bluuebunny/crossref_metadata_2025 huggingface dataset:
Product Liability Forecasting for Asbestos‐Related Personal Injury Claims
Authors: STALLARD ERIC
Published: July 2010

Abstract: This paper focuses on three aspects of forecasting models for asbestos‐related disease/injuries relating to the Manville asbestos case: (1) The structure of forecasting models for asbestos‐related personal injuries. (2) The epidemiologic evidence supporting the selected model structure and the constraints on the modeling assumptions imposed by that evidence. (3) The range of uncertainty associated with projections based on these forecasting models and issues relating to decision making under uncertainty.
Do People Make Environments or Do Environments Make People?
Authors: Rowe David C.
Published: July 2010

Abstract: This article discusses the influence of people's genetic make‐up on their mental states of happiness and depression. Contrary to the conventional wisdom, great fortune does not guarantee happiness; neither does great misfortune assure depression. Emotional states are surprisingly immune to “objective” social circumstances. A biological basis for this relative immunity is that people possess biological set points for these emotional states, rendering the effects of most life events transitory. Genotypes also have indirect effects. People react differently to psychological stressors depending on their genotypes. A susceptible person may succumb to depression, whereas a resilient person may remain unaffected. People also expose themselves to different social environments. Exposure to controllable life events is partly a result of genetic predispositions. Consilience requires that this biological individuality be considered in any understanding of human behavior, including the pursuit of happiness.
The Smoke Detector Principle
Authors: Nesse Randolph M.
Published: July 2010

Abstract: Defenses, such as flight, cough, stress, and anxiety, should theoretically be expressed to a degree that is near the optimum needed to protect against a given threat. Many defenses seem, however, to be expressed too readily or too intensely. Furthermore, there are remarkably few untoward effects from using drugs to dampen defensive responses. A signal detection analysis of defense regulation can help to resolve this apparent paradox. When the cost of expressing an all‐or‐none defense is low compared to the potential harm it protects against, the optimal system will express many false alarms. Defenses with graded responses are expressed to the optimal degree when the marginal cost equals the marginal benefit, a point that may vary considerably from the intuitive optimum. Models based on these principles show that the overresponsiveness of many defenses is only apparent, but they also suggest that, in specific instances, defenses can often be dampened without compromising fitness. The smoke detector principle is an essential foundation for making decisions about when drugs can be used safely to relieve suffering and block defenses.
Immunoalienation
Authors: Breznitz Shlomo
Published: July 2010

Abstract: Immunoalienation denotes the process through which the definition of self, as defined by the immune system, progressively deviates from the genetically determined definition of self. The mechanisms responsible for immunoalienation are discussed in light of the available evidence. The different kinds of immunoalienation are analyzed, and their theoretical as well as practical implications to disease, tumors, and transplant biology are briefly discussed.
The Anterior Cingulate Cortex
Authors: Allman John M. , Hakeem Atiya , Erwin Joseph M. , Nimchinsky Esther , Hof Patrick
Published: July 2010

Abstract: We propose that the anterior cingulate cortex is a specialization of neocortex rather than a more primitive stage of cortical evolution. Functions central to intelligent behavior, that is, emotional self‐control, focused problem solving, error recognition, and adaptive response to changing conditions, are juxtaposed with the emotions in this structure. Evidence of an important role for the anterior cingulate cortex in these functions has accumulated through single‐neuron recording, electrical stimulation, EEG, PET, fMRI, and lesion studies. The anterior cingulate cortex contains a class of spindle‐shaped neurons that are found only in humans and the great apes, and thus are a recent evolutionary specialization probably related to these functions. The spindle cells appear to be widely connected with diverse parts of the brain and may have a role in the coordination that would be essential in developing the capacity to focus on difficult problems. Furthermore, they emerge postnatally and their survival may be enhanced or reduced by environmental conditions of enrichment or stress, thus potentially influencing adult competence or dysfunction in emotional self‐control and problem‐solving capacity.
Exploring the Biology of Socialization
Authors: Posner Michael I. , Rothbart Mary K. , Gerardi‐Caulton Gina
Published: July 2010

Abstract:How will the social sciences take advantage of the revolution that has taken place in biology during the past two decades? Over the last fifteen years, neuroimaging has allowed the study of human cognition and emotion within psychology to achieve close alliances with biology through the development of cognitive and affective neuroscience. There is little doubt that a similar alliance between psychology and biology will occur in the domain of human brain development. In principle, understanding how the human brain is organized by experience (epigenetic rules) and how societies instruct their young could produce a link between natural and social science. The late David C. McClelland sought methods to base the social sciences on psychological ideas. McClelland sought to connect the values of achievement and power as coded from children's readers and popular ballads to societal economic growth and conflict. These efforts lacked knowledge of brain mechanisms of memory and attention and an understanding of the role of experience in organizing brain circuitry. Understanding of cognitive and brain systems related to knowledge and action may allow a new approach to forging connections between individual minds and social behavior.
K‐12 Science Education as the Road to Consilient Curricula
Authors: Lederman Leon M.
Published: July 2010

Abstract: We begin with the absurdity of ninth‐grade biology to bewail the fate of high school science education as one component of a wholly inadequate K‐12 education. Our proposal for a coherent physics‐chemistry‐biology core curriculum for all high school students leads naturally to seeking the connections between the sciences, the sciences and mathematics, and indeed to the social sciences and the humanities. Our goal is literacy—scientific and humanistic—as the sensible goal for a 21st century high school graduate.
Hereditary Disorders of Fibrinogen
Authors: MATSUDA MICHIO , SUGO TERUKO
Published: July 2010

Abstract: Fibrinogen, a 340‐kDa plasma protein, is composed of two identical molecular halves each consisting of three non‐identical Aα‐, Bβ‐ and γ‐chain subunits held together by multiple disulfide bonds. Fibrinogen is shown to have a trinodular structure; that is, one central nodule, the E domain, and two identical outer nodules, the D‐domains, linked by two coiled‐coil regions. After activation with thrombin, a pair of binding sites comprising Gly‐Pro‐Arg is exposed in the central nodule and combines with its complementary binding site a in the outer nodule of another molecules. By using crystallographic analysis, the α‐amino group of αGly‐1 is shown to be juxtaposed between γAsp‐364 and γAsp‐330, and the guanidino group of αArg‐3 between the carboxyl group of γAsp‐364 and γGln‐329 in the a site. Half molecule‐staggered, double‐stranded protofibrils are thus formed. Upon abutment of two adjacent D domains on the same strand, D‐D self association takes place involving Arg‐275, Tyr‐280, and Ser‐300 of the γ‐chain on the surface of the abutting two D domains. Thereafter, carboxyl‐terminal regions of the α‐chains are untethered and interact with those of other protofibrils leading to the formation of thick fibrin bundles and networks. Although many enigmas still remain concerning the exact mechanisms of these molecular interactions, fibrin assembly proceeds in a highly ordered fashion. In this review, these molecular interactions of fibrinogen and fibrin are discussed on the basis of the data provided by hereditary dysfibrinogens on introducing representative molecules at each step of fibrin clot formation.
Insight from Studies with Recombinant Fibrinogens
Authors: LORD SUSAN T. , GORKUN OLEG V.
Published: July 2010

Abstract: Using a two‐step cloning strategy, we have synthesized more than 20 variant human fibrinogens for biochemical studies. In preliminary experiments we showed that normal fibrinogen produced in CHO cells serves as an accurate model for plasma fibrinogen. We focus here on those variants whose characterization has provided insight into the mechanism of thrombin‐catalyzed polymerization. Analysis of N‐terminal variants showed that thrombin specificity dictates the ordered release of fibrinopeptides. Nevertheless, analysis of C‐terminal variants indicated that fibrinopeptide B (FpB) release is dependent on polymerization. Changes in the a polymerization site and the high‐affinity calcium‐binding site were associated with a complete loss of polymerization. These experiments showed that alterations in the calcium‐binding site influenced function of the a site; in contrast, alterations in the a site did not alter calcium binding. Analysis of variants in the N‐terminus of the Bβ chain provided the first direct evidence that this region impacts predominantly on lateral aggregation, as has long been presumed. These experiments also suggested that lateral aggregation facilitated by this region proceeds without the release of FpB. From these studies we learned that individual sites within fibrinogen do not function in isolation. We conclude that thrombin‐catalyzed polymerization is mediated by a continuum of concerted interactions.
The Fibrin Intermediate, Its Place in the Fibrinogen‐Fibrin Transformation
Authors: SHAINOFF JOHN R. , SMEJKAL GARY B. , DIBELLO PATRICIA M. , CHASE BARBARA , MITKEVICH OLGA V. , LILL HELMUT
Published: July 2010

Abstract: Our preceding study indicated that, in course of coagulation of human fibrinogen by thrombin, substantial production of the fibrin intermediate (α‐profibrin) lacking only one fibrinopeptide A (FPA) precedes the formation of α‐fibrin monomer lacking both FPAs. The plateau concentration of α‐profibrin (20% of initial fibrinogen) appearing in reactions indicated, however, that the second FPA is released four times faster than the first. The study reported here confirms those findings, and provides new insight into the significance of differing rate constants for the production of α‐profibrin and its conversion to α‐fibrin. The intermediate could be isolated in a distinct electrophoretic band by electrophoresing partial thrombin digests at high concentrations. Its identity was verified by digesting it with CNBr and by demonstrating that its N‐terminal domain, the NDSK fragment, both lacks an FPA and contains an FPA, unlike the NDSKs of the bands from fibrin which contained no FPA or the fibrinogen band that lacked no FPA. The single step isolation also enabled us to confirm the 15–20% plateau level of α‐profibrin in course of thrombin reactions, well below the 37% maximum that would be expected if release of the first and second FPA proceeded independently with no difference in rate. The 37% maximum is observed in reactions with atroxin, and it is suggested that the abundant production of α‐profibrin underlies the therapeutic utility of atroxin as a defibrinating agent. Gel chromatography procedures were optimized for isolation of α‐profibrin/fibrin mixtures free of fibrinogen, the final step of which involves literal use of agarose gel as a filter to remove fibrin aggregates from the fibrinogen free fractions (aggregates are left behind in gel filtration, rather than their moving ahead in gel chromatography). Unlike human fibrinogen, rabbit fibrinogen does not yield much α‐profibrin in course of its conversion to fibrin, less than 10% as determined by electrophoresis and comparison with abundant production with atroxin. This low production of α‐profibrin conformed with conclusions from our early studies on the generalized Shwartzman reaction in rabbits, and we now infer that the low production of α‐profibrin and rapid conversion to fibrin by rabbit fibrinogen underlies the unparalleled susceptibility of these animals toward fibrinoid formation in the generalized Shwartzman reaction.
The Formation of β Fibrin Requires a Functional a Site
Authors: HOGAN KELLY A. , BOLLIGER BETTINA , OKUMURA NOBUO , LORD SUSAN T.
Published: July 2010

Abstract: We used recombinant fibrinogens in which the a site is disrupted to examine β‐fibrin formation in the absence of a functional a site. Our variants have only b sites available, and they showed no evidence of fibrin polymer formation after cleavage of FpB with venzyme. We conclude that B‐b interactions are not strong enough to induce clot formation. Our studies do not rule out the involvement of b in the formation of β‐fibrin, yet they do provide evidence that a is likely to be essential in the formation of β‐fibrin.
Mode of Perturbation of Asahi Fibrin Assembly by the Extra Oligosaccharides
Authors: SUGO TERUKO , SEKINE OSAMU , NAKAMIKAWA CHIZUKO , ENDO HITOSHI , AROCHA‐PIÑANGO CARMEN L. , MATSUDA MICHIO
Published: July 2010

Abstract: Steric hindrance by the backbone of extra oligosaccharides at γ‐Asn 308 may cause the repulsive force to widen the junction at the D: D interface, and thus, interfere with the longitudinal elongation and lateral association of protofibrils.
Genetic Manipulation of Fibrinogen and Fibrinolysis in Mice
Authors: DEGEN JAY L. , DREW ANGELA F. , PALUMBO JOSEPH S. , KOMBRINCK KEITH W. , BEZERRA JORGE A. , DANTON MARY JO S. , HOLMBÄCK KENN , SUH THEODORE T.
Published: July 2010

Abstract: Vascular integrity is maintained by a sophisticated system of circulating and cell associated hemostatic factors that control local platelet deposition, the conversion of soluble fibrinogen to an insoluble fibrin polymer, and the dissolution of fibrin matrices. However, hemostatic factors are likely to be biologically more important than merely maintaining vascular patency and controlling blood loss. Specific hemostatic factors have been associated with a wide spectrum of physiological processes, including development, reproduction, tissue remodeling, wound repair, angiogenesis, and the inflammatory response. Similarly, it has been proposed that hemostatic factors are important determinants of a variety of pathological processes, including vessel wall disease, tumor dissemination, infectious disease, and inflammatory diseases of the joint, lung, and kidney. The development of gene targeted mice either lacking or expressing modified forms of selected hemostatic factors has provided a valuable opportunity to test prevailing hypotheses regarding the biological roles of key coagulation and fibrinolytic system components in vivo. Genetic analyses of fibrin(ogen) and its interacting factors in transgenic mice have proven to be particularly illuminating, often challenging long standing concepts. This review summarizes the key findings made in recent studies of gene targeted mice with single and combined deficits in fibrinogen and fibrinolytic factors. Studies illustrating the role and interplay of these factors in disease progression are highlighted.
Role of Fibrin Matrix in Angiogenesis
Authors: van HINSBERGH VICTOR W.M. , COLLEN ANNEMIE , KOOLWIJK PIETER
Published: July 2010

Abstract: Angiogenesis, the formation of new blood vessels from existing vessels, plays an important role during development. In the adult, it is limited to the female reproductive system and to tissue repair and pathological conditions. Repair associated angiogenesis is usually accompanied by the presence of inflammatory cells, vascular leakage, and fibrin deposition. The temporary fibrin matrix acts, not only as a sealing matrix, but also as a scaffolding for invading leukocytes and endothelial cells during tissue repair. We have used a three‐dimensional fibrin matrix to study the outgrowth of human microvascular endothelial cells in capillary‐like tubular structures. This process is induced by the simultaneous addition of an angiogenic growth factor (bFGF or VEGF) and the cytokine TNFα, and is enhanced by hypoxia. It involves proteolytic activities, in particular cell bound urokinase/plasmin and matrix metalloproteinase activities. Modulation of the fibrin structure markedly affects the extent and stability of capillary tube formation in vitro. Preparation of fibrin at different pH (7.0–7.8) or crosslinking of the fibrin matrix induces differences in fibrin matrix rigidity and structure. This is accompanied by a change in capillary ingrowth. Heparins, in particular low molecular weight heparins, modulate the fibrin structure and by this action affect angiogenesis in vitro. A mutant fibrinogenNieuwegein, which lacks the terminal part of the Aα chain of fibrin harboring an RGD sequence and the transglutaminase sequence, provided additional evidence that the structure of fibrin is an important determinant for angiogenesis. These findings may have impact on improving wound healing and on influencing angiogenesis in malignancies with a fibrinous stroma.
Fibrinogen Modulates Gene Expression in Wounded Fibroblasts
Authors: PEREIRA MARIAN , SIMPSON‐HAIDARIS PATRICIA J.
Published: July 2010

Abstract: Fibrinogen (FBG) has long been regarded as serving essentially a hemostatic role by its conversion from a soluble, plasma protein to an insoluble fibrin gel. However, several extrahepatic sites of FBG biosynthesis have been identified. Indeed, we have demonstrated that both lung epithelial cell derived and plasma FBG assemble into the extracellular matrix (ECM) of epithelial cells and fibroblasts. In this report, we determined that FBG assembly into the ECM is a cell dependent step that occurs in the absence of de novo protein synthesis. Using an in vitro model of wound repair, we examined the role of FBG in modulating gene expression. Data collected from cDNA array analysis indicated that FBG downregulates steady state levels of fibronectin mRNA, whereas cyclin D1 mRNA levels were upregulated in fibroblasts. Taken together, these data suggest that FBG may function independently of hemostasis in cellular adhesive interactions to modulate cellular signaling processes during wound repair.
Mutations on Fibrinogen (γ316–322) Are Associated with Reduction in Platelet Adhesion Under Flow Conditions
Authors: REMIJN JASPER A. , LOUNES KARIM C. , HOGAN KELLY A. , LORD SUSAN T. , GALANAKIS DENNIS K. , SIXMA JAN J. , DE GROOT PHILIP G.
Published: July 2010

Abstract: In this paper we report on studies of platelet adhesion to several fibrinogen γ chain variants under physiological flow conditions. Reduced platelet adhesion was found to patient dysfibrinogen Vlissingen and its recombinant form (deletion of γ319–320). Furthermore, substitutions of the amino acids 318, 320, or both in the recombinant fibrinogen γ chain showed a strong decrease in platelet adhesion under flow conditions in our perfusion system. Antibodies raised against peptides covering these sequences inhibited platelet adhesion completely, which suggested that the γ316–322 sequence could be involved in platelet adhesion in flowing blood.
Mutation of W215 Compromises Thrombin Cleavage of Fibrinogen, but Not of PAR1 or Protein C
Authors: AYALA YOUHNA M. , AROSIO DANIELE , Di CERA ENRICO
Published: July 2010

Abstract: W215 is a highly conserved residue that shapes the S3 and S4 specificity sites of thrombin. Replacement of W215 with Phe produces modest effects on thrombin function, whereas the W215Y replacement significantly compromises the amidolytic activity toward synthetic and natural substrates. Replacement of W215 with Ala reduces fibrinogen and PAR4 cleavage 500‐fold and 280‐fold, respectively. On the other hand, the mutant decreases protein C activation and PAR1 cleavage only threefold and 25‐fold, respectively. The W215A mutant cleaves PAR1 with a specificity constant more than 13‐fold greater than that of fibrinogen and protein C, and 800‐fold greater than PAR4. This is the first thrombin derivative to be described that functions as an almost exclusive activator of PAR1. The environment of W215 influences differentially three physiologically important interactions of thrombin, a feature that should assist in the separate study of each of these functions in vivo.
Platelets in Suspension Require Preactivation to Adhere to Immobilized Fibrinogen
Authors: BONNEFOY ARNAUD , LIU QINGDE , JEROME W. GRAY , LEGRAND CHANTAL , FROJMOVIC MONY M.
Published: July 2010

Abstract: Previous studies using whole blood perfusion through flow chambers have suggested that unactivated platelets can adhere to surface immobilized fibrinogen (Fg). However, the red blood cells needed for surface delivery of the platelets may activate platelets by released adenosine diphosphate (ADP). Our studies of coaggregation of unactivated or ADP‐activated platelets with Fg‐coated latex beads in flowing suspensions show that only preactivated platelets can adhere to Fg‐coated surfaces.
Platelet Adhesion to Fibrinogen Coated at Various Densities
Authors: JIROUŠKOVÁ MARKÉTA , COLLER BARRY S.
Published: July 2010

Abstract: Platelet adhesion to low‐density coated fibrinogen induces greater protein tyrosine phosphorylation of SYK and FAK than adhesion to high‐density coated fibrinogen, and leads to activation of integrin αIIbβ3 on the luminal side of adherent platelets.
Fibrinogen Biosynthesis
Authors: REDMAN COLVIN M. , XIA HUI
Published: July 2010

Abstract: Plasma fibrinogen is synthesized primarily in hepatocytes and assembly of the three component chains (Aα, Bβ, and γ) into its final form as a six‐chain dimer (Aα, Bβ, γ)2 occurs rapidly in the lumen of the endoplasmic reticulum (ER). Assembly takes place in a stepwise manner with single chains interacting with each other to form Aα‐γ and Bβ‐γ complexes. The two‐chain complexes then acquire another chain to form half‐molecules (Aα, Bβ, γ)1, which in a final step are linked to form the six‐chain (Aα, Bβ, γ)2 complex. As with other secreted glycoproteins, N‐linked glycosylation of Bβ and γ chains commences in the ER and is completed in Golgi organelles. Sulfation and phosphorylation occur at post‐ER stages of the secretory process. Since some ER chaperones coisolate with nascent fibrinogen chains they have been implicated in assisting chain assembly. Studies with recombinant systems, using deletion and substitution mutants, indicate that initial chain assembly depends on hydrophobic interactions present in the C‐terminal half of the coil‐coil domains and that inter‐ and intra‐disulfide bonds that stabilize fibrinogen are needed to complete chain assembly. Not all the chains that are synthesized are assembled into fibrinogen and the unassembled chains are not secreted. HepG2 cells contain surplus Aα and γ chains that accumulate as free γ chains and as an Aα‐γ complex. Aα‐γ is degraded by lysosomes whereas the γ chain is degraded by the proteasome‐ubiquitin system. Studies with expression of single chains by COS cells confirm that γ and Bβ are hydrolyzed by proteasomes and indicate that Aα is degraded partially both by lysosomes and proteasomes. The role of surplus chains in regulating fibrinogen assembly is not understood but overexpression of any one chain, elicited by transfection of HepG2 cells, results in the upregulation of the other two genes, increased fibrinogen synthesis and secretion, and maintenance of surplus intracellular Aα and γ chains. HepG2 cells, programmed in this manner to increase basal fibrinogen expression, have higher HMG‐CoA reductase mRNA levels, enhanced cholesterol and cholesterol ester synthesis, and increased secretion of apolipoprotein B (apoB). Overexpression of basal levels of fibrinogen does not affect synthesis of other acute phase proteins. Enhanced secretion of apoB is due to diminished degradation of nascent apoB by proteasomes and not to increased expression. Increased secretion of apoB is associated with increased basal expression of fibrinogen and is not affected when fibrinogen expression is stimulated by interleukin‐6. In HepG2 cells, a feedback mechanism exists and extracellular sterols specifically downregulate expression of the three fibrinogen genes. These studies link, at the cellular level, basal fibrinogen expression with lipid metabolism.
Hypofibrinogenemia Associated with a Heterozygous C→T Nucleotide Substitution at Position −1138 BP of the 5′‐Flanking Region of the Fibrinogen Aα‐Chain Gene
Authors: OKUMURA NOBUO , TERASAWA FUMIKO , YONEKAWA OSAMU , HAMADA ETSUKO , KANEKO HIROSHI
Published: July 2010

Abstract: We found a novel genetic abnormality, heterozygous C→T nucleotide substitution at position −1138 bp in the 5′‐flanking region of the fibrinogen Aα gene, in patients with hypofibrinogenemia. Luciferase reporter assay using the pGL3‐basic vector and CHO cells indicates that the transcriptional activity of a vector incorporated with −1138T was reduced to one‐third that of a vector incorporated with −1138C. These results suggest that the region adjacent to the −1138C bp of the 5′‐flanking region of the fibrinogen Aα gene is one of the most crucial sites for the transcription of the fibrinogen Aα gene.
Development of Pulmonary Fibrosis in Fibrinogen‐Deficient Mice
Authors: WILBERDING JULIE A. , PLOPLIS VICTORIA A. , McLENNAN LAURA , LIANG ZHONG , CORNELISSEN IVO , FELDMAN MATTHEW , DEFORD MELANIE E. , ROSEN ELLIOT D. , CASTELLINO FRANCIS J.
Published: July 2010

Abstract: Bleomycin is an antineoplastic drug commonly used for the treatment of many carcinomas and lymphomas. Its toxic side effect on lung tissue is a major limitation to its use, with approximately 3–5% of patients affected. Although the number of affected patients is small, the damage incurred by bleomycin in these patients is often irreversible and, at times, fatal. A number of therapies have been shown to be effective in animal studies to minimize damage, but to date no “magic bullet” has been identified. Many proteins of the fibrinolytic system have been implicated as playing a role in the progression of the disease, one of which is fibrinogen (Fg) acting in the context of a fibroproliferative agent. Its presence correlates with an upregulation of plasminogen activator inhibitor‐1 and tissue factor in alveolar cells surrounding the lesion area. It is believed that Fg participates in the activation and migration of fibroblasts and provides a scaffold, in the form of fibrin, for cell migration following induction of acute lung injury. To further understand the mechanism of injury following bleomycin treatment and the possible role of fibrinogen therein, mice have been generated with a targeted deletion of the gamma‐chain of Fg, which resulted in the absence of detectable circulating Fg. The offsprings of Fg heterozygous mice (FG+/−) mice follow Mendelian distributions indicating no embryonic lethality with this deletion. Approximately one‐half of the Fg‐deficient (FG−/−) neonates exhibited bleeding episodes, approximately one‐half of which were fatal. For the pulmonary fibrosis study, FG−/− mice and wildtype littermates were administered a bleomycin solution intratracheally and the disease was allowed to progress for two weeks. The mice were then sacrificed, the left lung was excised for hydroxyproline analysis, the right lung was processed for histologic profiling. Examination of trichrome stained sections, surprisingly, revealed no qualitative difference between wildtype and FG−/− animals. The extent and pattern of the deposition of collagen were also similar. These results were quantitatively confirmed by hydroxyproline analysis, which revealed equivalent increases in collagen content between wildtype and FG−/− animals when compared to appropriate saline controls. Analysis of the early acute inflammatory stage of the disease showed a difference in the neutrophil population between days three and five of the disease. These studies suggest that, although fibrinogen is not required for collagen deposition at the later stage of the disease, it may play a role in the early acute inflammation stage.
Fibrinogen Non‐Inherited Heterogeneity and Its Relationship to Function in Health and Disease
Authors: HENSCHEN‐EDMAN AGNES H.
Published: July 2010

Abstract: In healthy individuals fibrinogen occurs in more than one million non‐identical forms because of the many possible combinations of biosynthetically or postbiosynthetically modified or genetically polymorphic sites. The various forms may show considerable differences in their functional properties. Normal variant sites are due to alternative splicing, modification of certain amino acid residues, and proteolysis. Both the Aα and the γ chain occur in two splice forms, and it is known that only the shorter γ chain can interact with platelets, but the longer may bind thrombin and factor XIII. Many types of posttranslationally modified amino acid residues are present in fibrinogen. The Aα chain is partially phosphorylated at two sites, possibly leading to protection against proteolysis. The Bβ chain is N‐glycosylated and partially proline hydroxylated, each at one site. The γ chain is N‐glycosylated at one site and the longer splice form doubly tyrosine‐sulfated. The glycosylations are believed to protect against polymerization and proteolysis. All three chains are partially oxidized at methionine residues and deamidated at asparagine and glutamine residues. The Aα and γ chain are partially carboxy‐terminally degraded by proteolysis, the shorter forms causing a decrease in polymerization, crosslinking, and clot stability. Abnormal variants occur in patients with diabetes mellitus, in the form of glycated lysine residues; in patients with certain types of cancer, in the form of crosslinked degradation products; in patients with certain types of autoimmune disease, in the form of complexes with antibodies; in cigarette smokers; and in individuals treated with acetylsalicylic acid, in the form of acetylated lysine residues.
Fibrin Degradation Products
Authors: GAFFNEY PATRICK J.
Published: July 2010

Abstract: This review attempts to relate subunit structures of fibrin degradation products (FnDP) made in vitro with structures found in vivo. The domainally directed fragmentation in vitro of both fibrinogen and fibrin is emphasized, all fragments being various associations of the two core fibrin fragments D and E. The digestion of fibrinogen by plasmin in vivo is rare, and the crosslinking of fibrin in vivo takes place at a very early stage in the clotting/polymerization process. The notion that as fibrin forms in vivo it orchestrates its own destruction is developed. Plasmas from patients suffering from dessiminated intravascular coagulation demonstrate very large crosslinked FnDP fragments in their plasmas which seem to contain not alone fibrinopeptide A but also subunits with intact alpha chains. This is interpreted to mean that many of the large soluble fragments found in vivo, and heretofore known as FnDP, are in reality long fibrin polymers, random parts of whose structures have been converted to FnDP by lysis of the carboxy terminal regions of the alpha chains in the polymer. The ratio of intact fibrin to FnDP in these large soluble structures may be a useful clinical marker; however, such data can only be relied upon when blood samples are taken into an anticoagulant mix that contains a fibrinolytic inhibitor. Some of the biological effects of FnDP structures in vivo (fibrinogen synthesis, vasoactivity) are still quite ambiguous.
Influence of Plasma Triglyceride and Plasma Cholesterol Levels on the Clearance Rate of Fibrinogen
Authors: VERSCHUUR MAARTJE , BEKKERS MARIAN , van ERCK MONIQUE G.M. , EMEIS JEF J. , DE MAAT MONIEK P.M.
Published: July 2010

Abstract: Increased plasma levels of fibrinogen are associated with a higher risk of cardiovascular disease. It has been suggested that lipid levels may influence the fibrinogen levels by a mechanism other than the synthesis rate, for example a decreased clearance rate. We performed a pilot study to explore this possibility. Twelve male Wistar rats were fed for four weeks with a control low fat/low cholesterol diet, a high fat/high cholesterol diet, and a high fat/high cholesterol diet with an additional 0.5% cholic acid. Labeled 125I fibrinogen was injected, and blood was sampled repeatedly. From the plasma radioactivity of the samples, fibrinogen halflife time was calculated for each animal. Our results suggest that plasma lipids lengthen the fibrinogen halflife times, although the differences were not statistically significant in this small study. Our final conclusion from this study is that lipids may have an effect on the turnover rate of fibrinogen and possibly affect fibrinogen levels through this mechanism.
Transendothelial Migration of Hematopoietic Progenitor Cells
Authors: MÖHLE ROBERT , BAUTZ FRANK , DENZLINGER CLAUDIO , KANZ LOTHAR
Published: July 2010

Abstract: There is increasing evidence that hematopoietic stem cell mobilization and homing is regulated not only by adhesion molecules and cytokines, but also by chemotactic factors that support transendothelial migration across the bone marrow sinusoidal endothelium. Many receptors for chemotactic mediators belong to the family of G protein‐coupled seven‐transmembrane receptors (7‐TMR). Signaling via G proteins, particularly Gi proteins, results in a chemotactic response of the cells towards a gradient of the corresponding ligand. Recent studies have provided evidence for expression of several 7‐TMR on immature hematopoietic progenitor cells, which potentially mediate chemotactic effects: chemokine receptors (e.g., CXCR4, receptor for stromal cell‐derived factor‐1), receptors for lipid mediators (e.g., the cysteinyl leukotriene receptor cysLT1 and the peripheral cannabinoid receptor cb2), and receptors for neuroendocrine hormones (e.g., the somatostatin receptor sst2). From these studies it can be concluded that migration of hematopoietic progenitor and stem cells is controlled by a variety of chemotactic factors rather than by a single chemokine (e.g., SDF‐1). Trafficking of immature hematopoietic cells may require combined and interactive regulatory functions of these mediators.
Increase in Circulating SDF‐1 after Treatment with Sulfated Glycans
Authors: SWEENEY ELIZABETH A. , PAPAYANNOPOULOU THALIA
Published: July 2010

Abstract: SDF‐1 is a potent chemoattractant for mature white blood cells and hemopoietic stem/progenitor cells (HPCs). An important role for this chemo‐kine in mobilization has been postulated, but in vivo studies directly addressing its effects are lacking. After one injection of fucan sulfate (FucS) or dextran sulfate, plasma levels of SDF‐1 are greatly increased in mice or primates. Increases are dose‐dependent and correlate with mobilization of HPCs. Elevated levels of circulating SDF‐1 appear to be uniquely associated with this treatment, as it was not seen with cytokine or anti‐integrin antibody treatments that induce mobilization. In vitro, these sulfated glycans specifically bind to SDF‐1 and inhibit SDF‐1/heparin binding, suggesting a mechanism of release from sequestration on heparan sulfate proteoglycans in vivo. Although other chemokines including IL8 and cytokines like G‐CSF also increase, evidence in GCSFR‐deficient mice suggests that at least these two factors are unlikely participants in FucS‐induced mobilization. Likewise, although the activity of the metalloprotease MMP9 increases after FucS treatment, experiments in MMP9−/− mice indicate its presence is dispensable for mobilization or SDF‐1 release. However, effects of other proteases cannot be ruled out by these experiments. Finally, anti‐SDF‐1 antibodies partially inhibit FucS‐induced mobilization, supporting a causative relationship. Our data offer a unique insight into the mechanism of sulfated glycan‐induced mobilization and suggest a novel way of disturbing SDF‐1 gradients between bone marrow and peripheral blood.
Mechanism of Human Stem Cell Migration and Repopulation of NOD/SCID and B2mnull NOD/SCID Mice
Authors: Lapidot Tsvee
Published: July 2010

Abstract: The mechanism of hematopoietic stem cell migration and repopulation is not fully understood. Murine fetuses that lack the chemokine stromal‐derived factor one (SDF‐1null) or its receptor CXCR4 (CXCR4null) have multiple defects that are lethal, including impaired bone marrow hematopoiesis. These results suggest a major role for SDF‐1/CXCR4 interactions in murine stem cell homing from the fetal liver into the bone marrow and its repopulation during development. SDF‐1 is highly conserved between different species. Human and murine SDF‐1 are cross‐reactive and differ in one amino acid. Recently, we reported that SDF‐1 and CXCR4 are essential for homing and repopulation of immune‐deficient NOD/SCID and B2mnull NOD/SCID mice by human stem cells. In addition, immature human CD34+ cells and primitive CD34+/CD38‐/low cells, which do not migrate toward a gradient of SDF‐1 in vitro, and do not home and repopulate in vivo the murine bone marrow, can become functional repopulating cells by short‐term 16–48 hr in vitro stimulation with cytokines such as SCF and IL‐6 prior to transplantation. These cytokines increase surface CXCR4 expression, migration toward SDF‐1, and in vivo homing and repopulation. We discuss the pleiotropic roles of SDF‐1/CXCR4 interactions in human stem cell migration, development, and repopulation in transplanted immune‐deficient mice.
Observations of Residual Differentiation Potential during Lineage Commitment
Authors: SLAYTON WILLIAM B. , MOJICA MARILUZ P. , PIERCE L. JEANNE , SPANGRUDE GERALD J.
Published: July 2010

Abstract: We have recently described a subset of the multipotent progenitor pool that contains a common lymphoid progenitor. This subset of cells is lineage negative and expresses c‐kit and Sca‐1, but lacks expression of Thy 1.1 (Thyneg). Based on the observation that lethally irradiated mice transplanted with these cells die from anemia unless supported with competitor marrow, we hypothesized that these progenitors lacked erythroid potential. We analyzed the erythroid potential of these cells by transplanting them into mice allelic at the hemoglobin locus and compared their erythroid potential with the Thy‐1.1low (Thylow) subset that contains hematopoietic stem cells. We also performed CFU‐C assays in methylcellulose containing recombinant cytokines and determined erythroid contribution to colonies using in situ benzidine staining. Donor‐derived hemoglobin was observed following transplant of Thyneg cells, even though 19 of 20 of these animals died from anemia. In contrast, recipients of Thylow cells showed complete donor‐derived engraftment 30 days following transplant. While approximately 60% of day 4 colonies derived from Thyneg cells expressed hemoglobin, by day 11 less than 5% were hemoglobinized. In contrast, greater than 70% of the Thylow subset contained hemoglobinized cells at the end of the observation period. A similar transient appearance of myeloid progeny was also observed in colonies derived from c‐kitlow Thyneg lymphoid progenitor cells. We conclude that these studies demonstrate commitment to the lymphoid lineage at the Thylow ‐to‐Thyneg interface, and that the loss of erythroid and myeloid potential is gradual rather than abrupt. Hemoglobinized colonies may be undergoing apoptosis because of down‐regulation of GATA‐1 or because of a death signal from surrounding nonerythrocytic cells.
The Monoclonal Antibody W7C5 Defines a Novel Surface Antigen on Hematopoietic Stem Cells
Authors: GIESERT CHRISTINA , ALMEIDA‐PORADA GRAÇA , SCHEFFOLD ALEXANDER , KANZ LOTHAR , ZANJANI ESMAIL D. , BÜHRING HANS‐JÖRG
Published: July 2010

Abstract: We recently raised a monoclonal antibody, termed W7C5, against a surface antigen that is expressed at low levels on bone marrow and peripheral blood CD34+ stem/progenitor cells but at high levels on fetal liver CD34+ cells. A reasonable staining intensity was achieved using magnetofluorescent liposome conjugates to analyze expression of W7C5 antigen on CD34+CD38− bone marrow (BM) cells. Flow cytometric analyses revealed that W7C5 detects about 50% of immature CD34+CD38− BM cells that coexpressed the differentiation antigens CD164, CD133, and CD172a (SIRPα). In addition, W7C5 also recognized a CD34− BM fraction. These cells were negative for CD117 and CD133, but expressed CD45 and moderate levels of CD164. Injection of selected CD34+W7C5+ and CD34−W7C5+ cells into 55–60‐day‐old fetal sheep resulted in an engraftment of both fractions. Partial amino acid sequence analysis of affinity‐purified lysates of KU‐812 cells revealed that W7C5 detects a novel membrane protein. Together, W7C5 defines a novel molecule that is expressed on CD34+ as well as on CD34− stem cell subsets.
Transplanted Adult Bone Marrow Cells Repair Myocardial Infarcts in Mice
Authors: ORLIC DONALD , KAJSTURA JAN , CHIMENTI STEFANO , BODINE DAVID M. , LERI ANNAROSA , ANVERSA PIERO
Published: July 2010

Abstract: Occlusion of the anterior descending left coronary artery leads to ischemia, infarction, and loss of function in the left ventricle. We have studied the repair of infarcted myocardium in mice using highly enriched stem/progenitor cells from adult bone marrow. The left coronary artery was ligated and 5 hours later Lin− c‐kit+ bone marrow cells obtained from transgenic male mice expressing enhanced green fluorescent protein (EGFP) were injected into the healthy myocardium adjacent to the site of the infarct. After 9 days the damaged hearts were examined for regenerating myocardium. A band of new myocardium was observed in 12 surviving mice. The developing myocytes were small and resembled fetal and neonatal myocytes. They were positive for EGFP, Y chromosome, and several myocyte‐specific proteins including cardiac myosin, and the transcription factors GATA‐4, MEF2, and Csx/Nkx2.5. The cells were also positive for connexin 43, a gap junction/intercalated disc component indicating the onset of intercellular communication. Myocyte proliferation was demonstrated by incorporation of BrdU into the DNA of dividing cells and by the presence of the cell cycle‐associated protein Ki67 in their nuclei. Neo‐vascularization was also observed in regenerating myocardium. Endothelial and smooth muscle cells in developing capillaries and small arterioles were EGFP‐positive. These cells were positive for Factor VIII and α smooth muscle actin, respectively. No myocardial regeneration was observed in damaged hearts transplanted with Lin− c‐kit− bone marrow cells, which lack bone marrow‐regenerating activity. Functional competence of the repaired left ventricle was improved for several hemodynamic parameters. These in vivo findings demonstrate the capacity of highly enriched Lin− c‐kit+ adult bone marrow cells to acutely regenerate functional myocardium within an infarcted region.
RD114‐Pseudotyped Oncoretroviral Vectors
Authors: KELLY PATRICK F. , CARRINGTON JODY , NATHWANI AMIT , VANIN ELIO F.
Published: July 2010

Abstract: Limited functional expression of the viral envelope receptor is a recognized barrier to efficient oncoretroviral mediated gene transfer. To circumvent this barrier we evaluated a number of envelope proteins with respect to gene transfer efficiency into primitive human hematopoietic stem cell populations. We observed that oncoretroviral vectors pseudotyped with the envelope protein of feline endogenous virus (RD114) could efficiently transduce human repopulating cells capable of establishing multilineage hematopoiesis in immunodeficient mice after a single exposure to RD114‐pseudotyped vector. Comparable rates of gene transfer with amphotropic and GALV‐pseudotyped vectors have been reported, but only after multiple exposures to the viral supernatant. Oncoretroviral vectors pseudotyped with the RD114 or the amphotropic envelopes had similar stability in vitro, indicating that the increased efficiency in gene transfer is at the receptor level likely due to increased receptor expression or an increased receptor affinity for the RD114 envelope. We also found that RD114‐pseudotype vectors can be efficiently concentrated, thereby removing any adverse effects of the conditioned media to the long‐term repopulating potential of the target human hematopoietic stem cell. These studies demonstrate the potential of RD114‐pseudotyped vectors for clinical use.
Stem Cell Transplantation across Major Genetic Barriers
Authors: REISNER YAIR
Published: July 2010

Abstract: Megadose haploidentical transplants, mismatched at three HLA loci, engraft rapidly and durably without induction of graft‐versus‐host disease (GVHD). In vitro studies suggest that veto cells, contained in the population of hematopoietic progenitors, facilitate this favorable outcome. Cytotoxic T cells, not reactive against the recipient but reactive against a third party, are potent veto cells and can synergize with the stem cells and facilitate allogeneic bone marrow engraftment without GVHD. Experiments with mice deficient in FasL and Fas, with transfer of FasL gene and with anti‐CD8 antibody, suggest that the veto activity associated with cytotoxic T lymphocytes (CTLs) requires simultaneous expression of FasL and CD8.
Immunological Aspects of Haploidentical Stem Cell Transplantation in Children
Authors: Handgretinger R. , Lang P. , Schumm M. , Pfeiffer M. , Gottschling S. , Demirdelen B. , Bader P. , Kuci S. , Klingebiel T. , Niethammer D.
Published: July 2010

Abstract: Thirty‐eight children with high‐risk hematological malignancies underwent transplantation with megadoses of peripheral mobilized CD34+ cells from haploidentical parents (n= 24) or from matched unrelated donors (n= 14). The CD34+ cells were isolated to a purity of >98% using magnetic‐activated cell sorting. This high purity was associated with an almost complete depletion of T lymphocytes. No pharmacological prophylaxis for graft‐versus‐host disease (GvHD) was used, and significant primary GvHD was not seen. A final engraftment was seen in all patients. Sixteen patients are alive and disease‐free with a median follow‐up of 24 months. The immunological reconstitution was faster in the patients transplanted with CD34+ stem cells from the haploidentical donors compared to the matched unrelated donors, and the transplantation of large numbers of haploidentical CD34+ stem cells seems to be superior to that of the matched unrelated donors. The phenotypical and functional analysis of the immune reconstitution provided some insights into the biology of transplantation of highly purified CD34+cells. In this article, we summarize our current results with the transplantation of highly purified stem cells and discuss possible implications for further antileukemic post‐transplant therapeutic strategies.