bluuebunny/crossref_metadata_2025 huggingface dataset:
Lepr
db
Diabetic Mouse Bone Marrow Cells Inhibit Skin Wound Vascularization but Promote Wound Healing
Authors: Stepanovic Vesna , Awad Ola , Jiao Chunhua , Dunnwald Martine , Schatteman Gina C.
Published: May 2003

Bone marrow stem cells participate in tissue repair processes and may have roles in skin wound repair. Diabetes is characterized by delayed and poor wound healing, and type 1 diabetes seems to lead to stem cell dysfunction. Hence, stem cell dysfunction could contribute to poor healing, and stem cell–based therapies may be efficacious in diabetic wounds. We investigated the potential of exogenous stem cells to promote skin healing and possible effects of type 2 diabetes on stem cell function. Mouse bone marrow cells from nondiabetic and diabetic mice were enriched for putative stem cells and injected under skin wounds of nondiabetic or type 2 diabetic Lepr
db
mice. Using histology and morphometry, vascularization and healing in treated and untreated mice were analyzed. We anticipated a correlation between improved wound healing and vascularization, because therapies that increase tissue vascularization tend to enhance wound healing. Our data indicate that exogenous nondiabetic bone marrow–derived cells increase vascularization and improve wound healing in Lepr
db
mice but have little effect on nondiabetic controls. In contrast, Lepr
db
-derived marrow cells inhibit vascularization but promote wound healing in Lepr
db
mice. Thus, adult stem cell function may be impaired by type 2 diabetes; the ability to promote vascularization and wound healing are distinct functions of bone marrow cells; and neovascularization and wound healing may not be tightly coupled. Additionally, we observed little incorporation of injected cells into wound structures, suggesting that improved healing is mediated through mechanisms other than direct differentiation and incorporation of the cells.
Impulse Propagation in Synthetic Strands of Neonatal Cardiac Myocytes With Genetically Reduced Levels of Connexin43
Authors: Thomas Stuart P. , Kucera Jan P. , Bircher-Lehmann Lilly , Rudy Yoram , Saffitz Jeffrey E. , Kléber André G.
Published: May 2003

Connexin43 (Cx43) is a major determinant of the electrical properties of the myocardium. Closure of gap junctions causes rapid slowing of propagation velocity (θ), but the precise effect of a reduction in Cx43 levels due to genetic manipulation has only partially been clarified. In this study, morphological and electrical properties of synthetic strands of cultured neonatal ventricular myocytes from Cx43
+/+
(wild type, WT) and Cx
+/−
(heterozygote, HZ) mice were compared. Quantitative immunofluorescence analysis of Cx43 demonstrated a 43% reduction of Cx43 expression in the HZ versus WT mice. Cell dimensions, connectivity, and alignment were independent of genotype. Measurement of electrical properties by microelectrodes and optical mapping showed no differences in action potential amplitude or minimum diastolic potential between WT and HZ. However, maximal upstroke velocity of the transmembrane action potential, dV/dt
max
, was increased and action potential duration was reduced in HZ versus WT. θ was similar in the two genotypes. Computer simulation of propagation and dV/dt
max
showed a relatively small dependence of θ on gap junction coupling, thus explaining the lack of observed differences in θ between WT and HZ. Importantly, the simulations suggested that the difference in dV/dt
max
is due to an upregulation of
I
Na
in HZ versus WT. Thus, heterozygote-null mutation of Cx43 produces a complex electrical phenotype in synthetic strands that is characterized by both changes in ion channel function and cell-to-cell coupling. The lack of changes in θ in this tissue is explained by the dominating role of myoplasmic resistance and the compensatory increase of dV/dt
max
.
Physiological Coupling of Donor and Host Cardiomyocytes After Cellular Transplantation
Authors: Rubart Michael , Pasumarthi Kishore B.S. , Nakajima Hidehiro , Soonpaa Mark H. , Nakajima Hisako O. , Field Loren J.
Published: May 2003

Cellular transplantation has emerged as a potential approach to treat diseased hearts. Although cell transplantation can affect global heart function, it is not known if this results directly via functional integration of donor myocytes or indirectly via enhanced revascularization and/or altered postinjury remodeling. To determine the degree to which donor cardiomyocytes are able to functionally integrate with the host myocardium, fetal transgenic cardiomyocytes expressing enhanced green fluorescent protein were transplanted into the hearts of nontransgenic adult mice. Two-photon molecular excitation laser scanning microscopy was then used to simultaneously image cellular calcium transients in donor and host cells within the intact recipient hearts. Calcium transients in the donor cardiomyocytes were synchronous with and had kinetics indistinguishable from those of neighboring host cardiomyocytes. These results strongly suggest that donor cardiomyocytes functionally couple with host cardiomyocytes and support the notion that transplanted cardiomyocytes can form a functional syncytium with the host myocardium.
Adenovirus-Mediated Gene Transfer of Fibroblast Growth Factor-2 Increases BrdU-Positive Cells After Forebrain Ischemia in Gerbils
Authors: Matsuoka Norihiro , Nozaki Kazuhiko , Takagi Yasushi , Nishimura Masaki , Hayashi Junya , Miyatake Shin-Ichi , Hashimoto Nobuo
Published: May 2003

Background and Purpose—

Progenitor cells continue to generate neurons in the adult mammalian brain, and cerebral ischemia induces neurogenesis. We examined the efficacy of the intraventricular injection of a recombinant adenovirus-expressing fibroblast growth factor-2 (FGF-2) (AxCAMAssbFGF) on neurogenesis in both normal and ischemic brains.

Methods—

We used a gerbil model of transient global ischemia and counted the number of BrdU-positive cells after injection of AxCAMAssbFGF into the brain with or without ischemia.

Results—

Intraventricular AxCAMAssbFGF produced robust FGF-2 protein increases in diverse regions of the brain and markedly increased FGF-2 concentrations in cerebrospinal fluid 2 days after administration and evoked significant proliferation of BrdU-positive cells not only in the subventricular zone and dentate gyrus of the hippocampus but also in the cerebral cortex, and some BrdU-positive cells differentiated into neurons. Continuous intraventricular infusion of FGF-2 protein increased FGF-2 concentration in cerebrospinal fluid but not in brain tissues and produced BrdU-positive cell proliferation only in the subventricular zone of the lateral ventricle.

Conclusions—

Adenovirally mediated transfer of the FGF-2 gene promoted progenitor cell proliferation more efficiently in widespread regions of the brain after transient global ischemia than continuous intraventricular infusion of FGF-2 protein.
Neuroprotection in Transient Focal Cerebral Ischemia by Combination Drug Therapy and Mild Hypothermia
Authors: Zausinger Stefan , Westermaier Thomas , Plesnila Nikolaus , Steiger Hans-Jakob , Schmid-Elsaesser Robert
Published: May 2003

Background and Purpose—

A combined therapeutic approach has been advocated repeatedly for treatment of focal cerebral ischemia. A clinical example of combined therapy is administration of nimodipine, mannitol, dexamethasone, and barbiturates during temporary occlusion of a cerebral artery in neurovascular surgery. We have recently demonstrated outstanding neuroprotective properties of a combination therapy with magnesium (calcium antagonist and glutamate antagonist), tirilazad (antioxidant), and mild hypothermia (MTH). In this study we compared this treatment strategy with the customary treatment options in a rat model of transient focal cerebral ischemia.

Methods—

Sprague-Dawley rats (n=120) were subjected to 90 minutes of middle cerebral artery occlusion by an intraluminal filament (n=10 per group). In experiment 1, the customary treatment options (nimodipine, mannitol, dexamethasone, methohexital) were evaluated as monotherapy and in combination. In experiment 2, the customary and the new combination therapy (MTH) were compared. Mild hypothermia (33°C) was maintained for 2 hours. Neurological examinations were performed daily. Infarct size was assessed histologically after 7 days.

Results—

In experiment 1, infarct volume was attenuated by 34% at maximum, with mannitol and methohexital being the most effective drugs given as monotherapy. In experiment 2, combined administration of the customary treatment options had no additive effect (infarct volume −36%). Combination therapy with MTH reduced total infarction by 73% and almost completely abolished cortical infarction (−91%). None of the animals of this group had any residual neurological deficit at the end of the observation period (
P
<0.05 versus all other groups).

Conclusions—

The efficacy of drugs (monotherapy or in combination) most commonly used for neuroprotection during neurovascular surgery is limited. The newly proposed combination therapy (magnesium, tirilazad, and mild hypothermia), which is based on pathophysiological considerations, seems to be a promising alternative for neuroprotection in cerebrovascular surgery.
Expanded Modes of Tissue Plasminogen Activator Delivery in a Comprehensive Stroke Center Increases Regional Acute Stroke Interventions
Authors: Rymer Marilyn M. , Thurtchley Duane , Summers Deborah
Published: May 2003

Background and Purpose—

We sought to evaluate whether a comprehensive stroke center could work with regional hospitals to increase the use of tissue plasminogen activator (tPA) in acute stroke.

Methods—

In 30 months, 142 patients seen at the Mid America Brain and Stroke Institute received tPA. Site of presentation, protocol selection, and outcomes were analyzed.

Results—

We found that 18.2% (142 of 781) of all ischemic strokes received tPA. Of those, 70% (99 of 142) were transferred from hospitals within 100 miles of Kansas City (Mo). Mortality rate was 12.7% (18 of 142). Symptomatic hemorrhage rate was 9.2%.

Conclusions—

A comprehensive stroke center can serve as a hub for a regional network and increase the number of stroke interventions with acceptable outcomes.
Pioglitazone Improves Insulin Sensitivity Among Nondiabetic Patients With a Recent Transient Ischemic Attack or Ischemic Stroke
Authors: Kernan Walter N. , Inzucchi Silvio E. , Viscoli Catherine M. , Brass Lawrence M. , Bravata Dawn M. , Shulman Gerald I. , McVeety James C. , Horwitz Ralph I.
Published: May 2003

Background and Purpose—

The aim of this study was to determine the effectiveness of pioglitazone compared with placebo for improving insulin sensitivity among nondiabetic patients with a recent transient ischemic attack (TIA) or nondisabling ischemic stroke and impaired insulin sensitivity.

Methods—

Eligible subjects were men and women >45 years of age who had no history of diabetes, fasting glucose <7.0 mmol/L, and impaired insulin sensitivity according to an index calculated from insulin and glucose blood levels obtained during an oral glucose tolerance test. Eligible subjects were randomized to pioglitazone 45 mg/d or placebo. After 3 months of therapy, the glucose tolerance test was repeated.

Results—

Between July 2000 and June 2001, we performed oral glucose tolerance tests on 75 patients with no history of diabetes, among whom 36 (50%) were found to have impaired insulin sensitivity and fasting glucose <7.0 mmol/L. Among these 36, 20 consented to the trial. Patients assigned to pioglitazone (n=10) and placebo (n=10) were similar in insulin sensitivity, age, obesity, and index event (stroke compared with TIA), but patients assigned to pioglitazone were less likely to be male (4 compared with 9). The mean proportional increase in insulin sensitivity was 62% among patients assigned to pioglitazone compared with a −1% decline among patients assigned to placebo (
P
=0.0006). Mean C-reactive protein concentration declined from 0.30 to 0.20 mg/L among patients assigned to pioglitazone and increased from 0.41 to 0.45 mg/L among patients assigned to placebo (
P
=0.06 for comparison of mean change).

Conclusions—

Pioglitazone is effective for improving insulin sensitivity among patients with recent TIA or stroke and impaired insulin sensitivity.
Effect of Hypertonic Saline on Cerebral Blood Flow in Poor-Grade Patients With Subarachnoid Hemorrhage
Authors: Tseng Ming-Yuan , Al-Rawi Pippa G. , Pickard John D. , Rasulo Frank A. , Kirkpatrick Peter J.
Published: May 2003

Background and Purpose—

The goal of this study was to examine the effects of hypertonic saline on cerebral blood flow (CBF) in poor-grade patients with subarachnoid hemorrhage.

Methods—

We administered 23.5% hypertonic saline (2 mL/kg IV) 1 time to 10 patients, 2 times to 7 patients, and 3 times to 1 patient. All patients had transcranial Doppler (TCD), intracranial pressure (ICP) monitoring, and analysis of serum sodium and osmolality; 6 had xenon CT (XeCT). Data were used to characterize the changes in CBF, cerebral vascular resistance (CVR), ICP, cerebral perfusion pressure (CPP), and potential rheological mechanisms of action.

Results—

In the first treatment episode, CPP increased 26.8% (
P
=0.0003, at 28.3 minutes) from a rise in mean arterial blood pressure (ABP) of 10.5% (
P
=0.02, at 22.2 minutes) and a fall in ICP (−74.7%,
P
=0.002, at 60.0 minutes). Flow velocity (FV) of the middle cerebral artery increased 70.8% (
P
=0.00005, at 20.0 minutes), resulting in a corresponding fall in estimated CVR (−26.6%,
P
=0.01, at 16.3 minutes). The half-lives of effects on ABP, CPP, ICP, FV, and estimated CVR were 20.0, 53.6, 139.1, 42.7, and 27.1 minutes, respectively. In the second treatment episode, all these parameters had the same response except estimated CVR, which did not reach statistical significance. XeCT confirmed the increase in CBF (22.9%,
P
=0.02) without regional differences. A fall in CBF after hypertonic saline was identified in only a single region of interest in a patient in whom baseline flow was low but not infarcted. Serum sodium rose by 11.4 and 8.8 mmol/L, and osmolality rose by 26.7 and 16.3 mosm/L in the first and second treatment episodes, respectively. Hemoglobin decreased by 0.7 and 0.6 g/L and hematocrit decreased by 1.9% and 2.4% in the first and second treatment episodes, respectively.

Conclusions—

We found that 23.5% hypertonic saline increases CBF in poor-grade patients with subarachnoid hemorrhage. These effects are associated with improved indexes of blood rheology. Potential therapeutic benefits are discussed.
Comparison of P
2
Receptor Subtypes Producing Dilation in Rat Intracerebral Arterioles
Authors: Horiuchi Tetsuyoshi , Dietrich Hans H. , Hongo Kazuhiro , Dacey Ralph G.
Published: May 2003

Background and Purpose—

P
2
receptors are important regulators of cerebrovascular tone. However, there is functional heterogeneity of P
2Y
receptors along the vascular tree, and the functionality of P
2Y
receptors in small arterioles has not been studied in detail. We investigated the effects of activating P
2Y1
and P
2Y2
receptors and their underlying dilator mechanisms in rat intracerebral arterioles.

Methods—

We used computer-aided videomicroscopy to measure diameter responses from isolated and pressurized rat penetrating arterioles (39.9±1.2 μm) to the natural P
2
receptor agonist ATP in addition to ADP-β-S (P
2Y1
-selective) and ATP-γ-S (P
2Y2
-selective) and inhibitors of signaling pathways.

Results—

Extraluminal application of ATP-γ-S and ADP-β-S initiated a biphasic response (initial constriction followed by the secondary dilation) similar to ATP-induced responses. Pyridoxal phosphate-6-azophenyl-2′,4′-disulphonic acid (0.1 mmol/L; a P
2Y1
receptor antagonist) blocked ADP-β-S- but not ATP-γ-S-induced dilation and affected the ATP-mediated dilation at low concentrations.

N
ω

-Monomethyl-
l
-arginine partially inhibited the dilation of ATP and ADP-β-S but not ATP-γ-S. High K
+
saline suppressed the dilation of all agonists. Indomethacin had no effect.

Conclusions—

Both P
2Y1
and P
2Y2
receptors are functionally present in cerebral arterioles. ATP stimulates P
2Y1
receptors at low concentrations, while high concentrations of ATP activate P
2Y2
in addition to P
2Y1
receptors. Nitric oxide is involved in P
2Y1
but not P
2Y2
receptor activation. Potassium channels play an important role in the regulation of P
2Y
receptor-mediated dilation.
Oral Anticoagulation in Patients After Cerebral Ischemia of Arterial Origin and Risk of Intracranial Hemorrhage
Authors:   ESPRIT
Published: May 2003

Background and Purpose—

In the recently published Warfarin Aspirin Recurrent Stroke Study (WARSS), a low-intensity anticoagulation regimen was used because of safety concerns. Such concerns are corroborated by the results of the Stroke Prevention in Reversible Ischemia Trial (SPIRIT), which was stopped early because of a high incidence of intracranial hemorrhage with a target international normalized ratio (INR) of 3.0 to 4.5. In the ongoing European/Australasian Stroke Prevention in Reversible Ischaemia Trial (ESPRIT), an intermediate anticoagulation regimen (INR 2.0 to 3.0) is used.

Methods—

We performed an interim analysis of the incidence of intracranial hemorrhage in ESPRIT.

Results—

Thus far the overall rate of intracranial hemorrhage is 0.31% (95% CI, 0.18% to 0.52%) per year and 1.21% if all of these were in the anticoagulation group.

Conclusions—

We conclude that anticoagulation with achieved INR of 2.0 to 3.0 is reasonably safe in patients with cerebral ischemia of arterial origin.
Thrombolytic Therapy With Recombinant Tissue Plasminogen Activator for Acute Ischemic Stroke
Authors: Wardlaw J.M. , Sandercock P.A.G. , Berge E.
Published: May 2003

Background and Purpose—

Recombinant tissue plasminogen activator (rtPA; Actilyse) is not as widely used in clinical practice as it could be. Have new data since 1995 strengthened the evidence sufficiently to justify more widespread use of rtPA?

Methods—

We performed a sequential year-to-year cumulative meta-analysis of randomized controlled trials of rtPA in acute ischemic stroke.

Results—

Although the amount of data has doubled since 1995, effect estimates for key outcomes remain imprecise, and significant between-trial heterogeneity persists. In the most recent analysis, rtPA up to 6 hours after stroke yielded 55 fewer dead or dependent people per 1000 treated (95% CI, 18 to 92) despite some risk (nonsignificant excess of 19 deaths per 1000 patients treated; 95% CI, 6 fewer to 48 more). Severity of stroke, patient age, and aspirin use were possible sources of heterogeneity.

Conclusions—

Despite doubling of the data since 1995, the magnitude of risks and benefits with rtPA remains imprecise. This gap in knowledge may be hindering clinical use of rtPA and can be filled only by new trials designed to address these specific issues.
Precision of Exocentric Distance Judgments in Desktop and Cube Presentation
Authors: Wartenberg Constanze , Wiborg Per
Published: May 2003

Accuracy of space perception and distance estimation in virtual environments is an important precondition for the reliable use of virtual techniques in the design of products, workplaces, architecture, and production systems. The present study compares the accuracy of exocentric 1 distance estimations that a static perceiver achieves with two virtual presentation techniques: a desktop and an immersive cube presentation. Estimation accuracy in a physical mock-up is used as a point of reference. Subjects estimated exocentric distances in detailed models of a workplace previously unknown to them. All distances to be judged were located in the subjects' personal space (less than 1.5 m from the subject).

Major differences between the two virtual presentation modes are that stereo information is available in the cube but not in desktop environment, and that, in the cube, changes in perspective are achieved by actually moving inside the cube instead of using a mouse. Furthermore, the cube provides a wider absolute field of view than the desktop environment.

The experiment showed advantages of the cube over desktop presentation when estimating exocentric distances in “personal space” from a static position. The magnitude of distance estimation errors was significantly higher in the desktop than in the cube environment. However, estimation errors tended to be overestimations in the cube presentation, whereas over- and underestimation occurred with equal frequency in the desktop environment.

In the discussion it is argued that the higher estimation accuracy in the cube environment may mainly be due to the availability of stereoscopic depth cues. According to Cutting (1997), these cues are especially relevant for spatial perception in “personal space.”

1 The term exocentric distance is used for distances between two points external to the perceiver indicating (for example) interobject distances or distances colinear with the side length of an object. These distances are to be distinguished from egocentric distances, those distances between the perceiver and one point in the environment (Waller, 1999).
The “Botafumeiro” VR: Virtual Reality in the Liturgy of the Middle Ages
Authors: Flores Julián , Ferro Jose M. , Taboada José A. , Arias Juan E.
Published: May 2003

Santiago de Compostela, a city in Galicia, in the northwest of Spain, has been a famous Christian pilgrimage site since the Middle Ages. One distinctive element of the liturgy of the Cathedral of Santiago de Compostela is the use of a giant censer “O Botafumeiro.” It is tied to a rope that hangs from the center of the transept of the arms of the cathedral, and it is pulled through the transept of the cathedral, basically describing a pendulum movement. A team of men called “Os Tiraboleiros” pulls the supporting rope in a pumping cycle to increase the energy of the system, and therefore the angle of oscillation. This pumping process transforms the pendulum motion into a variable-length pendulum motion. We present the specific case of the virtual simulation of the liturgy of the Botafumeiro by VR techniques. The simulation allows users to play the role of the Tiraboleiros as a part of this old tradition. We present the system architecture, the design of the visualization system, a special user interface that simulates the pull of the Botafumeiro, and the experiences of its use with different users of the system.
Emergence of the Politics of Education Field: Making Sense of the Messy Center
Authors: Scribner Jay D. , Aleman Enrique , Maxcy Brendan
Published: May 2003

The authors place the evolution of politics in education and the politics of education field in historical context and introduce a framework for understanding how three theoretical streams-micropolitics, political culture, and neoinstitutionalism-emerged as the behavioralist movement receded. They argue that although there may appear to be a messy center lacking a single disciplinary paradigm, the field has been advancing by means of integrative and aggregative drives that are, indeed, complementary as well as competitive and result in a healthy and productive state of the field.
Those Nagging Headaches: Perennial Issues and Tensions in the Politics of Education Field
Authors: Johnson Bob L.
Published: May 2003

The politics of education is an exciting yet dynamic field of study. Consistent with the demands of systematic inquiry, it is imperative that those working in the field periodically assess its knowledge base, developmental needs, and level of theoretical maturity. Toward this end, the purpose of this article is to examine perennial issues, needs, and tensions within the field: issues associated with defining and focusing the field, problems with theoretical hegemony and group-think, addressing and bridging the macro-micro politics divide, and the challenges of sustaining conceptual and theoretical rigor. Implications of these tensions for the preparation of educational leaders in the political knowledge/skills domain are likewise examined. These issues and tensions are by no means exhaustive, yet they are indicative of the stresses and strains that have come to characterize the field as it seeks to come to grips with its identity.
The (Racially Neutral) Politics of Education: A Critical Race Theory Perspective
Authors: López Gerardo R.
Published: May 2003

Although Critical Race Theory (CRT) originated in the legal arena, its influence has proliferated throughout the social sciences literature. Yet CRT has not spread significantly into the field of educational leadership, where the discourse on diversity has failed to penetrate the salience of racism in schooling. The purpose of this article is to confront the silence on race in schools and to summon scholars in the politics of education to critical analysis of race as an issue in public schools.
Sissies, Faggots, Lezzies, and Dykes: Gender, Sexual Orientation, and a New Politics of Education?
Authors: Lugg Catherine A.
Published: May 2003

This article seeks to chart a course through the contested areas of gender and sexual orientation in hopes of establishing a theoretical framework and an agenda for much needed future research. In building this article, the author draws from two research traditions, particularly in the areas of history and law. Her stance is that of a critical policy scholar, that is, drawing on neo-Marxist theory generally and Queer Legal Theory specifically. Public schools are governmental entities ruled by laws, regulations, and policies. The people who teach, lead, study, play, and otherwise live within a public school's walls must conform to these dictates or face various legal sanctions including expulsion and job termination. These legal mandates are established through political processes that include court decisions at the state and federal levels. Therefore, legal theories can help analyze and explicate the basic structures that shape daily educational practices. In the areas of gender, sexual orientation, and a possible new politics of education, Queer Legal Theory can be particularly insightful.
Fatigue life prediction using two stage model for AISI 304L cruciform joints, with different fillet geometry, failing at toe
Authors: Singh P. Johan , Guha B. , Achar D. R. G.
Published: May 2003

Reports in the literature indicate that the fillet geometry affects the fatigue properties of cruciform welded joints in structural steels. In an attempt to study the above effect with respect to stainless steel sheet metal welded joints, load carrying transverse fillet welded cruciform joints having a two fillet geometry were fabricated from AISI 304L stainless steel using gas tungsten arc welding and gas metal arc welding with 308L electrodes. The objective of the present work is to predict the fatigue life of AISI 304L cruciform joints failing at the weld toe using a two stage model. The local stress life method was applied to calculate the fatigue crack initiation life, whereas the fatigue crack propagation life was estimated using fracture mechanics concepts. Constant amplitude fatigue tests with stress ratio R ∼ 0 were carried out using a 100 kN servohydraulic Dartec universal testing machine at a frequency of 30 Hz. An automatic crack monitoring system based on crack propagation gauges was used to obtain the propagation data during the fatigue process. The predicted lives were compared with the experimental values.
CD11c gene expression in hairy cell leukemia is dependent upon activation of the proto-oncogenes ras andjunD
Authors: Nicolaou Fotini , Teodoridis Jens M. , Park Heiyoung , Georgakis Alexander , Farokhzad Omid C. , Böttinger Erwin P. , Da Silva Nicolas , Rousselot Philippe , Chomienne Christine , Ferenczi Katalin , Arnaout M. Amin , Shelley C. Simon
Published: May 2003

Hairy cell leukemia (HCL) is a chronic lymphoproliferative disease, the cause of which is unknown. Diagnostic of HCL is abnormal expression of the gene that encodes the β2 integrin CD11c. In order to determine the cause of CD11c gene expression in HCL theCD11c gene promoter was characterized. Transfection of theCD11c promoter linked to a luciferase reporter gene indicated that it is sufficient to direct expression in hairy cells. Mutation analysis demonstrated that of predominant importance to the activity of the CD11c promoter is its interaction with the activator protein-1 (AP-1) family of transcription factors. Comparison of nuclear extracts prepared from hairy cells with those prepared from other cell types indicated that hairy cells exhibit abnormal constitutive expression of an AP-1 complex containing JunD. Functional inhibition of AP-1 expressed by hairy cells reducedCD11c promoter activity by 80%. Inhibition of Ras, which represents an upstream activator of AP-1, also significantly inhibited the CD11c promoter. Furthermore, in the hairy cell line EH, inhibition of Ras signaling through mitogen-activated protein kinase/extracellular signal–regulated kinase kinases 1 and 2 (MEK1/2) reduced not only CD11c promoter activity but also reduced both CD11c surface expression and proliferation. Expression in nonhairy cells of a dominant-positive Ras mutant activated the CD11cpromoter to levels equivalent to those in hairy cells. Together, these data indicate that the abnormal expression of the CD11cgene characteristic of HCL is dependent upon activation of the proto-oncogenes ras and junD.
Src and phosphatidylinositol 3–kinase mediate soluble E-selectin–induced angiogenesis
Authors: Kumar Pawan , Amin Mohammad A. , Harlow Lisa A. , Polverini Peter J. , Koch Alisa E.
Published: May 2003

Angiogenesis plays an important role in a variety of pathophysiologic processes, including tumor growth and rheumatoid arthritis. We have previously shown that soluble E-selectin (sE-selectin) is an important angiogenic mediator. However, the mechanism by which sE-selectin mediates angiogenesis is still unknown. In this study, we show that sE-selectin is a potent mediator of human dermal microvascular endothelial cell (HMVEC) chemotaxis, which is predominantly mediated through the Src and the phosphatidylinositiol 3–kinase (PI3K) pathways. Further, sE-selectin induced a 2.2-fold increase in HMVEC tube formation in the Matrigel in vitro assay. HMVECs pretreated with the Src inhibitor (PP2) and the PI3K inhibitor (LY294002) or transfected with Src antisense oligonucleotides or Akt dominant-negative mutants significantly inhibited sE-selectin–mediated HMVEC tube formation. In contrast, HMVECs transfected with an extracellular signal-related kinase 1/2 (ERK1/2) mutant or pretreated with the mitogen-activated protein kinase (MAPK) inhibitor PD98059 failed to show sE-selectin–mediated HMVEC tube formation. Similarly, in the Matrigel-plug in vivo assay, sE-selectin induced a 2.2-fold increase in blood vessel formation, which was significantly inhibited by PP2 and LY294002 but not by PD98059. sE-selectin induced a marked increase in Src, ERK1/2, and PI3K phosphorylation. PI3K and ERK1/2 phosphorylation was significantly inhibited by PP2, thereby suggesting that both of these pathways may be activated via Src kinase. Even though the ERK1/2 pathway was activated by sE-selectin in HMVECs, it seems not to be essential for sE-selectin–mediated angiogenesis. Taken together, our data clearly show that sE-selectin–induced angiogenesis is predominantly mediated through the Src-PI3K pathway.
Albumin-expressing hepatocyte-like cells develop in the livers of immune-deficient mice that received transplants of highly purified human hematopoietic stem cells
Authors: Wang Xiuli , Ge Shundi , McNamara George , Hao Qian-Lin , Crooks Gay M. , Nolta Jan A.
Published: May 2003

Rodent bone marrow cells can contribute to liver. If these findings are applicable to humans, marrow stem cells could theoretically be harvested from a patient and used to repair his/her damaged liver. To explore this potential, CD34+ or highly purified CD34+CD38−CD7− human hematopoietic stem cells from umbilical cord blood and bone marrow were transplanted into immunodeficient mice. One month after transplantation, carbon tetrachloride (CCl4) was administered into the mice to induce liver damage and hepatocyte proliferation. Mice were analyzed in comparison with CCl4-injured mice that did not receive transplants and noninjured controls that received transplants with the same stem cell populations, one month after liver damage. Human-specific albumin mRNA and protein were expressed in the mouse liver and human albumin was detected in the serum of mice that had received CCl4 injury. Human alpha-fetoprotein was never expressed, but in some mice, human cytokeratin 19 was expressed, which may indicate bile duct development in addition to the albumin-secreting hepatocyte-like cells. Human albumin was not expressed in the starting stem cell populations in injured mice that did not receive transplants nor in noninjured mice that had received transplants of human stem cells. Human albumin expression was detected only in CCl4-treated mice that received transplants of human stem cells, and recovery was increased by administration of human hepatocyte growth factor 48 hours after the CCl4-mediated liver injury. Our studies provide evidence that human “hematopoietic” stem/progenitor cell populations have the capacity to respond to the injured liver microenvironment by inducing albumin expression.
Nodular sclerosing Hodgkin disease: new grading predicts prognosis in intermediate and advanced stages
Authors: von Wasielewski Sabine , Franklin Jeremy , Fischer Robert , Hübner Klaus , Hansmann Martin L. , Diehl Volker , Georgii Axel , von Wasielewski Reinhard
Published: May 2003

The prognostic value of histologic classification and single histomorphologic parameters in Hodgkin disease has been widely debated in the literature. Whereas several former studies identified single parameters to be of clinical relevance, some recent reports have doubted the prognostic value of histology using modern treatment. Grading of the largest histologic category of Hodgkin disease, nodular sclerosis (NS), has been controversially discussed concerning clinical relevance. In this study, 965 cases of NS were reviewed to assess 9 histomorphologic parameters. The histologic results were correlated with laboratory and clinical findings and with overall survival and disease-free survival. Based on these results, a new grading of the NS category was established. The new grading, based on the 3 criteria eosinophilia, lymphocyte depletion, and atypia of the Hodgkin/Reed-Sternberg cells, was a significant indicator of prognosis in intermediate and advanced stages. Patients investigated in this study represent an outstanding collection because all of them were enrolled in the prospective multicenter clinical trial of the German Hodgkin Lymphoma Study Group. All of them had been staged uniformly according to the Ann Arbor system and had received stage-adapted modern treatment according to multimodality protocols. A subtle analysis of histology could represent a possible way to identify patients with a significantly better or worse prognosis. This new grading should help to avoid overtreatment to reduce severe therapy-related side effects such as acute toxicity and chronic sequelae such as cardiopulmonary complications and secondary neoplasias.
Alternative 5′ exons and differential splicing regulate expression of protein 4.1R isoforms with distinct N-termini
Authors: Parra Marilyn K. , Gee Sherry L. , Koury Mark J. , Mohandas Narla , Conboy John G.
Published: May 2003

Among the alternative pre-mRNA splicing events that characterize protein 4.1R gene expression, one involving exon 2′ plays a critical role in regulating translation initiation and N-terminal protein structure. Exon 2′ encompasses translation initiation site AUG1 and is located between alternative splice acceptor sites at the 5′ end of exon 2; its inclusion or exclusion from mature 4.1R mRNA regulates expression of longer or shorter isoforms of 4.1R protein, respectively. The current study reports unexpected complexity in the 5′ region of the 4.1R gene that directly affects alternative splicing of exon 2′. Identified far upstream of exon 2 in both mouse and human genomes were 3 mutually exclusive alternative 5′ exons, designated 1A, 1B, and 1C; all 3 are associated with strong transcriptional promoters in the flanking genomic sequence. Importantly, exons 1A and 1B splice differentially with respect to exon 2′, generating transcripts with different 5′ ends and distinct N-terminal protein coding capacity. Exon 1A-type transcripts splice so as to exclude exon 2′ and therefore utilize the downstream AUG2 for translation of 80-kDa 4.1R protein, whereas exon 1B transcripts include exon 2′ and initiate at AUG1 to synthesize 135-kDa isoforms. RNA blot analyses revealed that 1A transcripts increase in abundance in late erythroblasts, consistent with the previously demonstrated up-regulation of 80-kDa 4.1R during terminal erythroid differentiation. Together, these results suggest that synthesis of structurally distinct 4.1R protein isoforms in various cell types is regulated by a novel mechanism requiring coordination between upstream transcription initiation events and downstream alternative splicing events.
Peptide decoys selected by phage display block in vitro and in vivo activity of a human anti-FVIII inhibitor
Authors: Villard Sylvie , Lacroix-Desmazes Sébastien , Kieber-Emmons Thomas , Piquer Dominique , Grailly Sabrina , Benhida Abdellah , Kaveri Srini V. , Saint-Remy Jean-Marie , Granier Claude
Published: May 2003

Hemophilia A is a life-threatening, hemorrhagic, X-linked recessive disorder resulting in deficient factor VIII (FVIII) activity. After the infusion of therapeutic FVIII, 25% of patients develop anti-FVIII antibodies that inhibit FVIII procoagulant activity, thus precluding further administration of FVIII. Here we report a novel approach aimed at neutralizing the activity of FVIII inhibitors by peptide epitope surrogates. To illustrate our concept, we chose the human anti-FVIII monoclonal antibody, Bo2C11, as a representative of anti-FVIII antibodies and a phage-displayed peptide library approach to obtain surrogate peptides. We selected a series of constrained dodecapeptides with the core sequence W-NR, which specifically interacts with the combining site of Bo2C11. The peptides mimic the epitope recognized by Bo2C11 and are able to inhibit specifically and in a dose-dependent manner the binding of Bo2C11 to FVIII. Peptide 107, in particular, neutralized the activity of Bo2C11 in vitro and restored normal hemostasis in hemophilic mice. Thus, the use of peptide decoys may be a promising new approach for the neutralization of pathologic antibodies.
The role of the endothelium in severe sepsis and multiple organ dysfunction syndrome
Authors: Aird William C.
Published: May 2003

Severe sepsis, defined as sepsis with acute organ dysfunction, is associated with high morbidity and mortality rates. The development of novel therapies for sepsis is critically dependent on an understanding of the basic mechanisms of the disease. The pathophysiology of severe sepsis involves a highly complex, integrated response that includes the activation of a number of cell types, inflammatory mediators, and the hemostatic system. Central to this process is an alteration of endothelial cell function. The goals of this article are to (1) provide an overview of sepsis and its complications, (2) discuss the role of the endothelium in orchestrating the host response in sepsis, and (3) emphasize the potential value of the endothelium as a target for sepsis therapy.
Responding naive T cells differ in their sensitivity to Fas engagement: early death of many T cells is compensated by costimulation of surviving T cells
Authors: Maksimow Mikael , Santanen Minna , Jalkanen Sirpa , Hänninen Arno
Published: May 2003

Engagement of Fas (CD95) induces death of activated T cells but can also potentiate T-cell response to CD3 ligation. Yet, the effects of Fas-mediated signals on activation of naive T cells have remained controversial. We followed naive T cells responding under Fas ligation. Ligation of Fas simultaneously with activation by antigen-bearing dendritic cells promoted early death in half of the responding naive murine CD4 T cells. Surprisingly, it simultaneously accelerated cell division and interferon-γ (IFN-γ) production among surviving T cells. These cells developed quickly an activation-associated phenotype (CD44hi, CD62Llo), responded vigorously to antigen rechallenge, were partially resistant to subsequent induction of cell death via Fas, and were long-lived in vivo. Compared with cells becoming apoptotic, the surviving cells expressed lower levels of Fas and higher levels of T-cell receptor (TCR), CD4, and interleukin-2 receptor (IL-2R). Their survival was associated with expression of antiapoptotic cellular FLICE-inhibitory protein (c-FLIP), Bcl-XL, and Bcl-2. Thus, at the time of T-cell activation there is a subtle balance in the effects of Fas ligation that differs on a cell-to-cell basis. Factors that predict cell survival include expression levels of Fas, TCR, CD4, and IL-2R. Early death of some cells and a pronounced response of the surviving cells suggest that Fas ligation can both up- and down-regulate a primary T-cell response.
Kaposi sarcoma–associated viral cyclin K overrides cell growth inhibition mediated by oncostatin M through STAT3 inhibition
Authors: Lundquist Amy , Barré Benjamin , Bienvenu Frédéric , Hermann Jacques , Avril Sylvie , Coqueret Olivier
Published: May 2003

DNA viruses have evolved a number of mechanisms to inhibit the major cellular tumor-suppressor pathways. Viral oncogenes can override growth suppressive signals and extend the virus proliferative capacity. The Kaposi sarsoma–associated human herpesvirus 8 (KSHV) encodes a protein, cyclin K, that is similar to cellular cyclin D1 but behaves atypically. Cyclin K resists the actions of the p16 INK4a and p27Kip1 inhibitors and extends the range of cdk6 substrates, thereby inducing cell-cycle progression toward S phase. In this study, we show that cyclin K overrides growth suppressive signals through signal transducer and activator of transcription 3 (STAT3) inactivation. Cyclin K was found to associate with the activation domain of STAT3 to inhibit its DNA-binding and transcriptional activities. Overexpression of cyclin K and inhibition of STAT3 prevents the growth suppressive effect imposed by the interleukin 6–type cytokine, oncostatin M. Altogether, these results suggest that KSHV is able to override growth suppressive effects through multiple mechanisms, and they further indicate that cyclin K plays an important role in the oncogenic activity of these viruses.
Elevated plasma factor VIII in a mouse model of low-density lipoprotein receptor–related protein deficiency
Authors: Bovenschen Niels , Herz Joachim , Grimbergen Jos M. , Lenting Peter J. , Havekes Louis M. , Mertens Koen , van Vlijmen Bart J. M.
Published: May 2003

It has been established that low-density lipoprotein receptor-related protein (LRP) is involved in the cellular uptake and degradation of coagulation factor VIII (FVIII) in vitro. To address the physiologic role of LRP in regulating plasma FVIII in vivo, we used cre/loxP–mediated conditional LRP- deficient mice (MX1cre+LRPflox/flox). Upon inactivation of the LRP gene, MX1cre+LRPflox/flox mice had significantly higher plasma FVIII as compared with control LRPflox/floxmice (3.4 and 2.0 U/mL, respectively; P < .001). Elevated plasma FVIII levels in MX1cre+LRPflox/flox mice coincided with increased plasma von Willebrand factor (VWF) (2.0 and 1.6 U/mL for MX1cre+LRPflox/flox and control LRPflox/flox mice, respectively; P < .05). Elevation of plasma FVIII and VWF persisted for at least 6 weeks after inactivation of the LRP gene. Upon comparing plasma FVIII and VWF in individual mice, we observed an increase of the FVIII/VWF ratio in MX1cre+LRPflox/flox mice as compared with control LRPflox/flox mice. Administration of either a vasopressin analog or an endotoxin resulted in increased plasma VWF, but not FVIII. In clearance experiments, MX1cre+LRPflox/flox mice displayed a 1.5-fold prolongation of FVIII mean residence time. Adenovirus-mediated overexpression of the 39-kDa receptor–associated protein (RAP) in normal mice resulted in a 3.5-fold increase of plasma FVIII. These data confirm that the regulation of plasma FVIII in vivo involves a RAP-sensitive mechanism. Surprisingly, plasma FVIII in MX1cre+LRPflox/flox mice increased 2-fold after RAP gene transfer. We propose that RAP-sensitive determinants other than hepatic LRP contribute to the regulation of plasma FVIII in vivo.
A defect in hematopoietic stem cell migration explains the nonrandom X-chromosome inactivation in carriers of Wiskott-Aldrich syndrome
Authors: Lacout Catherine , Haddad Elie , Sabri Siham , Svinarchouk Fedor , Garçon Loic , Capron Claude , Foudi Adlen , Mzali Rym , Snapper Scott B. , Louache Fawzia , Vainchenker William , Duménil Dominique
Published: May 2003

A defect in cell trafficking and chemotaxis plays an important role in the immune deficiency observed in Wiskott-Aldrich syndrome (WAS). In this report, we show that marrow cells from WAS protein (WASP)–deficient mice also have a defect in chemotaxis. Serial transplantation and competitive reconstitution experiments demonstrated that marrow cells, including hematopoietic progenitors and stem cells (HSCs), have decreased homing capacities that were associated with a defect in adhesion to collagen. During development, HSCs migrate from the liver to the marrow and the spleen, prompting us to ask if a defect in HSC homing during development may explain the skewed X-chromosome inactivation in WAS carriers. Preliminary evidence has shown that, in contrast to marrow progenitor cells, fetal liver progenitor cells from heterozygous females had a random X-chromosome inactivation. When fetal liver cells from WASP-carrier females were injected into irradiated recipients, a nonrandom inactivation of the X-chromosome was found at the level of hematopoietic progenitors and HSCs responsible for the short- and long-term hematopoietic reconstitution. Therefore, the mechanism of the skewed X-chromosomal inactivation observed in WAS carriers may be related to a migration defect of WASP-deficient HSCs.
Adenosine affects expression of membrane molecules, cytokine and chemokine release, and the T-cell stimulatory capacity of human dendritic cells
Authors: Panther Elisabeth , Corinti Silvia , Idzko Marco , Herouy Yared , Napp Matthias , la Sala Andrea , Girolomoni Giampiero , Norgauer Johannes
Published: May 2003

Dendritic cells (DCs) express functional purinergic type 1 receptors, but the effects of adenosine in these antigen-presenting cells have been only marginally investigated. Here, we further characterized the biologic activity of adenosine in immature DCs (iDCs) and lipopolysaccharide (LPS)–matured DCs (mDCs). Chronic stimulation with adenosine enhanced the macropinocytotic activity and the membrane expression of CD80, CD86, major histocompatibility complex (MHC) class I, and HLA-DR molecules on iDCs. Adenosine also increased LPS-induced CD54, CD80, MHC class I, and HLA-DR molecule expression in mDCs. In addition, adenosine dose-dependently inhibited tumor necrosis factor α and interleukin-12 (IL-12) release, whereas it enhanced the secretion of IL-10 from mDCs. The use of selective receptor agonists revealed that the modulation of the cytokine and cell-surface marker profile was due to activation of A2 adenosine receptor. Functionally, adenosine reduced the allostimulatory capacity of iDCs, but not of mDCs. More important, DCs matured in the presence of adenosine had a reduced capacity to induce T helper 1 (Th1) polarization of naive CD4+ T lymphocytes. Finally, adenosine augmented the release of the chemokine CCL17 and inhibited CXCL10 production by mDCs. In aggregate, the results provide initial evidence that adenosine diminishes the capacity of DCs to initiate and amplify Th1 immune responses.