bluuebunny/crossref_metadata_2025 huggingface dataset:
Age-Related Changes in Vascular Endothelial Growth Factor Dependency and Angiopoietin-1-Induced Plasticity of Adult Blood Vessels
Authors: Baffert Fabienne , Thurston Gavin , Rochon-Duck Michael , Le Tom , Brekken Rolf , McDonald Donald M.
Published: March 2004

Vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1) are essential for vascular development, but this dependency has been assumed not to persist into adult life. In this study, we report that after 10 days of systemic treatment of 4-, 8-, and 16-week-old mice with VEGF-Trap, an inhibitor of VEGF, the number of capillaries in the tracheal mucosa was reduced by 39%, 28%, and 14%, respectively. The magnitude of the reduction decreased with age (
r
2
=0.6,
P
<0.001), but was still significant at 16 weeks. A corresponding age-related decrease in vascular endothelial growth factor receptor-2 (VEGFR-2) immunoreactivity suggests that diminished VEGFR-2 expression may contribute to resistance to VEGF signaling inhibition. VEGF-Trap further reduced VEGFR-2 expression in tracheal capillaries. By comparison, systemic treatment with adenovirus encoding Ang1 led to a significant enlargement of tracheal venules with little age effect (64%, 56%, and 49% increase in diameter at 10 days). When Ang1 was given in combination with VEGF-Trap, tracheal vessels presented the typical response to each factor, showing that the Ang1 effect was not VEGF-mediated, yet Ang1 seems to have a protective effect, as judged by prevention of VEGF-Trap-induced reduction in tracheal capillaries in the oldest group. Together, these findings indicate that VEGF and Ang1 participate in blood vessel survival and plasticity in adult life.
Conserved Enhancer in the Serum Response Factor Promoter Controls Expression During Early Coronary Vasculogenesis
Authors: Nelson Timothy J. , Duncan Stephen A. , Misra Ravi P.
Published: March 2004

Serum response factor (SRF) is a transcription factor required for mesoderm formation in the developing mouse embryo that is important for myogenic differentiation, including notably, the differentiation of the proepicardial organ (PEO) into coronary vascular cells during early development. To identify regulatory sequences that control SRF expression during early mouse development, we used a novel transgenic approach to study the role of conserved noncoding DNA sequences (CNCS) in the SRF gene. Embryonic stem (ES) cells containing a targeted single-copy of putative SRF regulatory sequences were used to directly generate transgenic embryos by tetraploid aggregation. Because the ES cell-derived targeted embryos are genetically equivalent, except for the putative regulatory sequence of interest, differences in transgene expression can be attributed directly to these sequences. Using this approach, we identified an E-box/Ets containing 270-bp
cis
-acting module in the SRF promoter that mediates expression in the PEO. Reporter transgenes containing this module express in derivatives of the PEO that give rise to the coronary vasculature, but do not express in the PEO-derived epicardium. These results are the first reported in vivo analysis of SRF regulatory elements that control expression during early development. Using this reporter module and this approach, it should be possible to begin to elucidate molecular mechanisms involved in the differentiation of coronary vasculature progenitor cells, as well as identify additional SRF regulatory elements important during mammalian development.
Focal Cerebral Ischemia Induces Active Proteases That Degrade Microvascular Matrix
Authors: Fukuda Shunichi , Fini Catherine A. , Mabuchi Takuma , Koziol James A. , Eggleston Leonard L. , del Zoppo Gregory J.
Published: March 2004

Background and Purpose—

Focal cerebral ischemia causes microvessel matrix degradation and generates proteases known to degrade this matrix. However, proof that the proteases generated do indeed degrade vascular matrix is lacking. Here we demonstrate that active proteases derived from ischemic tissue after middle cerebral artery occlusion (MCAO) and transferred to normal tissue can degrade vascular matrix.

Methods—

In an ex vivo bioassay, the effects of supernatants from ischemic and normal basal ganglia of nonhuman primates, proteases, and control buffer on the immunoreactivity of vascular matrix constituents in normal brain tissue sections were quantified. Protease families were identified with specific inhibitors.

Results—

Plasmin, active matrix metalloproteinase (MMP)-2, and active MMP-9 significantly reduced microvessel-associated collagen, laminin, and heparan sulfate proteoglycans (HSPG). The vascular HSPG perlecan was more sensitive than collagen or laminin in the bioassay and in the ischemic core 2 hours after MCAO. Two-hour and 7-day ischemic tissue samples significantly degraded matrix perlecan and collagen. Inhibitor studies confirmed that while active MMPs were generated, active cysteine proteases significantly degraded microvessel perlecan. The cysteine proteases cathepsins B and L were generated in the microvasculature and adjacent neurons or glial cells 2 hours after MCAO and decreased perlecan in the bioassay.

Conclusions—

This is the first direct evidence that active proteases are generated in ischemic cerebral tissues that are acutely responsible for vascular matrix degradation. Degradation of vascular perlecan, the most sensitive matrix component thus far identified, may be due to cathepsins B and L, generated very rapidly after MCAO.
Characterization of Carotid Artery Plaques Using Real-time Compound B-mode Ultrasound
Authors: Kern Rolf , Szabo Kristina , Hennerici Michael , Meairs Stephen
Published: March 2004

Background and Purpose—

Real-time compound ultrasound imaging is a new technique for improving the image quality of B-mode scanning. We investigated the value of this method for the characterization of atherosclerotic plaques in the internal carotid artery.

Methods—

Thirty-two patients (22 men, 10 women; mean age, 75 years) with plaques of the internal carotid artery as identified by high-resolution B-mode scanning were investigated with real-time compound ultrasound imaging with the use of a 5- to 12-MHz dynamic range linear transducer on a duplex scanner. Two independent observers rated plaque morphology according to a standardized protocol.

Results—

The majority of plaques was classified as predominantly echogenic and as plaques of irregular surface, whereas ulcerated plaques were rarely observed. The interobserver agreement for plaque surface characterization was good for both compound ultrasound (κ=0.72) and conventional B-mode (κ=0.65). For the determination of plaque echogenicity, the reproducibility of compound ultrasound (κ

w

=0.83) was even higher than that of conventional B-mode ultrasound (κ

w

=0.74). According to a semiquantitative analysis, real-time compound ultrasound was rated superior in the categories plaque texture resolution, plaque surface definition, and vessel wall demarcation. Furthermore, there was a significant reduction of acoustic shadowing and reverberations.

Conclusions—

Real-time compound ultrasound is a suitable technique for the characterization of atherosclerotic plaques, showing good general agreement with high-resolution B-mode imaging. This advanced technique allows reduction of ultrasound artifacts and improves the assessment of plaque texture and surface for enhanced evaluation of carotid plaque morphology.
Abnormal Vasoconstrictor Responses to Angiotensin II and Noradrenaline in Isolated Small Arteries From Patients With Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy (CADASIL)
Authors: Hussain Monira B. , Singhal Sumeet , Markus Hugh S. , Singer Donald R.J.
Published: March 2004

Background and Purpose—

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterized by ultrastructural abnormalities in small cerebral and systemic vessels. We assessed vasomotor function in systemic small arteries in CADASIL.

Methods—

We studied 10 CADASIL patients and 10 control subjects. Resistance arteries isolated from gluteal biopsies were mounted on small-vessel myographs, and concentration responses were determined for vasoconstrictors (noradrenaline, angiotensin II, and endothelin-I) and vasodilators (acetylcholine, bradykinin, spermine-NONOate, and nifedipine). Maximum data are shown as percent potassium contraction.

Results—

There was reduced potency for noradrenaline in CADASIL (CADASIL [38 arteries]: EC
50
, 240 nmol/L; control subjects [27 arteries]: EC
50
, 100 nmol/L; 2-way analysis of variance, F=9.76,
P
=0.002). Maximum response to angiotensin II was greater in CADASIL (120±8% versus 97±5% in control subjects; F=4.28,
P
=0.043). Tachyphylaxis to angiotensin II occurred in all control subjects studied but in only 3 of 9 CADASIL subjects (
P
=0.011, Fisher’s exact test). Vasodilation was similar in CADASIL patients compared with control subjects for endothelium-dependent dilators (acetylcholine and bradykinin) and endothelium-independent dilators (spermine-NONOate and nifedipine).

Conclusions—

These results suggest a selective systemic microvascular vasoconstrictor abnormality in CADASIL in noradrenaline and angiotensin II pathways that is not explained by vasodilator impairment in endothelium or vascular smooth muscle. This could have important implications for prophylaxis and treatment of CADASIL.
Emerging Therapies for Vascular Dementia and Vascular Cognitive Impairment
Authors: Erkinjuntti Timo , Román Gustavo , Gauthier Serge , Feldman Howard , Rockwood Kenneth
Published: March 2004

Background—

Cerebrovascular disease (CVD) and ischemic brain injury secondary to cardiovascular disease are common causes of dementia and cognitive decline in the elderly. CVD also contributes to cognitive loss in Alzheimer disease (AD).

Summary—

Progress in understanding vascular cognitive impairment (VCI) and vascular dementia (VaD) has resulted in promising symptomatic and preventive treatments. Cholinergic deficits in VaD due to ischemia of basal forebrain nuclei and cholinergic pathways can be treated with cholinesterase inhibitors used in AD. Controlled clinical trials with donepezil and galantamine in patients with VaD, as well as in patients with AD plus CVD, have demonstrated improvement in cognition, behavior, and activities of daily living. The
N
-methyl-
d
-aspartate receptor antagonist memantine stabilized progression of VaD compared with placebo. Primary and secondary stroke prevention, in particular with control of hypertension and hyperlipidemia, can decrease VaD incidence.

Conclusions—

From a public health viewpoint, recognition of VCI before the development of dementia and correction of vascular burden on the brain may lead to a global decrease of incident dementia.
Self-Reported Depression and Use of Antidepressants After Stroke: A National Survey
Authors: Eriksson Marie , Asplund Kjell , Glader Eva-Lotta , Norrving Bo , Stegmayr Birgitta , Terént Andreas , Åsberg Kerstin Hulter , Wester Per-Olov
Published: March 2004

Background and Purpose—

Depression after stroke is often described as underdiagnosed and undertreated. However, there are few data on self-reported depression and use of antidepressants in stroke patients at large.

Materials and Methods—

In the Swedish national quality assessment register, Riks-Stroke, 15 747 stroke survivors are recorded. They were asked about depressive mood and antidepressant treatment 3 months after stroke. Age-specific prevalence of antidepressant use after stroke was calculated.

Results—

At 3 months after stroke, 12.4% of male and 16.4% of female stroke survivors reported that they always or often felt depressed. In a multiple logistic regression model, female sex, age younger than 65 years, living alone, having had a recurrent stroke, being dependent on others, and institutional living 3 months after stroke were independent predictors of self-reported depression. Antidepressant medication was used by 22.5% of men and 28.1% of women who had had a stroke. Of patients using antidepressant drugs, 67.5% did not report depressive mood. However, 8.4% of the entire cohort reported depressive mood but no treatment with antidepressants. When compared with the general population, approximately twice as many of the stroke patients were using antidepressant treatment.

Conclusions—

In this national survey, 1 in 7 patients reported that they felt depressed and the use of antidepressant drugs after stroke was common. The widespread use of antidepressants challenges the contention that antidepressants are generally underused after stroke. However, the substantial proportion reporting depressive mood but not using treatment with antidepressants suggests that patient selection for treatment should be more precise.
Early and Repetitive Stimulation of the Arm Can Substantially Improve the Long-Term Outcome After Stroke: A 5-Year Follow-up Study of a Randomized Trial
Authors: Feys Hilde , De Weerdt Willy , Verbeke Geert , Steck Gail Cox , Capiau Chris , Kiekens Carlotte , Dejaeger Eddy , Van Hoydonck Gustaaf , Vermeersch Guido , Cras Patrick
Published: March 2004

Background and Purpose—Several studies have investigated the effect of therapeutic interventions for the arm in the acute phase after stroke, with follow-ups at a maximum of 12 months. The aim of this study was to examine the effect of repetitive sensorimotor training of the arm at 5 years after stroke.

Subjects and Methods—One hundred consecutive stroke patients were randomly allocated either to an experimental group that received daily additional sensorimotor stimulation of the arm or to a control group. The intervention period was 6 weeks. Assessments of the patients were made before, midway, and after intervention, and at 6 and 12 months after stroke. In this study, 62 patients were reassessed at 5 years after stroke. The Brunnström-Fugl-Meyer (BFM) test, Action Research Arm (ARA) test, and Barthel index (BI) were used as the primary outcome measures.

Results—At the 5-year follow-up, there was a statistically significant difference for both the BFM and ARA tests in favor of the experimental group. The mean differences in improvement between the groups from the initial evaluation to the 5-year assessment corresponded to 17 points on the BFM and 17.4 on the ARA. No effect was found for the BI. The treatment was most effective in patients with a severe initial motor deficit.

Conclusions—Adding a specific intervention for the arm during the acute phase after a stroke resulted in a clinically meaningful and long-lasting effect on motor function. The effect can be attributed to early, repetitive, and targeted stimulation.
Heritability of Ischemic Stroke in Relation to Age, Vascular Risk Factors, and Subtypes of Incident Stroke in Population-Based Studies
Authors: Schulz U.G.R. , Flossmann E. , Rothwell P.M.
Published: March 2004

Background—

Appropriate design of molecular genetic studies of ischemic stroke requires an understanding of the genetic epidemiology of stroke. However, there are no published population-based data on heritability of aetiological subtypes of ischemic stroke, confounding by heritability of other vascular risk factors, or the relationship between heritability and age of onset.

Methods—

We studied family history of stroke (FHx
Stroke
) and of myocardial infarction (FHx
MI
) in first-degree relatives in 2 population-based studies (Oxford Vascular Study [OXVASC]; Oxfordshire Community Stroke Project [OCSP]). We related FHx
Stroke
and FHx
MI
to subtype of ischemic stroke, age, and the presence of vascular risk factors and performed a systematic review of all studies of FHx
Stroke
by stroke subtype.

Results—

In our population-based studies and in 3 hospital-based studies, FHx
Stroke
was least frequent in cardioembolic stroke (OR=0.74, 95%CI=0.58 to 0.95,
P
=0.02) but was equally frequent in the other subtypes. In OXVASC and OCSP, FHx
Stroke
(
P
=0.02), FHx
MI
(
P
=0.04), and FHx of either (
P
=0.006) were associated with stroke at a younger age. Only FHx
Stroke
was associated with previous hypertension (OR=1.59, 95%CI=1.08 to 2.35,
P
=0.02). FHx
MI
was more frequent in large-artery stroke (OR=1.63, 95%CI=0.99 to 2.69,
P
=0.05).

Conclusion—

Consistent results in our population-based studies and previous hospital-based studies suggest that inclusion bias is not a major problem for studies of the genetic epidemiology of stroke. Molecular genetic studies might be best targeted at non-cardioembolic stroke and younger patients. However, genetic susceptibility to hypertension may account for a significant proportion of the heritability of ischemic stroke.
Prescription of Antithrombotic Therapy in Older Patients Hospitalized for Transient Ischemic Attack and Ischemic Stroke: The GIFA Study
Authors: Volpato Stefano , Maraldi Cinzia , Blè Alessandro , Ranzini Monica , Rita Atti Anna , Dominguez Ligia J. , Barbagallo Mario , Fellin Renato , Zuliani Giovanni
Published: March 2004

Background and Purpose—

Antithrombotic therapy has been demonstrated as an effective tool for secondary ischemic stroke prevention. Nevertheless, scant data are available on actual prescription of this therapy in clinical practice.

Methods—

A total of 17 337 patients admitted to geriatric and internal medicine wards participating in the study in the 1993 to 1998 survey period were analyzed. Patients with coded diagnoses of ischemic stroke and transient ischemic attack (TIA) were selected. Data recorded included demographic and clinical characteristics and medication prescription during hospital stay and at discharge. Logistic regression analyses were used to identify conditions associated with the prescription of antiplatelet or anticoagulant drugs.

Results—

Among 946 patients with diagnosis of stroke or TIA (mean age 78 years), >40% was discharged without antithrombotic prescription. Conditions that made the prescription more unlikely were diagnosis of stroke (odds ratio [OR]: 0.61; 95% confidence interval [CI]: 0.44 to 0.86), presence of anemia (OR: 0.70; 95% CI: 0.49 to 0.98), severe disability (OR: 0.48; 95% CI: 0.30 to 0.75), and cognitive impairment (OR: 0.58; 95% CI: 0.43 to 0.75). There was an independent and additive association of physical and cognitive status with antithrombotic therapy prescription.

Conclusions—

A high rate of patients affected by stroke or TIA are discharged from the hospital without antithrombotic therapy. The most important correlates of the likelihood of not receiving an antithrombotic medication were cognitive and functional status.
Correlation of Quantitative EEG in Acute Ischemic Stroke With 30-Day NIHSS Score
Authors: Finnigan Simon P. , Rose Stephen E. , Walsh Michael , Griffin Mark , Janke Andrew L. , McMahon Katie L. , Gillies Rowan , Strudwick Mark W. , Pettigrew Catharine M. , Semple James , Brown John , Brown Peter , Chalk Jonathan B.
Published: March 2004

Background and Purpose—

Magnetic resonance imaging (MRI) methods such as diffusion- (DWI) and perfusion-weighted (PWI) imaging have been widely studied as surrogate markers to monitor stroke evolution and predict clinical outcome. The utility of quantitative electroencephalography (qEEG) as such a marker in acute stroke has not been intensively studied. The aim of the present study was to correlate ischemic cortical stroke patients’ clinical outcomes with acute qEEG, DWI, and PWI data.

Materials and Methods—

DWI and PWI data were acquired from 11 patients within 7 and 16 hours after onset of symptoms. Sixty-four channel EEG data were obtained within 2 hours after the initial MRI scan and 1 hour before the second MRI scan. The acute delta change index (aDCI), a measure of the rate of change of average scalp delta power, was compared with the National Institutes of Health Stroke Scale scores (NIHSSS) at 30 days, as were MRI lesion volumes.

Results—

The aDCI was significantly correlated with the 30-day NIHSSS, as was the initial mean transit time (MTT) abnormality volume (ρ=0.80,
P
<0.01 and ρ=0.79,
P
<0.01, respectively). Modest correlations were obtained between the 15-hour DWI lesion volume and both the aDCI and 30-day NIHSSS (ρ=0.62,
P
<0.05 and ρ=0.73,
P
<0.05, respectively).

Conclusions—

In this small sample the significant correlation between 30-day NIHSSS and acute qEEG data (aDCI) was equivalent to that between the former and MTT abnormality volume. Both were greater than the modest correlation between acute DWI lesion volume and 30-day NIHSSS. These preliminary results indicate that acute qEEG data might be used to monitor and predict stroke evolution.
Decrease in Cortical Benzodiazepine Receptors in Symptomatic Patients With Leukoaraiosis
Authors: Ihara M. , Tomimoto H. , Ishizu K. , Mukai T. , Yoshida H. , Sawamoto N. , Inoue M. , Doi T. , Hashikawa K. , Konishi J. , Shibasaki H. , Fukuyama H.
Published: March 2004

Background and Purpose—

[
11
C]flumazenil (FMZ), a ligand that selectively binds to the central benzodiazepine receptor in the neuronal membrane, is useful for evaluating neuronal viability in a positron emission tomography (PET) scan. Using this ligand, we investigated whether there was a correlation between neuronal integrity in various brain structures and dementia in patients with leukoaraiosis.

Methods—

Twelve patients with extensive leukoaraiosis on magnetic resonance imaging were divided into groups of patients with or without dementia. Based on a 2-compartment, 2-parameter model that included metabolite-corrected arterial input and PET-measured cerebral radioactivity, the distribution volume of FMZ (FMZ-V
d
) was calculated in various regions of interest by nonlinear curve fitting. Additionally, tracer kinetic analysis was applied for voxel-by-voxel quantification of FMZ-V
d
, and data analysis was performed by statistical parametric mapping.

Results—

The presence of dementia was associated with a reduced FMZ-V
d
in widespread areas of the cerebral cortex, including the bilateral frontopolar and frontal/insular areas, the left temporo-occipital border areas, and the left marginal cortical areas.

Conclusions—

Differences in neuronal integrity in the cerebral cortex might determine whether patients with leukoaraiosis become symptomatic or not.
Assessing the Likelihood of Recurrence during RNA Evolution in Vitro
Authors: Lehman Niles
Published: March 2004

Recurrence is the possibility of resulting in the same endpoint multiple times when a living system is allowed to evolve repeatedly starting from a given initial point. This concept is of concern to both evolutionary theoreticians and molecular biologists who use nucleic acid selection techniques to mimic biotic and computorial processes in the test tube. Using the continuous in vitro evolution methodology, many replicate experimental evolutionary lineages with populations of catalytic RNA were performed to gain insight into the parameters that could affect recurrence. The likelihood that the same genotype will result in parallel trials of an evolution experiment in vitro depends on several factors, including the phenotype under selection, the size and composition of the initial diverse pool of nucleic acids used in the experiment, the degree of mutation possible during the experiment, the shape of the fitness landscape through which the population evolves, and the strategies used to invoke selection and to search the landscape, among others. By considering these factors, it can be predicted that recurrence is more likely when a small, wild-type-based starting pool is used with efficient selection and search strategies involving little online mutagenesis within a rugged adaptive landscape with a strong local optimum. The recurrence experiments performed here on the 150-nucleotide ligase ribozyme demonstrate that it repeatedly jumps from one peak in a fitness landscape to another, apparently hurdling a deep fitness valley. These predictions can and should be tested by additional multiple replicates of actual evolution experiments in the laboratory.
Folding Stabilizes the Evolution of Catalysts
Authors: Altmeyer Stephan , Füchslin Rudolf M. , McCaskill John S.
Published: March 2004

Sequence folding is known to determine the spatial structure and catalytic function of proteins and nucleic acids. We show here that folding also plays a key role in enhancing the evolutionary stability of the intermolecular recognition necessary for the prevalent mode of catalytic action in replication, namely, in trans, one molecule catalyzing the replication of another copy, rather than itself. This points to a novel aspect of why molecular life is structured as it is, in the context of life as it could be: folding allows limited, structurally localized recognition to be strongly sensitive to global sequence changes, facilitating the evolution of cooperative interactions. RNA secondary structure folding, for example is shown to be able to stabilize the evolution of prolonged functional sequences, using only a part of this length extension for intermolecular recognition, beyond the limits of the (cooperative) error threshold. Such folding could facilitate the evolution of polymerases in spatially heterogeneous systems. This facilitation is, in fact, vital because physical limitations prevent complete sequence-dependent discrimination for any significant-size biopolymer substrate. The influence of partial sequence recognition between biopolymer catalysts and complex substrates is investigated within a stochastic, spatially resolved evolutionary model of trans catalysis. We use an analytically tractable nonlinear master equation formulation called PRESS (McCaskill et al., Biol. Chem. 382: 1343–1363), which makes use of an extrapolation of the spatial dynamics down from infinite dimensional space, and compare the results with Monte Carlo simulations.
Development and the Baldwin Effect
Authors: Downing Keith L.
Published: March 2004

Baldwin's classic hypothesis states that behavioral plasticity can speed evolution by (a) smoothing the fitness landscape and (b) indirect genetic assimilation of acquired characteristics. This latter phase demands a strong correlation between genotype and phenotype space. But the natural world shows signs of this correlation at only a very coarse level, since the intervening developmental process greatly complicates the mapping from genetics to physiology and ethology. Hence, development appears to preclude a strong Baldwin effect. However, by adding a simple developmental mechanism to Hinton and Nowlan's classic model of the Baldwin effect, and by allowing evolution to determine the proper balance between direct and indirect mapping of genome to phenotype, this research reveals several different effects of development on the Baldwin effect, some promoting and others inhibiting. Perhaps the most interesting result is an evolved cooperation between direct blueprints and indirect developmental recipes in searching for unstructured and partially structured target patterns in large, needle-in-the-haystack fitness landscapes.
Self-Protection and Diversity in Self-Replicating Cellular Automata
Authors: Sayama Hiroki
Published: March 2004

The concept of self-protection, a capability of an organism to protect itself from exogenous attacks, is introduced into the design of artificial evolutionary systems as a possible method to create and maintain diversity in the population. Three different mechanisms of self-protection are considered and implemented on a cellular-automaton-based evolutionary system, the evoloop. Simulation results imply a positive effect of those mechanisms on diversity maintenance, especially when the self-protection is moderate so that it conserves both the attacker and the attacked. This letter briefly reports the models and the simulation results obtained using those models.
Building Artificial Life for Play
Authors: Dorin Alan
Published: March 2004

Playthings are often engineered to replicate the character of real organisms. In the past, inventors lavished great expense on their lifelike automata, their constraints being typically related to the mechanical technology they employed and the amount of time and effort they were able to commit to the enterprise. The devices that are currently produced are usually intended for the mass market. The cost of production therefore is a major concern, even though the technology is more sophisticated and highly automated than in the past. Consequently, toymakers and engineers, as well as artists, of the past and present alike have had to think abstractly about living systems in order to construct their simulacra economically. This essay examines a number of lifelike toys to discover the properties of real organisms that their designers have attempted to recreate. That we, as users of these devices, so readily recognize in them a degree of lifelikeness demonstrates the extent to which intuition may sway our intellectual reasoning about real biology. As a result, an innovative toymaker or artist is able to manipulate us to zoomorphize even the most extreme abstractions—at least momentarily—despite our rational reluctance to accept the trickery.
Lipopolysaccharide initiates a TRAF6-mediated endothelial survival signal
Authors: Wong Fred , Hull Christopher , Zhande Rachel , Law Jennifer , Karsan Aly
Published: March 2004

Similar to tumor necrosis factor (TNF), bacterial lipopolysaccharide (LPS) elicits parallel apoptotic and antiapoptotic pathways in endothelial cells. The overall result is that there is minimal endothelial cell death in response to LPS without inhibition of the cytoprotective pathway. While the TNF-induced death and survival pathways have been relatively well elucidated, much remains to be learned about LPS signaling events in this regard. It is known that the transcription factor nuclear factor-κB (NF-κB) provides a critical cell survival signal in response to TNF, but is not an essential component of the LPS-induced survival pathway. The TNF receptor-associated factor 6 (TRAF6) is a major effector of multiple LPS-induced signals, including a c-Jun N-terminal kinase (JNK)-mediated apoptotic response. In this report we demonstrate that following LPS stimulation, TRAF6 also transmits an important endothelial cell survival signal in a situation of complete NF-κB blockade. In response to LPS, TRAF6 activates the phosphatidylinositol 3′-kinase (PI3K)/Akt pathway, but not ERK1/2 mitogen-activated protein kinases (MAPKs) in endothelial cells. Activation of PI3K signals a critical antiapoptotic pathway in response to LPS in endothelial cells, whereas ERK1/2 does not. Thus TRAF6 acts as a bifurcation point of the LPS-initiated death and survival signals in endothelial cells. (Blood. 2004;103:4520-4526)
Preventing restimulation of memory B cells in hemophilia A: a potential new strategy for the treatment of antibody-dependent immune disorders
Authors: Hausl Christina , Ahmad Rafi U. , Schwarz Hans Peter , Muchitsch Eva M. , Turecek Peter L. , Dorner Friedrich , Reipert Birgit M.
Published: March 2004

Memory B cells are responsible for the rapidly emerging antibody response after antigen reexposure. The signals required for the restimulation of memory B cells have not been fully explained. We used a murine model of anti–factor VIII (FVIII) antibody responses in hemophilia A to study the requirements for the restimulation of FVIII-specific memory B cells and their differentiation into anti-FVIII antibody-producing cells. We were particularly interested in the significance of activated T cells and costimulatory interactions. Our results indicate that the restimulation of FVIII-specific memory B cells is strictly dependent on interactions with activated T cells. These activated T cells can be specific for either FVIII or third-party antigens. Restimulation by T cells specific for third-party antigens requires the presence of FVIII, indicating that signals induced by B-cell receptor (BCR) triggering and by interactions with activated T cells are important. The blockade of B7-1 or B7-2 as well as the blockade of CD40L inhibits the restimulation and differentiation of FVIII-specific memory B cells in vitro and in vivo. The interference with inducible costimulator–inducible costimulator ligand (ICOS-ICOSL) interactions, however, does not cause any modulation. As expected, the production of anti-FVIII antibodies by plasma cells is not dependent on any of the costimulatory interactions tested.
Recombinant prolylcarboxypeptidase activates plasma prekallikrein
Authors: Shariat-Madar Zia , Mahdi Fakhri , Schmaier Alvin H.
Published: March 2004

The serine protease prolylcarboxypeptidase (PRCP), isolated from human umbilical vein endothelial cells (HUVECs), is a plasma prekallikrein (PK) activator. PRCP cDNA was cloned in pMT/BIP/V5-HIS-C, transfected into Schneider insect (S2) cells, and purified from serum-free media. Full-length recombinant PRCP (rPRCP) activates PK when bound to high-molecular-weight kininogen (HK). Recombinant PRCP is inhibited by leupeptin, angiotensin II, bradykinin, anti-PRCP, diisopropyl-fluorophosphonate (DFP), phenylmethylsulfonyl fluoride (PMSF), and Z-Pro-Proaldehyde-dimethyl acetate, but not by 1 mM EDTA (ethylenediaminetetraacetic acid), bradykinin 1-5, or angiotensin 1-7. Corn trypsin inhibitor binds to prekallikrein to prevent rPRCP activation, but it does not directly inhibit the active site of either enzyme. Unlike factor XIIa, the ability of rPRCP to activate PK is blocked by angiotensin II, not by neutralizing antibody to factor XIIa. PRCP antigen is detected on HUVEC membranes using flow cytometry and laser scanning confocal microscopy. PRCP antigen does not colocalize with LAMP1 on nonpermeabilized HUVECs, but it partially colocalizes in permeabilized cells. PRCP colocalizes with all the HK receptors, gC1qR, uPAR, and cytokeratin 1 antigen, on nonpermeabilized HUVECs. PRCP activity and antigen expression on cultured HUVECs are blocked by a morpholino antisense oligonucleotide. These investigations indicate that rPRCP is functionally identical to isolated HUVEC PRCP and is a major HUVEC membrane-expressed, PK-activating enzyme detected in the intravascular compartment. (Blood. 2004;103:4554-4561)
Activation of the MAP kinase pathway by c-Kit is PI-3 kinase dependent in hematopoietic progenitor/stem cell lines
Authors: Wandzioch Ewa , Edling Charlotte E. , Palmer Ruth H. , Carlsson Leif , Hallberg Bengt
Published: March 2004

The Steel factor (SF) and its receptor c-Kit play a critical role for various cell types at different levels in the hematopoietic hierarchy. Whether similar or distinct signaling pathways are used upon c-Kit activation in different cell types within the hematopoietic hierarchy is not known. To study c-Kit signaling pathways in the hematopoietic system we have compared c-Kit downstream signaling events in SF-dependent hematopoietic stem cell (HSC)–like cell lines to those of mast cells. Both Erk and protein kinase B (PKB)/Akt are activated by ligand-induced activation of the c-Kit receptor in the HSC-like cell lines. Surprisingly, phosphoinositide-3 (PI-3) kinase inhibitors block not only PKB/Akt activation but also activation of Raf and Erk. SF-induced activation of Ras is not affected by inhibition of PI-3 kinase. In mast cells and other more committed hematopoietic precursors, the activation of Erk by SF is not PI-3 kinase dependent. Our results suggest that a molecular signaling switch occurs during differentiation in the hematopoietic system whereby immature hematopoietic progenitor/stem cells use a PI-3 kinase–sensitive pathway in the activation of both Erk and PKB/Akt, which is then switched upon differentiation to the more commonly described PI-3 kinase–independent mitogen-activated protein (MAP) kinase pathway.
Impaired natural and CD16-mediated NK cell cytotoxicity in patients with WAS and XLT: ability of IL-2 to correct NK cell functional defect
Authors: Gismondi Angela , Cifaldi Loredana , Mazza Cinzia , Giliani Silvia , Parolini Silvia , Morrone Stefania , Jacobelli Jordan , Bandiera Elisabetta , Notarangelo Luigi , Santoni Angela
Published: March 2004

In this study we show that Wiskott-Aldrich syndrome protein (WASp), a critical regulator of actin cytoskeleton that belongs to the Scar/WAVE family, plays a crucial role in the control of natural killer (NK) cell cytotoxicity. Analysis of NK cell numbers and cytotoxic activity in patients carrying different mutations in the WASP coding gene indicated that although the percentage of NK cells was normal or increased, natural cytotoxicity and antibody-mediated NK cell cytotoxicity were inhibited in all patients with the classical WAS phenotype and in most patients carrying mutations associated with the X-linked thrombocytopenia (XLT) phenotype. The inhibition of NK cell-mediated cytotoxicity was associated with the reduced ability of WAS and XLT NK cells to form conjugates with susceptible target cells and to accumulate F-actin on binding. Treatment with interleukin-2 (IL-2) corrected the functional defects of NK cells by affecting their ability to bind to sensitive target cells and to accumulate F-actin. In addition, we provide information on the molecular mechanisms that control WASp function, demonstrating that binding of NK cells to sensitive targets or triggering through CD16 by means of reverse antibody-dependent cellular cytotoxicity (ADCC) rapidly activates Cdc42. We also found that WASp undergoes tyrosine phosphorylation upon CD16 or β2-integrin engagement on NK cells. (Blood. 2004;104:436-443)
VEGF receptor phosphorylation status and apoptosis is modulated by a green tea component, epigallocatechin-3-gallate (EGCG), in B-cell chronic lymphocytic leukemia
Authors: Lee Yean K. , Bone Nancy D. , Strege Ann K. , Shanafelt Tait D. , Jelinek Diane F. , Kay Neil E.
Published: March 2004

We recently reported that chronic lymphocytic leukemia (CLL) cells synthesize and release vascular endothelial growth factor (VEGF) under normoxic and hypoxic conditions. CLL B cells also express VEGF membrane receptors (VEGF-R1 and VEGF-R2), suggesting that they use VEGF as a survival factor. To assess the mechanism of apoptosis resistance related to VEGF, we determined the impact of VEGF on CLL B cells, and we studied the impact of epigallocatechin-3-gallate (EGCG), a known receptor tyrosine kinase (RTK) inhibitor, on VEGF receptor status and viability of CLL B cells. VEGF165 significantly increased apoptotic resistance of CLL B cells, and immunoblotting revealed that VEGF-R1 and VEGF-R2 are spontaneously phosphorylated on CLL B cells. EGCG significantly increased apoptosis/cell death in 8 of 10 CLL samples measured by annexin V/propidium iodide (PI) staining. The increase in annexin V/PI staining was accompanied by caspase-3 activation and poly–adenosine diphosphate ribose polymerase (PARP) cleavage at low concentrations of EGCG (3 μg/mL). Moreover, EGCG suppressed the proteins B-cell leukemia/lymphoma-2 protein (Bcl-2), X-linked inhibitor of apoptosis protein (XIAP), and myeloid cell leukemia-1 (Mcl-1) in CLL B cells. Finally, EGCG (3-25 μg/mL) suppressed VEGF-R1 and VEGF-R2 phosphorylation, albeit incompletely. Thus, these results suggest that VEGF signaling regulates survival signals in CLL cells and that interruption of this autocrine pathway results in caspase activation and subsequent leukemic cell death.
Value of sequential monitoring of left ventricular ejection fraction in the management of thalassemia major
Authors: Davis Bernard A. , O'Sullivan Caoimhe , Jarritt Peter H. , Porter John B.
Published: March 2004

Regular monitoring of left ventricular ejection fraction (LVEF) for thalassemia major is widely practiced, but its informativeness for iron chelation treatment is unclear. Eighty-one patients with thalassemia major but no history of cardiac disease underwent quantitative annual LVEF monitoring by radionuclide ventriculography for a median of 6.0 years (interquartile range, 2-12 years). Intraobserver and interobserver reproducibility for LVEF determination were both less than 3%. LVEF values before and after transfusion did not differ, and exercise stress testing did not reliably expose underlying cardiomyopathy. An absolute LVEF of less than 45% or a decrease of more than 10 percentage units was significantly associated with subsequent development of symptomatic cardiac disease (P < .001) and death (P = .001), with a median interval between the first abnormal LVEF findings and the development of symptomatic heart disease of 3.5 years, allowing time for intervention. In 34 patients in whom LVEF was less than 45% or decreased by more than 10 percentage units, intensified chelation therapy was recommended (21 with subcutaneous and 13 with intravenous deferoxamine). All 27 patients who complied with intensification survived, whereas the 7 who did not comply died (P < .0001). The Kaplan-Meier estimate of survival beyond 40 years of age for all 81 patients is 83%. Sequential quantitative monitoring of LVEF is valuable for assessing cardiac risk and for identifying patients with thalassemia major who require intensified chelation therapy.
T-cell lymphoma as a model for the use of histone deacetylase inhibitors in cancer therapy: impact of depsipeptide on molecular markers, therapeutic targets, and mechanisms of resistance
Authors: Piekarz Richard L. , Robey Robert W. , Zhan Zhirong , Kayastha Ganesh , Sayah Anousheh , Abdeldaim Amina H. , Torrico Sonia , Bates Susan E.
Published: March 2004

Depsipeptide (FK228) is a novel histone deacetylase inhibitor currently in clinical trials and the first to demonstrate clinical activity in patients. Responses have been observed in patients with T-cell lymphomas, despite prior treatment with multiple chemotherapeutic agents. To better understand the effects of histone deacetylase inhibitors on T-cell lymphoma, the human T-cell lymphoma cell line HUT78 was tested for sensitivity and molecular response to depsipeptide. Treatment with depsipeptide, as well as other histone deacetylase inhibitors, caused induction of histone acetylation, induction of p21 expression, and substantial apoptosis without significant cell cycle arrest. Treatment with the caspase inhibitor z-VAD-fmk significantly inhibited depsipeptide-induced apoptosis, enabling detection of cell cycle arrest. Treatment with depsipeptide increased expression of the interleukin-2 (IL-2) receptor, and combination with the IL-2 toxin conjugate denileukin diftitox resulted in more than additive toxicity. Cells selected for resistance to depsipeptide overexpressed the multidrug resistance pump, P-glycoprotein (Pgp). However, cells selected for resistance to depsipeptide in the presence of a Pgp inhibitor had a Pgp-independent mechanism of resistance. These studies confirm the activity of depsipeptide in a T-cell lymphoma model and suggest a general sensitivity of T-cell lymphoma to histone deacetylase inhibitors, an emerging new class of anticancer agents. (Blood. 2004;103:4636-4643)
Homeostatic chemokines drive migration of malignant B cells in patients with non-Hodgkin lymphomas
Authors: Trentin Livio , Cabrelle Anna , Facco Monica , Carollo Davide , Miorin Marta , Tosoni Alicia , Pizzo Paola , Binotto Gianni , Nicolardi Linda , Zambello Renato , Adami Fausto , Agostini Carlo , Semenzato Gianpietro
Published: March 2004

This study investigated the role of several chemokines and their receptors on malignant B lymphocytes recovered from 13 patients with chronic lymphocytic leukemia (CLL), 9 with hairy cell leukemia (HCL), 5 with mantle cell lymphoma (MCL), 5 with marginal zone B-cell lymphoma (MZL), 6 with small lymphocytic lymphoma (SLL), and 5 with follicular cell lymphoma (FCL). Flow cytometry analysis demonstrated that CXCR4 and CXCR5 were expressed on all malignant and normal B cells. Considering CC receptors, CCR1 was expressed in 70% of patients with CLL and 40% of those with HCL but was lacking in patients with MCL, MZL, SLL, and normal B cells. CCR2 showed a heterogeneous pattern of expression. CCR3 was found in almost all patients with CLL and in the majority of those with HCL, whereas it was usually lacking in patients with MZL and SLL and in healthy subjects. CCR5 was expressed in patients with HCL and MCL. Migration assays showed that different chemokines, mainly CXCL12 and CXCL13, are able to trigger migration of malignant B lymphocytes. Some of these chemokines induce calcium mobilization. These data indicate that different patterns of chemokine receptor expression identify different malignant B-cell subsets and that these receptors are functional and might play a role in malignant B-cell circulation. (Blood. 2004;104:502-508)
The pu.1 promoter drives myeloid gene expression in zebrafish
Authors: Hsu Karl , Traver David , Kutok Jeffery L. , Hagen Andreas , Liu Ting-Xi , Paw Barry H. , Rhodes Jennifer , Berman Jason N. , Zon Leonard I. , Kanki John P. , Look A. Thomas
Published: March 2004

PU.1 is a member of the Ets family of transcription factors and plays an essential role in the development of both myeloid and lymphoid cells. To examine zebrafish pu.1 (zpu.1) expression in subpopulations of blood cells during zebrafish development, we linked a 9-kb zebrafish genomic fragment upstream of the zpu.1 initiator codon to green fluorescent protein (GFP) and microinjected this construct to generate stable transgenic lines. GFP-positive fluorescent myeloid precursors were observed migrating from the anterolateral mesoderm in living embryos from 16 to 28 hours after fertilization (hpf) in a pattern that overlaps the expression pattern of endogenous zpu.1 mRNA. Analysis of larval histologic sections revealed GFP-expressing hematopoietic cells in the developing zebrafish kidney. Flow cytometric analysis of cells from adult whole kidney marrow revealed 2 discrete subpopulations of GFP-positive cells, which after cell sorting exhibited either myeloid or early lymphoid morphology. Thus, the zebrafish zpu.1 promoter fragment used here is capable of driving reporter gene expression in subsets of embryonic and adult hematopoietic cells. These transgenic lines will be useful to dissect the cellular and molecular control of myeloid cell differentiation, and this promoter fragment may prove useful in the development of zebrafish models of acute myeloid leukemia.
Anemia, thrombocytopenia, leukocytosis, extramedullary hematopoiesis, and impaired progenitor function in Pten+/-SHIP-/- mice: a novel model of myelodysplasia
Authors: Moody Jennifer L. , Xu Lixin , Helgason Cheryl D. , Jirik Frank R.
Published: March 2004

The myeloproliferative disorder of mice lacking the Src homology 2 (SH2)-containing 5′ phosphoinositol phosphatase, SHIP, underscores the need for closely regulating phosphatidylinositol 3-kinase (PI3K) pathway activity, and hence levels of phosphatidylinositol species during hematopoiesis. The role of the 3′ phosphoinositol phosphatase Pten in this process is less clear, as its absence leads to embryonic lethality. Despite Pten heterozygosity being associated with a lymphoproliferative disorder, we found no evidence of a hematopoietic defect in Pten+/- mice. Since SHIP shares the same substrate (PIP3) with Pten, we hypothesized that the former might compensate for Pten haploinsufficiency in the marrow. Thus, we examined the effect of Pten heterozygosity in SHIP-/- mice, predicting that further dysregulation of PIP3 metabolism would exacerbate the pheno-type of the latter. Indeed, compared with SHIP-/- mice, Pten+/-SHIP-/- animals developed a myelodysplastic phenotype characterized by increased hepatosplenomegaly, extramedullary hematopoiesis, anemia, and thrombocytopenia. Consistent with a marrow defect, clonogenic assays demonstrated reductions in committed myeloid and megakaryocytic progenitors in these animals. Providing further evidence of a Pten+/-SHIP-/- progenitor abnormality, reconstitution of irradiated mice with marrows from these mice led to a marked defect in short-term repopulation of peripheral blood by donor cells. These studies suggest that the regulation of the levels and/or ratios of PI3K-derived phosphoinositol species by these 2 phosphatases is critical to normal hematopoiesis. (Blood. 2004;103:4503-4510)