bluuebunny/crossref_metadata_2025 huggingface dataset:
Activation of Human Platelets by Misfolded Proteins
Authors: Herczenik Eszter , Bouma Barend , Korporaal Suzanne J.A. , Strangi Remo , Zeng Qinghong , Gros Piet , Van Eck Miranda , Van Berkel Theo J.C. , Gebbink Martijn F.B.G. , Akkerman Jan-Willem N.
Published: May 2007

Objective—

Protein misfolding diseases result from the deposition of insoluble protein aggregates that often contain fibrils called amyloid. Amyloids are found in Alzheimer disease, atherosclerosis, diabetes mellitus, and systemic amyloidosis, which are diseases where platelet activation might be implicated.

Methods and Results—

We induced amyloid properties in 6 unrelated proteins and found that all induced platelet aggregation in contrast to fresh controls. Amyloid-induced platelet aggregation was independent of thromboxane A
2
formation and ADP secretion but enhanced by feedback stimulation through these pathways. Treatments that raised cAMP (iloprost), sequestered Ca
2+
(BAPTA-AM) or prevented amyloid-platelet interaction (sRAGE, tissue-type plasminogen activator [tPA]) induced almost complete inhibition. Modulation of the function of CD36 (CD36
−/−
mice), p38
MAPK
(SB203580), COX-1 (indomethacin), and glycoprotein Ibα (Nk-protease, 6D1 antibody) induced ≈50% inhibition. Interference with fibrinogen binding (RGDS) revealed a major contribution of α
IIb
β
3
-independent aggregation (agglutination).

Conclusions—

Protein misfolding resulting in the appearance of amyloid induces platelet aggregation. Amyloid activates platelets through 2 pathways: one is through CD36, p38
MAPK
, thromboxane A
2
–mediated induction of aggregation; the other is through glycoprotein Ibα–mediated aggregation and agglutination. The platelet stimulating properties of amyloid might explain the enhanced platelet activation observed in many diseases accompanied by the appearance of misfolded proteins with amyloid.
Vascular Responses to Drug Eluting Stents
Authors: Finn Aloke V. , Nakazawa Gaku , Joner Michael , Kolodgie Frank D. , Mont Erik K. , Gold Herman K. , Virmani Renu
Published: May 2007

Polymer-based sirolimus- (Cypher) and paclitaxel-eluting (Taxus) drug eluting stents have become the treatment of choice for patients with symptomatic coronary artery disease undergoing percutaneous coronary intervention (PCI). Although these stents reduce rates of restenosis compared with bare metal stents (BMS), late thrombosis, a life threatening complication, has emerged as a major safety concern. Our understanding of the pathophysiology of late DES thrombosis is derived from animal and human pathologic samples taken after implantation of these devices. These data indicate that both DES cause substantial impairment in arterial healing characterized by lack of complete reendothelialization and persistence of fibrin when compared with BMS. This delayed healing is the primary substrate underlying all cases of late DES thrombosis at autopsy. Several additional risk factors for late stent thrombosis such as penetration of necrotic core, malapposition, overlapping stent placement, excessive stent length, and bifurcation lesions represent additional barriers to healing and should be avoided if DES are to be used to minimize the risk of late thrombosis. Because the time course of complete healing with DES in man is unknown, the optimal duration of antiplatelet treatment remains to be determined.
Serum Adipocyte Fatty Acid-Binding Protein Levels Were Independently Associated With Carotid Atherosclerosis
Authors: Yeung D.C.Y. , Xu A. , Cheung C.W.S. , Wat N.M.S. , Yau M.H. , Fong C.H.Y. , Chau M.T. , Lam K.S.L.
Published: May 2007

Objective—

Adipocyte fatty acid–binding protein (A-FABP) has been shown to be an important player in atherosclerosis in animal models. However, the clinical relevance of these findings is still unknown. This study aims to examine the relationship between serum A-FABP level and carotid intima-media thickness (IMT), an indicator of atherosclerosis in humans.

Methods and Results—

The study cohort included 479 Chinese subjects who underwent carotid IMT measurement. Serum A-FABP levels were determined by enzyme-linked immunosorbent assays. Serum A-FABP levels positively correlated with carotid IMT in both men (
r
=0.211,
P
=0.001) and women (
r
=0.435,
P
<0.001). In women, but not in men, the presence of plaques was associated with significantly higher serum A-FABP levels (
P
<0.001 versus women without plaques). Stepwise multiple regression analysis showed that serum A-FABP level was independently associated with carotid IMT in women (
P
=0.034), together with age and hypertension (both
P
<0.001).

Conclusions—

A-FABP is an independent determinant of carotid atherosclerosis in Chinese women, but not in men. This gender difference may be attributed to the lower serum A-FABP levels in men, and the effect of other risk factors, such as smoking, among our male participants. Our results have provided clinical evidence supporting the role of A-FABP in the development of atherosclerosis.
Improvements in Speed-Based Gait Classifications Are Meaningful
Authors: Schmid Arlene , Duncan Pamela W. , Studenski Stephanie , Lai Sue Min , Richards Lorie , Perera Subashan , Wu Samuel S.
Published: May 2007

Background and Purpose—

Gait velocity is a powerful indicator of function and prognosis after stroke. Gait velocity can be stratified into clinically meaningful functional ambulation classes, such as household ambulation (<0.4 m/s), limited community ambulation (0.4 to 0.8 m/s), and full community ambulation (>0.8 m/s). The purpose of the current study was to determine whether changes in velocity-based community ambulation classification were related to clinically meaningful changes in stroke-related function and quality of life.

Methods—

In subacute stroke survivors with mild to moderate deficits who participated in a randomized clinical trial of stroke rehabilitation and had a baseline gait velocity of 0.8 m/s or less, we assessed the effect of success versus failure to achieve a transition to the next class on function and quality of life according to domains of the Stroke Impact Scale (SIS).

Results—

Of 64 eligible participants, 19 were initially household ambulators, and 12 of them (68%) transitioned to limited community ambulation, whereas of 45 initially limited community ambulators, 17 (38%) became full community ambulators. Function and quality-of-life SIS scores after treatment were significantly higher among survivors who achieved a favorable transition compared with those who did not. Among household ambulators, those who transitioned to limited or full community ambulation had significantly better SIS scores in mobility (
P
=0.0299) and participation (
P
=0.0277). Among limited community ambulators, those who achieved the transition to full community ambulatory status had significantly better scores in SIS participation (
P
=0.0085).

Conclusions—

A gait velocity gain that results in a transition to a higher class of ambulation results in better function and quality of life, especially for household ambulators. Household ambulators possibly had more severe stroke deficits, reducing the risk of “ceiling” effects in SIS-measured activities of daily living and instrumental activities of daily living. Outcome assessment based on transitions within a mobility classification scheme that is rooted in gait velocity yields potentially meaningful indicators of clinical benefit. Outcomes should be selected that are clinically meaningful for all levels of severity.
Longitudinal Changes in Cerebral Blood Flow in the Older Hypertensive Brain
Authors: Beason-Held Lori L. , Moghekar Abhay , Zonderman Alan B. , Kraut Michael A. , Resnick Susan M.
Published: May 2007

Background and Purpose—

Changes in patterns of regional cerebral blood flow (rCBF) were assessed over a period of 6 years in 14 treated hypertensive participants (HTNs) and 14 age-matched healthy older participants (healthy controls [HCs]) in the Baltimore Longitudinal Study of Aging.

Methods—

Resting-state PET scans collected at years 1, 3, 5, and 7 were used to determine differences in longitudinal patterns of rCBF change in HTNs relative to HCs. Pulse pressure, arterial pressure, systolic/diastolic blood pressure, and hypertension duration were also correlated with patterns of rCBF change in the HTN group.

Results—

Relative to HCs, the HTN group shows greater rCBF decreases in prefrontal, anterior cingulate, and occipital areas over time, suggesting that these regions are more susceptible to hypertension-related dysfunction with advancing age. The HTN group also fails to show preservation of function over time in motor regions and in the temporal cortex and hippocampus as observed in HC. Although pulse pressure, mean arterial pressure, and systolic and diastolic pressure all correlate similarly with longitudinal rCBF changes, increased duration of hypertension is associated with decreased rCBF in prefrontal and anterior cingulate areas of functional vulnerability observed in the HTN group.

Conclusions—

These results show that hypertension significantly affects resting brain function in older individuals and suggest that duration of hypertension contributes significantly to the patterns of change over time.
Clinical Significance of Microbleeds in Subcortical Vascular Dementia
Authors: Won Seo Sang , Hwa Lee Byung , Kim Eun-Joo , Chin Juhee , Sun Cho Yoon , Yoon Uicheul , Na Duk L.
Published: May 2007

Background and Purpose—

Despite many studies investigating the association between the ischemic changes and cognitive impairment in subcortical vascular dementia (SVaD), few studies correlated cognitive impairment with microbleeds (MBs) frequently seen in SVaD.

Methods—

Participants consisted of 86 patients with SVaD who fulfilled the criteria proposed by Erkinjuntti et al.

Results—

MBs occurred in 73 of 86 (84.9%) patients with SVaD. MBs were most commonly distributed in the cortex, and the cortical MBs were most pronounced in the temporoparietal area. A multiple regression showed that the number of cerebral MB was an independent predictor of cognitive impairment in multiple domains and the severity of dementia even after controlling confounding factors such as age, education, ischemic severity, and number of lacunes.

Conclusion—

These results indicate that cerebral MB is one of the important factors that cause cognitive impairments in SVaD.
Intravenous Brain-Derived Neurotrophic Factor Enhances Poststroke Sensorimotor Recovery and Stimulates Neurogenesis
Authors: Schäbitz Wolf-Rüdiger , Steigleder Tobias , Cooper-Kuhn Christiana M. , Schwab Stefan , Sommer Clemens , Schneider Armin , Kuhn H. Georg
Published: May 2007

Background and Purpose—

The discovery of spontaneous neuronal replacement in the adult brain has shifted experimental stroke therapies toward a combined approach of preventing neuronal cell death and inducing neuronal plasticity. Brain-derived neurotrophic factor (BDNF) was shown to induce antiapoptotic mechanisms after stroke and to reduce infarct size and secondary neuronal cell death. Moreover, in intact animals, BDNF is a potent stimulator of adult neurogenesis.

Methods—

The current study analyzed the effects of BDNF on induction of neuronal progenitor cell migration and sensorimotor recovery after cortical photothrombotic stroke.

Results—

Daily intravenous bolus applications of BDNF during the first 5 days after stroke resulted in significantly improved sensorimotor scores up to 6 weeks. At the structural level, BDNF significantly increased neurogenesis in the dentate gyrus and enhanced migration of subventricular zone progenitor cells to the nearby striatum of the ischemic hemisphere. BDNF treatment could not, however, further stimulate progenitor cell recruitment to the cortex.

Conclusions—

These findings consolidate the role of BDNF as a modulator of neurogenesis in the brain and as an enhancer of long-term functional neurological outcome after cerebral ischemia.
Readmission and Death After Hospitalization for Acute Ischemic Stroke
Authors: Bravata Dawn M. , Ho Shih-Yieh , Meehan Thomas P. , Brass Lawrence M. , Concato John
Published: May 2007

Background and Purpose—

Stroke is a leading cause of hospital admission among the elderly. Although studies have examined subsequent vascular outcomes, limited data are available regarding the full burden of hospital readmission after stroke. We sought to determine the rates of hospital readmissions and mortality and the reasons for readmission over a 5-year period after stroke.

Methods—

This retrospective observational cohort study included Medicare beneficiaries aged >65 years who survived hospitalization for an acute ischemic stroke (International Classification of Diseases, Ninth Revision, Clinical Modification codes 434 and 436) and who were discharged from Connecticut acute care hospitals in 1995. This population was followed from discharge in 1995 through 2000 using part A Medicare claims and Social Security Administration mortality data. The primary outcome was hospital readmission and mortality and readmission diagnosis.

Results—

Among 2603 patients discharged alive, more than half had died or been readmitted at least once during the first year after discharge (1388/2603, 53.3%), and <15% survived admission-free for 5 years (372/2603, 14.3%). The reasons for hospital readmission varied over time, with stroke remaining a leading cause for readmission (3.9 to 6.1% of patients annually). Acute myocardial infarction accounted for a comparable number of readmissions (4.2 to 6.0% of patients annually). The most common diagnostic category associated with readmission, however, was pneumonia or respiratory illnesses, with an annual readmission rate between 8.2% and 9.0% throughout the first 5 years after stroke.

Conclusions—

Few stroke patients survive for 5 years without a hospital readmission. Between the acute care setting and readmission to the hospital, a window of opportunity may exist for interventions, beyond prevention of recurrent vascular events alone, to reduce the huge public health burden of poststroke morbidity.
International Uncertainty, Foreign Policy Flexibility, and Surplus Majority Coalitions in Israel
Authors: Stinnett Douglas M.
Published: May 2007

This article explains the prevalence of surplus majority government coalitions in Israel as a result of the interaction between international uncertainty and the need to preserve both government stability and latitude in the conduct of foreign policy. I develop a game-theoretic model of government formation in which the international environment is a source of uncertainty for the policy preferences of the prime minister. The model predicts that when uncertainty is high enough, it is optimal for the prime minister to establish an oversized coalition government. By including expendable parties in a government, the prime minister has greater freedom to modify foreign policy in response to the international environment without jeopardizing majority status in parliament. The logic of the model is analyzed through two case studies: Menachem Begin, 1977-1981, and Ehud Barak, 1999-2000. The findings of the model have larger theoretical implications for the connection between domestic politics and international relations.
War Aims and War Outcomes
Authors: Sullivan Patricia L.
Published: May 2007

Why are states with tremendous advantages in capabilities and resources often unable to attain even limited objectives vis-à-vis much weaker adversaries? The theory I develop focuses on how the nature of a strong state's war aims affects prewar uncertainty about the cost of victory. I argue that the relative magnitude of the effect of military strength and resolve on war outcomes varies with the nature of the object at stake and that strong states become more likely to underestimate the cost of victory as the impact of resolve increases relative to that of war-fighting capacity. I evaluate the empirical implications of this theory against the historical record provided by the universe of major power military interventions since World War II. The results challenge both existing theories and conventional wisdom about the impact of factors such as military strength, resolve, troop commitment levels, and war-fighting strategies on asymmetric war outcomes.
Asymmetric Conflict
Authors: Clark Derek J. , Konrad Kai A.
Published: May 2007

The authors study conflict on multiple fronts. A defending player needs to successfully defend all fronts, and an attacker needs to win at only one. Multiple fronts result in a considerable disadvantage for the defending player, and even if there is a defense advantage at each of them, the payoff of the defending player is zero if the number of fronts is large. With some positive probability, in the equilibrium defending players surrender without expending effort.
Feminism and Profit in American Hospitals
Authors: Thomas Jan E. , Zimmerman Mary K.
Published: May 2007

This article provides a critical analysis of the evolution and impact of hospital-sponsored women's health centers. Using original data gathered from interviews, participant observation, and content analysis of documents and brochures, the authors describe the development of four models of hospital-sponsored women's health centers and illustrate three specific mechanisms of the co-optation process. They show how many elements of feminist health care were used for the purpose of marketing and revenue production rather than for empowering women and transforming the delivery of care. Following Stratigaki's notion of negative countereffect, the authors show how the key feminist concepts of women-centered care and empowerment ended up contradicting their original meaning and purpose. Rather than being the subject of care, women became the object of treatment and revenue production.
“Is This What Motherhood is All About?”
Authors: Miller Tina
Published: May 2007

This article focuses on transition to first-time motherhood and explores the experiences of a group of women as they anticipate, give birth, and engage in early mothering. It illuminates how these women draw on, weave together, and challenge dominant strands of discourse that circumscribe their journeys into motherhood. Using qualitative longitudinal data, prenatal and postnatal episodes of transition are explored. The analysis and juxtaposing of these data reveal the different ways women anticipate and gradually make sense of becoming mothers. While there is a disjuncture between expectations and experiences for these new mothers, this article draws attention to the different ways women discursively position themselves through transition. It reveals how birth experiences can act as a discursive turning point and underscores the obduracy of some strands of dominant discourse. These findings contribute to a subtler and more nuanced understanding of the dynamic interplay between personal experience and gendered discourses.
Strengthening Community Leadership: Evaluation Findings From the California Healthy Cities and Communities Program
Authors: Kegler Michelle C. , Norton Barbara L. , Aronson Robert E.
Published: May 2007

Collaborative approaches to community health improvement such as healthy cities and communities have the potential to strengthen community capacity through leadership development. The healthy cities and communities process orients existing local leadership to new community problem-solving strategies and draws out leadership abilities among residents not previously engaged in civic life. In an evaluation of the California Healthy Cities and Communities (CHCC) Program, leadership development was one of several outcomes assessed at the civic-participation level of the social ecology. Data collection methods included focus groups and surveys, semistructured interviews with coordinators and community leaders, and review of program documents. Findings suggest that the CHCC program enhanced capacity by expanding new leadership opportunities through coalition participation, program implementation, and civic leadership roles related to spin-off organizations and broader collaborative structures. Communities in rural regions were particularly successful in achieving significant leadership outcomes.
Bone marrow CD8 cells down-modulate membrane IL-7Rα expression and exhibit increased STAT-5 and p38 MAPK phosphorylation in the organ environment.
Authors: Cassese Giuliana , Parretta Elisabetta , Pisapia Laura , Santoni Angela , Guardiola John , Di Rosa Francesca
Published: May 2007

By comparing mature CD8-cell turnover in different organs, we previously demonstrated that CD8 cells proliferate predominantly in the bone marrow (BM). To investigate the mechanisms underlying such increased turnover, we compared BM, lymph nodes, and spleen CD8 cells from untreated C57BL/6 mice regarding in vivo proliferation within the organ; in vitro response to interleukin-7 (IL-7), IL-15, IL-21; ex vivo expression of membrane CD127 (IL-7Rα), intracellular Bcl-2, phospho–STAT-5 (signal transducer and activator of transcription 5), phospho-p38 mitogen activated protein kinase (MAPK); and in vivo proliferation on adoptive transfer. In the BM, the proliferation rate was increased for either total CD8 cells or individual CD44 and CD122 subsets. In contrast, purified CD8+ cells from the BM did not show an enhanced in vitro proliferative response to IL-7, IL-15, and IL-21 compared with corresponding spleen cells. After transfer and polyinosinic-polycytidylic acid (polyI:C) treatment, both spleen-derived and BM-derived CD8 cells from congenic donors proliferated approximately twice more in the recipient BM than in spleen and lymph nodes. Our results suggest that BM CD8 cells are not committed to self-renewal, but rather are stimulated in the organ. Molecular events constantly induced in the CD8 cells within the BM of untreated mice include increase of both phosphorylated STAT-5 and phosphorylated p38 intracellular levels, and the reduction of CD127 membrane expression.
The SOCS box of suppressor of cytokine signaling-3 contributes to the control of G-CSF responsiveness in vivo
Authors: Boyle Kristy , Egan Paul , Rakar Steven , Willson Tracy A. , Wicks Ian P. , Metcalf Donald , Hilton Douglas J. , Nicola Nicos A. , Alexander Warren S. , Roberts Andrew W. , Robb Lorraine
Published: May 2007

Suppressor of cytokine signaling 3 (SOCS3) is a negative regulator of granulocyte-colony stimulating factor (G-CSF) signaling in vivo. SOCS proteins regulate cytokine signaling by binding, via their SH2 domains, to activated cytokine receptors or their associated Janus kinases. In addition, they bind to the elongin B/C ubiquitin ligase complex via the SOCS box. To ascertain the contribution of the SOCS box of SOCS3 to in vivo regulation of G-CSF signaling, we generated mice expressing a truncated SOCS3 protein lacking the C-terminal SOCS box (SOCS3ΔSB/ΔSB). SOCS3ΔSB/ΔSB mice were viable, had normal steady-state hematopoiesis, and did not develop inflammatory disease. Despite the mild phenotype, STAT3 activation in response to G-CSF signaling was prolonged in SOCS3ΔSB/ΔSB bone marrow. SOCS3ΔSB/ΔSB bone marrow contained increased numbers of colony-forming cells responsive to G-CSF and IL-6. Treatment of the mice with pharmacologic doses of G-CSF, which mimics emergency granulopoiesis and therapeutic use of G-CSF, revealed that SOCS3ΔSB/ΔSB mice were hyperresponsive to G-CSF. Compared with wild-type mice, SOCS3ΔSB/ΔSB mice developed a more florid arthritis when tested using an acute disease model. Overall, the results establish a role for the SOCS box of SOCS3 in the in vivo regulation of G-CSF signaling and the response to inflammatory stimuli.
Phospholipase C and myosin light chain kinase inhibition define a common step in actin regulation during cytokinesis
Authors: Wong Raymond , Fabian Lacramioara , Forer Arthur , Brill Julie A
Published: May 2007

Background

Phosphatidylinositol 4,5-bisphosphate (PIP2) is required for successful completion of cytokinesis. In addition, both PIP2 and phosphoinositide-specific phospholipase C (PLC) have been localized to the cleavage furrow of dividing mammalian cells. PLC hydrolyzes PIP2 to yield diacylglycerol (DAG) and inositol trisphosphate (IP3), which in turn induces calcium (Ca2+) release from the ER. Several studies suggest PIP2 must be hydrolyzed continuously for continued cleavage furrow ingression. The majority of these studies employ the N-substituted maleimide U73122 as an inhibitor of PLC. However, the specificity of U73122 is unclear, as its active group closely resembles the non-specific alkylating agent N-ethylmaleimide (NEM). In addition, the pathway by which PIP2 regulates cytokinesis remains to be elucidated.

Results

Here we compared the effects of U73122 and the structurally unrelated PLC inhibitor ET-18-OCH3 (edelfosine) on cytokinesis in crane-fly and Drosophila spermatocytes. Our data show that the effects of U73122 are indeed via PLC because U73122 and ET-18-OCH3 produced similar effects on cell morphology and actin cytoskeleton organization that were distinct from those caused by NEM. Furthermore, treatment with the myosin light chain kinase (MLCK) inhibitor ML-7 caused cleavage furrow regression and loss of both F-actin and phosphorylated myosin regulatory light chain from the contractile ring in a manner similar to treatment with U73122 and ET-18-OCH3.

Conclusion

We have used multiple inhibitors to examine the roles of PLC and MLCK, a predicted downstream target of PLC regulation, in cytokinesis. Our results are consistent with a model in which PIP2 hydrolysis acts via Ca2+ to activate myosin via MLCK and thereby control actin dynamics during constriction of the contractile ring.
Variation of the Myelin Oligodendrocyte Glycoprotein gene is not primarily associated with multiple sclerosis in the Sardinian population
Authors: Marrosu Maria Giovanna , Murru Raffaele , Costa Gianna , Melis Maria Cristina , Rolesu Marcella , Schirru Lucia , Solla Elisabetta , Cuccu Stefania , Secci Maria Antonietta , Whalen Michael B , Cocco Eleonora , Pugliatti Maura , Sotgiu Stefano , Rosati Giulio , Cucca Francesco
Published: May 2007

Background

Multiple sclerosis (MS) is consistently associated with particular HLA-DRB1-DQB1haplotypes. However, existing evidence suggests that variation at these loci does not entirely explain association of the HLA region with the disease. TheMOGlocus is a prime positional and functional candidate for such additional predisposing effects but the analysis is complicated by the strong, albeit labyrinthine pattern of linkage disequilibrium in the region. Here we have assessed the association ofMOGvariation with MS in the Sardinian population to see if it represents an independent contributor to MS predisposition.

Results

After re-sequencing theMOGgene in 21 healthy parents of MS patients we detected 134 variants, 33 of which were novel. A set of 40 informative SNPs was then selected and assessed for disease association together with 1 intragenic microsatellite in an initial data set of 239 MS families. This microsatellite and 11 SNPs were found to be positively associated with MS, using the transmission disequilibrium test, and were followed up in an additional 158 families (total families analysed = 397). While in these 397 families, 8 markers showed significant association with MS, through conditional tests we determined that theseMOGvariants were not associated with MS independently of the mainDRB1-DQB1disease associations.

Conclusion

These results indicate that variation within theMOGgene is not an important independent determinant of MS-inherited risk in the Sardinian population.
Phase variation and microevolution at homopolymeric tracts in Bordetella pertussis
Authors: Gogol Emily B , Cummings Craig A , Burns Ryan C , Relman David A
Published: May 2007

Background

Bordetella pertussis, the causative agent of whooping cough, is a highly clonal pathogen of the respiratory tract. Its lack of genetic diversity, relative to many bacterial pathogens, could limit its ability to adapt to a hostile and changing host environment. This limitation might be overcome by phase variation, as observed for other mucosal pathogens. One of the most common mechanisms of phase variation is reversible expansion or contraction of homopolymeric tracts (HPTs).

Results

The genomes of B. pertussis and the two closely related species, B. bronchiseptica and B. parapertussis, were screened for homopolymeric tracts longer than expected on the basis of chance, given their nucleotide compositions. Sixty-nine such HPTs were found in total among the three genomes, 74% of which were polymorphic among the three species. Nine HPTs were genotyped in a collection of 90 geographically and temporally diverse B. pertussis strains using the polymerase chain reaction/ligase detection reaction (PCR/LDR) assay. Six HPTs were polymorphic in this collection of B. pertussis strains. Of note, one of these polymorphic HPTs was found in the fimX promoter, where a single base insertion variant was present in seven strains, all of which were isolated prior to introduction of the pertussis vaccine. Transcript abundance of fimX was found to be 3.8-fold lower in strains carrying the longer allele. HPTs in three other genes, tcfA, bapC, and BP3651, varied widely in composition across the strain collection and displayed allelic polymorphism within single cultures.

Conclusion

Allelic polymorphism at homopolymeric tracts is common within the B. pertussis genome. Phase variability may be an important mechanism in B. pertussis for evasion of the immune system and adaptation to different niches in the human host. High sensitivity and specificity make the PCR/LDR assay a powerful tool for investigating allelic variation at HPTs. Using this method, allelic diversity and phase variation were demonstrated at several B. pertussis loci.
Purification and preliminary crystallization of alanine racemase from Streptococcus pneumoniae
Authors: Strych Ulrich , Davlieva Milya , Longtin Joseph P , Murphy Eileen L , Im Hookang , Benedik Michael J , Krause Kurt L
Published: May 2007

Background

Over the past fifteen years, antibiotic resistance in the Gram-positive opportunistic human pathogen Streptococcus pneumoniae has significantly increased. Clinical isolates from patients with community-acquired pneumonia or otitis media often display resistance to two or more antibiotics. Given the need for new therapeutics, we intend to investigate enzymes of cell wall biosynthesis as novel drug targets. Alanine racemase, a ubiquitous enzyme among bacteria and absent in humans, provides the essential cell wall precursor, D-alanine, which forms part of the tetrapeptide crosslinking the peptidoglycan layer.

Results

The alanine racemases gene from S. pneumoniae (alr

SP
) was amplified by PCR and cloned and expressed in Escherichia coli. The 367 amino acid, 39854 Da dimeric enzyme was purified to electrophoretic homogeneity and preliminary crystals were obtained. Racemic activity was demonstrated through complementation of an alr auxotroph of E. coli growing on L-alanine. In an alanine racemases photometric assay, specific activities of 87.0 and 84.8 U mg-1 were determined for the conversion of D- to L-alanine and L- to D-alanine, respectively.

Conclusion

We have isolated and characterized the alanine racemase gene from the opportunistic human pathogen S. pneumoniae. The enzyme shows sufficient homology with other alanine racemases to allow its integration into our ongoing structure-based drug design project.
Duplication of the dystroglycan gene in most branches of teleost fish
Authors: Pavoni Ernesto , Cacchiarelli Davide , Tittarelli Roberta , Orsini Massimiliano , Galtieri Antonio , Giardina Bruno , Brancaccio Andrea
Published: May 2007

Background

The dystroglycan (DG) complex is a major non-integrin cell adhesion system whose multiple biological roles involve, among others, skeletal muscle stability, embryonic development and synapse maturation. DG is composed of two subunits: α-DG, extracellular and highly glycosylated, and the transmembrane β-DG, linking the cytoskeleton to the surrounding basement membrane in a wide variety of tissues. A single copy of the DG gene (DAG1) has been identified so far in humans and other mammals, encoding for a precursor protein which is post-translationally cleaved to liberate the two DG subunits. Similarly, D. rerio (zebrafish) seems to have a single copy of DAG1, whose removal was shown to cause a severe dystrophic phenotype in adult animals, although it is known that during evolution, due to a whole genome duplication (WGD) event, many teleost fish acquired multiple copies of several genes (paralogues).

Results

Data mining of pufferfish (T. nigroviridis and T. rubripes) and other teleost fish (O. latipes and G. aculeatus) available nucleotide sequences revealed the presence of two functional paralogous DG sequences. RT-PCR analysis proved that both the DG sequences are transcribed in T. nigroviridis. One of the two DG sequences harbours an additional mini-intronic sequence, 137 bp long, interrupting the uncomplicated exon-intron-exon pattern displayed by DAG1 in mammals and D. rerio. A similar scenario emerged also in D. labrax (sea bass), from whose genome we have cloned and sequenced a new DG sequence that also harbours a shorter additional intronic sequence of 116 bp. Western blot analysis confirmed the presence of DG protein products in all the species analysed including two teleost Antarctic species (T. bernacchii and C. hamatus).

Conclusion

Our evolutionary analysis has shown that the whole-genome duplication event in the Class Actinopterygii (ray-finned fish) involved also DAG1. We unravelled new important molecular genetic details about fish orthologous DGs, which might help to increase the current knowledge on DG expression, maturation and targeting and on its physiopathological role in higher organisms.
Access to electronic health knowledge in five countries in Africa: a descriptive study
Authors: Smith Helen , Bukirwa Hasifa , Mukasa Oscar , Snell Paul , Adeh-Nsoh Sylvester , Mbuyita Selemani , Honorati Masanja , Orji Bright , Garner Paul
Published: May 2007

Background

Access to medical literature in developing countries is helped by open access publishing and initiatives to allow free access to subscription only journals. The effectiveness of these initiatives in Africa has not been assessed. This study describes awareness, reported use and factors influencing use of on-line medical literature via free access initiatives.

Methods

Descriptive study in four teaching hospitals in Cameroon, Nigeria, Tanzania and Uganda plus one externally funded research institution in The Gambia. Survey with postgraduate doctors and research scientists to determine Internet access patterns, reported awareness of on-line medical information and free access initiatives; semi structured interviews with a sub-sample of survey participants to explore factors influencing use.

Results

In the four African teaching hospitals, 70% of the 305 postgraduate doctors reported textbooks as their main source of information; 66% had used the Internet for health information in the last week. In two hospitals, Internet cafés were the main Internet access point. For researchers at the externally-funded research institution, electronic resources were their main source, and almost all had used the Internet in the last week. Across all 333 respondents, 90% had heard of PubMed, 78% of BMJ on line, 49% the Cochrane Library, 47% HINARI, and 19% BioMedCentral. HINARI use correlates with accessing the Internet on computers located in institutions. Qualitative data suggested there are difficulties logging into HINARI and that sometimes it is librarians that limit access to passwords.

Conclusion

Text books remain an important resource for postgraduate doctors in training. Internet use is common, but awareness of free-access initiatives is limited. HINARI and other initiatives could be more effective with strong institutional endorsement and management to promote and ensure access.
A doxycycline-inducible urokinase receptor (uPAR) upregulates uPAR activities including resistance to anoikis in human prostate cancer cell lines
Authors: Hasanuzzaman Mohammad , Kutner Robert , Agha-Mohammadi Siamak , Reiser Jakob , Sehgal Inder
Published: May 2007

Background

The urokinase receptor (uPAR) mediates a diverse array of cellular processes including several events involved in prostate cancer metastasis. Many of these activities are initiated or enhanced by uPAR binding to its proteolytic ligand, urokinase (uPA). Our objective in this study was to generate and test an inducible lentiviral system capable of expressing uPAR and DsRed fluorescent protein in human prostate cancer cell lines.

Results

A DsRed-uPAR fusion construct was inserted into a lentiviral vector. Transduction of human prostate cancer cell lines with this virus and with a virus containing a reverse-tetracycline transactivator (rt-TA) resulted in a stable transgene which induced both uPAR and DsRed proteins in a dose-responsive fashion upon stimulation with doxycycline. Immunoblots and immunofluorescence studies indicated no detectable uPAR expression in non-induced prostate cancer cell lines. Cells with induced-uPAR demonstrated increased cellular adhesion to the matrix substrate vitronectin and increased net cell proliferation compared to uninduced cells. Finally, induced uPAR-expressing prostate cancer cells were resistant to anoikis over an extended time period when grown in suspension.

Conclusion

This doxycycline-inducible lentivirus system produces titerable levels of biologically active uPAR in vitro. This tool can be used to dissect cellular events following induction of uPAR in prostate cancer cells.
Immunogenicity of the outer domain of a HIV-1 clade C gp120
Authors: Chen Hongying , Xu Xiaodong , Jones Ian M
Published: May 2007

Background

The possibility that a sub domain of a C clade HIV-1 gp120 could act as an effective immunogen was investigated. To do this, the outer domain (OD) of gp120CN54was expressed and characterized in a construct marked by a re-introduced conformational epitope for MAb 2G12. The expressed sequence showed efficient epitope retention on the isolated ODCN54suggesting authentic folding. To facilitate purification and subsequent immunogenicity ODCN54was fused to the Fc domain of human IgG1. Mice were immunised with the resulting fusion proteins and also with gp120CN54-Fc and gp120 alone.

Results

Fusion to Fc was found to stimulate antibody titre and Fc tagged ODCN54was substantially more immunogenic than non-tagged gp120. Immunogenicity appeared the result of Fc facilitated antigen processing as immunisation with an Fc domain mutant that reduced binding to the FcR lead to a reduction in antibody titre when compared to the parental sequence. The breadth of the antibody response was assessed by serum reaction with five overlapping fragments of gp120CN54expressed as GST fusion proteins in bacteria. A predominant anti-inner domain and anti-V3C3 response was observed following immunisation with gp120CN54-Fc and an anti-V3C3 response to the ODCN54-Fc fusion.

Conclusion

The outer domain of gp120CN54is correctly folded following expression as a C terminal fusion protein. Immunogenicity is substantial when targeted to antigen presenting cells but shows V3 dominance in the polyvalent response. The gp120 outer domain has potential as a candidate vaccine component.
Meiosis specific coiled-coil proteins in Shizosaccharomyces pombe
Authors: Ohtaka Ayami , Saito Takamune T , Okuzaki Daisuke , Nojima Hiroshi
Published: May 2007

Many meiosis-specific proteins in Schizosaccharomyces pombe contain coiled-coil motifs which play essential roles for meiotic progression. For example, the coiled-coil motifs present in Meu13 and Mcp7 are required for their function as a putative recombinase cofactor complex during meiotic recombination. Mcp6/Hrs1 and Mcp5/Num1 control horsetail chromosome movement by astral microtubule organization and anchoring dynein respectively. Dhc1 and Ssm4 are also required for horsetail chromosome movement. It is clear from these examples that the coiled-coil motif in these proteins plays an important role during the progression of cells through meiosis. However, there are still many unanswered questions on how these proteins operate. In this paper, we briefly review recent studies on the meiotic coiled-coil proteins in Sz. pombe.
Sp8 exhibits reciprocal induction with Fgf8 but has an opposing effect on anterior-posterior cortical area patterning
Authors: Sahara Setsuko , Kawakami Yasuhiko , Izpisua Belmonte Juan Carlos , O'Leary Dennis DM
Published: May 2007

Telencephalic patterning centers, defined by the discrete expression domains of distinct morphogens, Fgf s in the commissural plate (CoP), Wnt s and Bmp s in the cortical hem, and a ventral domain of Sonic hedgehog (Shh), are postulated to establish during development the initial patterning of the telencepahlon, including the neocortex. We show that the expression patterns of Sp5, Sp8, and Sp9, members of the Sp8-like family that are homologues of Drosophila buttonhead, correlate during early embryonic development with these three telencephalic patterning centers. To study potential functional relationships, we focused on Sp8, because it is transiently expressed in the CoP coincident with the expression of Fgf8, a morphogen implicated in area patterning of the neocortex. We also show that Sp8 is expressed in cortical progenitors in a high to low anterior-medial to posterior-lateral gradient across the ventricular zone. We used in utero electroporation of full-length and chimeric expression constructs to perform gain-of-function and loss-of-function studies of interactions between Sp8 and Fgf8 and their roles in cortical area patterning. We show that Fgf8 and Sp8 exhibit reciprocal induction in vivo in the embryonic telencephalon. Sp8 also induces downstream targets of Fgf8, including ETS transcription factors. In vitro assays show that Sp8 binds Fgf8 regulatory elements and is a direct transcriptional activator of Fgf8. We also show that Sp8 induction of Fgf8 is repressed by Emx2 in vitro, suggesting a mechanism to limit Fgf8 expression to the CoP. In vivo expression of a dominant negative Sp8 in the CoP indicates that Sp8 maintains expression of Fgf8 and also its effect on area patterning. Ectopic expression of Sp8 in anterior or posterior cortical poles induces significant anterior or posterior shifts in area patterning, respectively, paralleled by changes in expression of gene markers of positional identity. These effects of Sp8 on area patterning oppose those induced by ectopic expression of Fgf8, suggesting that in parallel to regulating Fgf8 expression, Sp8 also activates a distinct signaling pathway for cortical area patterning. In summary, Sp8 and Fgf8 robustly induce one another, and may act to balance the anterior-posterior area patterning of the cortex.
Pro-apoptotic Bid is required for the resolution of the effector phase of inflammatory arthritis
Authors: Scatizzi John C , Hutcheson Jack , Bickel Emily , Haines G aKenneth , Perlman Harris
Published: May 2007

Rheumatoid arthritis is an autoimmune disease characterized by hyperplasia of the synovial lining and destruction of cartilage and bone. Recent studies have suggested that a lack of apoptosis contributes to the hyperplasia of the synovial lining and to the failure in eliminating autoreactive cells. Mice lacking Fas or Bim, two pro-apoptotic proteins that mediate the extrinsic and intrinsic death cascades, respectively, develop enhanced K/BxN serum transfer-induced arthritis. Since the pro-apoptotic protein Bid functions as an intermediate between the extrinsic and intrinsic apoptotic pathways, we examined the role that it plays in inflammatory arthritis. Mice deficient in Bid (Bid-/-) show a delay in the resolution of K/BxN serum transfer-induced arthritis. Bid-/- mice display increased inflammation, bone destruction, and pannus formation compared to wild-type mice. Furthermore, Bid-/- mice have elevated levels of CXC chemokine and IL-1β in serum, which are associated with more inflammatory cells throughout the arthritic joint. In addition, there are fewer apoptotic cells in the synovium of Bid-/- compared to Wt mice. These data suggest that extrinsic and intrinsic apoptotic pathways cooperate through Bid to limit development of inflammatory arthritis.
Diagnostic yield of quantitative endotracheal aspirates in patients with severe nursing home-acquired pneumonia
Authors: El Solh Ali A , Akinnusi Morohunfolu E , Pineda Lilibeth A , Mankowski Corey R
Published: May 2007

Introduction

Diagnostic strategies based on tracheal aspirates in patients with severe nursing home-acquired pneumonia have not previously been evaluated. The objectives of the study were to investigate, in patients with severe nursing home-acquired pneumonia, the diagnostic value of quantitative endotracheal aspirate (QEA) cultures using increasing interpretative cutoff points, as compared with bronchoalveolar lavage (BAL) and protected specimen brush (PSB) quantitative cultures.

Methods

Seventy-five nursing home patients requiring mechanical ventilation for suspected pneumonia were studied. Endotracheal aspirate, PSB, and BAL samples were obtained consecutively. The diagnostic yield of QEA at thresholds raging from 103 to 107 colony-forming units (cfu)/ml was assessed by calculating sensitivities, specificities, and accuracy rates. A receiver operator characteristic curve for the series of cutoff points was constructed.

Results

Forty-nine patients were diagnosed with pneumonia either by BAL (≤ 104 cfu/ml) or PSB (≤ 103 cfu/ml). Diagnostic accuracy of QEA was most favorable at 104 cfu/ml. At this threshold, endotracheal aspirates coincided with both BAL and PSB in 30 cases, whereas partial agreement was observed in 14 cases. This resulted in sensitivity and specificity of 90% (95% confidence interval 78% to 97%) and 77% (95% confidence interval 56% to 91%), respectively. QEA findings correlated significantly with both PSB and BAL quantitative cultures (r = 0.71 [P < 0.001] and r = 0.77 [P < 0.001], respectively).

Conclusion

QEA may be used as a diagnostic tool to determine the presence of pneumonia in ventilated patients admitted from nursing homes when bronchoscopic procedures are not feasible or available.