bluuebunny/crossref_metadata_2025 huggingface dataset:
Intracellular Efavirenz Levels in Peripheral Blood Mononuclear Cells from Human Immunodeficiency Virus-Infected Individuals
Authors: Tanaka Rie , Hanabusa Hideji , Kinai Ei , Hasegawa Naoki , Negishi Masayoshi , Kato Shingo
Published: December 2007

We describe a novel method for isolating plasma-free peripheral blood mononuclear cells retaining intracellular efavirenz. Quantification of efavirenz in 13 human immunodeficiency virus-infected patients by liquid chromatography-tandem mass spectrometry showed a higher correlation of intracellular levels with unbound plasma levels (accumulation ratio, 1,190) than with total plasma levels.
Effective Production and Purification of the Glycosylated TSOL18 Antigen, Which Is Protective against Pig Cysticercosis
Authors: Cai Xuepeng , Yuan Gailing , Zheng Yadong , Luo Xuenong , Zhang Shaohua , Ding Juntao , Jing Zhizhong , Lu Chengping
Published: December 2007

Cysticercosis caused by
Taenia solium
metacestodes is a worldwide public health problem. Important progress in the development of effective and practical vaccines against this disease has been made. In this study, the promising
T. solium
oncospheral vaccine candidate named TSOL18 antigen was produced in a 5-liter fermentor. During the process of fermentation, the pH of the culture was always kept below 5.0, and in order to prevent foaming, an antifoam agent was added. In addition, the oxygen content of the culture was constantly kept at >50% in our experiment. A high level of the glycosylated protein (2.5 g/liter) was obtained, and the protein was easily purified by gel chromatography. Vaccination trials showed that the recombinant TSOL18 antigen induced 94 and 100% reductions in metacestode burdens in vaccinated pigs, obviously higher than the 89% reduction in pigs immunized with cysticercus crude extracts in trial 1. These are very promising results in the development of an efficient tool to control cysticercosis in Asia.
Possible Role for Toll-Like Receptors in Interaction ofFasciola hepaticaExcretory/Secretory Products with Bovine Macrophages
Authors: Flynn Robin J. , Mulcahy Grace
Published: December 2007

Alternative activation of macrophages (Mφ) during helminth infection is a characteristic feature of the host immune response. Alternatively activated macrophages (AAMφ) are distinguished from others by high arginase 1 (Arg-1) activity, low nitric oxide (NO), and high interleukin 10 (IL-10) production. In murine models, these cells have been shown to possess anti-inflammatory properties. They have also been implicated in exacerbating a subsequent infection with a secondary pathogen. In this study we used cattle experimentally infected withFasciola hepaticato monitor the kinetics of IL-4 and IL-10 over the course of infection. Using naïve Mφ in vitro, we examined the effects of exposure toF.hepaticaexcretory/secretory products (FhepES) alone or in combination with IL-4. Our results suggest that FhepES may work in combination with IL-4 to produce AAMφ. The effects of FhepES on the subsequent responses to lipopolysaccharide (LPS) and purified protein derivative fromMycobacterium bovis(PPD-B), which are bovine Toll-like receptor 4 (TLR4) and TLR2 antagonists, respectively, were also examined. We found that Mφ stimulated with FhepES together with LPS or PPD-B have reduced NO or gamma interferon production, respectively. The ability of FhepES to produce AAMφ was found to be heat labile and partially dependent on glycan residues. A possible role for TLR recognition is discussed.
Enterobacter sakazakii
Invasion in Human Intestinal Caco-2 Cells Requires the Host Cell Cytoskeleton and Is Enhanced by Disruption of Tight Junction
Authors: Kim Kwang-Pyo , Loessner Martin J.
Published: December 2007

Enterobacter sakazakii
is an opportunistic pathogen that causes systemic bacteremia and meningitis with high mortality, and powdered infant formula is a frequent source of this bacterium. However, the mechanisms that this organism uses to invade and translocate through the intestinal barrier are unknown. Using Caco-2 epithelial cells, we were able to demonstrate penetration of
E. sakazakii
and to determine invasion-associated properties. We found that
E. sakazakii
entry and invasion were dependent on the exposure time and multiplicity of infection and required bacterial de novo protein synthesis but was independent of cell polarity in the presence of tight junctions. Moreover, the presence of actin filaments and microtubule structures was required, and disruption of the tight junction significantly enhanced the initial association with Caco-2 cells and the efficiency of invasion, which provides a possible explanation for the preferential occurrence of this infection in babies and neonates. This is the first description of
E. sakazakii
invasion of host intestinal cells, and our findings suggest that this emerging pathogen employs a novel invasion mechanism for development of systemic infection.
Genetic Diversity among
Escherichia coli
O157:H7 Isolates and Identification of Genes Linked to Human Infections
Authors: Wu Guanghui , Carter Ben , Mafura Muriel , Liebana Ernesto , Woodward Martin J. , Anjum Muna F.
Published: December 2007

An
Escherichia coli
oligonucleotide microarray based on three sequenced genomes was validated for comparative genomic microarray hybridization and used to study the diversity of
E. coli
O157 isolates from human infections and food and animal sources. Among 26 test strains, 24 (including both Shiga toxin [Stx]-positive and -negative strains) were found to be related to the two sequenced
E. coli
O157:H7 strains, EDL933 and Sakai. However, these strains showed much greater genetic diversity than those reported previously, and most of them could not be categorized as either lineage I or II. Some genes were found more often in isolates from human than from nonhuman sources; e.g., ECs1202 and ECs2976, associated with
stx2AB
and
stx1AB
, were in all isolates from human sources but in only 40% of those from nonhuman sources. Some (but not all) lineage I-specific or -dominant genes were also more frequently associated with isolates from human. The results suggested that it might be more effective to concentrate our efforts on finding markers that are directly related to infection rather than those specific to certain lineages. In addition, two Stx-negative O157 cattle isolates (one confirmed to be H7) were significantly different from other Stx-positive and -negative
E. coli
O157:H7 strains and were more similar to MG1655 in their gene content. This work demonstrates that not all
E. coli
O157:H7 strains belong to the same clonal group, and those that were similar to
E. coli
K-12 might be less virulent.
Activation of IκB Kinase β and NF-κB Is Essential for
Helicobacter pylori
-Induced Chronic Gastritis in Mongolian Gerbils
Authors: Yanai Ayako , Maeda Shin , Shibata Wataru , Hikiba Yohko , Sakamoto Kei , Nakagawa Hayato , Ohmae Tomoya , Hirata Yoshihiro , Ogura Keiji , Muto Susumu , Itai Akiko , Omata Masao
Published: December 2007

The Mongolian gerbil model of
Helicobacter pylori
infection resembles human gastritis. In this study, we investigated the role of NF-κB activation in
H. pylori
-infected gerbils. Activated macrophages were significantly increased in
H. pylori
-infected gastric mucosa and were identified as being important cells with potent activation of NF-κB, which plays an important part in producing proinflammatory cytokines. Macrophage depletion by the administration of clodronate resulted in milder inflammation in gerbils infected with
H. pylori
. In macrophages, the inhibition of IκB kinase β (IKKβ), which is a critical kinase for NF-κB activation, resulted in lower proinflammatory cytokine expression caused by heat-killed
H. pylori
cells. Furthermore, treatment with IKKβ inhibitor resulted in milder inflammation in gerbils with
H. pylori
gastritis. Collectively, our data suggest that
H. pylori
-mediated gastric inflammation critically depends on the efficient recruitment and activation of macrophages, with sufficient NF-κB activation.
Interferons Increase Cell Resistance to Staphylococcal Alpha-Toxin
Authors: Yarovinsky Timur O. , Monick Martha M. , Husmann Matthias , Hunninghake Gary W.
Published: December 2007

Many bacterial pathogens, includingStaphylococcus aureus, use a variety of pore-forming toxins as important virulence factors. Staphylococcal alpha-toxin, a prototype β-barrel pore-forming toxin, triggers the release of proinflammatory mediators and induces primarily necrotic death in susceptible cells. However, whether host factors released in response to staphylococcal infections may increase cell resistance to alpha-toxin is not known. Here we show that prior exposure to interferons (IFNs) prevents alpha-toxin-induced membrane permeabilization, the depletion of ATP, and cell death. Moreover, pretreatment with IFN-α decreases alpha-toxin-induced secretion of interleukin 1β (IL-1β). IFN-α, IFN-β, and IFN-γ specifically protect cells from alpha-toxin, whereas tumor necrosis factor alpha (TNF-α), IL-6, and IL-4 have no effects. Furthermore, we show that IFN-α-induced protection from alpha-toxin is not dependent on caspase-1 or mitogen-activated protein kinases, but requires protein synthesis and fatty acid synthase activity. Our results demonstrate that IFNs may increase cell resistance to staphylococcal alpha-toxin via the regulation of lipid metabolism and suggest that interferons play a protective role during staphylococcal infections.
Humoral Responses toPlasmodium falciparumBlood-Stage Antigens and Association with Incidence of Clinical Malaria in Children Living in an Area of Seasonal Malaria Transmission in Burkina Faso, West Africa
Authors: Nebie Issa , Diarra Amidou , Ouedraogo Alphonse , Soulama Issiaka , Bougouma Edith C. , Tiono Alfred B. , Konate Amadou T. , Chilengi Roma , Theisen Michael , Dodoo Daniel , Remarque Ed , Bosomprah Samuel , Milligan Paul , Sirima Sodiomon B.
Published: December 2007

There is longstanding evidence that immunoglobulin G (IgG) has a role in protection against clinical malaria, and human antibodies of the cytophilic subclasses are thought to be particularly critical in this respect. In this cohort study, 286 Burkinabè children 6 months to 15 years old were kept under malaria surveillance in order to assess the protective role of antibody responses against four antigens which are currently being evaluated as vaccine candidates: apical membrane antigen 1 (AMA1), merozoite surface protein 1-19 (MSP1-19), MSP3, and glutamate-rich protein (GLURP). Total IgG, IgM, and IgG subclass responses were measured just before the malaria transmission season. The incidence of malaria was 2.4 episodes per child year of risk. After adjusting for the confounding effects of age, the level of total IgG to GLURP was strongly associated with reduced malaria incidence (incidence rate ratio associated with a doubling of total IgG, 0.79; 95% confidence interval, 0.66 to 0.94;P= 0.009.); there was a borderline statistically significant association between the level of total IgG to MSP3 and malaria incidence and no evidence of an association for total IgG to AMA1 and to MSP1-19. Of the IgG subclass responses studied, only IgG3 and IgG4 against GLURP and IgG1 against AMA1 were associated with reduced risk of clinical malaria. There was no evidence of an interaction between responses to AMA1 and baseline parasitemia in their effects on malaria incidence. Currently included in malaria vaccine formulations for clinical trials in humans, these blood-stage antigens, AMA1 and GLURP, offer good prospects for malaria vaccine development.
Evasion of Innate Immune Responses: Evidence for Mannose Binding Lectin Inhibition of Tumor Necrosis Factor Alpha Production by Macrophages in Response toBlastomyces dermatitidis
Authors: Koneti Adi , Linke Michael J. , Brummer Elmer , Stevens David A.
Published: December 2007

Serum factors, including mannose binding lectins (MBL), influence innate responses to microbes. Little is known about the effects of serum factors or MBL on the interaction ofBlastomyces dermatitidis, a pulmonary fungal pathogen, with macrophages or on tumor necrosis factor alpha (TNF-α) production. Since macrophage production of TNF-α is an important innate immune response, we examined a mouse peritoneal macrophage (PM) cell line (RAW) and resident PM from CD-1 mice to study TNF-α production by PM stimulated with heat-killed (HK) or liveB. dermatitidisyeast cells. Mouse serum and heat-inactivated mouse serum inhibited TNF-α production 94% when macrophages were stimulated byB. dermatitidis, whereas mouse immunoglobulin G (IgG) did not have this effect. HKB. dermatitidisincubated with serum and then washed also failed to stimulate significant TNF-α production by PM. By the sandwich immunofluorescent antibody (IFA) method with anti-mouse MBL (MBL-A or -C), we showed that serum MBL bound toB. dermatitidis. When serum was absorbed with HKB. dermatitidisor liveB. dermatitidis, absorbed serum failed to significantly inhibit TNF-α production by RAW cells plusB. dermatitidis, and immunoblotting showed that absorbed serum was depleted of MBL-C. If serum was absorbed with liveB. dermatitidis, unbound serum was eluted, and bound serum factor(s) (BS) was released with guanidine buffer, BS inhibited TNF-α production by PM plusB. dermatitidisin a concentration-dependent manner. BS contained MBL-C, which boundB. dermatitidis, as shown by IFA assay. 1,3-β-Glucan stimulated TNF-α production by PM, and this was inhibited by mouse serum. Treatment ofB. dermatitidiswith anti-1,3-β-glucan antibody inhibited TNF-α production by PM. With anti-1,3-β-glucan antibody, we showed by IFA assay thatB. dermatitidiscontained 1,3-β-glucan. In an IFA study withB. dermatitidis, serum with an anti-mouse IgG conjugate did not result in fluorescence, yet serum blocked IFA staining ofB. dermatitidisby anti-1,3-β-glucan IgG antibody. This indicated that non-IgG serum factors binding toB. dermatitidisprevented access to 1,3-β-glucan by anti-1,3-β-glucan antibody. These results suggest that the mechanism of inhibition of the innate proinflammatory immune response of PM toB. dermatitidisis mediated by serum MBL binding toB. dermatitidisat 1,3-β-glucan sites or sterically masking 1,3-β-glucan sites, thus preventing 1,3-β-glucan stimulation of PM for TNF-α production.
Chlamydia pneumoniaeInfection Increases Adherence of Mouse Macrophages to Mouse Endothelial Cells In Vitro and to Aortas Ex Vivo
Authors: Takaoka Naohisa , Campbell Lee Ann , Lee Amy , Rosenfeld Michael E. , Kuo Cho-Chou
Published: December 2007

Interactions between monocytes/macrophages and endothelial cells play an important role in the pathogenesis of atherosclerosis, and the adherence of monocytes to the arterial endothelium is one of the early events in atherogenesis. In the present study, peritoneal macrophages harvested from green fluorescent protein (GFP) transgenic mice were used to analyze howChlamydia pneumoniaeinfection affects the adherence of GFP-macrophages to mouse endothelial cells in vitro and to the aorta from normolipidemic and hyperlipidemic mice ex vivo. In vitro studies showed thatC.pneumoniae-infected GFP-macrophages adhered better than uninfected macrophages to endothelial cells and GFP-macrophages adhered better to infected than uninfected endothelial cells. The ex vivo studies showed thatC.pneumoniae-infected macrophages adhered better than uninfected macrophages to aortas from both normolipidemic and hyperlipidemic C57BL/6J mice and apolipoprotein E (ApoE)-deficient mice. In contrast, adherence ofC.pneumoniae-infected macrophages to the aortas of intercellular adhesion molecule 1 (ICAM-1) knockout mice was not enhanced, suggesting that ICAM-1 is crucial for activation of the adherence ofC.pneumoniae-infected macrophages to the endothelium. In conclusion, the present study defined a homing mechanism by whichC.pneumoniaepromotes the adherence of mononuclear phagocytes to the endothelium at the site of atherosclerotic lesion formation to promote the progression of atherosclerosis.
Immunogenic and Plasminogen-Binding Surface-Associated α-Enolase of
Trichomonas vaginalis
Authors: Mundodi V. , Kucknoor A. S. , Alderete J. F.
Published: December 2007

Trichomonas vaginalis
is a protist that causes the most common human sexually transmitted infection. A
T
.
vaginalis
cDNA expression library was screened with pooled sera from patients with trichomoniasis. A highly reactive cDNA clone of 1,428 bp encoded a trichomonad protein of 472 amino acids with sequence identity to α-enolase (tv-
eno1
). The sequence alignment confirmed the highly conserved nature of the enzyme with 65% to 84% identity among organisms. The expression of tv-
eno1
was up-regulated by contact of parasites with vaginal epithelial cells, and this is the first report demonstrating up-regulation by cytoadherence of a plasminogen-binding α-enolase in
T
.
vaginalis
. Immunofluorescence with monoclonal antibody of nonpermeabilized trichomonads showed tv-ENO1 on the surface. The recombinant tv-ENO1 was expressed in
Escherichia coli
as a glutathione
S
-transferase (GST)::tv-ENO1 fusion protein, which was cleaved using thrombin to obtain affinity-purified recombinant tv-ENO1 protein (tv-rENO1) detectable in immunoblots by sera of patients. Immobilized tv-rENO1 bound human plasminogen in a dose-dependent manner, and plasminogen binding by tv-rENO1 was confirmed in a ligand blot assay. The plasminogen-specific inhibitor ε-aminocaproic acid blocked the tv-rENO1-plasminogen association, indicating that lysines play a role in binding to tv-rENO1. Further, both parasites and tv-rENO1 activate plasminogen to plasmin that is mediated by tissue plasminogen activator. These data indicate that as with other bacterial pathogens, tv-ENO1 is an anchorless, surface-associated glycolytic enzyme of
T
.
vaginalis
.
Dose-Response Model for
Listeria monocytogenes
-Induced Stillbirths in Nonhuman Primates
Authors: Smith Mary Alice , Takeuchi Kazue , Anderson Gary , Ware Glenn O. , McClure Harold M. , Raybourne Richard B. , Mytle Nutan , Doyle Michael P.
Published: December 2007

A dose-response model using rhesus monkeys as a surrogate for pregnant women indicates that oral exposure to 10
7
CFU of
Listeria monocytogenes
results in about 50% stillbirths. Ten of 33 pregnant rhesus monkeys exposed orally to a single dose of 10
2
to 10
10
CFU of
L
.
monocytogenes
had stillbirths. A log-logistic model predicts a dose affecting 50% of animals at 10
7
CFU, comparable to an estimated 10
6
CFU based on an outbreak among pregnant women but much less than the extrapolated estimate (10
13
CFU) from the FDA-U.S. Department of Agriculture-CDC risk assessment using an exponential curve based on mouse data. Exposure and etiology of the disease are the same in humans and primates but not in mice. This information will aid in risk assessment, assist policy makers, and provide a model for mechanistic studies of
L
.
monocytogenes
-induced stillbirths.
Fast and slow myosins as markers of muscle injury
Authors: Guerrero Mario , Guiu- Comadevall Marc , Cadefau Joan Aureli , Parra Joan , Balius Ramón , Estruch Assumpta , Rodas Gil , Bedini José Luis , Cussó Roser
Published: December 2007

Objective:The diagnostic of muscular lesions suffered by athletes is done through a clinical diagnosis accompanied by confirmation tests using imaging techniques on the lesion (ultrasonography and/or magnetic resonance) as well as laboratory techniques for blood analysis that detect usually the presence of non-specific muscle markers . The aim of the study is the evaluation of fast and slow-twitch fibres injury using specific muscle markers for those fibres.Design:Blood samples were obtained from 51 non-sport people and 36 sportsmen with skeletal muscle injury. Western blood was performed to determine fast and slow myosin and creatin kinase. Skeletal muscle damage was diagnosed according to physical examination, ultrasonography and magnetic resonance and biochemical markers criterion.Results:The imaging tests have been shown to be excellent for the detection and confirmation of Grade II and III lesions. However, Grade I lesions often remain unconfirmed by these techniques. Grade I lesions show higher fast myosin than slow myosin with very low CK increase. Grade II and III show high values of both myosin.Conclusions:The evaluation of fast and slow myosin in the blood 48 hours after the lesion occurs has been seen to be a good parameter for the detection of Type I lesions specially, based on the fact that fast myosin is an exclusive skeletal muscle marker. The correct diagnosis of Grade I lesions can promote prevention of the injury’s progression in athletes undergoing continual training sessions and competitions, thus aiding sports physicians in their decisions.
Characteristics at haematoxylin and eosin staining of ruptures of the long head of the biceps tendon
Authors: Longo U G , Franceschi F , Ruzzini L , Rabitti C , Morini S , Maffulli N , Denaro V
Published: December 2007

Objective:

To examine the relative prevalence of histological changes that have been found to be associated with the process of tendinopathy in lesions of the tendon of the long head of the biceps brachii and to evaluate the reliability of histopathological evaluation of tendon tissue in lesions of the tendon of the long head of the biceps.

Design:

Tendon samples were taken from 51 patients (31 men, 20 women; mean age 63.2 years) who underwent arthroscopic release of the long head of the biceps tendon because of refractory biceps tendinopathy and from 5 male patients who died of cardiovascular events (mean age 69.6 years). Histological examination was performed using haematoxylin and eosin staining of sections, which were interpreted using a semiquantitative grading scale assessing fibre structure and arrangement, rounding of the nuclei, regional variations in cellularity, increased vascularity, decreased collagen staining and hyalinisation.

Results:

The mean (SD) pathological sum score of ruptured tendons was greater than that of control tendons (15.76 (3.11) vs 3.4 (1.9), p<0.001). Within each specific category of tendon abnormalities, the χ2test showed significant differences between the control and ruptured tendons; all the variables were significantly different (Mann–Whitney U test 0.05, p<0.001). Using the κ statistic, the agreement between the two readings ranged from 0.53 to 0.85.

Conclusions:

Unruptured tendons of the long head of the biceps, even at an advanced age and ruptured tendons of the long head of the biceps are clearly part of two distinct populations.
Two months of endurance training does not alter diastolic function evaluated by TDI in 9–11-year-old boys and girls
Authors: Obert P , Nottin S , Baquet G , Thevenet D , Gamelin F-X , Berthoin S
Published: December 2007

Objective:

Superior global cardiac performance (ie stroke volume) is classically reported after training in children. Current knowledge of the impact of exercise training on myocardial relaxation, a major component of left ventricular (LV) filling and subsequently stroke volume, is, however, limited in the paediatric population. This study aimed to investigate the effect of aerobic training on LV wall motion velocities by tissue Doppler imaging (TDI) in healthy children.

Methods:

25 children (11 girls, 14 boys) were enrolled in a 2 month high-intensity aerobic training programme and 25 (12 girls and 13 boys) served as controls. The children (9–11 years old) performed a graded maximal exercise test on a treadmill to evaluate maximal oxygen uptake. Standard Doppler echocardiography and TDI measurements were performed at baseline and end of the study. Tissue Doppler systolic, early and late myocardial velocities were obtained at the mitral annulus in the septal, lateral, inferior and posterior walls.

Results:

Maximal oxygen uptake increased by 6.5% (before: 51.6 (SD 4.2), after: 55.0 (4.5) ml/min/kg p<0.001) after training. A modest but significant increase in left ventricular end-diastolic diameter was also noticed (before: 46.1 (3.4), after: 48.3 (4.3) mm.BSA-1/2, p<0.001), whereas left ventricular wall thickness and mass were unchanged. Neither transmitral inflow velocities nor early and late wall motion (Em: before = 18.4 (2.7), after = 18.0 (2.3) cm/s, Am: before = 6.8 (1.2), after = 6.7 (1.3) cm/s) were affected by training. Shortening fraction and regional systolic function (Sm: before = 10.1 (1.6), after = 10.2 (1.4) cm/s) by TDI were also unchanged.

Conclusion:

High-intensity aerobic sessions repeated over a 2 month period failed to improve regional diastolic function assessed by TDI in healthy young children.
Why does exercise terminate at the maximal lactate steady state intensity?
Authors: Baron B , Noakes T D , Dekerle J , Moullan F , Robin S , Matran R , Pelayo P
Published: December 2007

Objective:

The purpose of this study was to measure physiological responses during exercise performed until exhaustion at the exercise intensity corresponding to the maximal lactate steady state (MLSS) in order to determine why subjects stopped.

Methods:

Eleven male trained subjects performed a test at MLSS on a cycle ergometer until exhaustion.

Results:

Time to exhaustion was 55.0 (SD 8.5) min. No variation was observed between the 10th and the last minute for arterial pyruvate, bicarbonate, and haemoglobin concentrations, redox state, arterial oxygen pressure, arterial oxygen saturation, osmolality, haematocrit, oxygen uptake, carbon dioxide output, and gas exchange ratio (p>0.05). Arterial lactate concentration and arterial carbon dioxide pressure decreased significantly whereas pH, base excess and the Ratings of Perceived Exertion (RPE) increased significantly (p<0.05). Although respiratory rate, minute ventilation and heart rate increased significantly until exhaustion (p<0.05), values at termination of the MLSS test were significantly lower than values measured during a maximal exercise test (p<0.05). Blood ammonia concentrations rose progressively during the MLSS test. However, there is no known mechanism by which this change could cause peripheral fatigue.

Conclusions:

Exercise termination was not associated with evidence of failure in any physiological system during prolonged exercise performed at MLSS. Thus the biological mechanisms of exercise termination at MLSS were compatible with an integrative homoeostatic control of peripheral physiological systems during exercise.
Effect of commercial airline travel on oxygen saturation in athletes
Authors: Geertsema C , Williams A B , Dzendrowskyj P , Hanna C
Published: December 2007

Background:

Aircraft cabins are pressurised to maximum effective altitudes of 2440 metres, resulting in significant decline in oxygen saturation in crew and passengers. This effect has not been studied in athletes.

Objective:

To investigate the degree of decline in oxygen saturation in athletes during long-haul flights.

Methods:

A prospective cross-sectional study. National-level athletes were recruited. Oxygen saturation and heart rate were measured with a pulse oximeter at sea level before departure, at 3 and 7 hours into the flight, and again after arrival at sea level. Aircraft cabin pressure and altitude, cabin fraction of inspired oxygen and true altitude were also recorded.

Results:

45 athletes and 18 healthy staff aged between 17 and 70 years were studied on 10 long-haul flights. Oxygen saturation levels declined significantly after 3 hours and 7 hours (3–4%), compared with sea level values. There was an associated drop in cabin pressure and fraction of inspired oxygen, and an increase in cabin altitude.

Conclusions:

Oxygen saturation declines significantly in athletes during long-haul commercial flights, in response to reduced cabin pressure. This may be relevant for altitude acclimatisation planning by athletes, as the time spent on the plane should be considered time already spent at altitude, with associated physiological changes. For flights of 10–13 hours in duration, it will be difficult to arrive on the day of competition to avoid the influence of these changes, as is often suggested by coaches.
Effects of exercise intensity on lymphocyte H2O2production and antioxidant defences in soccer players
Authors: Sureda A , Ferrer M D , Tauler P , Romaguera D , Drobnic F , Pujol P , Tur J A , Pons A
Published: December 2007

Objective:

Physical exercise is capable of enhancing or suppressing the immune response depending on the intensity and duration of exercise. This study investigated how exercise intensity influences the lymphocyte antioxidant response and the induction of cellular oxidative damage.

Design:

Eighteen voluntary male pre-professional soccer players participated in this study. Sportsmen played a 60 min training match, and were divided into three groups depending on the intensity degree during the match: low, medium and high intensities.

Measurements:

Malondialdehyde (MDA), vitamins C and E and haem oxygenase-1 (HO-1) gene expression were measured in lymphocytes. Reactive oxygen species (ROS) production was determined in lymphocytes and neutrophils.

Results:

Lymphocyte MDA levels and H2O2production were significantly increased in the group which performed the most intense exercise. Neutrophil counts and ROS production increased progressively with the exercise intensity. Vitamin C significantly decreased after exercise in the highest-intensity group in comparison with initial values, whereas vitamin E levels significantly increased in the medium and high-intensity groups. HO-1 gene expression significantly increased in the medium and high-intensity groups.

Conclusions:

Exercise intensity affects the lymphocyte and neutrophil oxidant/antioxidant balance, but only exercise of high intensity induces lymphocyte oxidative damage.
Low organic solvent exposure and combined maternal–infant gene polymorphisms affect gestational age
Authors: Qin X , Wu Y , Wang W , Liu T , Wang L , Hu Y , Chen D
Published: December 2007

Objective:

Little information is available on the associations of combined maternal–infant genetic susceptibility, environmental exposures and reproductive outcomes, especially in the Chinese population. The aim of this study was to investigate whether the polymorphisms of combined maternal–infant metabolic genes,CYP1A1HincII,CYP1A1MspI,GSTT1andGSTM1affect the association of maternal exposure to organic solvents with gestational age.

Methods:

1113 mother–infant pairs were enrolled from the Beijing Yanshan Petrochemical Corporation between June 1997 and June 2002, of which 546 mothers were exposed to organic solvents and 567 were not. Multiple linear regression models were used to estimate the combined maternal–infant gene effects, and to characterise combined maternal–infant genetic susceptibility to organic solvents in relation to gestation.

Results:

Organic solvent exposure was significantly related to shortened gestation (−1.2 weeks, 95% CI−1.6 to −0.9). Additionally, combined maternal–infant genotypes including Ile/Ile462–Ile/Ile462 (−0.6 weeks, 95% CI−0.9 to −0.4) inCYP1A1HincII and absent–absent inGSTT1(−0.4 weeks, 95% CI−0.9 to −0.3) were significantly associated with shorter gestation. When considering both organic solvent exposure and combined maternal–infant genotypes, the largest associations were found among exposed women with the absent–absent genotype (−1.5 weeks, 95% CI −1.8 to −1.2) inGSTT1and the Ile/Ile462–Ile/Ile462 genotype (−1.5 weeks, 95% CI −1.8 to −1.2) inCYP1A1HincII, suggesting that combined genotypes would modify the effect of exposure to organic solvents on gestation.

Conclusions:

This study demonstrates the role of combined maternal–infant genotypes in modifying the adverse effects of organic solvent exposure on gestation, and the maternal–infant interaction of four genes was determined.
New Cortinarius species associated with Quercus and Comarostaphylis in Costa Rica
Authors: Ammirati Joe , Garnica Sigisfredo , Halling Roy E. , Mata Milagro , Mueller Gregory M. , Carranza Julieta
Published: December 2007

Ten new species of Cortinarius are described from Costa Rican neotropical montane forests based on morphological and molecular phylogenetic data. Morphological features of the basidiomes and nuclear rDNA sequence analyses place these species in the following clades: Anomali ( Cortinarius sericeolazulinus ), Cotoneus ( Cortinarius aureopigmentatus ), Limonii ( Cortinarius aurantiobrunneus ), Lustrati ( Cortinarius comarostaphylii , Cortinarius comparioides , Cortinarius ovreboi ), Myxacium ( Cortinarius costaricensis ), and Telamonia ( Cortinarius carranzae , Cortinarius quercoarmillatus , Cortinarius savegrensis ). Species delimitations, diagnostic characters, sequence pair wise comparisons, and affinities to closely related species are included for each species. These Cortinarii occur with several species of Quercus with the exception of C. comarostaphylii, which is associated with Comarostaphylis (Ericaceae) in the páramo and in mixed forests with Quercus and Comarostaphylis.
Studies on the diatom genus Stenopterobia (Bacillariophyceae) including descriptions of two new species
Authors: Siver Peter A. , Camfield Lee
Published: December 2007

During an investigation of freshwater diatoms from highly acidic ponds scattered along the Atlantic Coastal Plain of North Carolina we encountered a large number of specimens from the genus Stenopterobia . All of the specimens were representative of straight, not sigmoidal-shaped, taxa and collectively ranged in length from ca. 10 µm to over 200 µm. In the process of making species determinations we examined type material for four species of Stenopterobia originally described by Lewis (1864) from Saco Pond, a small spring-fed waterbody nestled in the White Mountains of New Hampshire. The four species, Stenopterobia baileyi (Lewis) Brébisson ex Van Heurck, Stenopterobia anceps (Lewis) Brébisson ex Van Heurck, Stenopterobia delicatissima (Lewis) Brébisson ex Van Heurck, and Surirella intermedia Lewis (=Stenopterobia curvula (W. Smith) Krammer), were originally placed by Lewis within the genus Surirella. We examined seven permanent slides archived at the Academy of Natural Sciences of Philadelphia that contained material collected by Lewis. In addition, we collected new material from Saco Pond, including a sediment core, and examined these samples using SEM. We also examined type material for another species, Stenopterobia cuspidata (Hustedt) Vyverman, using SEM. We concluded that the North Carolina collections contained five species, two described as new ( Stenopterobia gracilis sp. nov. Siver & Camfield and Stenopterobia fusiformis sp. nov. Siver & Camfield), two representing organisms originally described by Lewis (S. baileyi and S. delicatissima), and the fifth recently described from Cape Cod ( Stenopterobia pseudodelicatissima Siver & Hamilton). New characters, including externally capped areolae, valve face coverings, and laterally opened girdle bands, are described for the genus. Lastly, lectotypes for three of Lewis’ taxa were selected.
Nitrogen fixation makes biomass allocation to roots independent of soil nitrogen supply
Authors: Markham John H. , Zekveld Corinthe
Published: December 2007

Biomass allocation patterns in plants are known to be affected by soil nitrogen availability. Since nitrogen availability can depress symbiotic nitrogen fixation, and nitrogen fixation can make plant growth independent of soil nitrogen availability but is energetically costly, it is unclear how allocation patterns in nitrogen-fixing species should respond to variation in soil nitrogen availability. We examined the effect of nitrogen source and concentration on the growth and allocation patterns in the nitrogen-fixing shrub Alnus viridis subsp. crispa (Aiton) Turrill. Plants were grown with either NH4+-N or NO3–-N at a range of low N concentrations, from 0 to 2 mmol·L–1, and either inoculated with Frankia or not. Plants without nodules had 25.l% lower biomass and had double the allocation to roots at all but the 2 mmol·L–1nitrogen concentration. Even though nodulated plants increased growth with nitrogen concentration, allocation to roots as a fraction of total biomass did not vary in these plants, suggesting increased growth resulted from more efficient nitrogen acquisition. Allocation to roots was a significant predictor of plant growth in non-nodulated plants (r2= 0.318, for linear least squares fit with log mass) but not for nodulated plants (r2= 0.108). As nitrogen concentrations increased, allocation to nodules, specific nodule numbers, and the proportion of nitrogen fixed by the plants decreased, demonstrating a shift to soil nitrogen use.
Coefficient of earth pressure at rest for sands subjected to vibration
Authors: Vardhanabhuti Barames , Mesri Gholamreza
Published: December 2007

An oedometer instrumented to measure horizontal pressure was used to examine the behavior of the coefficient of earth pressure at rest, Ko, of clean sands subjected to vertical vibration. Reconstituted specimens of Ottawa, Lake Michigan Beach, and Niigata sands were used in a comprehensive series of tests. The dynamic effort is defined by the ratio of dynamic increase in effective vertical stress to the static effective vertical stress, and frequency and duration of vibration. Dynamic changes in Koare referenced to a series of lines representing the ratio of the increase in effective horizontal stress to the increase in effective vertical stress corresponding to different void ratios or friction angles through the Jaky equation. An increase in Kooccurs when the combination of the initial sand state and dynamic effort results in periodic disengagement of interparticle contacts, producing a periodic decrease in interparticle shearing resistance and thus a periodic fluidization of the sand. The highest values of [Ko]maxas well as the lowest values of eminwere obtained with dynamic stress ratios equal to or greater than 3–4. Vibration of overconsolidated sands results in an initial Kodrop that increases with previbration density and overconsolidation ratio. Thereafter, the behavior of Koand void ratio with vibration depend on the potential for fluidization.
Colloquium 2004: Hydrogeotechnical properties of hard rock tailings from metal mines and emerging geoenvironmental disposal approaches
Authors: Bussière Bruno
Published: December 2007

Tailings are ground rock particles from which the valuable minerals or metals have been extracted. An historical overview on hard rock mines shows that since the 1930s, it has become current practice to pump the tailings into storage areas circumscribed by dykes made of the tailings themselves. However, numerous physical and chemical stability problems were observed mainly owing to the particular hydrogeotechnical and mineralogical properties of the tailings. Therefore, modifications to the conventional methods were proposed, but these were relatively costly, not always efficient, and sometimes difficult to implement. New management methods that improve the physical and (or) chemical stability have hence been developed to reduce environmental risks associated with tailings storage, namely, densified tailings, environmental desulphurization, covers built with tailings, and co-disposal of tailings and waste rock. Even if many aspects need to be optimized, these approaches can be considered today as interesting alternatives to conventional tailings management approaches.
Influence of soil permeability on rainfall-induced flowslides in laboratory flume tests
Authors: Wang Fawu , Shibata Hiroki
Published: December 2007

The mobility of flowslides is influenced by various factors. In this paper, laboratory flume tests were used to evaluate the influence of soil permeability using different soils with different permeabilities in a model slope, while keeping the slope condition and artificial rainfall intensity constant. It was found that the permeability of soil has a significant influence on the initialization of flowslides and that there is an optimal soil permeability existing for the mobility of flowslides when rainfall intensity is kept constant.
Long-term investigation of a deep-seated creeping landslide in crystalline rock. Part II. Mitigation measures and numerical modelling of deep drainage at Campo Vallemaggia
Authors: Eberhardt E. , Bonzanigo L. , Loew S.
Published: December 2007

For more than 200 years, the villages of Campo Vallemaggia and Cimalmotto have been slowly moving on top of a deep-seated landslide in the southern Swiss Alps. Numerous mitigation measures have been carried out during this time to stabilize the landslide but with limited to no success. Those attempts largely focussed on minimizing erosion at the toe of the landslide. More recently, the need to stabilize the slope began to intensify, as with each passing year the two villages were being pushed closer to the edge of a 100 m high erosion front at the foot of the landslide. This led to an extensive investigation and monitoring campaign to better understand the factors controlling the landslide movements, which as reported in Part I (see companion paper, this issue), pointed to high artesian pore pressures as being the primary destabilizing mechanism. Here in Part II, the arguments supporting the need for a deep drainage solution are reported, as is the history, implementation, and measured response of the Campo Vallemaggia landslide to the various mitigative measures taken. Numerical modelling results are also presented, based on hydromechanically coupled distinct-element models, to help demonstrate why deep drainage succeeded where other mitigation measures failed.
Responses of single piles to tunneling-induced soil movements in sandy ground
Authors: Chiang Kuo-Hui , Lee Chung-Jung
Published: December 2007

The responses of single piles under various working loads to nearby tunneling were investigated using centrifuge model tests. First, the tunneling-induced soil movements and the tunnel stability in saturated sandy ground were examined. Two instrumented piles with penetration depths of 27 m were located either side of, and at various distances from, tunnels embedded at depths with various cover-to-diameter ratios, and used to measure the bending moments and axial forces at various depths for various ground loss ratios during tunneling simulations. The test results show that in the case of shallow tunneling near a long pile the unit skin frictions on the pile from the tunnel axis to an elevation of 1.5 tunnel diameters above the tunnel axis rapidly decrease with increases in the ground loss ratio. A significant degradation of the end bearing capacity results in a large settlement of the pile if the pile tip is near the tunnel. The depth ratio was found to be a significant influence on the bending moment profiles along the piles, but both the depth ratio and the working loads on the pile head determine the axial load profile and the pile settlement. A mechanism for pile load transfer during new tunneling is proposed to enable construction engineers to prevent structure failure in piles and excessive pile settlement.
Artificial neural networks approach for swell pressure versus soil suction behaviour
Authors: Erzin Yusuf
Published: December 2007

In this study, the swell pressure versus soil suction behaviour was investigated using artificial neural networks (ANNs). To achieve this, the results of the total suction measurements using thermocouple psychrometer technique and constant-volume swell tests in oedometers performed on statically compacted specimens of Bentonite–Kaolinite clay mixtures with varying soil properties were used. Two different ANN models have been developed to predict the total suction and swell pressure. The ANNs results were compared with the experimental values and found close to the experimental results. Moreover, several performance indices such as correlation coefficient, variance account for (VAF), and root mean square error (RMSE) were calculated to check the prediction capacity of the ANN models developed. Both ANN models have shown a high prediction performance based on the performance indices. Therefore, it can be concluded that the initial soil suction is the most relevant state of suction that characterizes the potential swell pressures.
Effet de la température sur le comportement des sols non saturés sur les chemins de drainage et d’humidification
Authors: Ghembaza Moulay-Smaïne , Taïbi Said , Fleureau Jean-Marie
Published: December 2007

The behaviour of soils subject to suction on drying and wetting paths depends on the type of material and its initial state. Exposure to heat modifies the state of pore water and therefore the hydromechanical behaviour of the soil. A new experimental device has been developed to study the thermohydric behaviour of unsaturated soils. Salt solution desiccators and polyethylene glycol (PEG) osmotic solutions are dipped in thermostatic baths, whose temperature ranges from room temperature to 80 °C. Tests were carried out on a sandy clay prepared in the laboratory and on a natural undisturbed clay, extracted from an experimental site for deep underground storage of radioactive waste. Results show that temperature plays an important role in the shrinkage of soil, especially when subjected to high levels of suction. The results can be applied to observe the response of confining clay barriers submitted to hydric and thermal changes.
Water retention curve and hydraulic conductivity function of highly compressible materials
Authors: Parent Serge-Étienne , Cabral Alexandre , Zornberg Jorge G.
Published: December 2007

A model capable of describing the suction-induced consolidation curve (void ratio function) and water retention curve (WRC) of highly compressible materials (HCM) is developed, validated, and finally applied to describe the WRC of deinking by-products (DBP). DBP are a highly compressible by-product of paper recycling used in geoenvironmental applications. Validation is conducted by modelling the WRC and the void ratio function for a well documented silty sand from Saskatchewan, Canada. The WRC and void ratio function were used to predict its hydraulic conductivity function (k-function). The water content, suction, and volumetric deformation data of DBP are obtained using an experimental technique that allows determination of the WRCs of HCMs that is suitable for prediction of the DBP k-function. The results show that volumetric water contents are underestimated if volume changes are not accounted for, leading to inaccuracies in the WRCs, thus inaccurately predicted k-functions. It is shown that the newly developed model is better suited for HCMs than currently available models, in particular for HCMs that continue to undergo significant volume changes when the applied suction exceeds the air-entry value.
Precipitation of gold by the reaction of aqueous gold(III) chloride with cyanobacteria at 25–80 °C — Studied by X-ray absorption spectroscopy
Authors: Lengke Maggy F , Ravel Bruce , Fleet Michael E , Wanger Gregory , Gordon Robert A , Southam Gordon
Published: December 2007

The mechanisms of gold precipitation by the interaction of cyanobacteria (Plectonema boryanum UTEX 485) and gold(III) chloride aqueous solutions (7.6 mmol/L final gold) have been studied at 25, 60, and 80 °C, using both laboratory and real-time synchrotron radiation absorption spectroscopy experiments. Addition of aqueous gold(III) chloride to the cyanobacterial culture initially promoted the precipitation of amorphous gold(I) sulfide at the cell walls and finally caused the formation of octahedral (111) platelets (<1 to 6 µm) of gold metal near cell surfaces and in solutions. X-ray absorption spectroscopy results confirmed that the reduction mechanism of gold(III) chloride to elemental gold by cyanobacteria involves the formation of an intermediate Au(I) species, gold(I) sulfide, with sulfur originating from cyanobacterial proteins, presumably cysteine or methionine. Although the bioreduction of gold(III) chloride to gold(I) sulfide was relatively rapid at all temperatures, the reaction rate increased with the increase in temperature. At the completion of the experiments, elemental gold was the major species present at all temperatures.Key words: gold, X-ray absorption spectroscopy (XAS), cyanobacteria, transmission electron microscopy (TEM), precipitation, biosynthesis.