bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the dual endothelin receptor antagonist tezosentan and hypertonic saline/dextran on porcine endotoxin shock
Authors: Somell A. , Weitzberg E. , Suneson A. , Sollevi A. , Hjelmqvist H.
Published: May 2007

Aim:  To evaluate the haemodynamic effects of the dual endothelin receptor antagonist tezosentan, both alone and combined with hypertonic saline/dextran (HSD), on porcine endotoxin shock, with focus on cardiopulmonary circulation. The effects on gas exchange and short‐term survival were also studied.

Methods:  A prospective, randomized experimental study was carried out. Thirty‐two anaesthetized pigs underwent pulmonary and carotid artery catheterization. Following haemodynamic stabilization and baseline measurements, endotoxaemia was induced by an Escherichia coli‐endotoxin infusion over 180 min and the animals observed another 120 min. After 60 min of endotoxaemia, directly before intervention, animals were randomized into four groups: a tezosentan group, an HSD group, a combined tezosentan/HSD group and a control group. The consequent haemodynamic effects and blood gas results were recorded.

Results:  The endotoxin infusion reduced mean arterial blood pressure from 111 ± 14 (mean ± standard deviation) to 77 ± 27 mmHg and cardiac index from 126.9 ± 27.2 to 109.3 ± 22.6 mL min−1 kg−1 within 90 min in the control group. In addition, endotoxin simultaneously increased mean pulmonary artery pressure from 24 ± 17 to 38 ± 19 mmHg and reduced arterial oxygenation from 18.9 ± 2.0 to 12.2 ± 5.3 kPa. Tezosentan, alone and combined with HSD, reversed the pulmonary hypertension and prevented the reduction in cardiac index and arterial oxygenation, resulting in reduced metabolic acidosis. Additionally, in the tezosentan group, the mean arterial blood pressure was reduced to the same level as in controls, an effect not prevented by the addition of HSD. It was found that all three interventions improved survival rates.

Conclusion:  Tezosentan, alone and in combination with HSD, improved cardiac index and arterial oxygenation. The addition of HSD to tezosentan treatment did not improve the endotoxin‐induced hypotension, but beneficial effects on microcirculation and systemic oxygenation were seen despite low perfusion pressure, as indicated by increased SvO2 and reduced metabolic acidosis.
Incomplete caudal duplication in a puppy: gross and radiological observations
Authors: Mazzullo G. , Monteverde V. , Macrì F. , Partanna S. , Caracappa S.
Published: May 2007

Caudal duplication is a rare type of conjoined twinning. The aim of this case report is to describe a case of caudal duplication in a male crossbreed puppy. The puppy was macroscopically and radiographically examined after death. External features included a supernumerary limb projecting from the perineum, complete lack of tail, anal atresia, double penis and absence of scrotal sacs. Internal examination showed anomalies involving the intestine and the urinary system. At x‐ray examination, the supernumerary limb showed features similar to that of the normal right hindlimb but showed absence of fibula and tibia and presence of three metatarsi and phalanges. The authors discuss the pathogenic mechanisms of this condition, infrequently reported in veterinary practice, pointing out the importance of embryonic duplications commonly associated with dystocia.
Central tarsal bone fracture in the border collie
Authors: Guilliard M.
Published: May 2007

Fracture of the plantar process of the central tarsal bone together with a dorsomedial displacement of the body of the bone was seen in six border collies. All injuries occurred during free exercise, with no extrinsic trauma. Three dogs had concomitant tarsal fractures. Primary treatment was by lag screwing the central tarsal bone to the fourth tarsal bone. All cases eventually made an excellent recovery. The superficial radiographic appearance was of a luxation of the bone as reported in a previous series, but appraisal of the radiographs showed evidence of fracture in all cases. A cadaver study to assess the mechanism of luxation showed that it is unlikely to occur naturally.
Cerebellar cortical abiotrophy in Lagotto Romagnolo dogs
Authors: Jokinen T. S. , Rusbridge C. , Steffen F. , Viitmaa R. , Syrjä P. , De Lahunta A. , Snellman M. , Cizinauskas S.
Published: May 2007

This case report documents two pathological variations of potentially inherited, cerebellar cortical abiotrophy in two unrelated Lagotto Romagnolo breed dogs. The first dog had an atypical lesion in the cerebellar cortex with depletion of cerebellar granular cell layer and sparing of the Purkinje cell layer. The second case had degenerative changes in both Purkinje and granular cell layers. The clinical picture was similar in both cases presented, although the severity of the signs of cerebellar dysfunction varied.
Variation of Nitrogen Concentrations in Stormpipe Discharge in a Residential Watershed1
Authors: Toran Laura , Grandstaff David
Published: May 2007

Abstract:  Use of lawn chemicals in residential areas may contribute nonpoint source (NPS) pollutants, such as nutrients, pesticides, and herbicides to streams. We conducted a 2‐year screening study of discharge in stormwater pipes in the Wissahickon Valley Watershed (suburban Philadelphia) using nitrogen as an indicator of lawn chemical use. Stormwater samples representing first flush and composite runoff were collected approximately twice a month using automatic samplers triggered by rise in water level during storms. The runoff collected by the stormpipes was from neighborhoods with 15‐100 residences, and from 2 to 18 ha (5‐45 acres). Several factors were examined to evaluate the effects on nitrate concentration. These factors included time of sampling (season), number of homes, total area, size of the storm, and time since last storm. Nitrate levels were generally less than 5 mg/l, but still above background in typical undeveloped areas. Concentrations were slightly higher in the first summer than during a drought in the second year, but the difference was not statistically significant. There was a positive correlation between size of the neighborhood (capture area) and peak concentration of nitrate. Storm characteristics (size of storm and time since last storm) did not correlate with nitrate concentrations. The variation in both space and time suggests that a more local control may be a factor. Although individual lawn chemical applications were not monitored, they may influence the timing of increased loading. Furthermore, the variability indicates that quarterly monitoring will not capture discharge characteristics of storm basins.
Introduction of new guidelines for emergency patients: motivational counselling among smokers
Authors: Backer Vibeke , Nelbom Bente Munkholm , Duus Benn Rønnow , Tønnesen Hanne
Published: May 2007

Introduction:  Smoking is the most important risk factor for morbidity and mortality in hospital patients. Patient contact with the healthcare system should include smoking cessation counselling. Emergency admissions are seldom given this opportunity.

Objective:  The aim of the study was to illustrate the implementation of motivational counselling in a department of acute surgery.

Methods:  Between May 2003 and January 2004, 200 emergency patients were offered motivational counselling and a 6‐week smoking cessation programme.

Results:  We measured the number of patients who accepted motivational counselling. Of the initial 200 patients, 121 (61%) accepted motivational counselling. The only factor related to the level of motivation was age. The most motivated group had an average age of 45 years, whereas the average age of the least motivated group was 64. There was no correlation between the Fagerstrom score, pack‐years, gender, illness, employment, or alcohol consumption and the outcome. Fifty‐seven patients agreed to us following them up, of which 10% quit smoking for 6 months; 44% either quit or reduced their smoking for a shorter period of time, and 17% of the continuing smokers requested admission to the smoking cessation programme.

Conclusion:  The majority of smokers acutely admitted to an acute orthopaedic department accepted motivational counselling against smoking, the youngest being the most motivated. It appears possible to implement motivational counselling for smoking cessation in an acute orthopaedic department. It is relevant to consider how, and for which groups, a smoking intervention programme can be offered to acutely admitted patients.

Please cite this paper as: Backer V, Nelbom BM, Duus BR and Tønnesen H. Introduction of new guidelines for emergency patients: motivational counselling among smokers. The Clinical Respiratory Journal 2007;1:37–41.
A Review of a Community Program Aimed at Preventing Early Childhood Caries among Jerusalem Infants – A Brief Communication
Authors: Livny Alon , Sgan‐Cohen Harold D.
Published: May 2007

Early childhood caries (ECC) has not been adequately investigated in Israel. A previous Jerusalem study has demonstrated a potential effect on toothbrushing among infants. The present study was initiated in order to examine caries prevalence and the potential effect of a community intervention program.

Objectives: This study aims to review an intervention program and assess ECC distribution and associated variables.

Methods: The study sample included 1,500 infants in matched “intervention” and “control” Mother and Child Health centers. The 2‐year program, initially including all children at the age of 6 months, focused on the free distribution of toothbrushes and toothpastes. ECC prevalence was determined in a cross‐sectional study.

Results: At 2.5 years, 596 children were examined (40 percent compliance). About half of the parents reported that they had participated once or not at all over the 2‐year period, which demonstrated low program participation. Among the examined children, ECC prevalence was 15.3 percent. No difference in caries levels was found between the program and control groups. The reported level of brushing twice daily was 13.9 percent, while 26.8 percent reported not brushing at all. Eighty‐one percent reported going to bed at night with a bottle. Children who drank sugar‐sweetened beverages had ECC levels significantly higher than those who drank milk or natural juice (18.8 percent versus 8.9 percent).

Conclusions: The dental health and behavior and lack of intervention success emphasized the need to seek a more effective strategy. Emphasis on toothbrushing might not be the only nor optimal solution for this serious public health problem.
Evaluation of a Word Recognition Instrument to Test Health Literacy in Dentistry: The REALD‐99
Authors: Richman Julia A. , Lee Jessica Y. , Rozier R. Gary , Gong Debra A. , Pahel Bhavna T. , Vann William F.
Published: May 2007

Objective: This study aims to evaluate a dental health literacy word recognition instrument.

Methods: Based on a reading recognition test used in medicine, the Rapid Estimate of Adult Literacy in Medicine (REALM), we developed the Rapid Estimate of Adult Literacy in Dentistry (REALD‐99). Parents of pediatric dental patients were recruited from local dental clinics and asked to read aloud words in both REALM and REALD‐99. REALD‐99 scores had a possible range of 0 (low literacy) to 99 (high literacy); REALM scores ranged from 0 to 66. Outcome measures included parents’ perceived oral health for themselves and of their children, and oral health‐related quality of life of the parent as measured by the short‐form Oral Health Impact Profile (OHIP‐14). To determine the validity, we tested bivariate correlations between REALM and REALD‐99, REALM and perceived dental outcomes, and REALD‐99 and perceived dental outcomes. We used ordinary least squares regression and logit models to further examine the relationship between REALD‐99 and dental outcomes. We determined internal reliability using Cronbach’s alpha.

Results: One hundred two parents of children were interviewed. The average REALD‐99 and REALM‐66 scores were high (84 and 62, respectively). REALD‐99 was positively correlated with REALM (PCC=0.80). REALM was not related to dental outcomes. REALD‐99 was associated with parents’ OHIP‐14 score in multivariate analysis. REALD‐99 had good reliability (Cronbach’s alpha=0.86).

Conclusions: REALD‐99 has promise for measuring dental health literacy because it demonstrated good reliability and is quick and easy to administer. Additional studies are needed to examine the validity of REALD‐99 using objective clinical oral health measures and more proximal outcomes such as behavior and compliance to specific health instructions.
Development and Testing of the Test of Functional Health Literacy in Dentistry (TOFHLiD)
Authors: Gong Debra A. , Lee Jessica Y. , Rozier R. Gary , Pahel Bhavna T. , Richman Julia A. , Vann William F.
Published: May 2007

Objective: This study aims to evaluate the reliability and validity of the Test of Functional Health Literacy in Dentistry (TOFHLiD), a new instrument to measure functional oral health literacy.

Methods: TOFHLiD uses text passages and prompts related to fluoride use and access to care to assess reading comprehension and numerical ability. Parents of pediatric dental patients (n=102) were administered TOFHLiD, a medical literacy comprehension test (TOFHLA), and two word recognition tests [Rapid Estimate of Adult Literacy in Dentistry (REALD), Rapid Estimate of Adult Literacy in Medicine (REALM)]. This design provided assessments of dental and medical health literacy by all subjects, both measured with two different methods (reading/numeracy ability and word recognition). Construct validity of TOFHLiD was assessed by entering the correlation coefficients for all pairwise comparisons of literacy instruments into a multitrait‐multimethod matrix. Internal reliability of TOFHLiD was assessed with Cronbach’s alpha. Criterion‐related predictive validity was tested by associations between the TOFHLiD scores and the three measures of oral health in multivariate regression analyses.

Results: The correlation coefficient for TOFHLiD and REALD‐99 scores (monotrait‐heteromethod) was high (r=0.82, P < 0.05). Coefficients between TOFHLiD and TOFHLA (heterotrait‐monomethod: r=0.52) and REALM (heterotrait‐heteromethod: r=0.53) were smaller than coefficients for convergent validity. Cronbach’s alpha for TOFHLiD was 0.63. TOFHLiD was positively correlated with OHIP‐14 (P < 0.05), but not with parent or child oral health. TOFHLA was not related to dental outcomes.

Conclusions: TOFHLiD demonstrates good convergent validity but only moderate ability to discriminate between dental and medical health literacy. Its predictive validity is only partially established, and internal consistency just meets the threshold for acceptability. Results provide solid support for more research, but not widespread use in clinical or public health practice.
The Orientation of the Local Interstellar Magnetic Field
Authors: Opher M. , Stone E. C. , Gombosi T. I.
Published: May 2007

The orientation of the local interstellar magnetic field introduces asymmetries in the heliosphere that affect the location of heliospheric radio emissions and the streaming direction of ions from the termination shock of the solar wind. We combined observations of radio emissions and energetic particle streaming with extensive three-dimensional magnetohydrodynamic computer simulations of magnetic field draping over the heliopause to show that the plane of the local interstellar field is ∼60° to 90° from the galactic plane. This finding suggests that the field orientation in the Local Interstellar Cloud differs from that of a larger-scale interstellar magnetic field thought to parallel the galactic plane.
The World of Science
Authors: Lipton Peter
Published: May 2007

Scientific Perspectivism
.
By Ronald N. Giere
. University of Chicago Press, Chicago, 2006. 168 pp. $30, £19. ISBN 9780226292120.

Giere argues that the perspectival nature of both observing and theorizing makes scientific knowledge contingent.
Bat Flight Generates Complex Aerodynamic Tracks
Authors: Hedenström A. , Johansson L. C. , Wolf M. , von Busse R. , Winter Y. , Spedding G. R.
Published: May 2007

The flapping flight of animals generates an aerodynamic footprint as a time-varying vortex wake in which the rate of momentum change represents the aerodynamic force. We showed that the wakes of a small bat species differ from those of birds in some important respects. In our bats, each wing generated its own vortex loop. Also, at moderate and high flight speeds, the circulation on the outer (hand) wing and the arm wing differed in sign during the upstroke, resulting in negative lift on the hand wing and positive lift on the arm wing. Our interpretations of the unsteady aerodynamic performance and function of membranous-winged, flapping flight should change modeling strategies for the study of equivalent natural and engineered flying devices.
Induction of Specific Immune Responses by Severe Acute Respiratory Syndrome Coronavirus Spike DNA Vaccine with or without Interleukin-2 Immunization Using Different Vaccination Routes in Mice
Authors: Hu Hui , Lu Xinya , Tao Ling , Bai Bingke , Zhang Zhenfeng , Chen Yao , Zheng Fangliang , Chen Jianjun , Chen Ze , Wang Hanzhong
Published: May 2007

DNA vaccines induce humoral and cellular immune responses in animal models and humans. To analyze the immunogenicity of the severe acute respiratory syndrome (SARS) coronavirus (CoV), SARS-CoV, spike DNA vaccine and the immunoregulatory activity of interleukin-2 (IL-2), DNA vaccine plasmids pcDNA-S and pcDNA-IL-2 were constructed and inoculated into BALB/c mice with or without pcDNA-IL-2 by using three different immunization routes (the intramuscular route, electroporation, or the oral route with live attenuatedSalmonella entericaserovar Typhimurium). The cellular and humoral immune responses were assessed by enzyme-linked immunosorbent assays, lymphocyte proliferation assays, enzyme-linked immunospot assays, and fluorescence-activated cell sorter analyses. The results showed that specific humoral and cellular immunities could be induced in mice by inoculating them with SARS-CoV spike DNA vaccine alone or by coinoculation with IL-2-expressing plasmids. In addition, the immune response levels in the coinoculation groups were significantly higher than those in groups receiving the spike DNA vaccine alone. The comparison between the three vaccination routes indicated that oral vaccination evoked a vigorous T-cell response and a weak response predominantly with subclass immunoglobulin G2a (IgG2a) antibody. However, intramuscular immunization evoked a vigorous antibody response and a weak T-cell response, and vaccination by electroporation evoked a vigorous response with a predominant subclass IgG1 antibody response and a moderate T-cell response. Our findings show that the spike DNA vaccine has good immunogenicity and can induce specific humoral and cellular immunities in BALB/c mice, while IL-2 plays an immunoadjuvant role and enhances the humoral and cellular immune responses. Different vaccination routes also evoke distinct immune responses. This study provides basic information for the design of DNA vaccines against SARS-CoV.
Legionella jordanis
Lower Respiratory Tract Infection: Case Report and Review
Authors: Vinh Donald C. , Garceau Richard , Martinez Gabriela , Wiebe Debbie , Burdz Tamara , Reimer Aleisha , Bernard Kathryn
Published: May 2007

Legionella jordanis
was first described in 1982 after isolation from environmental sources and is otherwise a very rare human pathogen. Here, we report the recovery of
L. jordanis
from a bronchoalveolar lavage specimen from a patient who presented with an indolent lower respiratory tract infection associated with constitutional symptoms. This case is the first culture-positive case of infection involving this species in Canada.
Insertion Sequence
1515
in the
ply
Gene of a Type 1 Clinical Isolate of
Streptococcus pneumoniae
Abolishes Pneumolysin Expression
Authors: Garnier Fabien , Janapatla Rajendra Prasad , Charpentier Emmanuelle , Masson Geoffrey , Grélaud Carole , Stach Jean François , Denis François , Ploy Marie-Cécile
Published: May 2007

A serotype 1
Streptococcus pneumoniae
strain isolated by blood culture from a woman with pneumonia was found to harbor insertion sequence (IS)
1515
in the pneumolysin gene, abolishing pneumolysin expression. To our knowledge, this is the first report of an IS in the pneumolysin gene of
S. pneumoniae
.
Multiple-Locus Variable-Number Tandem-Repeat Assay Analysis of Methicillin-ResistantStaphylococcus aureusStrains
Authors: Tenover Fred C. , Vaughn Rebekah R. , McDougal Linda K. , Fosheim Gregory E. , McGowan John E.
Published: May 2007

Our objective was to determine if a multiple-locus variable-number tandem-repeat assay (MLVA) forStaphylococcus aureuscould predict pulsed-field gel electrophoresis (PFGE) types (i.e., USA types), thus allowing us to replace PFGE with a simpler and more rapid typing method. One hundred three well-characterized isolates representing 13 major lineages ofS. aureuswere tested by both PFGE and MLVA. MLVA was performed using a rapid DNA extraction technique and PCR primers forsdrCDE,clfA,clfB,sspA, andspa.PFGE was performed with genomic DNA fragments generated using SmaI, as per CDC protocols. Banding patterns were analyzed both visually and with BioNumerics software. All isolates were typeable with MLVA and PFGE. MLVA patterns were highly reproducible. PFGE separated the isolates into 13 types with 42 subtypes. Using any band difference to designate a novel MLVA type, MLVA produced 45 types, including 9 clusters containing multiple isolates. Using BioNumerics and a cutoff of >75% relatedness, MLVA produced 28 types, 11 of which contained >1 isolate. Epidemiologically related outbreak isolates of USA300-0114 from five states clustered in one MLVA pattern. USA100 isolates were present in several unrelated (<40%) MLVA types. A cutoff of >80% separated outbreak strains of USA300-0114 into three distinct MLVA types. MLVA did not differentiate community methicillin-resistantS. aureus(MRSA) lineages (USA300, USA400, USA1000, and USA1100) from health care MRSA lineages (USA100, USA200, or USA500). The ability of MLVA to differentiate among strains that are indistinguishable by PFGE may be of epidemiologic value and warrants further study.
Contribution of Recombination to the Evolution of Human Immunodeficiency Viruses Expressing Resistance to Antiretroviral Treatment
Authors: Nora Tamara , Charpentier Charlotte , Tenaillon Olivier , Hoede Claire , Clavel François , Hance Allan J.
Published: May 2007

Viral recombination has been postulated to play two roles in the development of human immunodeficiency virus (HIV) resistance to antiretroviral drugs. First, recombination has the capacity to associate resistance mutations expressed by distinct viruses, thereby contributing to the development of viruses with improved drug resistance. In addition, recombination could preserve diversity in regions outside those subject to strong selective pressure. In this study, we sought direct evidence for the occurrence of these processes in vivo by evaluating clonal virus populations obtained from the same patient before and after a treatment change that, while unsuccessful in controlling viral replication, led to the emergence of viruses expressing a different profile of resistance mutations. Phylogenetic studies supported the conclusion that the genotype arising after the treatment change resulted from the emergence of recombinant viruses carrying previously existing resistance mutations in novel combinations, whereas alternative explanations, including convergent evolution, were not consistent with observed genotypic changes. Despite evidence for a strong loss of genetic diversity in genomic regions coding for the protease and reverse transcriptase, diversity in regions coding for Gag and envelope was considerably higher, and recombination between the emerging viruses expressing the new pattern of resistance mutations and viral quasispecies in the previously dominant population contributed to this preservation of diversity in the envelope gene. These findings emphasize that recombination can participate in the adaptation of HIV to changing selective pressure, both by generating novel combinations of resistance mutations and by maintaining diversity in genomic regions outside those implicated in a selective sweep.
Cholesterol Dependence of Varicella-Zoster Virion Entry into Target Cells
Authors: Hambleton S. , Steinberg S. P. , Gershon M. D. , Gershon A. A.
Published: May 2007

The entry of inhaled virions into airway cells is presumably the initiating step of varicella-zoster infection. In order to characterize viral entry, we studied the relative roles played by lipid rafts and clathrin-mediated transport. Virus and target cells were pretreated with agents designed to perturb selected aspects of endocytosis and membrane composition, and the effects of these perturbations on infectious focus formation were monitored. Infectivity was exquisitely sensitive to methyl-β-cyclodextrin (MβCD) and nystatin, which disrupt lipid rafts by removing cholesterol. These agents inhibited infection by enveloped, but not cell-associated, varicella-zoster virus (VZV) in a dose-dependent manner and exerted these effects on both target cell and viral membranes. Inhibition by MβCD, which could be reversed by cholesterol replenishment, rapidly declined as a function of time after exposure of target cells to VZV, suggesting that an early step in viral infection requires cholesterol. No effect of cholesterol depletion, however, was seen on viral binding; moreover, there was no reduction in the surface expression or internalization of mannose 6-phosphate receptors, which are required for VZV entry. Viral entry was energy dependent and showed concentration-dependent inhibition by chlorpromazine, which, among other actions, blocks clathrin-mediated endocytosis. These data suggest that both membrane lipid composition and clathrin-mediated transport are critical for VZV entry. Lipid rafts are likely to contribute directly to viral envelope integrity and, in the host membrane, may influence endocytosis, evoke downstream signaling, and/or facilitate membrane fusion.
Human and Simian Immunodeficiency Virus-Mediated Upregulation of the Apoptotic Factor TRAIL Occurs in Antigen-Presenting Cells from AIDS-Susceptible but Not from AIDS-Resistant Species
Authors: Kim Nayoung , Dabrowska Alicja , Jenner Richard G. , Aldovini Anna
Published: May 2007

Human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) infections lead to AIDS in humans and rhesus macaques (RM), while they are asymptomatic in species naturally infected with SIV, such as chimpanzees, sooty mangabeys (SM), and African green monkeys (AGM). Differential CD4+T-cell apoptosis may be responsible for these species-specific differences in susceptibility to disease. To identify factors that influence the different apoptotic responses of these species, we analyzed virus-infected human and nonhuman primate peripheral blood mononuclear cells (PBMC). We found that the apoptotic factor TRAIL was present at higher levels in human and RM PBMC cultures and was mediating, at least in part, CD4+T-cell apoptosis in these cultures. The species-specific increase in TRAIL and death receptor expression observed with cultures also occurred in vivo in SIV-infected RM but not in SIV-infected SM. In human and RM myeloid immature dendritic cells and macrophages, the virus-induced expression of TRAIL and other interferon-inducible genes, which did not occur in the same cells from chimpanzee, SM, and AGM, was Tat dependent. Our results link the differential induction of TRAIL in human and nonhuman primate cells to species-specific differences in disease susceptibility.
Human Immunodeficiency Virus Type 1 Replication in Dendritic Cell-T-Cell Cocultures Is Increased upon Incorporation of Host LFA-1 due to Higher Levels of Virus Production in Immature Dendritic Cells
Authors: Gilbert Caroline , Cantin Réjean , Barat Corinne , Tremblay Michel J.
Published: May 2007

Dendritic cells (DCs) act as a portal for invasion by human immunodeficiency virus type-1 (HIV-1). Here, we investigated whether virion-incorporated host cell membrane proteins can affect virus replication in DC-T-cell cocultures. Using isogenic viruses either devoid of or bearing host-derived leukocyte function-associated antigen 1 (LFA-1), we showed that HIV-1 production is augmented when LFA-1-bearing virions are used compared to that for viral entities lacking this adhesion molecule. This phenomenon was observed in immature monocyte-derived DCs (IM-MDDCs) only and not in DCs displaying a mature phenotype. The increase is not due to higher virus production in responder CD4+T cells but rather is linked with a more important productive infection of IM-MDDCs. We provided evidence that virus-associated host LFA-1 molecules do not affect a late event in the HIV-1 life cycle but rather exert an effect on an early step in virus replication. We demonstrated that the enhancement of productive infection of IM-MDDCs that is conferred by virus-anchored host LFA-1 involves the protein kinase A (PKA) and PKC signal transduction pathways. The biological significance of this phenomenon was established by performing experiments with virus stocks produced in primary human cells and anti-LFA-1 antibodies. Together, our results indicate that the association between some virus-bound host proteins and their natural cognate ligands can modulate de novo HIV-1 production by IM-MDDCs. Therefore, the additional interactions between virus-bound host cell membrane constituents and counter receptors on the surfaces of DCs can influence HIV-1 replication in IM-MDDC-T-cell cocultures.
BIFURCATIONS IN DYNAMICS OF SHEPHERD SYSTEMS
Authors: MACABÉA JOYCE
Published: May 2007

A small moon orbiting near the edge of a ring of particles can act as a "shepherd", keeping errant ring particles from drifting away and keeping the ring boundary sharp. This phenomenon was predicted before it was observed [Goldreich & Tremaine, 1979] and has been successfully modeled by many authors, see [Murray & Dermott, 1999]. In this paper we focus on the bifurcations that occur in the motion of a ring particle as the mass of the moon and the distance between orbits of the moon and the particle are adjusted.
NUMERICAL CONTINUATION FOR NONLINEAR SCHRÖDINGER EQUATIONS
Authors: CHANG S.-L. , CHIEN C.-S.
Published: May 2007

We discuss numerical methods for studying numerical solutions of N-coupled nonlinear Schrödin-ger equations (NCNLS), N = 2, 3. First, we discretize the equations by centered difference approximations. The chemical potentials and the coupling coefficient are treated as continuation parameters. We show how the predictor–corrector continuation method can be exploited to trace solution curves and surfaces of the NCNLS, where the preconditioned Lanczos method with iterative refinement is used as the linear solver. When the chemical potential is large enough, we obtain peak solutions of the NCNLS for certain values of the coupling coefficient. The contours of the peak solutions resemble those of the experimental results of Anglin and Ketterle [2002], and Anderson et al. [1995].
OPTIMAL CONVERGENCE RATES FOR THE COMPRESSIBLE NAVIER–STOKES EQUATIONS WITH POTENTIAL FORCES
Authors: DUAN RENJUN , UKAI SEIJI , YANG TONG , ZHAO HUIJIANG
Published: May 2007

For the viscous and heat-conductive fluids governed by the compressible Navier–Stokes equations with an external potential force, there exist non-trivial stationary solutions with zero velocity. By combining the Lp - Lq estimates for the linearized equations and an elaborate energy method, the convergence rates are obtained in various norms for the solution to the stationary profile in the whole space when the initial perturbation of the stationary solution and the potential force are small in some Sobolev norms. More precisely, the optimal convergence rates of the solution and its first order derivatives in L2-norm are obtained when the L1-norm of the perturbation is bounded.
HOMOGENIZATION OF MATERIALS WITH PERIODIC TRUSS OR FRAME MICRO-STRUCTURES
Authors: MARTINSSON P. G. , BABUŠKA IVO
Published: May 2007

The equations that govern elastostatic equilibrium between a prescribed force field and an unknown displacement field for materials with periodic skeletal micro-structures are studied. It is shown that as the size of the micro-structure tends to zero, the displacement field will converge to the solution of a constant coefficient partial differential equation. This equation is shown to be either a classical or a micro-polar continuum elasticity equation, depending on the micro-structural geometry and the nature of the external load field. Convergence is proved for representative model problems in Sobolev energy norms and in the maximum norm. In addition, it is shown that by considering pseudo-differential homogenized equations, any order of convergence can be achieved.
Deciphering PiT transport kinetics and substrate specificity using electrophysiology and flux measurements
Authors: Ravera Silvia , Virkki Leila V. , Murer Heini , Forster Ian C.
Published: May 2007

Members of the SLC20 family or type III Na+-coupled Pi cotransporters (PiT-1, PiT-2) are ubiquitously expressed in mammalian tissue and are thought to perform a housekeeping function for intracellular Pi homeostasis. Previous studies have shown that PiT-1 and PiT-2 mediate electrogenic Pi cotransport when expressed in Xenopus oocytes, but only limited kinetic characterizations were made. To address this shortcoming, we performed a detailed analysis of SLC20 transport function. Three SLC20 clones ( Xenopus PiT-1, human PiT-1, and human PiT-2) were expressed in Xenopus oocytes. Each clone gave robust Na+-dependent 32Pi uptake, but only Xenopus PiT-1 showed sufficient activity for complete kinetic characterization by using two-electrode voltage clamp and radionuclide uptake. Transport activity was also documented with Li+ substituted for Na+. The dependence of the Pi-induced current on Pi concentration was Michaelian, and the dependence on Na+ concentration indicated weak cooperativity. The dependence on external pH was unique: the apparent Pi affinity constant showed a minimum in the pH range 6.2–6.8 of ∼0.05 mM and increased to ∼0.2 mM at pH 5.0 and pH 8.0. Xenopus PiT-1 stoichiometry was determined by dual 22Na-32Pi uptake and suggested a 2:1 Na+:Pi stoichiometry. A correlation of 32Pi uptake and net charge movement indicated one charge translocation per Pi. Changes in oocyte surface pH were consistent with transport of monovalent Pi. On the basis of the kinetics of substrate interdependence, we propose an ordered binding scheme of Na+:H2PO4−:Na+. Significantly, in contrast to type II Na+-Pi cotransporters, the transport inhibitor phosphonoformic acid did not inhibit PiT-1 or PiT-2 activity.
Oxidant-impaired intracellular Ca2+ signaling in pancreatic acinar cells: role of the plasma membrane Ca2+-ATPase
Authors: Bruce Jason I. E. , Elliott Austin C.
Published: May 2007

Pancreatitis is an inflammatory disease of pancreatic acinar cells whereby intracellular calcium concentration ([Ca2+]i) signaling and enzyme secretion are impaired. Increased oxidative stress has been suggested to mediate the associated cell injury. The present study tested the effects of the oxidant, hydrogen peroxide, on [Ca2+]i signaling in rat pancreatic acinar cells by simultaneously imaging fura-2, to measure [Ca2+]i, and dichlorofluorescein, to measure oxidative stress. Millimolar concentrations of hydrogen peroxide increased cellular oxidative stress and irreversibly increased [Ca2+]i, which was sensitive to antioxidants and removal of external Ca2+, and ultimately led to cell lysis. Responses were also abolished by pretreatment with (sarco)endoplasmic reticulum Ca2+-ATPase inhibitors, unless cells were prestimulated with cholecystokinin to promote mitochondrial Ca2+ uptake. This suggests that hydrogen peroxide promotes Ca2+ release from the endoplasmic reticulum and the mitochondria and that it promotes Ca2+ influx. Lower concentrations of hydrogen peroxide (10–100 μM) increased [Ca2+]i and altered cholecystokinin-evoked [Ca2+]i oscillations with marked heterogeneity, the severity of which was directly related to oxidative stress, suggesting differences in cellular antioxidant capacity. These changes in [Ca2+]i also upregulated the activity of the plasma membrane Ca2+-ATPase in a Ca2+-dependent manner, whereas higher concentrations (0.1–1 mM) inactivated the plasma membrane Ca2+-ATPase. This may be important in facilitating “Ca2+ overload,” resulting in cell injury associated with pancreatitis.
IL-4 stimulates the expression of CXCL-8, E-selectin, VEGF, and inducible nitric oxide synthase mRNA by equine pulmonary artery endothelial cells
Authors: Huang Hong , Lavoie-Lamoureux Anouk , Moran Kantuta , Lavoie Jean-Pierre
Published: May 2007

Little is known concerning the possible contribution of T helper 2 (Th2)-type cytokines to the recruitment of neutrophils into the lung tissue. In the present study, endothelial cells from equine pulmonary arteries were cultured in the presence of recombinant equine (re) IL-4 and reIL-5, and the cytokine mRNA expression of molecules implicated in the chemotaxis and migration of neutrophils was studied using real-time RT-PCR. The functional response of reIL-4-induced endothelial cell stimulation on neutrophil migration was also studied using a chemotaxis chamber. ReIL-4 either increased the expression of CXCL-8, E-selectin, vascular endothelial growth factor (VEGF), and inducible nitric oxide synthase (iNOS), or potentiated the coeffects of lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) on CXCL-8. Supernatants collected from cultured endothelial cells stimulated with reIL-4 significantly promoted neutrophil migration in a dose-dependent manner. Dexamethasone (DXM) decreased the expression of CXCL-8, VEGF, and iNOS induced by reIL-4, while 1400W dihydrochloride (1400W), a selective inhibitor of iNOS, decreased the expression of E-selectin, VEGF, and iNOS. DXM and 1400W attenuated the mRNA expression of E-selectin and iNOS induced by the costimulation of reIL-4, reTNF-α, and LPS. Neither equine nor human recombinant IL-5 influenced the mRNA expression of CXCL-8, E-selectin, or VEGF. These findings suggest that Th2-type cytokines may contribute to pulmonary neutrophilia during allergic inflammation by the increased expression of neutrophil chemokines and adhesion molecules by endothelial cells. DXM and the iNOS inhibitors may decrease pulmonary neutrophilia due, in part, to a direct inhibition of some of these factors.
Changes in renal hemodynamics and excretory function induced by a reduction of ANG II effects during renal development
Authors: Loria Analia , Reverte Virginia , Salazar Francisco , Saez Fara , Llinas M. Teresa , Salazar F. Javier
Published: May 2007

The aim was to evaluate whether blockade of ANG II effects during renal development modifies the renal response to an increment of plasma amino acid concentration. It was also examined in anesthetized rats whether the reduction of the renal ability to eliminate an acute volume expansion (VE), elicited by blockade of ANG II during renal development, is sex and/or age dependent. Newborn Sprague-Dawley rats were treated with vehicle or an AT1-receptor antagonist (ARA) during postnatal nephrogenesis. Amino acid infusion induced increments ( P < 0.05) of glomerular filtration rate (31 ± 6%) and renal plasma flow (26 ± 5%) in male but not in female vehicle-treated rats. Natriuretic and diuretic responses to amino acid infusion were similar in male and female vehicle-treated rats. These renal hemodynamics and excretory responses to amino acid infusion were abolished in ARA-treated rats. Renal responses to VE were evaluated at 3–4 and 9–10 mo of age in vehicle and ARA-treated rats. VE-induced natriuresis and diuresis were reduced by more than 38% ( P < 0.05) in 3- to 4-mo-old male and female ARA-treated rats. An age-dependent reduction ( P < 0.05) in the renal ability to eliminate VE was found in male but not in female rats treated with ARA. Our results demonstrate that the renal effects induced by an increment in amino acids are abolished when ANG II effects have been reduced during nephrogenesis. In addition, this reduction of ANG II effects elicits an impairment of the renal ability to eliminate an acute VE in males and females, which is aggravated by age only in male rats.
Timing of puberty and synchronization of seasonal rhythms by simulated natural photoperiods in female Siberian hamsters
Authors: Butler Matthew P. , Trumbull Justin J. , Turner Kevin W. , Zucker Irving
Published: May 2007

The timing of puberty is a critical life history trait of short-lived species; spring-born individuals mature rapidly and breed in the season of birth, whereas young born in mid- to late summer delay puberty until the next spring. The cues that govern the transition from rapid to delayed maturation in natural populations remain unknown. To identify ecologically relevant photoperiod cues that control timing of puberty, we monitored nine cohorts of female Siberian hamsters ( Phodopus sungorus) born every 2 wk from 4 wk before to 12 wk after the summer solstice in a simulated natural photoperiod (SNP). Hamsters born by the summer solstice underwent rapid somatic growth and achieved puberty that summer; among females born 2–4 wk after the solstice, some delayed puberty by many weeks, whereas others manifested early puberty. Hamsters born 6 or more weeks after the solstice generally delayed puberty until the following spring. The transition from accelerated to delayed pubertal development in the SNP occurred at day lengths that induce early puberty when presented as static photoperiods. Despite differences in timing of birth and timing of puberty, fall and subsequent spring seasonal events occurred at similar calendar dates in all cohorts. We found no evidence that prenatal photoperiod history influenced postnatal development of female hamsters. Considered together with a parallel study on males, the present findings point to sex differences in responsiveness to natural photoperiod variations. In both sexes, incrementally changing photoperiods exert a strong organizing effect on seasonal rhythms.
Diabetes slows the recovery from urinary incontinence due to simulated childbirth in female rats
Authors: Kim Ja-Hong , Huang Xiao , Liu Guiming , Moore Courtenay , Bena James , Damaser Margot S. , Daneshgari Firouz
Published: May 2007

This study was done to test the hypothesis that simulated vaginal birth by vaginal distension (VD) causes more severe urinary incontinence and slower recovery in diabetic rats. After measuring baseline leak point pressure (LPP) in 16 diabetes mellitus (DM) and 16 age- and weight-matched control (Ct) female Sprague-Dawley rats, these animals underwent either VD or sham VD (sham). Four and ten days after the procedures, LPP and conscious cystometry were assessed. Tissues were then harvested and examined by light microscopy. LPP at baseline was equal among all four groups. Four days after VD, LPP in both VD groups dropped to significantly lower levels than in sham rats ( P < 0.001). Moreover, LPP in the DM+VD group was significantly lower than in the Ct+VD group. At 10 days, LPP in the Ct+VD group had recovered to its baseline value, whereas the LPP in the DM+VD group remained significantly reduced. DM rats had larger bladder capacity and longer voiding intervals than Ct rats. Histological findings included more severe damage to the external sphincter striated musculature of the urethra in DM+VD group compared with Ct+VD. In conclusion, these findings suggest that DM causes increased severity and delayed functional recovery from the effects of simulated childbirth.
Endotoxin and cisplatin synergistically induce renal dysfunction and cytokine production in mice
Authors: Ramesh Ganesan , Zhang Binzhi , Uematsu Satoshi , Akira Shizuo , Reeves W. Brian
Published: May 2007

A major toxicity of the cancer chemotherapeutic agent cisplatin is acute renal failure. Sepsis is a common cause of acute renal failure in humans and patients who receive cisplatin are at increased risk for sepsis. Accordingly, this study examined the interactions between cisplatin and endotoxin in vivo with respect to renal function and cytokine production. Mice were treated with either a single dose of cisplatin or two doses of LPS administered 24 h apart, or both agents in combination. Administration of 10 mg/kg cisplatin had no effect on blood urea nitrogen or creatinine levels throughout the course of the study. LPS resulted in a modest rise in blood urea nitrogen at 24 and 48 h, which returned to normal by 72 h. In contrast, mice treated with both cisplatin and LPS developed severe renal failure and an increase in mortality. Urine, but not serum, TNF-α levels showed a synergistic increase by cisplatin and LPS. Urinary IL-6, MCP-1, KC, and GM-CSF also showed a synergistic increase with cisplatin+LPS treatment. The renal dysfunction induced by cisplatin+LPS was completely dependent on TLR4 signaling and partially dependent on TNF-α production. Increased cytokine production was associated with a moderate increase in infiltrating leukocytes which was not different between cisplatin+LPS and LPS alone. These results indicate that cisplatin and LPS act synergistically to produce nephrotoxicity which may involve proinflammatory cytokine production.
In vitro models of TGF-β-induced fibrosis suitable for high-throughput screening of antifibrotic agents
Authors: Xu Qihe , Norman Jill T. , Shrivastav Shashi , Lucio-Cazana Javier , Kopp Jeffrey B.
Published: May 2007

Progressive fibrosis is a cause of progressive organ dysfunction. Lack of quantitative in vitro models of fibrosis accounts, at least partially, for the slow progress in developing effective antifibrotic drugs. Here, we report two complementary in vitro models of fibrosis suitable for high-throughput screening. We found that, in mesangial cells and renal fibroblasts grown in eight-well chamber slides, transforming growth factor-β1 (TGF-β1) disrupted the cell monolayer and induced cell migration into nodules in a dose-, time- and Smad3-dependent manner. The nodules contained increased interstitial collagens and showed an increased collagen I:IV ratio. Nodules are likely a biological consequence of TGF-β1-induced matrix overexpression since they were mimicked by addition of collagen I to the cell culture medium. TGF-β1-induced nodule formation was inhibited by vacuum ionized gas treatment of the plate surface. This blockage was further enhanced by precoating plates with matrix proteins but was prevented, at least in part, by poly-l-lysine (PLL). We have established two cell-based models of TGF-β-induced fibrogenesis, using mesangial cells or fibroblasts cultured in matrix protein or PLL-coated 96-well plates, on which TGF-β1-induced two-dimensional matrix accumulation, three-dimensional nodule formation, and monolayer disruption can be quantitated either spectrophotometrically or by using a colony counter, respectively. As a proof of principle, chemical inhibitors of Alk5 and the antifibrotic compound tranilast were shown to have inhibitory activities in both assays.