bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is There a Typical Germinal Center? A Large-Scale Immunohistological Study on the Cellular Composition of Germinal Centers during the Hapten-Carrier–Driven Primary Immune Response in Mice
Authors: Wittenbrink Nicole , Klein Anke , Weiser Armin A. , Schuchhardt Johannes , Or-Guil Michal 
Published: November 2011

Abstract
Germinal centers (GCs) are complex, multicell-type, transient structures that form in secondary lymphatic tissues in response to T cell-dependent stimulation. This process is crucial to the adaptive immune response because it is the source of affinity maturation and long-lived B cell memory. Our previous studies showed that the growth of murine splenic GCs is nonsynchronized, involving broad-volume distributions of individual GCs at any time. This raises the question whether such a thing as a typical GC exists. To address this matter, we acquired large-scale confocal data on GCs throughout the course of the 2-phenyl-5-oxazolone chicken serum albumin-driven primary immune response in BALB/c mice. Semiautomated image analysis of 3457 GC sections revealed that, although there is no typical GC in terms of size, GCs have a typical cellular composition in that the cell ratios of resident T cells, macrophages, proliferating cells, and apoptotic nuclei are maintained during the established phase of the response. Moreover, our data provide evidence that the dark zone (DZ) and light zone (LZ) compartments of GCs are about the same size and led us to estimate that the minimal cell loss rate in GCs is 3% per hour. Furthermore, we found that the population of GC macrophages is larger and more heterogeneous than previously thought, and that despite enrichment of T cells in the LZ, the DZ of murine splenic GCs is not poor in T cells. DZ and LZ differ in the T cell-to-macrophage ratio rather than in the density of T cells.
Interaction of Streptavidin-Based Peptide–MHC Oligomers (Tetramers) with Cell-Surface TCRs
Authors: Stone Jennifer D. , Artyomov Maxim N. , Chervin Adam S. , Chakraborty Arup K. , Eisen Herman N. , Kranz David M. 
Published: November 2011

Abstract
The binding of oligomeric peptide–MHC (pMHC) complexes to cell surface TCR can be considered to approximate TCR–pMHC interactions at cell-cell interfaces. In this study, we analyzed the equilibrium binding of streptavidin-based pMHC oligomers (tetramers) and their dissociation kinetics from CD8pos T cells from 2C-TCR transgenic mice and from T cell hybridomas that expressed the 2C TCR or a high-affinity mutant (m33) of this TCR. Our results show that the tetramers did not come close to saturating cell-surface TCR (binding only 10–30% of cell-surface receptors), as is generally assumed in deriving affinity values (KD), in part because of dissociative losses from tetramer-stained cells. Guided by a kinetic model, the oligomer dissociation rate and equilibrium constants were seen to depend not only on monovalent association and dissociation rates (koff and kon), but also on a multivalent association rate (μ) and TCR cell-surface density. Our results suggest that dissociation rates could account for the recently described surprisingly high frequency of tetramer-negative, functionally competent T cells in some T cell responses.
Eosinophils as a Novel Cell Source of Prostaglandin D2: Autocrine Role in Allergic Inflammation
Authors: Luna-Gomes Tatiana , Magalhães Kelly G. , Mesquita-Santos Fabio P. , Bakker-Abreu Ilka , Samico Rafaela F. , Molinaro Raphael , Calheiros Andrea S. , Diaz Bruno L. , Bozza Patrícia T. , Weller Peter F. , Bandeira-Melo Christianne 
Published: November 2011

Abstract
PGD2 is a key mediator of allergic inflammatory diseases that is mainly synthesized by mast cells, which constitutively express high levels of the terminal enzyme involved in PGD2 synthesis, the hematopoietic PGD synthase (H-PGDS). In this study, we investigated whether eosinophils are also able to synthesize, and therefore, supply biologically active PGD2. PGD2 synthesis was evaluated within human blood eosinophils, in vitro differentiated mouse eosinophils, and eosinophils infiltrating inflammatory site of mouse allergic reaction. Biological function of eosinophil-derived PGD2 was studied by employing inhibitors of synthesis and activity. Constitutive expression of H-PGDS was found within nonstimulated human circulating eosinophils. Acute stimulation of human eosinophils with A23187 (0.1–5 μM) evoked PGD2 synthesis, which was located at the nuclear envelope and was inhibited by pretreatment with HQL-79 (10 μM), a specific H-PGDS inhibitor. Prestimulation of human eosinophils with arachidonic acid (10 μM) or human eotaxin (6 nM) also enhanced HQL-79–sensitive PGD2 synthesis, which, by acting on membrane-expressed specific receptors (D prostanoid receptors 1 and 2), displayed an autocrine/paracrine ability to trigger leukotriene C4 synthesis and lipid body biogenesis, hallmark events of eosinophil activation. In vitro differentiated mouse eosinophils also synthesized paracrine/autocrine active PGD2 in response to arachidonic acid stimulation. In vivo, at late time point of the allergic reaction, infiltrating eosinophils found at the inflammatory site appeared as an auxiliary PGD2-synthesizing cell population. Our findings reveal that eosinophils are indeed able to synthesize and secrete PGD2, hence representing during allergic inflammation an extra cell source of PGD2, which functions as an autocrine signal for eosinophil activation.
Deciphering the Pathways of Death ofHistoplasma capsulatum-Infected Macrophages: Implications for the Immunopathogenesis of Early Infection
Authors: Deepe George S. , Buesing William R. 
Published: November 2011

AbstractApoptosis of leukocytes is known to strongly influence the immunopathogenesis of infection. In this study, we dissected the death pathways of murine macrophages (MΦs) infected with the intracellular pathogen Histoplasma capsulatum. Yeast cells caused apoptosis of MΦs at a wide range of multiplicity of infection, but smaller inocula resulted in delayed detection of apoptosis. Upon infection, caspases 3 and 1 were activated, and both contributed to cell death; however, only the former was involved in apoptosis. The principal driving force for apoptosis involved the extrinsic pathway via engagement of TNFR1 by TNF-α. Infected MΦs produced IL-10 that dampened apoptosis. The chronology of TNF-α and IL-10 release differed in vitro. The former was detected by 2 h postinfection, and the latter was not detected until 8 h postinfection. In vivo, the lungs of TNFR1−/− mice infected for 1 d contained fewer apoptotic MΦs than wild-type mice, whereas the lungs of IL-10−/− mice exhibited more. Blockade of apoptosis by a pan-caspase inhibitor or by simvastatin sharply reduced the release of TNF-α but enhanced IL-10. However, these treatments did not modify the fungal burden in vitro over 72 h. Thus, suppressing cell death modulated cytokine release but did not alter the fungal burden. These findings provide a framework for the early pathogenesis of histoplasmosis in which yeast cell invasion of lung MΦs engenders apoptosis, triggered in part in an autocrine TNF-α–dependent manner, followed by release of IL-10 that likely prevents apoptosis of newly infected neighboring phagocytes.
Assessing the Diagnostic Imaging needs for Five Selected Hospitals in Uganda
Authors: Kawooya Michael G , Pariyo George , Malwadde Elsie K , Byanyima Rosemary , Kisembo Harrient 
Published: November 2011

Introduction:
Uganda has limited health resources. It is important to measure the need for imaging in order to set policy and plan for imaging services.

Objectives:
The first specific objective was to develop and apply four imaging needs indices on a case study basis, in five selected Ugandan hospitals. The indices were: Imaging Load (IL), Imaging Burden (IB), Type Specific Imaging Burden (TSIB), and Disease Specific Imaging Burden (DSIB). The second objective was to explore the perceptions of the patient, referring clinician, and radiologist regarding the values, meaning, and objective of imaging in patient care.

Materials and Methods:
This was a cross-sectional survey employing triangulation methodology, conducted in 5 Ugandan hospitals over a period of 3 years during 2005 - 2008. The subjects were divided into four clusters: Obstetrics and gynecology (obs/gynae), surgery, internal medicine, and pediatrics. For the quantitative component of the study, data from case notes was used to calculate the indices. The qualitative component explored the non-measurable aspects of imaging needs from the clinician's, radiologist's, and patient's perspective.

Results:
A total of 1961 patient case notes were studied. The IB was 460 per 1000 hospital patients per year. The highest TSIB was for ultrasound at 232 per 1000 hospital patients per year, followed by 191 patients for general X-ray. The majority of the patients interviewed had special desires, expectations, and misconceptions.

Conclusions:
There is a high IB of 460 per thousand patient populations per year, mainly due to ultrasound. The majority of the patients have perceptions, misconceptions, beliefs, and values which influence the need for imaging. There is a need to address the medical and non-tangible imaging needs of the patient and to counteract imaging-related misconceptions and over-expectations. Public awareness of the value, capabilities, limitations, and adverse effects of various imaging modalities need to be addressed to ensure that the patients make informed imaging choices and readily avail themselves of interventions in situations when imaging is crucial, for example in suspected high-risk pregnancy.
Aberrant Signaling Pathways in Squamous Cell Lung Carcinoma
Authors: Shi Ivy , Sadraei Nooshin Hashemi , Duan Zhong-Hui , Shi Ting 
Published: November 2011

Lung cancer is the second most commonly occurring non-cutaneous cancer in the United States with the highest mortality rate among both men and women. In this study, we utilized three lung cancer microarray datasets generated by previous researchers to identify differentially expressed genes, altered signaling pathways, and assess the involvement of Hedgehog (Hh) pathway. The three datasets contain the expression levels of tens of thousands genes in normal lung tissues and squamous cell lung carcinoma. The datasets were combined and analyzed. The dysregulated genes and altered signaling pathways were identified using statistical methods. We then performed Fisher's exact test on the significance of the association of Hh pathway downstream genes and squamous cell lung carcinoma. 395 genes were found commonly differentially expressed in squamous cell lung carcinoma. The genes encoding fibrous structural protein keratins and cell cycle dependent genes encoding cyclin-dependent kinases were significantly up-regulated while the ones encoding LIM domains were down. Over 100 signaling pathways were implicated in squamous cell lung carcinoma, including cell cycle regulation pathway, p53 tumor-suppressor pathway, IL-8 signaling, Wnt-β-catenin pathway, mTOR signaling and EGF signaling. In addition, 37 out of 223 downstream molecules of Hh pathway were altered. The P-value from the Fisher's exact test indicates that Hh signaling is implicated in squamous cell lung carcinoma. Numerous genes were altered and multiple pathways were dysfunctional in squamous cell lung carcinoma. Many of the altered genes have been implicated in different types of carcinoma while some are organ-specific. Hh signaling is implicated in squamous cell lung cancer, opening the door for exploring new cancer therapeutic treatment using GLI antagonist GANT 61.
Role of Antibiofilm-Antimicrobial Agents in Controlling Device-Related Infections
Authors: Aslam Saima , Darouiche Rabih O. 
Published: November 2011

Objectives To assess the effects of N-acetylcysteine (NAC) on organism viability in planktonic and biofilm phases, biofilm thickness, and extracellular polysaccharide content. Methods We performed time-kill curves and broth macrodilution assays of bacterial and fungal clinical isolates with varying concentrations of NAC. We also created in vitro bacterial biofilms, incubated them with NAC or control, and then stained with propidium iodide and FITC-labeled concanavalin A. We measured biofilm thickness, number of non-viable cells, and fluorescent intensity as a marker of extracellular matrix via a confocal laser scanning microscope. All experiments were conducted in triplicate. Tested organisms included methicillin-sensitive and -resistant Staphylococcus aureus (MSSA, MRSA), S. epidermidis, vancomycin-resistant Enterococcus faecalis (VRE), Pseudomonas aeruginosa, Enterobacter cloacae, Klebsiella pneumoniae, Candida albicans and C. krusei. Results NAC 80 mg/ml was uniformly bactericidal (>99.9% reduction) against all tested bacteria with no recoverable organisms after 30 minutes of incubation, but was fungistatic against candida species. Minimum inhibitory and bactericidal concentrations of NAC ranged from 5–10 mg/ml. Biofilm thickness was significantly decreased in NAC-treated biofilms for all organisms except VRE. The number of non-viable cells in NAC-treated Gram-positive biofilms was increased (p<0.05 for MRSA and VRE). NAC-treated Gram-negative biofilms had scant cellularity and lacked complex 3-dimensional structures that were characteristic of controls. Fluorescent intensity was similar in the experimental and control arms. Conclusions NAC is bactericidal against clinically relevant and drug-resistant bacteria and also leads to biofilm disruption. NAC has the potential for use as a novel agent for prevention or treatment of biofilm-related infections.
Preoperative Nutritional Status and Post-Operative Infection in Total Knee Replacements: A Prospective Study of 213 Patients
Authors: Font-Vizcarra Lluís , Lozano Luis , Ríos José , Forga Maria Teresa , Soriano Alex 
Published: November 2011

Purpose To assess the potential relationship between preoperative nutritional status, including anthropometric parameters, and infection following total knee replacement surgery. Methods A total of 213 patients undergoing total knee replacement between December 2007 and May 2008 were prospectively studied. Patients with rheumatoid arthritis were excluded. For each patient we pre-operatively checked biochemical and anthropometric parameters of nutrition information about co-morbidities such as diabetes and high blood pressure, ASA score, age, and gender. Information about early infections, both superficial and deep, was collected. A descriptive statistical analysis and univariate/multivariate logistic regression model for risk factors were performed. Results Eleven patients (5.16%) had an infection, 5 deep and 6 superficial. Neither co-morbidities nor preoperatively biochemical parameters were associated with infection. However, in the univariate logistic regression model there was an inversely proportional relationship between triceps skinfold (TSF) and infection. After adjusting for age, ASA score and gender (multivariate logistic regression), TSF remained significantly associated with infection. Conclusion There was a statistically significant association between TSF and post-operative infection risk after TKR. Level of evidence Level I (Prospective prognostic study).
Relationship between Intraoperative Cultures during Hip Arthroplasty, Obesity, and the Risk of Early Prosthetic Joint Infection: A Prospective Study of 428 Patients
Authors: Font-Vizcarra Lluís , Tornero Eduard , Bori Guillem , Bosch Jordi , Mensa Josep , Soriano Alex 
Published: November 2011

Purpose To evaluate the relationship between intraoperative cultures during hip arthroplasty, the different patient characteristics, and the risk of developing a prosthetic joint infection (PJI). Methods A prospective observational study was performed. Patients who underwent elective THA from March 2007 to March of 2011 were included. Three samples were taken just after arthrotomy: synovial fluid inoculated into blood culture flasks (SF), a tissue sample (TS), and a swab of periprosthetic tissue (S). Patients received standard antibiotic prophylaxis. The PJI rate within the first 3 months after arthroplasty was recorded. Results 402 prostheses were included in the study. Contamination rate of synovial fluid was 10.2%. The most frequent isolated microorganism was coagulase-negative staphylococci (CoNS) (32 out of 41). Body mass index (BMI) was the only host characteristic associated with positive intraoperative culture (p=0.009). The PJI rate was 3.7%. Variables associated with PJI in the univariate and multivariate analysis were: age ≥67 years (p=0.012 OR: 5.35 (1.45–19.81); CI95%) and a BMI ≥35 (p=0.002, OR: 7.7 (2.12–27.85) CI95%). PJI rate among patients with BMI<35 with negative and positive intraoperative cultures was 3% and 2.7%, respectively, however, the rate among patients with BMI ≥ 35 was 15% and 25%, respectively. Conclusion A BMI ≥35 was associated with a higher risk of positive intraoperative culture during hip arthroplasty. In addition, a BMI ≥35 was independently associated with a high risk of PJI and the highest rate was documented among obese patients with positive intraoperative cultures.
Efficacy of Debridement in Hematogenous and Early Post-Surgical Prosthetic Joint Infections
Authors: Vilchez Félix , Martínez-Pastor Juan C. , García-Ramiro Sebastián , Bori Guillem , Tornero Eduard , García Esther , Mensa Josep , Soriano Alex 
Published: November 2011

Purposes To review patients with a hematogenous and early post-surgical prosthetic joint infection (PJI) due to S. aureus treated with debridement and retention of the implant and to compare their clinical characteristics and outcome. Methods From January 2000 all patients with a prosthetic joint infection treated in a single-center were prospectively registered and followed-up. All potentially variables associated with outcome were recorded. For the present study, cases with a hematogenous or early post-surgical PJI due to S. aureus treated with debridement and at least 2 years of follow-up were reviewed. Cox regression model to identify factors associated with outcome were applied. Results 12 hematogenous and 53 early post-surgical PJI due to S. aureus were included. Number of patients presenting with fever, leucocyte count, C-reactive protein concentration, and the number of bacteremic patients were significantly higher in hematogenous infections while the number of polymicrobial infections was lower in hematogenous than in early post-surgical infections. The global failure rate in hematogenous and early post-surgical PJI was 58.7% and 24.5%, respectively (p=0.02). The Cox regression model identified hematogenous infections (OR: 2.57, CI95%: 1.02–6.51, p=0.04) and the need of a second debridement (OR: 4.61, CI95%: 1.86–11.4, p=0.001) as independent predictors of failure. Conclusion Hematogenous infections were monomicrobial and had more severe symptoms and signs of infection than early post-surgical PJI. Hematogenous PJI due to S. aureus, using debridement with implant retention, had a worse outcome than early post-surgical infections.
Influence of Co-Cr Particles and Co-Cr Ions on the Growth of Staphylococcal Biofilms
Authors: Hosman Anton H. , van der Mei Henny C. , Bulstra Sjoerd K. , Kuijer Roel , Busscher Henk J. , Neut Daniëlle 
Published: November 2011

Purpose In the last decades, hip prostheses with a metal-on-metal (MOM) bearing have been implanted by orthopedic surgeons worldwide. However, concerns are now raised towards the metal particles and degradation products released by MOM-bearings into surrounding tissue, although effects of Co-Cr wear on infection are also unknown. Therefore, we here determine the viable volumes of staphylococcal biofilms formed on polystyrene in the absence and presence of Co-Cr particles and Co-Cr ions. Methods Three clinically derived and two commercially available staphylococcal strains were grown in the presence of 2 mg/mL Co-Cr particles or 1000/500 μg/L Co-Cr ions derived from Co-Cr salts or from particle supernatant, under static and dynamic growth conditions. A dynamic model simulates the conditions that apply for biofilm formation in the human body, as synovial fluid in mobile patients with hip prostheses is in constant motion with accompanying shear rates. Images of 24 h old biofilms were made with confocal laser scanning microscopy and analyzed with the mathematical computer program COMSTAT, yielding the biovolume of a biofilm. X-ray photoelectron spectroscopy was performed on the particles to study their elemental surface composition. Results Most isolates showed a tendency of reduced biofilm growth in the presence of Co-Cr particles compared to growth during exposure to metal ions, but this was only significant in one strain under the dynamic growth condition (Staphylococcus aureus 7388). Characterization of the outer surface of the particles revealed a Co-Cr oxide layer enriched by Mo relative to the bulk concentration. Conclusions MOM bearings produce metal particles which were found to possess antibacterial characteristics under dynamic growth conditions. Further research is needed towards the clinical relevance of this finding.
Poly(Ethylene Glycol) and Hydroxy Functionalized Alkane Phosphate Self-Assembled Monolayers Reduce Bacterial Adhesion and Support Osteoblast Proliferation
Authors: Bozzini Sabrina , Petrini Paola , Tanzi Maria Cristina , Arciola Carla Renata , Tosatti Samuele , Visai Livia 
Published: November 2011

Purpose Presently there is interest today in designing improved titanium surfaces capable of high bioactivity in order to promote strong anchorage of the bone surrounding implants while at the same time discouraging bioadhesion. Poly(ethylene glycol)-modified (PEG) alkane phosphate and OH-terminated alkane phosphates have been demonstrated to be spontaneously adsorbed onto titanium oxide surfaces and produce surfaces with different protein resistance in relation to the PEG surface density. This study aims to evaluate caries-associated Streptococcus mutans (S. mutans) adhesion and osteoblast proliferation while varying the PEG surface density of titanium surfaces. Methods Bacterial adhesion was quantified by fluorescence microscopy and SAOS-2 human osteoblast proliferation was evaluated up to 7 days of culture in vitro. Metabolic activity of osteoblasts was measured by MTT test and the secretion of extracellular matrix proteins (osteopontin, osteocalcin and type I collagen) in culture medium was determined by immunoenzymatic assays. Results As the PEG surface density increased, the bacterial adhesion considerably decreased when compared to uncoated titanium surfaces. The monomolecular coatings proved to be capable of supporting osteoblast proliferation with the greatest levels of metabolic activity at the highest PEG surface concentrations. Conclusions These results are extremely promising for potential clinical application in implant uses where both reduction of bacteria adhesion and stimulation of bone formation are highly desirable.