while patients with high BL pm-SCL had higher event rates (HR 1.29 (0.74–2.24, p=0.799)) than corresponding P-treated patients. Patients with circadian SCL changes above the median receiving P experienced the composite primary endpoint least, while both subgroups with circadian SCL changes below the median and also patients with circadian SCL changes above the median on E had higher event rates (HR 0.66 (0.45–0.97, p=0.039), Figure B).

Conclusion

In depressed patients with systolic HF high pm-SCL are associated with more severe disease (depression and cardiac dysfunction). Extending primary MOOD-HF results indicating unfavourable outcomes related to E, the current findings suggest a SCL x treatment interaction with higher event rates in (sicker) patients with high pm-SCL and lower event rates in (less sick) patients with low pm-SCL when treated with the antidepressant. Low circadian changes of SCL were always associated with higher event rates.

Acknowledgement/Funding

BMBF (Grant 01 KG0702) and Lundbeck A/S Denmark

A New Angiotensin-Ll- Receptor Blocker, Cgp 48933: Local Tolerance and Effect on Intraocular Pressure. A Pilot Study

CGP 48933, a new angiotensin-II-receptor antagonist, has been shown to lower intraocular pressure (IOP) in two different rabbit glaucoma models in a dose-dependent manner after local application. As a further step a pilot study was performed in human eyes. The trial consisted of three parts. Parts 1 and 2 comprised a double-masked intraindividual trial between CGP 48933 and its vehicle (saline) in five healthy volunteers (Part 1) and five patients with early stages of primary open-angle glaucoma (Part 2), to assess local tolerance and the effect on IOP. Part 3 was a single-masked intraindividual trial between CGP 48933 and saline, to find the effective dose range of the new compound. Local tolerance was assessed as excellent in all subjects. No conjunctival hyperemia burning or itching occurred. There were no significant changes in IOP from baseline in drug or vehicle-treated eyes. In addition, there was no dose-dependent (200 micrograms to 1 mg) effect of CGP 48933 on IOP. Systemic blood pressure, heart rate and pupil size did not change during the observation period. Topical application of CGP 48933 in its present formulation is thus not suitable for lowering IOP in humans.

Cavitation Threshold with Respect to Dp/Dt: Evaluation in 29 Mm Bileaflet, Pyrolitic Carbon Heart Valves

A total of 15 bileaflet mechanical heart valves were studied in a pulse duplicator at the Helmholtz Institute (Aachen, Germany) under conditions approximating first, a physiological pressure curve and subsequently, a sinusoidal pressure curve. In this study Edwards-Duromedics valves of the modified specification were compared with the earlier version of the Edwards-Duromedics valve as well as with St. Jude Medical valves. Each valve was tested at a series of nine (9) conditions. At each condition, without altering the valve installation or the systemic conditions, each valve was filmed by two separate video systems: the Helmholtz Institute strobe light system and a high speed video recording system. All data, as recorded by each system, was then independently analyzed by both of the two contributing groups and subsequently compared. In this manner, it was possible to objectively verify not only the consistency of the data obtained, but to also determine the relative reliability of the methods for cavitation threshold detection.

Protein and DNA-based assays as complementary tools for fish allergen detection

BACKGROUND

Fish is one of the most important, allergenic foods worldwide. Parvalbumin is the well characterized, major allergen in fish muscle. In this study, we developed a protein- and a DNA-based method for the sensitive detection and authentication of eight commonly consumed fishes in food and compared their applicability.

METHODS

Fish parvalbumins were purified. Polyclonal, anti-parvalbumin antibodies were raised in rabbits and mice. Protein extracts from food were analyzed by quantitative ELISA. Parvalbumin genes were cloned and sequenced for the design of parvalbumin gene-specific PCR-primers. DNA extracted from food was subjected to specific PCR.

RESULTS

Increasing parvalbumin contents were quantified by ELISA in fresh fish, in the order of tuna < mackerel < cod < salmon/trout < redfish < carp < herring. The parvalbumin content of processed fish was up to 67% lower than in fresh fish. In spiked food samples, 1 to 15 ppm fresh fish and 30 to 170 ppm processed fish were still detectable by ELISA. The eight fishes were identified by specific PCR using 0.2 to 10 ng fish DNA. PCRs detected still 3 ppm fresh fish and 30 to 150 ppm processed fish in spiked samples.

CONCLUSIONS

Both the protein- and the DNA-based method have sufficient sensitivity to protect fish-allergic consumers. The ELISA allows allergen quantification, while the PCR identifies the fish present in the food. The detection limits of both methods vary depending on different factors. Both methods need to be carefully validated for each fish and fish product when used in detection assays.

Single-grating-mirror intracavity stretcher design for chirped pulse regenerative amplification

We report for the first time, to the best of our knowledge, an innovative design concept for intracavity pulse stretching in a regenerative amplifier, employing a single "grating-mirror" based on a leaky-mode grating-waveguide design. The very compact and flexible layout allows for femtosecond pulses to be in principle easily stretched up to nanosecond durations. The design has been tested in a diode-pumped Yb:CALGO regenerative amplifier followed by a standard transmission grating compressor. Sub-200-fs pulses (stretched pulses ≈110  ps) with 205-μJ energy at 20-kHz repetition rate have been demonstrated. In order to prove the robustness and potential for energy scaling of leaky-mode grating-waveguide intracavity stretcher, we generated stretched pulses with energies of up to ≈700  μJ (400-ps long) at a lower repetition rate of 10 kHz. A simple model is proposed for the study of the cavity in presence of induced spatial chirp.

Enhanced efficiency of AlGaInP disk laser by in-well pumping

The performance of a 665-nm GaInP disk laser operated continuous-wave at 15°C both in-well-pumped at 640 nm and barrier pumped at 532 nm is reported. The efficiency with respect to the absorbed power was enhanced by 3.5 times when using a 640-nm pump instead of a 532-nm pump. In-well pumping which is based on the absorption of the pump photons within the quantum-well heterostructures of the gain region instead of short-wavelength absorption in the barrier and spacer regions reduces the quantum defect between pump and laser photon and hence the heat generation. A slope efficiency of 60% with respect to the absorbed pump power was obtained by in-well pumping at 15°C. Continuous-wave laser operation was further demonstrated at heat sink temperatures of up to 55°C. Both the measurement of photoluminescence and COMSOL simulation show that the overall heat load in the in-well pumped laser is smaller than in the barrier-pumped laser. These results demonstrate the potential of optical in-well pumping for the operation of red AlGaInP disk lasers if combined with means for efficient pump-light absorption.

["Fit4You"--A Programme for Prevention and Reduction of Overweight in Apprentices in the Workplace Setting]

The effect of health promotion at the worksite for overweight adolescents is not known. This 2-year intervention study examined the effect of a multimodal programme including nutrition counselling, sport, and life-skill training on medical and psychological outcomes. The body mass index increased slightly less in the intervention group. Semistructured interviews at the end showed that participants are highly interested in health promotion at the worksite.

Femtosecond Yb:CaGdAlO4 thin-disk oscillator

A mode-locked thin-disk laser based on Yb:CALGO is demonstrated for the first time. At an average output power of 28 W we obtained pulses with a duration of 300 fs and a pulse energy of 1.3 μJ. 197 fs pulses with 0.9 μJ of energy were achieved at an average output power of 20 W. The shortest pulse duration measured in our experiments was 135 fs with a spectrum centered at 1043 nm. The experiments also revealed a very broad tunability from 1032 to 1046 nm with sub-200 fs pulses.

Yb:CaGdAlO4 thin-disk laser

We present the first demonstration of a Yb:CALGO thin-disk laser. In a slightly multimode configuration, we obtained up to 30 W of average power at a slope efficiency of 40% and an optical-to-optical efficiency of 32%. With a single-mode cavity, an average power of 25 W was achieved. A tuning range from 1018 to 1052 nm could be demonstrated by inserting a prism into the cavity. In the Q-switched regime, we obtained 1 mJ of pulse energy at a repetition rate of 100 Hz.

Is the proton radius a player in the redefinition of the International System of Units?

It is now recognized that the International System of Units (SI units) will be redefined in terms of fundamental constants, even if the date when this will occur is still under debate. Actually, the best estimate of fundamental constant values is given by a least-squares adjustment, carried out under the auspices of the Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants. This adjustment provides a significant measure of the correctness and overall consistency of the basic theories and experimental methods of physics using the values of the constants obtained from widely differing experiments. The physical theories that underlie this adjustment are assumed to be valid, such as quantum electrodynamics (QED). Testing QED, one of the most precise theories is the aim of many accurate experiments. The calculations and the corresponding experiments can be carried out either on a boundless system, such as the electron magnetic moment anomaly, or on a bound system, such as atomic hydrogen. The value of fundamental constants can be deduced from the comparison of theory and experiment. For example, using QED calculations, the value of the fine structure constant given by the CODATA is mainly inferred from the measurement of the electron magnetic moment anomaly carried out by Gabrielse's group. (Hanneke et al. 2008 Phys. Rev. Lett. 100, 120801) The value of the Rydberg constant is known from two-photon spectroscopy of hydrogen combined with accurate theoretical quantities. The Rydberg constant, determined by the comparison of theory and experiment using atomic hydrogen, is known with a relative uncertainty of 6.6×10(-12). It is one of the most accurate fundamental constants to date. A careful analysis shows that knowledge of the electrical size of the proton is nowadays a limitation in this comparison. The aim of muonic hydrogen spectroscopy was to obtain an accurate value of the proton charge radius. However, the value deduced from this experiment contradicts other less accurate determinations. This problem is known as the proton radius puzzle. This new determination of the proton radius may affect the value of the Rydberg constant . This constant is related to many fundamental constants; in particular, links the two possible ways proposed for the redefinition of the kilogram, the Avogadro constant N(A) and the Planck constant h. However, the current relative uncertainty on the experimental determinations of N(A) or h is three orders of magnitude larger than the 'possible' shift of the Rydberg constant, which may be shown by the new value of the size of the proton radius determined from muonic hydrogen. The proton radius puzzle will not interfere in the redefinition of the kilogram. After a short introduction to the properties of the proton, we will describe the muonic hydrogen experiment. There is intense theoretical activity as a result of our observation. A brief summary of possible theoretical explanations at the date of writing of the paper will be given. The contribution of the proton radius puzzle to the redefinition of SI-based units will then be examined.

Randomized clinical trial of the i-gel™ and Magill tracheal tube or single-use ILMA™ and ILMA™ tracheal tube for blind intubation in anaesthetized patients with a predicted difficult airway

BACKGROUND

The single-use supraglottic airway device i-gel™ has been described in several case reports as a conduit for intubation, but no prospective data about success rates of blind intubation are available. Therefore, we performed this prospective randomized controlled trial to compare the success rate of blind tracheal intubation with a Magill PVC tube through the i-gel™ with intubation using an sILMA™ PVC tube through the single-use intubating laryngeal mask airway (sILMA™).

METHODS

With ethics committee approval and written informed consent, 80 patients with predictors of a difficult airway were computer randomized to either supraglottic airway device (SAD). The corresponding tracheal tube (TT) was introduced through the SAD under fibreoptic visualization but without fibreoptic guidance. Primary outcome was blind intubation success rate. Times, airway leak pressure, fibreoptic view, and adverse events were recorded. To control for the influence of the TT, we compared data from 40 patients described in an accompanying study (sILMA™ with Magill TT and i-gel™ with sILMA™ TT).

RESULTS

Blind intubation success rate through the sILMA™ (69%) was higher than with the i-gel™ (15%, P<0.001). Data from the other patient group excluded the TT type as the primary cause for the difference in success rate. Removal of SADs was without problems with no difference between the type of SAD.

CONCLUSIONS

Blind tracheal intubation using the sILMA™ tube through the sILMA™ is much more successful than blind intubation with a Magill PVC tube through the i-gel™. Because of its low success rate, we would not recommend blind intubation through the i-gel™.

Urocortin III, a brain neuropeptide of the corticotropin-releasing hormone family: modulation by stress and attenuation of some anxiety-like behaviours

Following its discovery 20 years ago, corticotropin-releasing hormone (CRH) has been postulated to mediate both hormonal and behavioural responses to stressors. Here, we characterize and describe a behavioural role for the murine gene, UcnIII, which encodes a recently discovered CRH-related neuropeptide, urocortin III. We found that mouse UcnIII is expressed predominantly in regions of the brain known to be involved in stress-related behaviours, and its expression in the hypothalamus increases following restraint. In addition, we found that intracerebroventricular administration of mUcnIII stimulates behaviours that are associated with reduced anxiety, including exploration of an open field and decreased latency to enter the lit compartment of a dark-light chamber, but has no effect on the elevated-plus maze. Finally, we found that mUcnIII does not exert any effects on the hormonal stress response. Based upon our findings, UcnIII may be an endogenous brain neuropeptide that is modulated by stress and stimulates behaviours associated with reduced anxiety. In this capacity, UcnIII may attenuate stress-related behaviours, which may be useful both to help cope with stressful situations as well as to avoid pathology associated with excessive reaction to stressors.

Diode-pumped passively mode-locked Nd:KGd(WO(4))(2) laser with 1-W average output power

Continuous-wave passive mode locking of a diode-pumped Nd:KGd(WO(4))(2) laser is demonstrated. The use of a saturable Bragg reflector as the mode-locking element permits the generation of 6.3-ps pulses, assuming a sech(2) pulse shape. An output power of 1 W was obtained, which corresponds to a slope efficiency of 34.5%.

High frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral cortex: EEG topography during waking and subsequent sleep

Repetitive transcranial magnetic stimulation (rTMS) is a novel research tool in neurology and psychiatry. It is currently being evaluated as a conceivable alternative to electroconvulsive therapy for the treatment of mood disorders. Eight healthy young (age range 21-25 years) right-handed men without sleep complaints participated in the study. Two sessions at a 1-week interval, each consisting of an adaptation night (sham stimulation) and an experimental night (rTMS in the left dorsolateral prefrontal cortex or sham stimulation; crossover design), were scheduled. In each subject, 40 trains of 2-s duration of rTMS (inter-train interval 28 s) were applied at a frequency of 20 Hz (i.e. 1600 pulses per session) and at an intensity of 90% of the motor threshold. Stimulations were scheduled 80 min before lights off. The waking EEG was recorded for 10-min intervals approximately 30 min prior to and after the 20-min stimulations, and polysomnographic recordings were obtained during the subsequent sleep episode (23.00-07.00 h). The power spectra of two referential derivations, as well as of bipolar derivations along the antero-posterior axis over the left and right hemispheres, were analyzed. rTMS induced a small reduction of sleep stage 1 (in min and percentage of total sleep time) over the whole night and a small enhancement of sleep stage 4 during the first non-REM sleep episode. Other sleep variables were not affected. rTMS of the left dorsolateral cortex did not alter the topography of EEG power spectra in waking following stimulation, in the all-night sleep EEG, or during the first non-REM sleep episode. Our results indicate that a single session of rTMS using parameters like those used in depression treatment protocols has no detectable side effects with respect to sleep in young healthy males.

Accuracy and safety of online clearance monitoring based on conductivity variation

BACKGROUND

Haemodialysis dose has been shown to have a distinct impact upon the morbidity and mortality rate in patients on regular dialysis therapy. Accordingly, the adequacy of dialysis treatment should be guaranteed.

METHODS

In 200 dialysis sessions two or three +/-10% dialysate conductivity variations were applied to test patient compliance and the accuracy of an electrolyte based online clearance measurement (OCM) reflecting the total clearance of urea.

RESULTS

Using a step profile the electrolytic clearance showed highly significant correlation with the reference data in the blood side (n=118, r=0.867, P<0.001) and dialysate side (n=118, r=0.820, P<0.001) if only reference values were taken into account for which the error in mass balance did not exceed 5%. Kt/V according to the single pool model (n=35, r=0.940, P<0.001), the equilibrated single pool variable volume kinetic model (n=36, r=0.982, P<0.001), Daugirdas formula (n=34, r=0.951, P<0.001) and direct quantification of dialysance via spent dialysate (n=26, r=0.900, P<0.001) showed outstanding correlations with electrolyte-based Kt/V at mass balance error below 5%. No adverse clinical effect of OCM was reported. Serum sodium, body weight, heart rate and breathing rate at rest, arterial pO(2) and pCO(2) and blood pressure before haemodialysis remained unaffected in OCM measurements in comparison with baseline parameters. A small influx of sodium (1.53+/-7.62 mmol) into the patient was seen following the impulse, but no signs associated with fluid overload were observed during the study period of 10 consecutive dialysis sessions.

CONCLUSIONS

The OCM option of the haemodialysis machine provides a safe and accurate tool for continuous online monitoring of total urea clearance.

A new approach to measure single-event related brain activity using real-time fMRI: feasibility of sensory, motor, and higher cognitive tasks

Real-time fMRI is a rapidly emerging methodology that enables monitoring changes in brain activity during an ongoing experiment. In this article we demonstrate the feasibility of performing single-event sensory, motor, and higher cognitive tasks in real-time on a clinical whole-body scanner. This approach requires sensitivity optimized fMRI methods: Using statistical parametric mapping we quantified the spatial extent of BOLD contrast signal changes as a function of voxel size and demonstrate that sacrificing spatial resolution and readout bandwidth improves the detection of signal changes in real time. Further increases in BOLD contrast sensitivity were obtained by using real-time multi-echo EPI. Real-time image analysis was performed using our previously described Functional Imaging in REal time (FIRE) software package, which features real-time motion compensation, sliding window correlation analysis, and automatic reference vector optimization. This new fMRI methodology was validated using single-block design paradigms of standard visual, motor, and auditory tasks. Further, we demonstrate the sensitivity of this method for online detection of higher cognitive functions during a language task using single-block design paradigms. Finally, we used single-event fMRI to characterize the variability of the hemodynamic impulse response in primary and supplementary motor cortex in consecutive trials using single movements. Real-time fMRI can improve reliability of clinical and research studies and offers new opportunities for studying higher cognitive functions.

Suppression of HIV type 1 replication by a dominant-negative Ets-1 mutant

Activity of the distal region of the human immunodeficiency virus (HIV-1) long terminal repeat (LTR), which contains binding sites for the Ets-1 and USF-1 proteins, is integral for HIV-1 replication. The Ets-1 and USF-1 proteins play a critical role in the activity of the HIV-1 LTR distal enhancer region, as indicated by the potent dominant negative effect of a mutant Ets-1 lacking trans-activation domains on the transcriptional activity of the LTR. To determine the biological relevance of the Ets-1 and USF-1 proteins in HIV-1 replication, we examined the effect of expression of the dominant-negative mutant of Ets-1 (dnEts-1) on HIV-1 infection of T cells. We demonstrated that expression of dnEts markedly suppressed HIV-1 infection of a T cell line. This finding indicates that formation of a transcriptionaly active USF-1/Ets-1 complex is important in the productive infection of cells by HIV-1, and suggests that inhibition of the interaction between USF-1 and Ets-1 with the HIV-1 LTR may provide a new target for anti-HIV-1 gene therapy.

A new approach to measure single-event related brain activity using real-time fMRI: feasibility of sensory, motor, and higher cognitive tasks

Real-time fMRI is a rapidly emerging methodology that enables monitoring changes in brain activity during an ongoing experiment. In this article we demonstrate the feasibility of performing single-event sensory, motor, and higher cognitive tasks in real-time on a clinical whole-body scanner. This approach requires sensitivity optimized fMRI methods: Using statistical parametric mapping we quantified the spatial extent of BOLD contrast signal changes as a function of voxel size and demonstrate that sacrificing spatial resolution and readout bandwidth improves the detection of signal changes in real time. Further increases in BOLD contrast sensitivity were obtained by using real-time multi-echo EPI. Real-time image analysis was performed using our previously described Functional Imaging in REal time (FIRE) software package, which features real-time motion compensation, sliding window correlation analysis, and automatic reference vector optimization. This new fMRI methodology was validated using single-block design paradigms of standard visual, motor, and auditory tasks. Further, we demonstrate the sensitivity of this method for online detection of higher cognitive functions during a language task using single-block design paradigms. Finally, we used single-event fMRI to characterize the variability of the hemodynamic impulse response in primary and supplementary motor cortex in consecutive trials using single movements. Real-time fMRI can improve reliability of clinical and research studies and offers new opportunities for studying higher cognitive functions.

Exposure to pulsed high-frequency electromagnetic field during waking affects human sleep EEG

The aim of the study was to investigate whether the electromagnetic field (EMF) emitted by digital radiotelephone handsets affects brain physiology. Healthy, young male subjects were exposed for 30 min to EMF (900 MHz; spatial peak specific absorption rate 1 W/kg) during the waking period preceding sleep. Compared with the control condition with sham exposure, spectral power of the EEG in non-rapid eye movement sleep was increased. The maximum rise occurred in the 9.75-11.25 Hz and 12.5-13.25 Hz band during the initial part of sleep. These changes correspond to those obtained in a previous study where EMF was intermittently applied during sleep. Unilateral exposure induced no hemispheric asymmetry of EEG power. The present results demonstrate that exposure during waking modifies the EEG during subsequent sleep. Thus the changes of brain function induced by pulsed high-frequency EMF outlast the exposure period.

Antagonism between C/EBPbeta and FOG in eosinophil lineage commitment of multipotent hematopoietic progenitors

The commitment of multipotent cells to particular developmental pathways requires specific changes in their transcription factor complement to generate the patterns of gene expression characteristic of specialized cell types. We have studied the role of the GATA cofactor Friend of GATA (FOG) in the differentiation of avian multipotent hematopoietic progenitors. We found that multipotent cells express high levels of FOG mRNA, which were rapidly down-regulated upon their C/EBPbeta-mediated commitment to the eosinophil lineage. Expression of FOG in eosinophils led to a loss of eosinophil markers and the acquisition of a multipotent phenotype, and constitutive expression of FOG in multipotent progenitors blocked activation of eosinophil-specific gene expression by C/EBPbeta. Our results show that FOG is a repressor of the eosinophil lineage, and that C/EBP-mediated down-regulation of FOG is a critical step in eosinophil lineage commitment. Furthermore, our results indicate that maintenance of a multipotent state in hematopoiesis is achieved through cooperation between FOG and GATA-1. We present a model in which C/EBPbeta induces eosinophil differentiation by the coordinate direct activation of eosinophil-specific promoters and the removal of FOG, a promoter of multipotency as well as a repressor of eosinophil gene expression.

Insertion of enhanced green fluorescent protein into the lysozyme gene creates mice with green fluorescent granulocytes and macrophages

Pluripotent hematopoietic stem cells have been studied extensively, but the events that occur during their differentiation remain largely uncharted. To develop a system that allows the differentiation of cultured multipotent progenitors by time-lapse fluorescence microscopy, myelomonocytic cells were labeled with green fluorescent protein (GFP) in vivo. This was achieved by knocking the enhanced GFP (EGFP) gene into the murine lysozyme M (lys) locus and using a targeting vector, which contains a neomycin resistant (neo) gene flanked by LoxP sites and "splinked" ends, to increase the frequency of homologous recombination. Analysis of the blood and bone marrow of the lys-EGFP mice revealed that most myelomonocytic cells, especially mature neutrophil granulocytes, were fluorescence-positive, while cells from other lineages were not. Removal of the neo gene through breeding of the mice with the Cre-deleter strain led to an increased fluorescence intensity. Mice with an inactivation of both copies of the lys gene developed normally and were fertile. (Blood. 2000;96:719-726)

MafB is an inducer of monocytic differentiation

The bZip transcription factor MafB is expressed specifically in the myeloid lineage of the hematopoietic system and is up-regulated successively during myeloid differentiation from multipotent progenitors to macrophages. Here we report that this induction reflects an essential role of MafB in early myeloid and monocytic differentiation. We observed that the expression of MafB in transformed chicken hematopoietic precursors dramatically increases the proportion of myeloid colony formation at the expense of multipotent progenitor-type colonies. In addition, the overexpression of MafB in transformed myeloblasts stimulates the rapid formation of macrophages, as judged by morphology, surface marker expression and functional criteria. MafB-induced macrophages exhibit typical levels of phagocytic activity and nitric oxide release after activation by lipopolysaccharide. By contrast, overexpression of the myeloid transcription factor PU.1 in these cells does not induce macrophage differentiation. Furthermore, a dominant-negative allele of MafB inhibits both myeloid colony formation and the differentiation of myeloblasts into macrophages. Taken together, our results indicate that MafB induction is a specific and essential determinant of the monocytic program in hematopoietic cells.