bluuebunny/crossref_metadata_2025 huggingface dataset:
A Hierarchical View of Convergent Evolution in Microbial Eukaryotes1
Authors: LEANDER BRIAN S.
Published: January 2008

ABSTRACT. Distinguishing convergent evolution from other causes of similarity in organisms is necessary for reconstructing phylogenetic relationships, inferring patterns of character evolution, and investigating the forces of natural selection. In contrast to animals and land plants, the pervasiveness and adaptive significance of convergent evolution in microbes has yet to be systematically explored or articulated. Convergent evolution in microbial eukaryotes, for instance, often involves very distantly related lineages with relatively limited repertoires of morphological features. These large phylogenetic distances weaken the role of ancestral developmental programs on the subsequent evolution of morphological characters, making convergent evolution between very distantly related lineages fundamentally different from convergent evolution between closely related lineages. This suggests that examples of convergence at different levels in the phylogenetic hierarchy offer different clues about the causes and processes of macroevolutionary diversification. Accordingly (and despite opinions to the contrary), I recognize three broad and overlapping categories of phenotypic convergence—“parallel”, “proximate” and “ultimate”—that represent either (1) subcellular analogues, (2) subcellular analogues to multicellular systems (and vice versa), or (3) multicellular analogues. Microbial eukaryotes living in planktonic environments, interstitial environments, and the intestinal environments of metazoan hosts provide compelling examples of ultimate convergence. After describing selected examples in microbial eukaryotes, I suggest some future directions needed to more fully understand the hierarchical structure of convergent evolution and the overall history of life.
Redescription of the Tintinnid Stenosemella pacifica Kofoid and Campbell, 1929 (Ciliophora, Spirotricha) Based on Live Observation, Protargol Impregnation, and Scanning Electron Microscopy
Authors: AGATHA SABINE , TSAI SHENG‐FANG
Published: January 2008

ABSTRACT. The tintinnid ciliate Stenosemella pacificaKofoid and Campbell, 1929 was occasionally recorded from the pelagial of temperate, subtropical, and tropical neritic waters. Since its cytological features were unknown, the species is redescribed from material collected in the pelagial of the Irish Sea, using live observation, protargol impregnation, and scanning electron microscopy. Furthermore, the species diagnosis is improved to include new characteristics, e.g. the somatic ciliary pattern comprising a ventral, dorsal, and posterior kinety as well as a right, left, and lateral ciliary field. The stomatogenesis of S. pacifica is typical for species with such a complex somatic ciliary pattern: the oral primordium develops hypoapokinetally posterior to the lateral ciliary field. The presence of windows in the lorica collar of Stenosemella ventricosa, the type of the genus, necessitates (i) an improved genus diagnosis, (ii) a synonymization of the genus LuminellaKofoid and Campbell, 1939, and (iii) a transfer of the Luminella species to the genus Stenosemella, including Luminella neocalifornica, which becomes Stenosemella neocalifornica nov. comb. Owing to the lack of a description, Stenosemella crateri is considered a nomen nudum.
Influence of suture tension to the tearing characteristics of the soft tissues: an in vitro experiment
Authors: Burkhardt Rino , Preiss Axel , Joss Andreas , Lang Niklaus P.
Published: January 2008

Objectives: To evaluate the influence of flap tension on the tearing characteristics of mucosal tissue samples in relation to various suture and needle characteristics.

Material and methods: Lining and masticatory mucosal tissue samples obtained from pig jaws were prepared for in vitro testing. Tension tearing diagrams of 60 experiments were traced for 3‐0, 5‐0 and 7‐0 sutures with applied forces up to 20 N. In the second part, the same experiments were repeated with 100 diagrams to test the influence of needle characteristics with 5‐0 and 6‐0 sutures using only gingival tissue samples.

Results: 3‐0 sutures mainly lead to tissue breakage at an average of 13.4 N. In contrast, 7‐0 sutures only resulted in breakage of the thread at a mean applied force of 3.7 N. With 5‐0 sutures, both events occurred at random at a mean force of 14.6 N. Irrespective of the needle characteristics, the mean breaking force for gingival samples with 5‐0 and 6‐0 sutures was approximately 10 N.

Conclusions: Tissue trauma may be reduced by choosing finer suture diameters, because thinner (6‐0, 7‐0) sutures lead to thread breakage rather than tissue breakage.
Long‐term bio‐degradation of cross‐linked and non‐cross‐linked collagen barriers in human guided bone regeneration
Authors: Tal Haim , Kozlovsky Avital , Artzi Zvi , Nemcovsky Carlos E. , Moses Ofer
Published: January 2008

Objective: This double‐blind study clinically and histologically evaluated long‐term barrier bio‐durability of cross‐linked and non‐cross‐linked collagen membranes (CLM and NCLM) in sites treated by guided bone regeneration procedures.

Materials and methods: In 52 patients, 52 bony defects were randomly assigned to treatment with either a CLM or a NCLM. Post‐surgical spontaneous membrane exposures were recorded. Before implant placement, full‐thickness standard soft tissue discs were retrieved wherever suitable for histologic examination.

Results: Spontaneous membrane exposure was observed in 13 (50%) CLM sites and in six (23.1%) NCLM sites (P<0.05). Clinical healing at exposed sites lasted 2–4 weeks. CLM were histologically intact in all non‐perforated sites, were interrupted in five perforated sites, and undetected in four. NCLMs were undetected in all 18 specimens examined. In three non‐perforated CLM sites, bone apposition and ossification at or within the membrane was observed.

Conclusions: CLMs were more resistant to tissue degradation than NCLMs, and maintained integrity during the study. Neither membrane was resistant to degradation when exposed to the oral environment. CLMs were associated with a higher incidence of tissue perforations. In non‐perforated sites, CLM ossification at or within the membrane was occasionally observed.
Biomechanical rationale for a single implant‐retained mandibular overdenture: an in vitro study
Authors: Maeda Yoshinobu , Horisaka Mitsuhiro , Yagi Kaztomo
Published: January 2008

Objectives: This study aimed to examine the biomechanical rationale of a single implant‐retained overdenture (SIO) system using an in vitro model.

Material and methods: Laboratory implant analogs (3.75 × 13 mm) were embedded into the midline and canine regions on both sides of the mandibular phantom model with artificial mucosa. Magnetic attachments (flat, FM; dome, DM) and a ball attachment (Ball) were mounted to the abutment where lateral forces were measured with four miniature strain gauges attached to the surface. A 50 N static load was applied at five different sites of the occlusal surface of the simulated denture base using each counterpart of the attachments. Strain data were compared between SIO and two implant‐retained configurations (TIO) with three attachments. Three‐dimensional (3D) denture base displacements were also measured. Statistical analysis was performed by multiple comparisons using a post hoc test (P<0.05).

Results: Statistically significantly smaller lateral forces to abutments were obtained in SIO than in TIO with the Ball with the molar load, while there were no statistical differences between SIO and TIO with FM. There were no statistical differences in 3D denture base movements between SIO and TIO in the midline and molar regions, while there were larger movements in SIO than in TIO with FM.

Conclusion: Within the limitations of our in vitro study, we suggested that single‐implant overdentures with dome‐type magnet or ball attachments had biomechanical effects similar to two‐implant overdentures in terms of lateral forces to the abutment and denture base movements under molar functional loads.
One‐year bacterial colonization patterns of Staphylococcus aureus and other bacteria at implants and adjacent teeth
Authors: Salvi Giovanni E. , Fürst Mirjam M. , Lang Niklaus P. , Persson G. Rutger
Published: January 2008

Aims: (i) To assess the pattern of early bacterial colonization on titanium oral implants after installation, at 12 weeks and at 12 months, (ii) to compare the microbiota at submucosal implant sites and adjacent subgingival tooth sites and (iii) to assess whether or not early colonization was predictive of 12‐month colonization patterns.

Material and methods: Submucosal/subgingival plaque samples from 17 titanium oral implants and adjacent teeth were analyzed by checkerboard DNA–DNA hybridization 30 min, 12 weeks and 12 months after implant installation.

Results: At 12 months, none of the inserted implants had been lost or presented with signs of peri‐implantitis. The distribution of sites at implants and teeth with bleeding on probing varied between 2% and 11%. Probing pocket depths ≤3 mm were found at 75% of implant sites. At 12 months, the sum of the bacterial counts of 40 species was statistically significantly higher at tooth compared with implant sites (mean difference: 34.4 × 105, 95% confidence interval −0.4 to 69.4, P<0.05). At 12 months, higher individual bacterial counts at tooth sites were found for 7/40 species compared with implant sites. Detection or lack of detection of Staphylococcus aureus at implant sites at 12 weeks resulted in the highest positive (e.g. 80%) and negative (e.g. 90%) predictive values, respectively. Between 12 weeks and 12 months, the prevalence of Tannerella forsythia increased statistically significantly at implant sites (P<0.05). Lack of detection of Porphyromonas gingivalis at 12 weeks yielded a negative predictive value of 93.1% of this microorganism being undetectable at implant sites at 12 months.

Conclusions: Within the limits of this study, the findings showed (i) a few differences in the prevalence of bacterial species between implant and adjacent tooth sites at 12 months and (ii) high positive and negative predictive values for selected bacterial species.
Immediate occlusal loading and tilted implants for the rehabilitation of the atrophic edentulous maxilla: 1‐year interim results of a multicenter prospective study
Authors: Testori Tiziano , Del Fabbro Massimo , Capelli Matteo , Zuffetti Francesco , Francetti Luca , Weinstein Roberto L.
Published: January 2008

Objectives: The aims of this prospective study were to assess the treatment outcome of immediately loaded full‐arch fixed bridges anchored to both tilted and axially placed implants for the rehabilitation of fully edentulous maxillae and to compare the outcome of axial vs. tilted implants.

Material and methods: Forty‐one patients with edentulous maxillae were included in the study. Each patient received a full‐arch fixed bridge supported by four axial implants and two distal tilted implants. Loading was applied within 48 h from surgery. Patients were scheduled for follow‐up at 6 months, 1 year and annually up to 5 years. Radiographic evaluation of marginal bone‐level change was performed at 1 year.

Results: One patient died 4 months after surgery. Thirty patients were followed for a minimum of 1 year (range 3–42 months, mean 22.1 months). Three failures were recorded at 1‐year follow‐up (two axial implants and one tilted). Two more implants (one tilted and one axially placed) were lost within 18 months of loading. The 1‐year implant survival rate was 98.8% for both axial and tilted implants. Prosthesis success rate was 100% at 1 year. Marginal bone loss around axial and tilted implants at 12‐month evaluation was similar, being, respectively, 0.9±0.4 (standard deviation) mm and 0.8±0.5 mm.

Conclusions: The present preliminary data suggest that immediate loading associated with tilted implants could be considered to be a viable treatment modality for the atrophic maxilla and that there does not seem to be a different clinical outcome between tilted and axial implants.
A 10‐year prospective clinical and radiographic study of one‐stage dental implants
Authors: Kim David M. , Badovinac Rachel L. , Lorenz Rachel L. , Fiorellini Joseph P. , Weber Hans P.
Published: January 2008

Objective: The purpose of this prospective study was to evaluate one‐stage dental implants clinically and radiographically after 10 years in function.

Material and methods: Twenty‐five patients with a total of 68 implants [46 hollow screws (HS) and 22 hollow cylinders (HC)] who previously participated in 5‐year prospective clinical study returned for a 10‐year follow‐up. For each patient, informed consent was obtained, medical and dental history was reviewed and soft and hard tissue conditions were evaluated using the modified plaque index, modified sulcus bleeding index, probing depth, suppuration, attachment level, distance from the implant crown margin to the coronal border of the peri‐implant mucosa keratinized mucosa and periapical radiographs to calculate crestal bone‐level changes.

Results: As expected, the mean crestal bone‐level changes were the greatest in the first year following restoration placement, while only minimal changes were noticed in the subsequent years. HC implants showed a statistically significant higher mean crestal bone loss when compared with HS implants at year 10. Gender was also statistically significantly related to the mean crestal bone loss at years 1, 3, 5 and 10, with male subjects exhibiting more bone loss than female subjects. However, age and peri‐implant soft tissue parameters showed low levels of correlation with the mean crestal bone‐level changes, and proved to be weak predictors for the mean crestal bone loss at years 5 and 10.

Conclusions: This study confirms that the mean crestal bone loss rates of the HS and HC implants are well within the clinically acceptable parameters. In addition, some of the clinical parameters could be used to assess and predict future crestal bone loss.
Isolation and characterization of human gingival microvascular endothelial cells
Authors: DeCarlo A. A. , Cohen J. A. , Aguado A. , Glenn B.
Published: January 2008

Background and Objective:  Endothelial cells have a substantial role in maintaining vascular homeostasis, and their dysregulation can contribute to the development of pathology. The plasminogen activators and their inhibitors may, arguably, be the single most important proteolytic system of the endothelium for vascular maintenance by controlling plasminogen activation and other proteolytic cascades that impact on clotting, hemodynamics, angiogenesis and the character of the vascular wall. In chronic periodontal disease, significant changes to the microvasculature occur in association with the severity of the disease. Investigation of the role played by endothelial cells in periodontal health and disease has been limited to in situ immunolocalization or to the use of endothelial cells of nongingival origin, such as human umbilical vein endothelial cells. The objective of this research was to establish a replicable protocol for isolating microvascular endothelial cells from the gingiva.

Material and Methods:  From inflamed gingiva, isolated cells were characterized by morphology, the expression of factor VIII‐related antigen, the expression of UEA‐1 ligand, the uptake of acetylated low‐density lipoprotein, network formation on Matrigel, and by the expression levels of urokinase plasminogen activator, tissue plasminogen activator, plasminogen activator inhibitor‐1 and collagen IV.

Results and Conclusion:  Gingival endothelial cells were most readily obtained from inflamed gingival tissues, and these endothelial cells, when isolated by the protocol established herein, demonstrated endothelial characteristics and constitutively secreted plasminogen activators and plasminogen activator inhibitor‐1 in culture.
Cementum–periodontal ligament complex regeneration using the cell sheet technique
Authors: Flores M. Gomez , Hasegawa M. , Yamato M. , Takagi R. , Okano T. , Ishikawa I.
Published: January 2008

Background and Objective:  In the present study we evaluated if a multilayered human periodontal ligament cell sheet could reconstruct the physiological architecture of a periodontal ligament–cementum complex.

Material and methods:  Human periodontal ligament cells were isolated and then cultured in dishes coated with a temperature‐responsive polymer to allow cell detachment as a cell sheet. In the control group, human periodontal ligament cells were cultured in Dulbecco’s modified Eagle’s minimal essential medium containing 10% fetal bovine serum and 1% antibiotics. In the experimental group, human periodontal ligament cells were cultured in Dulbecco’s modified Eagle’s minimal essential medium and osteodifferentiation medium containing dexamethasone, ascorbic acid and β‐glycerophosphate. After 3 wk, scanning electron microscopy was carried out, in addition to staining for alkaline phosphatase activity and for calcium (using the Von Kossa stain). Then human periodontal ligament cell sheets were multilayered and placed onto dentin blocks. The constructs were transplanted subcutaneously into the back of immunodeficient rats. At 1 and 6 wk after transplantation, the animals were killed. Demineralized tissue sections were stained using hematoxylin and eosin, and Azan, and then analyzed.

Results:  After 3 wk of culture in osteodifferentiation medium, human periodontal ligament cells produced mineral‐like nodules and also showed positive staining for alkaline phosphatase, calcium (Von Kossa) and mRNA expression of type I collagen. By contrast, in the control group only weak alkaline phosphatase staining was observed, the Von Kossa stain was negative and there was no mRNA expression of type I collagen. Six weeks after transplantation with human periodontal ligament cells cultured in osteodifferentiation medium, most of the dentin surfaces showed a newly immature cementum‐like tissue formation and periodontal ligament with perpendicular orientation inserted into the newly deposited cementum‐like tissue.

Conclusion:  This study suggests that the multilayered temperature‐responsive culture system can be used as a novel strategy for periodontal regeneration. The human periodontal ligament cell sheet technique may be applicable for regeneration of the clinical periodontal ligament–cementum complex.
Macrophage tolerance response to Aggregatibacter actinomycetemcomitans lipopolysaccharide induces differential regulation of tumor necrosis factor‐α, interleukin‐1β and matrix metalloproteinase 9 secretion
Authors: Tanabe S‐I , Grenier D
Published: January 2008

Background and Objective:  The lipopolysaccharide of Aggregatibacter actinomycetemcomitans, a potent stimulator of the immune system, induces the secretion of inflammatory mediators that modulate periodontal tissue destruction. In this study, we investigated the tolerance response of human macrophages to stimulation with A. actinomycetemcomitans lipopolysaccharide.

Material and Methods:  U937 monocytes were differentiated into adherent macrophage‐like cells by treatment with phorbol myristic acid. Macrophage‐like cells were then pretreated for 24 h with either 0.01 or 0.1 μg/mL LPS A. actinomycetemcomitans. Culture medium supernatants were removed and cells were restimulated with LPS at 1 μg/mL. Cell‐free supernatants were collected after 24 h of stimulation and analyzed by ELISA for TNF‐α, IL‐1β, IL‐6, IL‐8, PGE2 and MMP‐9.

Results:  Phorbol myristic acid‐differentiated U937 macrophages treated with low doses of lipopolysaccharide developed tolerance to subsequent lipopolysaccharide treatments, resulting in significantly reduced secretion of tumor necrosis factor‐α. However, this tolerance response was associated with increased secretion of interleukin‐1β and matrix metalloproteinase 9, whereas the secretion of interleukin‐6, interleukin‐8 and prostaglandin E2 was unaffected. Phosphatidylinositol‐3′‐kinase inhibitors added during the tolerance‐induction period markedly attenuated the increase in interleukin‐1β secretion but had no effect on tumor necrosis factor‐α.

Conclusion:  This study showed that A. actinomycetemcomitans lipopolysaccharide can induce a tolerance response in macrophages that alters the secretion of two important inflammatory mediators as well as of the tissue‐degrading enzyme matrix metalloproteinase‐9. This phenomenon may play a role in modulating the host inflammatory response and the progression of periodontitis.
Attitudes toward Dental Appearance in 50‐ and 60‐Year‐Old Subjects Living in Sweden
Authors: CARLSSON GUNNAR E. , JOHANSSON ANDERS , JOHANSSON ANN‐KATRIN , ORDELL SVEN , EKBÄCK GUNNAR , UNELL LENNART
Published: January 2008

Background:  Attitudes toward the importance of general appearance have varied much, not only over time but also among groups of individuals of different age and other characteristics. Whether the situation is similar regarding dental appearance does not seem to have been studied.

Purpose:  The aim was to study the differences in attitudes toward dental appearance between two large samples of 50‐ and 60‐year‐old subjects.

Materials and Methods:  Identical questionnaires were sent to all subjects born in 1942 and 1952 living in two Swedish counties in 2002 (N=17,444; N50=8,881, N60=8,563). The final response rate was 72.2% (N=12,599). In this study, responses to four statements on the importance of dental appearance have been analyzed with respect to gender and age.

Results:  Many of the responses to the four statements differed with gender and age. To the first statement (“To have beautiful and perfect teeth is very important for how you are treated by other people”), 73% agreed at age 60 compared with 64% at age 50 (p < 0.001). Approximately 90% of the subjects agreed with the second statement (“Minor esthetic imperfections of the teeth have no importance, only they function well”). Logistic regression indicated that several variables were significantly associated with the statements. Besides age and gender, education and self‐assessed dental problems were most important.

Conclusion:  Attitudes toward the importance of dental appearance differed both between genders and age groups in these population samples living in Sweden.

CLINICAL SIGNIFICANCE

The varying attitudes toward dental appearance in the population must be acknowledged in treatment decisions.

(J Esthet Restor Dent 20:46–56, 2008)
EFFECTS OF BLEACHING ON TOOTH STRUCTURE AND RESTORATIONS, PART II: ENAMEL BONDING
Authors: Swift Edward J.
Published: January 2008

Tooth whitening has become a common treatment over the last 15 years, and much research has been reported on the effects of bleaching procedures on enamel, dentin, and restorative materials. We are presenting a series of Critical Appraisals covering recent research in this area. This installment focuses on resin bonding to enamel.
A short proregion of trialysin, a pore‐forming protein of Triatoma infestans salivary glands, controls activity by folding the N‐terminal lytic motif
Authors: Martins Rafael M. , Amino Rogerio , Daghastanli Katia R. , Cuccovia Iolanda M. , Juliano Maria A. , Schenkman Sergio
Published: January 2008

Triatoma infestans (Hemiptera: Reduviidae) is a hematophagous insect that transmits the protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas’ disease. Its saliva contains trialysin, a protein that forms pores in membranes. Peptides based on the N‐terminus of trialysin lyse cells and fold into α‐helical amphipathic segments resembling antimicrobial peptides. Using a specific antiserum against trialysin, we show here that trialysin is synthesized as a precursor that is less active than the protein released after saliva secretion. A synthetic peptide flanked by a fluorophore and a quencher including the acidic proregion and the lytic N‐terminus of the protein is also less active against cells and liposomes, increasing activity upon proteolysis. Activation changes the peptide conformation as observed by fluorescence increase and CD spectroscopy. This mechanism of activation could provide a way to impair the toxic effects of trialysin inside the salivary glands, thus restricting damaging lytic activity to the bite site.
On the nature of precursors in the radio pulsar profiles
Authors: Petrova S. A.
Published: January 2008

In the average profiles of several radio pulsars, the main pulse is accompanied by the preceding component. This so-called precursor is known for its distinctive polarization, spectral and fluctuation properties. Recent single-pulse observations hint that the sporadic activity at the extreme leading edge of the pulse may be prevalent in pulsars. We for the first time propose a physical mechanism of this phenomenon. It is based on the induced scattering of the main pulse radiation into the background. We show that the scattered component is directed approximately along the ambient magnetic field and, because of rotational aberration in the scattering region, appears in the pulse profile as a precursor to the main pulse. Our model naturally explains high linear polarization of the precursor emission, its spectral and fluctuation peculiarities as well as suggests a specific connection between the precursor and the main pulse at widely spaced frequencies. This is believed to stimulate multifrequency single-pulse studies of intensity modulation in different pulsars.
Outflowing atomic and molecular gas at z∼ 0.67 towards 1504 + 377
Authors: Kanekar Nissim , Chengalur Jayaram N.
Published: January 2008

We report the detection of OH 1667-MHz and wide H i 21-cm absorption at z∼ 0.67 towards the red quasar 1504 + 377, with the Green Bank Telescope and the Giant Metrewave Radio Telescope. The H i 21-cm absorption extends over a velocity range of ∼600 km s−1 blueward of the quasar redshift (z= 0.674), with the new OH 1667-MHz absorption component at ∼ −430 km s−1, nearly coincident with earlier detections of millimetre-wave absorption at z∼ 0.6715. The atomic and molecular absorption appear to arise from a fast gas outflow from the quasar, with a mass outflow rate and a molecular hydrogen fraction . The radio structure of 1504 + 377 is consistent with the outflow arising as a result of a jet–cloud interaction, followed by rapid cooling of the cloud material. The observed ratio of HCO+ and OH column densities is ∼20 times higher than typical values in Galactic and high-z absorbers. This could arise because of small-scale structure in the outflowing gas on sub-parsec scales, which would also explain the observed variability in the H i 21-cm line.
H i power spectrum of the spiral galaxy NGC 628
Authors: Dutta Prasun , Begum Ayesha , Bharadwaj Somnath , Chengalur Jayaram N.
Published: January 2008

We have measured the H i power spectrum of the nearly face-on spiral galaxy NGC 628 (M74) using a visibility-based estimator. The power spectrum is well fitted by a power law P(U) =AUα, with α=−1.6 ± 0.2 over the length-scale 800 pc to 8 kpc. The slope is found to be independent of the width of the velocity channel. This value of the slope is a little more than one in excess of what has been seen at considerably smaller length-scales in the Milky Way, the Small Magellanic Cloud, the Large Magellanic Cloud (LMC) and the dwarf galaxy DDO 210. We interpret this difference as indicating a transition from three-dimensional turbulence at small scales to two-dimensional turbulence in the plane of the galaxy disc at length-scales larger than the H i scaleheight of the galaxy. The slope measured here is similar to that found at large scales in the LMC. Our analysis also places an upper limit to the galaxy scaleheight at 800 pc.
Influence of AGN outbursts on the surrounding galaxies
Authors: Fujita Yutaka
Published: January 2008

We study the influence of a strong AGN outburst on the surrounding galaxies. The AGN is assumed to reside in a group of galaxies, and an outburst excites a shock wave in the hot gas in the group. We calculate the impact of the shock wave on the galaxies. We find that if the energy of the outburst is extremely large (EAGN∼ 6 × 1061 erg) as the one recently observed in clusters, the impact is strong enough to strip the cold interstellar medium in the disc of the galaxies in the inner region of the group. Moreover, even in the outer region of the group, the warm gas in the halo of the galaxies would be stripped, even if the energy of the outburst is ∼6 × 1060 erg. These would decrease star formation activity of the galaxies. If these galaxies fall into the group centre through dynamical friction and their interstellar medium is the fuel of the supermassive black hole in the AGN, the outburst would serve as feedback. While this mechanism works only when EAGN is extremely large, such outbursts have not been observed in groups at low redshift; it would work at high redshift rather than at low redshift.
Alcohol and Drug Use in Rural Colonias and Adjacent Urban Areas of the Texas Border
Authors: Spence Richard T. , Wallisch Lynn S.
Published: January 2008

ABSTRACT: 
Context: Little is known about substance use and treatment utilization in rural communities of the United States/Mexico border. Purpose: To compare substance use and need and desire for treatment in rural colonias and urban areas of the border. Methods: Interviews were conducted in 2002‐2003 with a random sample of adults living in the lower Rio Grande Valley of Texas, adjacent to the Mexican border. The present analysis compares responses from 400 residents of rural colonias to those of 395 residents of cities and towns in the same geographic region. Findings: While the prevalence of drug use and drug‐related problems was similar in both areas, binge drinking and alcohol dependence were higher in rural colonias than in urban areas and remained so after taking demographic and neighborhood variables into account. An increase in illicit drug use and substance‐related problems in rural but not urban areas was seen when comparing results from this study with those of a previous survey conducted in 1996. The percentage of adults in potential need of treatment and the percentage motivated to seek it were similar in both urban and rural areas. However, colonia residents were more likely than their urban counterparts to be recent immigrants and to have lower incomes and educational attainment, factors that can increase the barriers they face in getting needed services. Conclusions: Rural areas are “catching up” with urban areas in problematic substance use. Given the potential barriers to accessing treatment services in rural areas, efforts should be focused on reaching those residents.
Meeting a Binational Research Challenge: Substance Abuse Among Transnational Mexican Farmworkers in the United States
Authors: Garcia Victor
Published: January 2008

ABSTRACT:  To help in understanding the manner in which community, individual, and other factors in the United States and Mexico contribute to drug use among transnational migrants, this paper introduces a binational social ecology model of substance abuse in this population. We draw on our 2 NIH‐funded ethnographic studies—1 on problem drinking and the other on drug abuse—among transnational Mexican workers in the mushroom industry of southeastern Pennsylvania. Our model demonstrates that major reasons for substance abuse among transnational migrants include nontraditional living arrangements in labor camps and overcrowded apartments, the absence of kin and community deterrents to drug use, social isolation, the presence of drug use and binge drinking subcultures, the availability of drugs, family history of drugs, previous drug use or witnessing of drug use in Mexico, and drug use norms and drug availability in Mexico. It suggests the need for US and Mexican researchers to collaborate in binational teams and address factors on both sides of the border. Our binational social ecology model, together with our research recommendations, will assist alcohol and drug researchers to discover how community and individual factors in both the United States and abroad fit and interact beyond mere association and provide a more comprehensive research approach to substance abuse research among transnational migrants.
Illicit Drug Use and the Social Context of HIV/AIDS in Alabama's Black Belt
Authors: Lichtenstein Bronwen
Published: January 2008

ABSTRACT: 
Context: The rural Black Belt of Alabama is among the poorest areas of the nation. Poverty, lack of health infrastructure, and health disparities involving HIV/AIDS and other diseases reflect the lower life expectancy of people in the region. The Black Belt region has the highest HIV rates in rural America. Purpose: Using Alabama as a case example, the paper describes the role of illicit drug use in pathways to HIV transmission in the Black Belt and examines the relationship between drug use and social context with respect to HIV/AIDS disparities in the region. Methods: Published research and national and state data were triangulated for information on interactions between illicit drug use, social context, and HIV/AIDS. Findings: Illicit drug use is implicated in HIV risk in Alabama's Black Belt, but less so than in other parts of the nation. Published research suggests that the impetus for drug use involves status seeking in the context of heterosexual contact and economic disparities. HIV transmission in Alabama's Black Belt speaks to the tyranny of small places; that is, the risk of HIV/AIDS occurs in geographically bounded areas with a history of racial homogeneity, historically high rates of sexually transmitted infections, and clustered sexual networks in this isolated region. Conclusions: Social context is an important correlate of HIV risk in the Black Belt. The role of drug use in HIV risk is secondary to social‐contextual factors involving rural isolation, racial homogeneity, and the racial disparities of the region.
Growth of the tufted‐tailed rat
Authors: RANDRIANJAFY Vololomboahangy R. , RAMILIJAONA Olga , RAKOTONDRAVONY Daniel
Published: January 2008

Eliurus myoxinus (Rodentia: Nesomyidae, Nesomyinae) is one of the four species of endemic Malagasy rodents known to exist in the Ankarafantsika National Park, northwestern Madagascar. In order to study growth parameters and to determine at which age E. myoxinus commences breeding, we used two different techniques: captive breeding and a capture‐mark‐release field program in the species' natural habitat. The data collected on the breeding of E. myoxinus in captivity demonstrated that females can give birth to a litter of up to four pups, with up to four litters per calendar year. Reproduction of E. myoxinus was more likely to be continuous in captivity than under natural habitat conditions. If parturition failed, then post‐partum mating occurred. Pups had a rapid linear growth phase from birth until 1 month of age. Between 1.5 and 2 months of age, the growth rate continued to increase, but then decreased at around the time of weaning, which occurred by 3.5 months of age. The successive maximum method of age determination showed that individuals at the “young” stage had an average body length of 90 mm and a weight of 30 g and were between 1.5 and 2 months old. The greatest variation in measurements of juveniles occurred at the age of 3.5 months. At this stage, sub‐adults resembled adults but their external genitalia were not well developed. Individuals were classified as adults if they had reached a body length of 110 mm and a body weight of 40 g. This occurred at more than 4.5 months of age when the animals were generally reproductively active. The Vo n Bertalanffy method indicated that individuals reach the adult stage by 6 to 7 months. Males grew more rapidly than females, reaching adulthood by 5.5 months of age, whereas females only reached adulthood several weeks later. This species is polygamous. The sex ratio of pups at birth favored females by approximately 3:1. The higher proportion of female pups at birth may represent a survival strategy of this species, possibly associated with ecological conditions.
Anti‐fertility effect of levonorgestrel and quinestrol in Brandt's voles (Lasiopodomys brandtii)
Authors: ZHAO Meirong , LIU Ming , LI Dong , WAN Xinrong , HINDS Lyn A. , WANG Yanling , ZHANG Zhibin
Published: January 2008

The combination of levonorgestrel and quinestrol (EP‐1) has been shown to have anti‐fertility effects on several wild rodents, but the mechanism underlying these effects is poorly understood. We investigated the effects of EP‐1 and each of its components, levonorgestrel (P) and quinestrol (E), on the fertility of Brandt's voles (Lasiopodomys brandtii) by using a gastric gavage method. The doses for EP‐1, E and P were 1, 0.34 and 0.66 mg/kg body weight, respectively. Male voles (n = 98) were treated daily for 5 or 14 days, then the testes and epididymides were collected, weighed and examined histologically at 30 (D30), 60 (D60) or 90 (D90) days after the end of treatment. Four males were allowed to mate with normal females at D90. Female voles (n = 75) were treated for 3 days and a further 3 days after a 7‐day interval. The uteri and ovaries were weighed and examined histologically at 15 (D15), 30 (D30) or 75 (D75) days after the end of treatment. Each of three females were mated with fertile males at D30 and D75, respectively. Our results indicated that quinestrol (E) significantly decreased the sperm numbers in the testes as well as the weight of the testes and epididymides, with both of these tissues showing obvious structural abnormalities, and significantly reduced the litter size and the pup weight for females mated with males of the E treatment group. For female voles, treatment with E, P or EP‐1 resulted in no marked influence on the fertility status. These data indicate that quinestrol (E) alone has a significant anti‐fertility effect on male Brandt's voles, but is ineffective in combination with levonorgestrel (P).
Adaptation as a potential response to sea‐level rise: a genetic basis for salinity tolerance in populations of a coastal marsh fish
Authors: Purcell Kevin M. , Hitch Alan T. , Klerks Paul L. , Leberg Paul L.
Published: January 2008

Relative sea‐level rise is resulting in the intrusion of saline waters into marshes historically dominated by fresh water. Saltwater intrusions can potentially affect resident marsh species, especially when storm‐related tidal surges cause rapid changes in salinity. We examined the role of historical salinity exposure on the survival of Gambusia affinis from two locations in coastal Louisiana. At each location, we sampled fish populations from fresh, intermediate and brackish marshes. Individuals were then exposed to a salinity of 25‰ and survival time was measured. We found that fish from brackish and intermediate marshes had an increased tolerance to salinity stress relative to fish from freshwater environments. We then tested the descendents of fish from the fresh and brackish marshes, reared for two generation in fresh water, to determine if there was a genetic basis for differential survival. We found that descendents of individuals from brackish marshes showed elevated survivals relative to the descendents of fish with no historical exposure to salinity. The most reasonable mechanism to account for the differences in survival relative to historical exposure is genetic adaptation, suggesting that natural selection may play a role in the responses of resident marsh fishes to future increases in salinity.
Introgression and dispersal among spotted owl (Strix occidentalis) subspecies
Authors: Funk W. Chris , Forsman Eric D. , Mullins Thomas D. , Haig Susan M.
Published: January 2008

Population genetics plays an increasingly important role in the conservation and management of declining species, particularly for defining taxonomic units. Subspecies are recognized by several conservation organizations and countries and receive legal protection under the US Endangered Species Act (ESA). Two subspecies of spotted owls, northern (Strix occidentalis caurina) and Mexican (S. o. lucida) spotted owls, are ESA‐listed as threatened, but the California (S. o. occidentalis) spotted owl is not listed. Thus, determining the boundaries of these subspecies is critical for effective enforcement of the ESA. We tested the validity of previously recognized spotted owl subspecies by analysing 394 spotted owls at 10 microsatellite loci. We also tested whether northern and California spotted owls hybridize as suggested by previous mitochondrial DNA studies. Our results supported current recognition of three subspecies. We also found bi‐directional hybridization and dispersal between northern and California spotted owls centered in southern Oregon and northern California. Surprisingly, we also detected introgression of Mexican spotted owls into the range of northern spotted owls, primarily in the northern part of the subspecies’ range in Washington, indicating long‐distance dispersal of Mexican spotted owls. We conclude with a discussion of the conservation implications of our study.
Invasion thresholds and the evolution of nonequilibrium virulence
Authors: Bull James J. , Ebert Dieter
Published: January 2008

The enterprise of virulence management attempts to predict how social practices and other factors affect the evolution of parasite virulence. These predictions are often based on parasite optima or evolutionary equilibria derived from models of host‐parasite dynamics. Yet even when such models accurately capture the parasite optima, newly invading parasites will typically not be at their optima. Here we show that parasite invasion of a host population can occur despite highly nonoptimal virulence. Fitness improvements soon after invasion may proceed through many steps with wide changes in virulence, because fitness depends on transmission as well as virulence, and transmission improvements can overwhelm nonoptimal virulence. This process is highly sensitive to mutation supply and the strength of selection. Importantly, the same invasion principle applies to the evolution of established parasites, whenever mutants arise that overcome host immunity/resistance. A host population may consequently experience repeated invasions of new parasite variants and possible large shifts in virulence as it evolves in an arms race with the parasite. An experimental study of phage lysis time and examples of mammalian viruses matching some of these characteristics are reviewed.
Adaptation, extinction and global change
Authors: Bell Graham , Collins Sinéad
Published: January 2008

We discuss three interlinked issues: the natural pace of environmental change and adaptation, the likelihood that a population will adapt to a potentially lethal change, and adaptation to elevated CO2, the prime mover of global change.

1. Environmental variability is governed by power laws showing that ln difference in conditions increases with ln elapsed time at a rate of 0.3–0.4. This leads to strong but fluctuating selection in many natural populations.

2. The effect of repeated adverse change on mean fitness depends on its frequency rather than its severity. If the depression of mean fitness leads to population decline, however, severe stress may cause extinction. Evolutionary rescue from extinction requires abundant genetic variation or a high mutation supply rate, and thus a large population size. Although natural populations can sustain quite intense selection, they often fail to adapt to anthropogenic stresses such as pollution and acidification and instead become extinct.

3. Experimental selection lines of algae show no specific adaptation to elevated CO2, but instead lose their carbon‐concentrating mechanism through mutational degradation. This is likely to reduce the effectiveness of the oceanic carbon pump. Elevated CO2is also likely to lead to changes in phytoplankton community composition, although it is not yet clear what these will be.

We emphasize the importance of experimental evolution in understanding and predicting the biological response to global change. This will be one of the main tasks of evolutionary biologists in the coming decade.
Why is HIV not vector‐borne?
Authors: Day Troy , Mideo Nicole , Alizon Samuel
Published: January 2008

Many pathogens of humans are blood borne, including HIV, Malaria, Hepatitis B and C, West Nile virus, Dengue, and other viral hemorrhagic fevers. Although several of these pathogens are transmitted by blood‐feeding arthropods, HIV is not. A number of properties of HIV and its life cycle have been identified as proximate explanations for the absence of arthropod transmission, but little consideration has been given to why HIV has not evolved this form of transmission. We consider the empirical evidence for arthropod transmission, and suggest that mechanical transmission has not evolved in HIV because such strains would induce a faster onset of AIDS during infection, which would thereby limit their ability to spread. On the other hand, it is not as clear why biological transmission has not occurred. Available data suggests that a lack of appropriate genetic variation in HIV is one explanation, but it is also possible that a conflict between natural selection occurring within and between infected individuals has prevented its evolution instead. We discuss the potential significance of these ideas, and argue that taking such an evolutionary perspective broadens our understanding of infectious diseases and the potential consequences of public health interventions.
Expression and function of the ion channel TRPA1 in vagal afferent nerves innervating mouse lungs
Authors: Nassenstein Christina , Kwong Kevin , Taylor‐Clark Thomas , Kollarik Marian , MacGlashan Donald M. , Braun Armin , Undem Bradley J.
Published: January 2008

Transient receptor potential (TRP) A1 and TRPM8 are ion channels that have been localized to afferent nociceptive nerves. These TRP channels may be of particular relevance to respiratory nociceptors in that they can be activated by various inhaled irritants and/or cold air. We addressed the hypothesis that mouse vagal sensory nerves projecting to the airways express TRPA1 and TRPM8 and that they can be activated via these receptors. Single cell RT‐PCR analysis revealed that TRPA1 mRNA, but not TRPM8, is uniformly expressed in lung‐labelled TRPV1‐expressing vagal sensory neurons. Neither TRPA1 nor TRPM8 mRNA was expressed in TRPV1‐negative neurons. Capsaicin‐sensitive, but not capsaicin‐insensitive, lung‐specific neurons responded to cinnamaldehyde, a TRPA1 agonist, with increases in intracellular calcium. Menthol, a TRPM8 agonist, was ineffective at increasing cellular calcium in lung‐specific vagal sensory neurons. Cinnamaldehyde also induced TRPA1‐like inward currents (as measured by means of whole cell patch clamp recordings) in capsaicin‐sensitive neurons. In an ex vivo vagal innervated mouse lung preparation, cinnamaldehyde evoked action potential discharge in mouse vagal C‐fibres with a peak frequency similar to that observed with capsaicin. Cinnamaldehyde inhalation in vivo mimicked capsaicin in eliciting strong central‐reflex changes in breathing pattern. Taken together, our results support the hypothesis that TRPA1, but not TRPM8, is expressed in vagal sensory nerves innervating the airways. TRPA1 activation provides a mechanism by which certain environmental stimuli may elicit action potential discharge in airway afferent C‐fibres and the consequent nocifensor reflexes.