bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduction of IMRT beam complexity through the use of beam modulation penalties in the objective function
Authors: Matuszak Martha M. , Larsen Edward W. , Fraass Benedick A.
Published: February 2007

Inverse planned intensity modulated radiation therapy (IMRT) has become commonplace in treatment centers across the world. Due to the implications of beam complexity on treatment planning, delivery, and quality assurance, several methods have been proposed to reduce the complexity. These methods include beamlet intensity restrictions, smoothing procedures, and direct aperture optimization. Many of these methods typically sacrifice target coverage and/or normal tissue sparing in return for increased beam smoothness and delivery efficiency. In the present work, we penalize beam modulation in the inverse planning cost function to reduce beam complexity and increase delivery efficiency, while maintaining dosimetric quality. Three modulation penalties were tested: two that penalized deviation from Savitzky‐Golay filtered versions of the optimized beams, and one that penalized the plan intensity map variation (a measure of overall beam modulation). The modulation penalties were applied at varying weights in a weighted sum objective (or cost) function to investigate their ability to reduce beam complexity while preserving IMRT plan quality. The behavior of the penalties was characterized on a CT phantom, and then clinical optimization comparisons were performed in the brain, prostate, and head/neck. Comparisons were made between plans with a baseline cost function plans with a baseline cost function employing maximum beamlet intensity limits, and plans with each of the modulation penalties added to the baseline cost function. Plan analysis was based upon dose‐volume histograms, relevant dose metrics, beam modulation, and monitor units required for step and shoot delivery. Each of the techniques yielded improvements over a baseline cost function in terms of MU reduction. In most cases, this was achieved with minimal change to the plan DVHs and metrics. In all cases, an acceptable plan was reached with each of the methods while reducing MU substantially. Each individual method has merit as a tool for reducing IMRT beam complexity and could be easily applied in the clinic to improve overall inverse plan quality. However, the penalty based upon the plan intensity map variation consistently produced the most delivery‐efficient plans with the fewest computations.
Intra‐fraction dose delivery timing during stereotactic radiotherapy can influence the radiobiological effect
Authors: Murphy Martin J. , Lin Peck‐Sun , Ozhasoglu Cihat
Published: February 2007

The sequence of incremental dose delivery during a radiotherapy fraction can potentially influence the radiobiological effect. This would be most noticeable during the long fractions characteristic of hypo‐fractionated stereotactic radiotherapy and radiosurgery. We demonstrate here the spatio‐temporal variation of dose delivery by the CyberKnife to a lung tumor and propose strategies to reduce and/or correct for any resultant dose‐time cytotoxic effects.
Grid removal and impact on population dose in full‐field digital mammography
Authors: Gennaro Gisella , Katz Luc , Souchay Henri , Klausz Remy , Alberelli Claudio , di Maggio Cosimo
Published: February 2007

The study purpose was to determine the impact of anti‐scatter grid removal on patient dose, in full field digital mammography. Dose saving, phantom based, was evaluated with the constraint that images acquired with and without grid would provide the same contrast‐to‐noise ratio (CNR). The digital equipment employed a flat panel detector with cesium iodide for x‐ray to light conversion, pixel size; the x‐ray source was a dual‐track tube with selectable filtration. Poly(methylemathocrylate) (PMMA) layers in the range were used to simulate the absorption of different breast thickness, while two Al foils, 0.1 and thick were used to provide a certain CNR. Images with grid were acquired with the same beam quality as selected in full automatic exposure mode and the mAs levels as close as possible, and the CNR measured for each thickness between 20 and . Phantom images without grid were acquired in manual exposure mode, by selecting the same anode/filter combination and as the image with grid at the same thickness, but varying mAs from 10 to 200. For each thickness, an image without aluminum was acquired for each mAs value, in order to obtain a flat image to be used to subtract the scatter nonuniformity from the phantom images. After scatter subtraction, the CNR was measured on images without grid. The mAs value that should be set to acquire a phantom image without grid so that it has the same CNR as the corresponding grid image was calculated. Therefore, mAs reduction percentage was determined versus phantom thickness. Results showed that dose saving was lower than 30% for PMMA equivalent breast thinner than , decreased below 10% for intermediate thickness , but there was no dose gain for thickness beyond . By applying the mAs reduction factors to a clinical population derived from a data base of 4622 breasts, dose benefit was quantified in terms of population dose. On the average, the overall dose reduction was about 8%. It was considered small, not sufficient to justify a clinical implementation, and the anti‐scatter grid was maintained.
Experimental verification of a Monte Carlo‐based MLC simulation model for IMRT dose calculation
Authors: Tyagi Neelam , Moran Jean M. , Litzenberg Dale W. , Bielajew Alex F. , Fraass Benedick A. , Chetty Indrin J.
Published: February 2007

Inter‐ and intra‐leaf transmission and head scatter can play significant roles in intensity modulated radiation therapy (IMRT)‐based treatment deliveries. In order to accurately calculate the dose in the IMRT planning process, it is therefore important that the detailed geometry of the multi‐leaf collimator (MLC), in addition to other components in the accelerator treatment head, be accurately modeled. In this paper, we have used the Monte Carlo method (MC) to develop a comprehensive model of the Varian 120 leaf MLC and have compared it against measurements in homogeneous phantom geometries under different IMRT delivery circumstances. We have developed a geometry module within the DPM MC code to simulate the detailed MLC design and the collimating jaws. Tests consisting of leakage, leaf positioning and static MLC shapes were performed to verify the accuracy of transport within the MLC model. The calculations show agreement within 2% in the high dose region for both film and ion‐chamber measurements for these static shapes. Clinical IMRT treatment plans for the breast [both segmental MLC (SMLC) and dynamic MLC (DMLC)], prostate (SMLC) and head and neck split fields (SMLC) were also calculated and compared with film measurements. Such a range of cases were chosen to investigate the accuracy of the model as a function of modulation in the beamlet pattern, beamlet width, and field size. The overall agreement is within of the film data for all IMRT beams except the head and neck split field, which showed differences up to 5% in the high dose regions. Various sources of uncertainties in these comparisons are discussed.
Determination of output factors for small proton therapy fields
Authors: Fontenot Jonas D. , Newhauser Wayne D. , Bloch Charles , White R. Allen , Titt Uwe , Starkschall George
Published: February 2007

Current protocols for the measurement of proton dose focus on measurements under reference conditions; methods for measuring dose under patient‐specific conditions have not been standardized. In particular, it is unclear whether dose in patient‐specific fields can be determined more reliably with or without the presence of the patient‐specific range compensator. The aim of this study was to quantitatively assess the reliability of two methods for measuring dose per monitor unit values for small‐field treatment portals: one with the range compensator and one without the range compensator. A Monte Carlo model of the Proton Therapy Center‐Houston double‐scattering nozzle was created, and estimates of values were obtained from 14 simulated treatments of a simple geometric patient model. Field‐specific calibration measurements were simulated with a dosimeter in a water phantom with and without the range compensator. values from the simulated calibration measurements were compared with values from the corresponding treatment simulation in the patient model. To evaluate the reliability of the calibration measurements, six metrics and four figures of merit were defined to characterize accuracy, uncertainty, the standard deviations of accuracy and uncertainty, worst agreement, and maximum uncertainty. Measuring without the range compensator provided superior results for five of the six metrics and for all four figures of merit. The two techniques yielded different results primarily because of high‐dose gradient regions introduced into the water phantom when the range compensator was present. Estimated uncertainties in the position of the dosimeter in these regions resulted in large uncertainties and high variability in values. When the range compensator was absent, these gradients were minimized and values were less sensitive to dosimeter positioning errors. We conclude that measuring without the range compensator present provides more reliable results than measuring it with the range compensator in place.
Dosimetric evaluation of parallel opposed spatially fractionated radiation therapy of deep‐seated bulky tumors
Authors: Meigooni Ali S. , Gnaster Michael , Dou Kai , Johnson Ellis L. , Meigooni Navid J. , Kudrimoti Mahesh
Published: February 2007

Application of a single fraction of parallel opposed GRID beams as a means of increasing the efficiency of radiation delivery to deep‐seated tumors has been investigated. This evaluation was performed by measurement of dosimetric characteristics of the GRID radiation field in parallel opposed and single beam geometry. The limitations of the parallel opposed technique in terms of field size and tumor thickness have been evaluated for the conditions of acceptable spatial modulation. The results of this investigation have demonstrated an increase in therapeutic advantage for the parallel opposed technique over the single beam method when treating a deep seated tumor.
Detection of breast cancer with ultrasound tomography: First results with the Computed Ultrasound Risk Evaluation (CURE) prototype
Authors: Duric Nebojsa , Littrup Peter , Poulo Lou , Babkin Alex , Pevzner Roman , Holsapple Earle , Rama Olsi , Glide Carri
Published: February 2007

Although mammography is the gold standard for breast imaging, its limitations result in a high rate of biopsies of benign lesions and a significant false negative rate for women with dense breasts. In response to this imaging performance gap we have been developing a clinical breast imaging methodology based on the principles of ultrasound tomography. The Computed Ultrasound Risk Evaluation (CURE) system has been designed with the clinical goals of whole breast, operator‐independent imaging, and differentiation of breast masses. This paper describes the first clinical prototype, summarizes our initial image reconstruction techniques, and presents phantom and preliminary in vivo results. In an initial assessment of its in vivo performance, we have examined 50 women with the CURE prototype and obtained the following results. (1) Tomographic imaging of breast architecture is demonstrated in both CURE modes of reflection and transmission imaging. (2) In‐plane spatial resolution of in reflection and in transmission is achieved. (3) Masses in size are routinely detected. (4) Reflection, sound speed, and attenuation imaging of breast masses are demonstrated. These initial results indicate that operator‐independent, whole‐breast imaging and the detection of breast masses are feasible. Future studies will focus on improved detection and differentiation of masses in support of our long‐term goal of increasing the specificity of breast exams, thereby reducing the number of biopsies of benign masses.
Clinical Fundamentals for Radiation Oncology Residents
Authors: LeFave Kelly E. , Both Joseph A.
Published: February 2007

Clinical Fundamentals for Radiation Oncology Residents Murshed Hasan. 343 pp. Medical Physics Publishing, Madison, WI, 2006. $60.00 (Paperback).
Bactericidal Activities of Meropenem and Ertapenem against Extended-Spectrum-β-Lactamase-Producing
Escherichia coli
and
Klebsiella pneumoniae
in a Neutropenic Mouse Thigh Model
Authors: DeRyke C. Andrew , Banevicius Mary Anne , Fan Hong Wei , Nicolau David P.
Published: February 2007

The purpose of this study was to examine the in vivo efficacies of meropenem and ertapenem against extended-spectrum-β-lactamase (ESBL)-producing isolates with a wide range of MICs. Human-simulated dosing regimens in mice were designed to approximate the free drug percent time above the MIC (
f
T>MIC) observed for humans following meropenem at 1 g every 8 h and ertapenem at 1 g every 24 h. An in vivo neutropenic mouse thigh infection model was used to examine the bactericidal effects against 31 clinical ESBL
Escherichia coli
and
Klebsiella pneumoniae
isolates and 2 non-ESBL isolates included for comparison at a standard 10
5
inoculum. Three isolates were examined at a high 10
7
inoculum as well. Meropenem displayed greater in vitro potency, with a median MIC (range) (μg/ml) of 0.125 (0.03 to 32), than did ertapenem, with 0.5 (0.012 to 128). Seven of the 31 ESBL isolates were removed from the efficacy analysis due to their inability to establish infection in the mouse model. When MICs were ≤1.5 μg/ml for ertapenem (≤0.5 μg/ml for meropenem), similar reductions in CFU (≈ 2-log kill) were observed for both ertapenem (
f
T>MIC ≥ 23%) and meropenem (
f
T>MIC ≥ 75%). Ertapenem showed bacterial regrowth for seven of eight isolates, with MICs of ≥2 μg/ml (
f
T>MIC ≤ 20%), while meropenem displayed antibacterial potency that varied from a static effect to a 1-log bacterial reduction in these isolates (
f
T>MIC = 30 to 65%). At a 10
7
inoculum, both agents eradicated bacteria due to adequate exposures (
f
T>MIC = 20 to 45%). Due to low MICs, no difference in bacterial kill was noted for the majority of ESBL isolates tested. However, for isolates with raised ertapenem MICs of ≥2 μg/ml, meropenem displayed sustained efficacy due to its greater in vitro potency and higher resultant
f
T>MIC.
In Vitro Inhibition of
Plasmodium falciparum
Rosette Formation by Curdlan Sulfate
Authors: Kyriacou Helen M. , Steen Katie E. , Raza Ahmed , Arman Monica , Warimwe George , Bull Peter C. , Havlik Ivan , Rowe J. Alexandra
Published: February 2007

Spontaneous binding of infected erythrocytes to uninfected erythrocytes to form rosettes is a property of some strains of
Plasmodium falciparum
that is linked to severe complications of malaria. Curdlan sulfate (CRDS) is a sulfated glycoconjugate compound that is chemically similar to known rosette-inhibiting drugs such as heparin. CRDS has previously been shown to have antimalarial activity in vitro and is safe for clinical use. Here we show that CRDS at therapeutic levels (10 to 100 μg/ml) significantly reduces rosette formation in vitro in seven
P. falciparum
laboratory strains and in a group of 18 African clinical isolates. The strong ability to inhibit rosetting suggests that CRDS has the potential to reduce the severe complications and mortality rates from
P. falciparum
malaria among African children. Our data support further clinical trials of CRDS.
Molecular Epidemiology of CTX-M-Producing
Escherichia coli
in the Calgary Health Region: Emergence of CTX-M-15-Producing Isolates
Authors: Pitout Johann D. D. , Church Deirdre L. , Gregson Daniel B. , Chow Barbara L. , McCracken Melissa , Mulvey Michael R. , Laupland Kevin B.
Published: February 2007

A study was designed to describe the molecular epidemiology of CTX-M-producing
Escherichia coli
over a 6-year period (2000 to 2005) in a large well-defined Canadian region with a centralized laboratory system. Molecular characterization was done by isoelectric focusing, PCR, and automated sequencing, while genetic relatedness was determined by pulsed-field gel electrophoresis with XbaI. Of the 552 viable extended-spectrum β-lactamase-producing
E. coli
isolates isolated, 354 (64%) were positive for
bla
CTX-M
genes associated with IS
Ecp1
; 211 produced CTX-M-14, 128 produced CTX-M-15, 5 produced CTX-M-2, 4 produced CTX-M-3, 4 produced CTX-M-24, and 2 produced CTX-M-27. CTX-M-positive isolates were significantly more resistant to the fluoroquinolones than CTX-M-negative isolates, while CTX-M-15 producers were more likely to be resistant to gentamicin and tobramycin. There was a predominance of CTX-M-14 during the first 4 years of the study period, with community outbreaks associated with cluster 14A during 2000, 2001, and 2003. A substantial increase in CTX-M-15 producers occurred during the last 18 months and was due to clusters 15A and 15AR (where AR indicates related to A) in the hospital and nursing home sectors. Our results demonstrate that the persistence and dissemination of CTX-M genes among
E. coli
populations in larger geographic health care regions is dynamic, with the continuous emergence of clonally related CTX-M-15. This study illustrates the importance of molecular surveillance in tracking CTX-M-producing
E. coli
strains in the community and investigating their influx into hospitals.
Miltefosine (Hexadecylphosphocholine) Inhibits Cytochrome
c
Oxidase in
Leishmania donovani
Promastigotes
Authors: Luque-Ortega Juan Román , Rivas Luis
Published: February 2007

Miltefosine (hexadecylphosphocholine [HePC]) is currently on trial as a first-choice, orally active drug for the treatment of visceral leishmaniasis when resistance to organic pentavalent antimonials becomes epidemic. However, data on the targets involved in its leishmanicidal mechanism have, until now, been only fragmentary. We have carried out a systematic study of the alterations induced on the bioenergetic metabolism of
Leishmania donovani
promastigotes by HePC. Overnight incubation with HePC caused a significant decline in the intracellular ATP levels of the parasites, together with a reduction in the oxygen consumption rate and mitochondrial depolarization, while the integrity of the plasma membrane remained undamaged. In a further step, the effects of HePC on the respiratory chain were addressed in digitonized parasites. The inhibition of the oxygen consumption rate caused by HePC was not reverted either with the uncoupling agent carbonyl cyanide
p
-trifluoromethoxyphenylhydrazone or with tetramethyl-
p
-phenylenediamine plus ascorbate, which feeds the electron transport chain at the level of cytochrome
c
. These results suggest that cytochrome
c
oxidase is a likely target in the complex leishmanicidal mechanism of HePC. This was further confirmed from the finding that this enzyme was specifically inhibited in a dose-dependent manner by HePC, but not the cytochrome
c
reductase, ruling out an unspecific effect of HePC on the respiratory chain.
Inflammatory Lipoproteins Purified from a Toxigenic and Arthritogenic Strain ofMycoplasma arthritidisAre Dependent on Toll-Like Receptor 2 and CD14
Authors: Hasebe Akira , Mu Hong-Hua , Washburn Leigh R. , Chan Fok V. , Pennock Nathan D. , Taylor Michael L. , Cole Barry C.
Published: February 2007

Mycoplasma arthritidisis a naturally occurring murine pathogen, and the disease model has been used extensively to understand inflammatory mechanisms. Recently, Triton X-114 extracts of a virulent strain ofM. arthritidiswere found to be more potent in activating macrophages than were those from an avirulent strain, suggesting a role in disease. Here, octyl glucoside extraction of cells was used to identify four distinct bioactive moieties, with molecular masses of ∼41, 37, 34, and 17 kDa. Their bioactivities were resistant to proteinase K but were destroyed by alkaline hydrolysis and oxidation. As for MALP-2, all were dependent upon Toll-like receptor 2, but unlike MALP-2, they were also dependent upon CD14. TheM. arthritidislipoproteins exhibited infrared absorbances at 2,900 cm−1and 1,662 cm−1, similar to those seen in Pam3-Cys-Ser-(Lys)4. Edman degradation failed to reveal N-terminal sequences, suggesting that they were blocked and therefore might be triacylated. However, mass spectrometry of fragments revealed that the 41-kDa moiety, which binds to serum apolipoprotein A-1, had similarity with the recently described MlpD lipoprotein ofM. arthritidis.
Carboxypeptidases B of
Anopheles gambiae
as Targets for a
Plasmodium falciparum
Transmission-Blocking Vaccine
Authors: Lavazec C. , Boudin C. , Lacroix R. , Bonnet S. , Diop A. , Thiberge S. , Boisson B. , Tahar R. , Bourgouin C.
Published: February 2007

Anopheles gambiae
is the major African vector of
Plasmodium falciparum
, the most deadly species of human malaria parasite and the most prevalent in Africa. Several strategies are being developed to limit the global impact of malaria via reducing transmission rates, among which are transmission-blocking vaccines (TBVs), which induce in the vertebrate host the production of antibodies that inhibit parasite development in the mosquito midgut. So far, the most promising components of a TBV are parasite-derived antigens, although targeting critical mosquito components might also successfully block development of the parasite in its vector. We previously identified
A. gambiae
genes whose expression was modified in
P. falciparum
-infected mosquitoes, including one midgut carboxypeptidase gene,
cpbAg1.
Here we show that
P. falciparum
up-regulates the expression of
cpbAg1
and of a second midgut carboxypeptidase gene,
cpbAg2
, and that this up-regulation correlates with an increased carboxypeptidase B (CPB) activity at a time when parasites establish infection in the mosquito midgut. The addition of antibodies directed against CPBAg1 to a
P. falciparum
-containing blood meal inhibited CPB activity and blocked parasite development in the mosquito midgut. Furthermore, the development of the rodent parasite
Plasmodium berghei
was significantly reduced in mosquitoes fed on infected mice that had been immunized with recombinant CPBAg1. Lastly, mosquitoes fed on anti-CPBAg1 antibodies exhibited reduced reproductive capacity, a secondary effect of a CPB-based TBV that could likely contribute to reducing
Plasmodium
transmission. These results indicate that
A. gambiae
CPBs could constitute targets for a TBV that is based upon mosquito molecules.
Immunoglobulin G Antibody Reactivity to a Group A
Plasmodium falciparum
Erythrocyte Membrane Protein 1 and Protection from
P. falciparum
Malaria
Authors: Magistrado Pamela A. , Lusingu John , Vestergaard Lasse S. , Lemnge Martha , Lavstsen Thomas , Turner Louise , Hviid Lars , Jensen Anja T. R. , Theander Thor G.
Published: February 2007

Variant surface antigens (VSA) on the surface of
Plasmodium falciparum
-infected red blood cells play a major role in the pathogenesis of malaria and are key targets for acquired immunity. The best-characterized VSA belong to the
P. falciparum
erythrocyte membrane protein 1 (PfEMP1) family. In areas where
P. falciparum
is endemic, parasites causing severe malaria and malaria in young children with limited immunity tend to express semiconserved PfEMP1 molecules encoded by group A
var
genes. Here we investigated antibody responses of Tanzanians who were 0 to 19 years old to PF11_0008, a group A PfEMP1. PF11_0008 has previously been found to be highly transcribed in a nonimmune Dutch volunteer experimentally infected with NF54 parasites. A high proportion of the Tanzanian donors had antibodies against recombinant PF11_0008 domains, and in children who were 4 to 9 years old the presence of antibodies to the PF11_0008 CIDR2β domain was associated with reduced numbers of malaria episodes. These results indicate that homologues of PF11_0008 are present in
P. falciparum
field isolates and suggest that PF11_0008 CIDR2β-reactive antibodies might be involved in protection against malaria episodes.
Effect of Farnesol on a Mouse Model of Systemic Candidiasis, Determined by Use of a
DPP3
Knockout Mutant of
Candida albicans
Authors: Navarathna Dhammika H. M. L. P. , Hornby Jacob M. , Krishnan Navasona , Parkhurst Anne , Duhamel Gerald E. , Nickerson Kenneth W.
Published: February 2007

This work extends our previous observation that the fungus
Candida albicans
secretes micromolar levels of farnesol and that accumulation of farnesol in vitro prevents the yeast-to-mycelium conversion in a quorum-sensing manner. What does farnesol do in vivo? The purpose of this study was to determine the role of farnesol during infection with a well-established mouse model of systemic candidiasis with
C. albicans
A72 administered by tail vein injection. This question was addressed by altering both endogenous and exogenous farnesol. For endogenous farnesol, we created a knockout mutation in
DPP3
, the gene encoding a phosphatase which converts farnesyl pyrophosphate to farnesol. This mutant (KWN2) produced six times less farnesol and was ca. 4.2 times less pathogenic than its SN152 parent. The strain with
DPP3
reconstituted (KWN4) regained both its farnesol production levels and pathogenicity. These mutants (KWN1 to KWN4) retained their full dimorphic capability. With regard to exogenous farnesol, farnesol was administered either intraperitoneally (i.p.) or orally in the drinking water. Mice receiving
C. albicans
intravenously and farnesol (20 mM) orally had enhanced mortality (
P
< 0.03). Similarly, mice (
n
= 40) injected with 1.0 ml of 20 mM farnesol i.p. had enhanced mortality (
P
< 0.03), and the onset of mortality was 30 h sooner than for mice which received a control injection without farnesol. The effect of i.p. farnesol was more pronounced (
P
< 0.04) when mice were inoculated with a sublethal dose of
C. albicans
. These mice started to die 4 days earlier, and the percent survival on day 6 postinoculation (p.i.) was five times lower than for mice receiving
C. albicans
with control i.p. injections. In all experiments, mice administered farnesol alone or Tween 80 alone remained normal throughout a 14-day observation period. Finally, beginning at 12 h p.i., higher numbers of
C. albicans
cells were detected in kidneys from mice receiving i.p. farnesol than in those from mice receiving control i.p. injections. Thus, reduced endogenous farnesol decreased virulence, while providing exogenous farnesol increased virulence. Taken together, these data suggest that farnesol may play a role in disease pathogenesis, either directly or indirectly, and thus may represent a newly identified virulence factor.
Cloning, Expression, and Characterization of the Superantigen Streptococcal Pyrogenic Exotoxin G from
Streptococcus dysgalactiae
Authors: Zhao Jizi , Hayashi Tomohito , Saarinen Susanna , Papageorgiou Anastassios C. , Kato Hidehito , Imanishi Ken'ichi , Kirikae Teruo , Abe Ryo , Uchiyama Takehiko , Miyoshi-Akiyama Tohru
Published: February 2007

We identified seven novel variants of streptococcal pyrogenic exotoxin G (SPEGG), a superantigen, in
Streptococcus dysgalactiae
subsp.
dysgalactiae
or
equisimilis
isolates from clinical cases of infection in humans and animals. Phylogenetic analysis of the SPEGG variants indicated two clades in the dendrogram: one composed of variants derived from the bacteria isolated from the humans and the other composed of variants from the bacteria isolated from the animals. Bovine peripheral blood mononuclear cells (PBMCs) were stimulated effectively by recombinant SPEGGs (rSPEGGs) expressed in
Escherichia coli
, while human PBMCs were not stimulated well by any of the rSPEGGs tested. SPEGGs selectively stimulated bovine T cells bearing Vβ1,10 and Vβ4. Bovine serum showed reactivity to the rSPEGG proteins. These results indicated that SPEGGs have properties as superantigens, and it is likely that SPEGGs play a pathogenic role in animals.
Dependence of Macrophage Phagocytic Efficacy on Antibody Concentration
Authors: Macura Nataša , Zhang Tong , Casadevall Arturo
Published: February 2007

Macrophages ingest the fungus
Cryptococcus neoformans
only in the presence of opsonins, and this provides a remarkably clean system for the detailed analysis of phagocytosis. This system is also unusual in that antibody-mediated phagocytosis involves ingestion through both Fc and complement receptors in the absence of complement. Mathematical modeling was used to analyze and explain the experimental data that the macrophage phagocytic index increased with increasing doses of antibody despite saturating concentrations and declined at high concentrations. A model was developed that explains the increase in phagocytic index with increasing antibody doses, differentiates among the contributions from Fc and complement receptors, and provides a tool for estimating antibody concentrations that optimize efficacy of phagocytosis. Experimental results and model calculations revealed that blocking of Fc receptors by excess antibody caused a reduction in phagocytic index but increased phagocytosis through complement receptors rapidly compensated for this effect. At high antibody concentrations, a further reduction in phagocytic index was caused by interference with complement receptor ingestion as a consequence of saturation of the fungal capsule. The ability of our model to predict the antibody dose dependence of the macrophage phagocytic efficacy for
C. neoformans
strongly suggest that the major variables that determine the efficacy of this process have been identified. The model predicts that the affinity constant of the opsonic antibody for the Fc receptor and the association-dissociation constant of antibody from the microbial antigen are critical parameters determining the efficacy of phagocytosis.
Solitary Intestinal Lymphoid Tissue Provides a Productive Port of Entry for
Salmonella enterica
Serovar Typhimurium
Authors: Halle Stephan , Bumann Dirk , Herbrand Heike , Willer Yvonne , Dähne Sabrina , Förster Reinhold , Pabst Oliver
Published: February 2007

Oral infection of mice with
Salmonella enterica
serovar Typhimurium results in the colonization of Peyer's patches, triggering a vigorous inflammatory response and immunopathology at these sites. Here we demonstrate that in parallel to Peyer's patches a strong inflammatory response occurs in the intestine, resulting in the appearance of numerous inflammatory foci in the intestinal mucosa. These foci surround small lymphoid cell clusters termed solitary intestinal lymphoid tissue (SILT).
Salmonella
can be observed inside SILT at early stages of infection, and the number of infected structures matches the number of inflammatory foci arising at later time points. Infection leads to enlargement and morphological destruction of SILT but does not trigger de novo formation of lymphoid tissue. In conclusion, SILT, a lymphoid compartment mostly neglected in earlier studies, represents a major site for
Salmonella
invasion and ensuing mucosal pathology.
Evidence for Widespread Epithelial Damage and Coincident Production of Monocyte Chemotactic Protein 1 in a Murine Model of Intestinal Ricin Intoxication
Authors: Yoder J. Marina , Aslam Rabia U. , Mantis Nicholas J.
Published: February 2007

The development of small-animal models is necessary to understand host responses and immunity to emerging infectious diseases and potential bioterrorism agents. In this report we have characterized a murine model of intestinal ricin intoxication. Ricin administered intragastrically (i.g.) to BALB/c mice at doses ranging from 1 to 10 mg/kg of body weight induced dose-dependent morphological changes in the proximal small intestine (i.e., duodenum), including widespread villus atrophy and epithelial damage. Coincident with epithelial damage was a localized increase in monocyte chemotactic protein 1, a chemokine known to be associated with inflammation of the intestinal mucosa. Immunity to intestinal ricin intoxication was achieved by immunizing mice i.g. with ricin toxoid and correlated with elevated levels of antitoxin mucosal immunoglobulin A (IgA) and serum IgG antibodies. We expect that this model will serve as a valuable tool in identifying the inflammatory pathways and protective immune responses that are elicited in the intestinal mucosa following ricin exposure and will prove useful in the evaluation of antitoxin vaccines and therapeutics.
Regulation of Exoprotein Gene Expression by the
Staphylococcus aureus cvfB
Gene
Authors: Matsumoto Yasuhiko , Kaito Chikara , Morishita Daisuke , Kurokawa Kenji , Sekimizu Kazuhisa
Published: February 2007

We previously reported that the
cvfB
gene (SA1223) of
Staphylococcus aureus
is responsible for the virulence of this pathogenic bacterium. We show here that the
cvfB
gene regulates exoprotein gene expression. In a
cvfB
gene deletion mutant, hemolysin, DNase, and protease production were decreased, whereas protein A expression was increased. The amount of RNAIII, the transcript from the P3 promoter in the
agr
locus that regulates the expression of various virulence factors, was also reduced in the
cvfB
mutant. In addition, P2 and P3 promoter activity in the
agr
locus was decreased in the mutant. Under the genetic background of the
agr
-null mutation,
cvfB
gene disruption decreased the production levels of DNase and protease. Moreover, the
cvfB
and
agr
double mutant was less virulent than the
agr
mutant in silkworms. These results suggest that the
cvfB
gene product contributes to the expression of virulence factors and to pathogenicity
via
both
agr
-dependent and
agr
-independent pathways.
Induction of Human β-Defensin 2 by the ProbioticEscherichia coliNissle 1917 Is Mediated through Flagellin
Authors: Schlee Miriam , Wehkamp Jan , Altenhoefer Artur , Oelschlaeger Tobias A. , Stange Eduard F. , Fellermann Klaus
Published: February 2007

Human β-defensin 2 (hBD-2) is an inducible antimicrobial peptide synthesized by the epithelium to counteract bacterial adherence and invasion. Proinflammatory cytokines, as well as certain bacterial strains, have been identified as potent endogenous inducers. Recently, we have found that hBD-2 induction by probioticEscherichia coliNissle 1917 was mediated through NF-κB- and AP-1-dependent pathways. The aim of the present study was to identify the responsible bacterial factor.E. coliNissle 1917 culture supernatant was found to be more potent than the pellet, indicating a soluble or shed factor. Chemical analysis demonstrated the factor to be heat resistant and proteinase digestible. SeveralE. coliNissle 1917 deletion mutants were constructed and tested for their ability to induce hBD-2 expression in Caco-2 cells. Deletion mutants for flagellin specifically exhibited an impaired immunostimulatory capacity. Reinsertion of the flagellin gene restored the induction capacity to normal levels. Isolated flagellin fromE. coliNissle 1917 and fromSalmonella entericaserovar Enteritidis induced hBD-2 mRNA significantly in contrast to the flagellin of the apathogenicE. colistrain ATCC 25922. H1 flagellin antiserum abrogated hBD-2 expression induced by flagellin as well asE. coliNissle 1917 supernatant, confirming that flagellin is the major stimulatory factor ofE. coliNissle 1917.
The SAG1Toxoplasma gondiiSurface Protein Is Not Required for Acute Ocular Toxoplasmosis in Mice
Authors: Charles Elizabeth , Callegan Michelle C. , Blader Ira J.
Published: February 2007

The SAG1Toxoplasma gondiisurface protein stimulates acute ileitis. To determine whether SAG1 is also important in the eye, wild-type or SAG1 knockout parasites were injected intravitreally into mice. No differences in retinal damage or parasite growth were observed, indicating that unlike the case for the intestine, factors besides SAG1 are important for retinal damage.
Mice Lacking CD21 and CD35 Proteins Mount Effective Immune Responses againstBorrelia burgdorferiInfection
Authors: Jacobson Amanda C. , Ma Ying , Zachary James F. , Weis Janis J. , Weis John H.
Published: February 2007

CD21/35−/−mice, deficient in CD21 and CD35 (complement receptors 2 and 1, respectively), were infected withBorrelia burgdorferito assess the role of these receptors in a chronic bacterial infection. Although CD21/35−/−mice on both C57BL/6 and BALB/c backgrounds produced lessB. burgdorferi-specific antibodies than did wild-type mice, spirochete levels and arthritis severity were similar.
Resistance toPseudomonas aeruginosaChronic Lung Infection Requires Cystic Fibrosis Transmembrane Conductance Regulator-Modulated Interleukin-1 (IL-1) Release and Signaling through the IL-1 Receptor
Authors: Reiniger Nina , Lee Martin M. , Coleman Fadie T. , Ray Christopher , Golan David E. , Pier Gerald B.
Published: February 2007

Innate immunity is critical for clearingPseudomonas aeruginosafrom the lungs. In response toP. aeruginosainfection, a central transcriptional regulator of innate immunity—NF-κB—is translocated within 15 min to the nuclei of respiratory epithelial cells expressing wild-type (WT) cystic fibrosis (CF) transmembrane conductance regulator (CFTR).P. aeruginosaclearance from lungs is impaired in CF, and rapid NF-κB nuclear translocation is defective in cells with mutant or missing CFTR. We used WT and mutantP. aeruginosaand strains of transgenic mice lacking molecules involved in innate immunity to identify additional mediators required forP. aeruginosa-induced rapid NF-κB nuclear translocation in lung epithelia. We found neither Toll-like receptor 2 (TLR2) nor TLR4 nor TLR5 were required for this response. However, both MyD88-deficient mice and interleukin-1 receptor (IL-1R)-deficient mice failed to rapidly translocate NF-κB to the nuclei of respiratory epithelial cells in response toP. aeruginosa. Cultured human bronchial epithelial cells rapidly released IL-1β in response toP. aeruginosa; this process was maximized by expression of WT-CFTR and dramatically muted in cells with ΔF508-CFTR. The IL-1R antagonist blockedP. aeruginosa-induced NF-κB nuclear translocation. Oral inoculation via drinking water of IL-1R knockout mice resulted in higher rates of lung colonization and elevatedP. aeruginosa-specific antibody titers in a manner analogous to that of CFTR-deficient mice. Overall, rapid IL-1 release and signaling through IL-1R represent key steps in the innate immune response toP. aeruginosainfection, and this process is deficient in cells lacking functional CFTR.
Evidence of Immunostimulating Lipoprotein Existing in the Natural Lipoteichoic Acid Fraction
Authors: Hashimoto Masahito , Furuyashiki Maiko , Kaseya Ryoko , Fukada Yuka , Akimaru Mai , Aoyama Kazue , Okuno Toshiomi , Tamura Toshihide , Kirikae Teruo , Kirikae Fumiko , Eiraku Nobutaka , Morioka Hirofumi , Fujimoto Yukari , Fukase Koichi , Takashige Katsuhiro , Moriya Yoichiro , Kusumoto Shoichi , Suda Yasuo
Published: February 2007

Lipoteichoic acid (LTA) is a cell surface glycoconjugate of gram-positive bacteria and is reported to activate the innate immune system. We previously reported that purified LTA obtained from
Enterococcus hirae
has no immunostimulating activity, but a subfraction (Eh-AF) in an LTA fraction possesses activity. In this study, we established a mouse monoclonal antibody neutralizing the activity of Eh-AF and investigated its inhibitory effects. Monoclonal antibody (MAbEh1) was established by the immunization of BALB/c mice with Eh-AF, followed by hybridoma screening based on its inhibitory effect for the production of interleukin-6 (IL-6) induced by Eh-AF. MAbEh1 neutralized the production of IL-6 by LTA fraction from not only
E. hirae
but also
Staphylococcus aureus
, while it failed to block that of lipopolysaccharide, suggesting that the antibody recognized a common active structure(s) in LTA fractions. Synthetic glycolipids in these LTAs did not induce cytokine production, at least in our system. Interestingly, the antibody was found to inhibit the activity of immunostimulating synthetic lipopeptides, Pam
3
CSK
4
and FSL-1. These results suggest that MAbEh1 neutralizes the activity of lipoprotein-like compounds which is responsible for the activity of the LTA fraction of
E. hirae
and
S. aureus
.
Exercise-induced hemolysis is caused by protein modification and most evident during the early phase of an ultraendurance race
Authors: Yusof Ashril , Leithauser Renate M. , Roth Heinz J. , Finkernagel Holger , Wilson Michael T. , Beneke Ralph
Published: February 2007

Whether structural changes of the erythrocyte membrane increase the susceptibility to hemolysis particularly of the relatively older cell population during the early phase of a 216-km ultrarace was tested in six male runners (age 53.6 ± 10.4 yr, height 175.8 ± 11.1 cm, body mass 75.9 ± 8.4 kg). Erythrocyte membrane spectrins were lowest ( P < 0.001) after 42 km (75.59 ± 5.25% of prerace) and increased ( P < 0.001) toward 216 km (88.27 ± 3.37%). Susceptibility to osmotic hemolysis was highest ( P < 0.01) after 42 km (107.34 ± 3.02 mOsm sodium phosphate buffer) with almost identical ( P > 0.05) values prerace (97.98 ± 3.41 mOsm) and postrace (98.61 ± 3.26 mOsm). Haptoglobin indicated intravascular hemolysis of 9.27 × 109cells/l ( P < 0.05) during the initial 84 km. Changes in hematocrit and plasma proteins indicated an estimated total net erythrocyte loss of 3.47 × 1011cells/l ( P < 0.05) after 21 km. This was compensated by a gain in erythrocytes ( P < 0.05) of 3.31 × 1011cells/l during the final 132 km. A main effect ( P < 0.05) on erythropoietin suggests increased erythropoiesis throughout the race. Exercise-induced hemolysis reflects alterations in erythrocyte membrane spectrins and occurs particularly in the early phase of an ultraendurance race because of a relative older cell population.
High Blood Pressure in Pregnancy and Coronary Calcification
Authors: Sabour Siamak , Franx Arie , Rutten Annemarieke , Grobbee Diederick E. , Prokop Mathias , Bartelink Marie-Louise , van der Schouw Yvonne T. , Bots Michiel L.
Published: February 2007

A considerable proportion of pregnant women develop high blood pressure in pregnancy. Although it is assumed that this condition subsides after pregnancy, many of these women develop the metabolic syndrome later in life and are at increased risk to develop coronary heart disease. Atherosclerosis development is considered in between risk factors and occurrence of vascular symptoms. We set out to cross-sectionally study the relation of high blood pressure during pregnancy with risk of coronary calcification. The study population was composed 491 healthy postmenopausal women selected from a population-based cohort study. Information on high blood pressure during pregnancy was obtained using a questionnaire. Between 2004 and 2005, the women underwent a multidetector computed tomography (Philips Mx 8000 IDT 16) to assess coronary calcium. The Agatston score, volume, and mass measurements were used to quantify coronary calcium. A total of 30.7% of the women reported to have had high blood pressure in pregnancy. Body mass index (odds ratio [OR]: 1.05; 95% CI: 1.01 to 1.09) and diastolic blood pressure (OR: 1.03; 95% CI: 1.01 to 1.05) were significantly related to a history of high blood pressure in pregnancy. Age was significantly related to increased coronary calcification. Women with a history of high blood pressure during pregnancy had a 57% increased risk of having coronary calcification compared with those women without this condition (OR: 1.57; 95% CI: 1.04 to 2.37). After adjusting for age, the relation did not change (OR: 1.64; 95% CI: 1.07 to 2.53). We concluded that high blood pressure during pregnancy is associated with an increased risk of coronary calcification later in life.
β1 Integrins Modulate β-Adrenergic Receptor–Stimulated Cardiac Myocyte Apoptosis and Myocardial Remodeling
Authors: Krishnamurthy Prasanna , Subramanian Venkateswaran , Singh Mahipal , Singh Krishna
Published: February 2007

Sympathetic nerve activity increases in the heart during cardiac failure. Here, we hypothesized that β1 integrins play a protective role in chronic β-adrenergic receptor–stimulated cardiac myocyte apoptosis and heart failure.
l
-isoproterenol (iso; 400 μg/kg per hour) was infused in a group of wild-type (WT) and β1 integrin heterozygous knockout (hKO) mice. Left ventricular structural and functional remodeling was studied at 7 and 28 days of iso-infusion. Western blot analysis demonstrated reduced β1 integrin levels in the myocardium of hKO-sham. Iso-infusion increased heart weight:body weight ratios in both groups. However, the increase was significantly higher in WT-iso. M-mode echocardiography indicated increased left ventricular end-diastolic diameter, percentage of fractional shortening, and ejection fraction in the WT-iso group. The percentage of fractional shortening and ejection fraction were significantly lower in hKO-iso versus hKO-sham and WT-iso. Peak left ventricular developed pressure and left ventricular end-diastolic pressure measured using Langendorff–perfusion analyses were significantly higher in the WT-iso group (
P
<0.05 versus WT-sham and hKO-Iso). The number of TUNEL-positive myocytes was significantly higher in hKO-iso hearts 7 and 28 days after iso-infusion. The increase in myocyte cross-sectional area and fibrosis was higher in the WT-iso group. Matrix metalloproteinase-9 protein levels were significantly higher in WT-iso, whereas matrix metalloproteinase-2 levels were increased in hKO-iso hearts. Iso-infusion increased phosphorylation of c-Jun N-terminal kinase and extracellular signal-regulated kinase 1/2 in both groups. The increase in c-Jun N-terminal kinase phosphorylation was significantly higher in hKO-iso (
P
<0.001 versus WT-iso). Thus, β1 integrins play a crucial role in β-adrenergic receptor–stimulated myocardial remodeling with effects on cardiac myocyte hypertrophy, apoptosis, and left ventricular function.
Diastolic Heart Failure
Authors: Martos Ramón , Baugh John , Ledwidge Mark , O’Loughlin Christina , Conlon Carmel , Patle Anil , Donnelly Seamas C. , McDonald Kenneth
Published: February 2007

Background—

The pathophysiology of diastolic heart failure (DHF) is poorly understood. One potential explanation is an active fibrotic process that produces increased ventricular stiffness, which compromises filling. The present study investigates collagen metabolism in hypertensive patients in different phases of diastolic function with and without proven DHF.

Methods and Results—

We studied 86 hypertensive patients divided into groups according to the presence of DHF (32 with, 54 without) and phase of diastolic function (20 with normal function, 38 with impaired relaxation, 10 with pseudonormalization, and 16 with restrictive-like filling). Serum carboxy-terminal, amino-terminal, and carboxy-terminal telopeptide of procollagen type I, amino-terminal propeptide of procollagen type III, matrix metalloproteinases (MMPs; total MMP-1, active MMP-2, and MMP-9), and tissue inhibitor of MMPs levels were assayed by radioimmunoassay and ELISA. Doppler-echocardiographic assessment of diastolic filling was made with measurements of E/A ratio, E-wave deceleration time, and isovolumic relaxation time. Serum carboxy-terminal telopeptide of procollagen type I, carboxy-terminal telopeptide of procollagen type I, amino-terminal propeptide of procollagen type III, MMP-2, and MMP-9 levels (
P
<0.001 for all, controlled for age and gender) were greater in patients with DHF than in those without. When we controlled for age and gender, levels of serum carboxy-terminal telopeptide of procollagen type I, tissue inhibitor of MMP-1, amino-terminal propeptide of procollagen type III (all
P
<0.001), carboxy-terminal telopeptide of procollagen type I(
P
=0.008), and MMP-2 (
P
=0.03) were greater in more severe phases of diastolic dysfunction. Within phases of diastolic dysfunction, serum carboxy-terminal telopeptide of procollagen type I, amino-terminal propeptide of procollagen type III, MMP-2, and MMP-9 were elevated in those with DHF compared with those without DHF (all
P
<0.001).

Conclusions—

These data demonstrate serological evidence of an active fibrotic process in DHF, which is more marked in more severe diastolic dysfunction. This observation may help explain the pathophysiology of DHF and may suggest new avenues for diagnostic and therapeutic intervention.