bluuebunny/crossref_metadata_2025 huggingface dataset:
Sphingosine 1-Phosphate-Metabolizing Enzymes Control Influenza Virus Propagation and Viral Cytopathogenicity
Authors: Seo Young-Jin , Blake Celeste , Alexander Stephen , Hahm Bumsuk
Published: June 2010

Sphingosine 1-phosphate (S1P)-metabolizing enzymes regulate the level of sphingolipids and have important biological functions. However, the effects of S1P-metabolizing enzymes on host defense against invading viruses remain unknown. In this study, we investigated the role of S1P-metabolizing enzymes in modulating cellular responses to influenza virus infection. Overexpression of S1P lyase (SPL), which induces the degradation of S1P, interfered with the amplification of infectious influenza virus. Accordingly, SPL-overexpressing cells were much more resistant than control cells to the cytopathic effects caused by influenza virus infection. SPL-mediated inhibition of virus-induced cell death was supported by impairment of the upregulation of the proapoptotic protein Bax, a critical factor for influenza virus cytopathogenicity. Importantly, influenza virus infection of SPL-overexpressing cells induced rapid activation of extracellular signal-regulated kinase (ERK) and STAT1 but not of p38 mitogen-activated protein kinase (MAPK), Akt, or c-Jun N-terminal kinase (JNK). Blockade of STAT1 expression or inhibition of Janus kinase (JAK) activity elevated the level of influenza virus replication in the cells, indicating that SPL protects cells from influenza virus via the activation of JAK/STAT signaling. In contrast to that of SPL, the overexpression of S1P-producing sphingosine kinase 1 heightened the cells' susceptibility to influenza virus infection, an effect that was reversed by the inhibition of its kinase activity, representing opposed enzymatic activity. These findings indicate that the modulation of S1P-metabolizing enzymes is crucial for controlling the host defense against infection with influenza virus. Thus, S1P-metabolizing enzymes are novel potential targets for the treatment of diseases caused by influenza virus infection.
A Single Immunization with CoVaccine HT-Adjuvanted H5N1 Influenza Virus Vaccine Induces Protective Cellular and Humoral Immune Responses in Ferrets
Authors: Bodewes R. , Kreijtz J. H. C. M. , van Amerongen G. , Geelhoed-Mieras M. M. , Verburgh R. J. , Heldens J. G. M. , Bedwell J. , van den Brand J. M. A. , Kuiken T. , van Baalen C. A. , Fouchier R. A. M. , Osterhaus A. D. M. E. , Rimmelzwaan G. F.
Published: June 2010

Highly pathogenic avian influenza A viruses of the H5N1 subtype continue to circulate in poultry, and zoonotic transmissions are reported frequently. Since a pandemic caused by these highly pathogenic viruses is still feared, there is interest in the development of influenza A/H5N1 virus vaccines that can protect humans against infection, preferably after a single vaccination with a low dose of antigen. Here we describe the induction of humoral and cellular immune responses in ferrets after vaccination with a cell culture-derived whole inactivated influenza A virus vaccine in combination with the novel adjuvant CoVaccine HT. The addition of CoVaccine HT to the influenza A virus vaccine increased antibody responses to homologous and heterologous influenza A/H5N1 viruses and increased virus-specific cell-mediated immune responses. Ferrets vaccinated once with a whole-virus equivalent of 3.8 μg hemagglutinin (HA) and CoVaccine HT were protected against homologous challenge infection with influenza virus A/VN/1194/04. Furthermore, ferrets vaccinated once with the same vaccine/adjuvant combination were partially protected against infection with a heterologous virus derived from clade 2.1 of H5N1 influenza viruses. Thus, the use of the novel adjuvant CoVaccine HT with cell culture-derived inactivated influenza A/H5N1 virus antigen is a promising and dose-sparing vaccine approach warranting further clinical evaluation.
Identification of Wild-Derived Inbred Mouse Strains Highly Susceptible to Monkeypox Virus Infection for Use as Small Animal Models
Authors: Americo Jeffrey L. , Moss Bernard , Earl Patricia L.
Published: June 2010

Infection with monkeypox virus (MPXV) causes disease manifestations in humans that are similar, although usually less severe, than those of smallpox. Since routine vaccination for smallpox ceased more than 30 years ago, there is concern that MPXV could be used for bioterrorism. Thus, there is a need to develop animal models to study MPXV infection. Accordingly, we screened 38 inbred mouse strains for susceptibility to MPXV. Three highly susceptible wild-derived inbred strains were identified, of which CAST/EiJ was further developed as a model. Using an intranasal route of infection with an isolate of the Congo Basin clade of MPXV, CAST/EiJ mice exhibited weight loss, morbidity, and death in a dose-dependent manner with a calculated 50% lethal dose (LD
50
) of 680 PFU, whereas there were no deaths of BALB/c mice at a 10,000-fold higher dose. CAST/EiJ mice exhibited greater MPXV sensitivity when infected via the intraperitoneal route, with an LD
50
of 14 PFU. Both routes resulted in MPXV replication in the lung, spleen, and liver. Intranasal infection with an isolate of the less-pathogenic West African clade yielded an LD
50
of 7,600 PFU. The immune competence of CAST/EiJ mice was established by immunization with vaccinia virus, which induced antigen-specific T- and B-lymphocyte responses and fully protected mice from lethal doses of MPXV. The new mouse model has the following advantages for studying pathogenesis of MPXV, as well as for evaluation of potential vaccines and therapeutics: relative sensitivity to MPXV through multiple routes, genetic homogeneity, available immunological reagents, and commercial production.
The ESCRT-Associated Protein Alix Recruits the Ubiquitin Ligase Nedd4-1 To Facilitate HIV-1 Release through the LYPX
n
L L Domain Motif
Authors: Sette Paola , Jadwin Joshua A. , Dussupt Vincent , Bello Nana F. , Bouamr Fadila
Published: June 2010

The p6 region of HIV-1 Gag contains two late (L) domains, PTAP and LYPX
n
L, that bind Tsg101 and Alix, respectively. Interactions with these two cellular proteins recruit members of the host's fission machinery (ESCRT) to facilitate HIV-1 release. Other retroviruses gain access to the host ESCRT components by utilizing a PPXY-type L domain that interacts with cellular Nedd4-like ubiquitin ligases. Despite the absence of a PPXY motif in HIV-1 Gag, interaction with the ubiquitin ligase Nedd4-2 was recently shown to stimulate HIV-1 release. We show here that another Nedd4-like ubiquitin ligase, Nedd4-1, corrected release defects resulting from the disruption of PTAP (PTAP
−
), suggesting that HIV-1 Gag also recruits Nedd4-1 to facilitate virus release. Notably, Nedd4-1 remediation of HIV-1 PTAP
−
budding defects is independent of cellular Tsg101, implying that Nedd4-1's function in HIV-1 release does not involve ESCRT-I components and is therefore distinct from that of Nedd4-2. Consistent with this finding, deletion of the p6 region decreased Nedd4-1-Gag interaction, and disruption of the LYPX
n
L motif eliminated Nedd4-1-mediated restoration of HIV-1 PTAP
−
. This result indicated that both Nedd4-1 interaction with Gag and function in virus release occur through the Alix-binding LYPX
n
L motif. Mutations of basic residues located in the NC domain of Gag that are critical for Alix's facilitation of HIV-1 release, also disrupted release mediated by Nedd4-1, further confirming a Nedd4-1-Alix functional interdependence. In fact we found that Nedd4-1 binds Alix in both immunoprecipitation and yeast-two-hybrid assays. In addition, Nedd4-1 requires its catalytic activity to promote virus release. Remarkably, RNAi knockdown of cellular Nedd4-1 eliminated Alix ubiquitination in the cell and impeded its ability to function in HIV-1 release. Together our data support a model in which Alix recruits Nedd4-1 to facilitate HIV-1 release mediated through the LYPX
n
L/Alix budding pathway via a mechanism that involves Alix ubiquitination.
Lentiviral Vif Degrades the APOBEC3Z3/APOBEC3H Protein of Its Mammalian Host and Is Capable of Cross-Species Activity
Authors: LaRue Rebecca S. , Lengyel Joy , Jónsson Stefán R. , Andrésdóttir Valgerdur , Harris Reuben S.
Published: June 2010

All lentiviruses except equine infectious anemia virus (EIAV) use the small accessory protein Vif to counteract the restriction activity of the relevant APOBEC3 (A3) proteins of their host species. Prior studies have suggested that the Vif-A3 interaction is species specific. Here, using the APOBEC3H (Z3)-type proteins from five distinct mammals, we report that this is generally not the case: some lentiviral Vif proteins are capable of triggering the degradation of both the A3Z3-type protein of their normal host species and those of several other mammals. For instance, SIV
mac
Vif can mediate the degradation of the human, macaque, and cow A3Z3-type proteins but not of the sheep or cat A3Z3-type proteins. Maedi-visna virus (MVV) Vif is similarly promiscuous, degrading not only sheep A3Z3 but also the A3Z3-type proteins of humans, macaques, cows, and cats. In contrast to the neutralization capacity of these Vif proteins, human immunodeficiency virus (HIV), bovine immunodeficiency virus (BIV), and feline immunodeficiency virus (FIV) Vif appear specific to the A3Z3-type protein of their hosts. We conclude, first, that the Vif-A3Z3 interaction can be promiscuous and, second, despite this tendency, that each lentiviral Vif protein is optimized to degrade the A3Z3 protein of its mammalian host. Our results thereby suggest that the Vif-A3Z3 interaction is relevant to lentivirus biology.
Competitive Fitness of Oseltamivir-Sensitive and -Resistant Highly Pathogenic H5N1 Influenza Viruses in a Ferret Model
Authors: Govorkova Elena A. , Ilyushina Natalia A. , Marathe Bindumadhav M. , McClaren Jennifer L. , Webster Robert G.
Published: June 2010

The fitness of oseltamivir-resistant highly pathogenic H5N1 influenza viruses has important clinical implications. We generated recombinant human A/Vietnam/1203/04 (VN; clade 1) and A/Turkey/15/06 (TK; clade 2.2) influenza viruses containing the H274Y neuraminidase (NA) mutation, which confers resistance to NA inhibitors, and compared the fitness levels of the wild-type (WT) and resistant virus pairs in ferrets. The VN-H274Y and VN-WT viruses replicated to similar titers in the upper respiratory tract (URT) and caused comparable disease signs, and none of the animals survived. On days 1 to 3 postinoculation, disease signs caused by oseltamivir-resistant TK-H274Y virus were milder than those caused by TK-WT virus, and all animals survived. We then studied fitness by using a novel approach. We coinoculated ferrets with different ratios of oseltamivir-resistant and -sensitive H5N1 viruses and measured the proportion of clones in day-6 nasal washes that contained the H274Y NA mutation. Although the proportion of VN-H274Y clones increased consistently, that of TK-H274Y virus decreased. Mutations within NA catalytic (R292K) and framework (E119A/K, I222L, H274L, and N294S) sites or near the NA enzyme active site (V116I, I117T/V, Q136H, K150N, and A250T) emerged spontaneously (without drug pressure) in both pairs of viruses. The NA substitutions I254V and E276A could exert a compensatory effect on the fitness of VN-H274Y and TK-H274Y viruses. NA enzymatic function was reduced in both drug-resistant H5N1 viruses. These results show that the H274Y NA mutation affects the fitness of two H5N1 influenza viruses differently. Our novel method of assessing viral fitness accounts for both virus-host interactions and virus-virus interactions within the host.
Influence of pr-M Cleavage on the Heterogeneity of Extracellular Dengue Virus Particles
Authors: Junjhon Jiraphan , Edwards Thomas J. , Utaipat Utaiwan , Bowman Valorie D. , Holdaway Heather A. , Zhang Wei , Keelapang Poonsook , Puttikhunt Chunya , Perera Rushika , Chipman Paul R. , Kasinrerk Watchara , Malasit Prida , Kuhn Richard J. , Sittisombut Nopporn
Published: June 2010

During dengue virus replication, an incomplete cleavage of the envelope glycoprotein prM, generates a mixture of mature (prM-less) and prM-containing, immature extracellular particles. In this study, sequential immunoprecipitation and cryoelectron microscopy revealed a third type of extracellular particles, the partially mature particles, as the major prM-containing particles in a dengue serotype 2 virus. Changes in the proportion of viral particles in the pr-M junction mutants exhibiting altered levels of prM cleavage suggest that the partially mature particles may represent an intermediate subpopulation in the virus maturation pathway. These findings are consistent with a model suggesting the progressive mode of prM cleavage.
A Polymorphism in the Hemagglutinin of the Human Isolate of a Highly Pathogenic H5N1 Influenza Virus Determines Organ Tropism in Mice
Authors: Mänz Benjamin , Matrosovich Mikhail , Bovin Nicolai , Schwemmle Martin
Published: June 2010

We characterized a human H5N1 virus isolate (KAN-1) encoding a hemagglutinin (HA) with a K-to-E substitution at amino acid position 222 that was previously described to be selected in the lung of the infected patient. In mice, the growth of the HA
222E
-encoding virus was mainly confined to the lung, but reversion to 222K allowed virus to spread to the brain. The HA
222E
variant showed an overall reduced binding affinity compared to that of HA
222K
for synthetic Neu5Ac2-3Gal-terminated receptor analogues, except for one analogue [Neu5Acα2-3Galβ1-4(Fucα1-3)(6-HSO
3
)GlcNAcβ, Su-SLe
x
]. Our results suggest that human-derived mutations in HA of H5N1 viruses can affect viral replication efficiency and organ tropism.
The 3C Protein of Enterovirus 71 Inhibits Retinoid Acid-Inducible Gene I-Mediated Interferon Regulatory Factor 3 Activation and Type I Interferon Responses
Authors: Lei Xiaobo , Liu Xinlei , Ma Yijie , Sun Zhenmin , Yang Yaowu , Jin Qi , He Bin , Wang Jianwei
Published: June 2010

Enterovirus 71 (EV71) is a human pathogen that induces hand, foot, and mouth disease and fatal neurological diseases. Immature or impaired immunity is thought to associate with increased morbidity and mortality. In a murine model, EV71 does not facilitate the production of type I interferon (IFN) that plays a critical role in the first-line defense against viral infection. Administration of a neutralizing antibody to IFN-α/β exacerbates the virus-induced disease. However, the molecular events governing this process remain elusive. Here, we report that EV71 suppresses the induction of antiviral immunity by targeting the cytosolic receptor retinoid acid-inducible gene I (RIG-I). In infected cells, EV71 inhibits the expression of IFN-β, IFN-stimulated gene 54 (ISG54), ISG56, and tumor necrosis factor alpha. Among structural and nonstructural proteins encoded by EV71, the 3C protein is capable of inhibiting IFN-β activation by virus and RIG-I. Nevertheless, EV71 3C exhibits no inhibitory activity on MDA5. Remarkably, when expressed in mammalian cells, EV71 3C associates with RIG-I via the caspase recruitment domain. This precludes the recruitment of an adaptor IPS-1 by RIG-I and subsequent nuclear translocation of interferon regulatory factor 3. An R84Q or V154S substitution in the RNA binding motifs has no effect. An H40D substitution is detrimental, but the protease activity associated with 3C is dispensable. Together, these results suggest that inhibition of RIG-I-mediated type I IFN responses by the 3C protein may contribute to the pathogenesis of EV71 infection.
An Antibody against a Novel and Conserved Epitope in the Hemagglutinin 1 Subunit Neutralizes Numerous H5N1 Influenza Viruses
Authors: Oh Hsueh-Ling Janice , Åkerström Sara , Shen Shuo , Bereczky Sándor , Karlberg Helen , Klingström Jonas , Lal Sunil K. , Mirazimi Ali , Tan Yee-Joo
Published: June 2010

The spread of the recently emerged, highly pathogenic H5N1 avian influenza virus has raised concern. Preclinical studies suggest that passive immunotherapy could be a new form of treatment for H5N1 virus infection. Here, a neutralizing monoclonal antibody (MAb) against the hemagglutinin (HA) of the influenza A/chicken/Hatay/2004 H5N1 virus, MAb 9F4, was generated and characterized. MAb 9F4 binds both the denatured and native forms of HA. It was shown to recognize the HA proteins of three heterologous strains of H5N1 viruses belonging to clades 1, 2.1, and 2.2, respectively. By use of lentiviral pseudotyped particles carrying HA on the surface, MAb 9F4 was shown to effectively neutralize the homologous strain, Hatay04, and another clade 1 strain, VN04, at a neutralization titer of 8 ng/ml. Furthermore, MAb 9F4 also neutralized two clade 2 viruses at a neutralizing titer of 40 ng/ml. The broad cross-neutralizing activity of MAb 9F4 was confirmed by its ability to neutralize live H5N1 viruses of clade 2.2.2. Epitope-mapping analysis revealed that MAb 9F4 binds a previously uncharacterized epitope below the globular head of the HA1 subunit. Consistently, this epitope is well conserved among the different clades of H5N1 viruses. MAb 9F4 does not block the interaction between HA and its receptor but prevents the pH-mediated conformational change of HA. MAb 9F4 was also found to be protective, both prophylactically and therapeutically, against a lethal viral challenge of mice. Taken together, our results showed that MAb 9F4 is a neutralizing MAb that binds a novel and well-conserved epitope in the HA1 subunit of H5N1 viruses.
Chikungunya Virus Arthritis in Adult Wild-Type Mice
Authors: Gardner Joy , Anraku Itaru , Le Thuy T. , Larcher Thibaut , Major Lee , Roques Pierre , Schroder Wayne A. , Higgs Stephen , Suhrbier Andreas
Published: June 2010

Chikungunya virus is a mosquito-borne arthrogenic alphavirus that has recently reemerged to produce the largest epidemic ever documented for this virus. Here we describe a new adult wild-type mouse model of chikungunya virus arthritis, which recapitulates the self-limiting arthritis, tenosynovitis, and myositis seen in humans. Rheumatic disease was associated with a prolific infiltrate of monocytes, macrophages, and NK cells and the production of monocyte chemoattractant protein 1 (MCP-1), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ). Infection with a virus isolate from the recent Reunion Island epidemic induced significantly more mononuclear infiltrates, proinflammatory mediators, and foot swelling than did an Asian isolate from the 1960s. Primary mouse macrophages were shown to be productively infected with chikungunya virus; however, the depletion of macrophages ameliorated rheumatic disease and prolonged the viremia. Only 1 μg of an unadjuvanted, inactivated, whole-virus vaccine derived from the Asian isolate completely protected against viremia and arthritis induced by the Reunion Island isolate, illustrating that protection is not strain specific and that low levels of immunity are sufficient to mediate protection. IFN-α treatment was able to prevent arthritis only if given before infection, suggesting that IFN-α is not a viable therapy. Prior infection with Ross River virus, a related arthrogenic alphavirus, and anti-Ross River virus antibodies protected mice against chikungunya virus disease, suggesting that individuals previously exposed to Ross River virus should be protected from chikungunya virus disease. This new mouse model of chikungunya virus disease thus provides insights into pathogenesis and a simple and convenient system to test potential new interventions.
Mutations in the M112/M113-Coding Region Facilitate Murine Cytomegalovirus Replication in Human Cells
Authors: Schumacher Uwe , Handke Wiebke , Jurak Igor , Brune Wolfram
Published: June 2010

Cytomegaloviruses, representatives of the
Betaherpesvirinae
, cause opportunistic infections in immunocompromised hosts. They infect various cells and tissues in their natural host but are highly species specific. For instance, human cytomegalovirus (HCMV) does not replicate in mouse cells, and human cells are not permissive for murine cytomegalovirus (MCMV) infection. However, the underlying molecular mechanisms are so far poorly understood. In the present study we isolated and characterized a spontaneously occurring MCMV mutant that has gained the capacity to replicate rapidly and to high titers in human cells. Compared to the parental wild-type (wt) virus, this mutant formed larger nuclear replication compartments and replicated viral DNA more efficiently. It also disrupted promyelocytic leukemia (PML) protein nuclear domains with greater efficiency but caused less apoptosis than did wt MCMV. Sequence analysis of the mutant virus genome revealed mutations in the M112/M113-coding region. This region is homologous to the HCMV UL112-113 region and encodes the viral early 1 (E1) proteins, which are known to play an important role in viral DNA replication. By introducing the M112/M113 mutations into wt MCMV, we demonstrated that they are sufficient to facilitate MCMV replication in human cells and are, at least in part, responsible for the efficient replication capability of the spontaneously adapted virus. However, additional mutations probably contribute as well. These results reveal a previously unrecognized role of the viral E1 proteins in regulating viral replication in different cells and provide new insights into the mechanisms of the species specificity of cytomegaloviruses.
Coal workers' pneumoconiosis and progressive massive fibrosis are increasingly more prevalent among workers in small underground coal mines in the United States
Authors: Laney A Scott , Attfield Michael D
Published: June 2010

Objective

To determine whether the prevalence of coal workers' pneumoconiosis (CWP) or progressive massive fibrosis (PMF) among United States underground miners is associated with mine size.

Methods

We examined chest radiographs from 1970 to 2009 of working miners who participated in the National Coal Workers Health Surveillance Program for the presence of small and large opacities consistent with pneumoconiosis, based upon the International Labour Organization classification system.

Results

A total of 145 512 miners contributed 240 067 radiographs for analysis. From the 1990s to the 2000s, the prevalence of radiographic CWP increased among miners in mines of all sizes, while miners working in mines with fewer than 50 employees had a significantly higher prevalence of CWP compared to miners who worked in mines with 50 or more employees (p<0.0001). When adjusted for age and within-miner correlation, the difference in prevalence of CWP by mine size was significant for all decades. Since 1999, miners from small mines were five times more likely to have radiographic evidence of PMF (1.0% of miners) compared to miners from larger mines (0.2% of miners) with a prevalence ratio of 5.0 and 95% CI 3.3 to 7.5.

Conclusion

The prevalence of CWP among United States coal miners is increasing in mines of all sizes, while CWP and PMF are much more prevalent among workers from underground mines with fewer than 50 workers.
INTERMEDIATE MODEL FOR SPATIAL EVOLUTION IN NONLINEAR OPTICS
Authors: LESCARRET VINCENT
Published: June 2010

This paper follows the work of Colin–Gallice–Laurioux6 in which a new model generalizing the Schrödinger (NLS) model of the diffractive optics is derived for the laser propagation in nonlinear media. In particular, it provides good approximate solutions of the Maxwell–Lorentz system for highly oscillating initial data with broad spectrum. In real situations one is given boundary data. We propose to derive a similar evolution model but in the variable associated to the direction of propagation. However, since the space directions for the Maxwell equations are not hyperbolic, the boundary problem is ill-posed and one needs to apply a cutoff defined in the Fourier space, selecting those frequencies for which the operator is hyperbolic. The model we obtain is nearly L2 conservative on its domain of validity.

We then give a justification of the derivation. For this purpose we introduce a related well-posed initial boundary value problem. Finally, we perform numerical computations on the example of Maxwell with Kerr nonlinearity in some cases of short or spectrally chirped data where our model outperforms the Schrödinger one.
Thermoreception and nociception of the skin: a classic paper of Bessou and Perl and analyses of thermal sensitivity during a student laboratory exercise
Authors: Kuhtz-Buschbeck Johann P. , Andresen Wiebke , Göbel Stephan , Gilster René , Stick Carsten
Published: June 2010

About four decades ago, Perl and collaborators were the first ones who unambiguously identified specifically nociceptive neurons in the periphery. In their classic work, they recorded action potentials from single C-fibers of a cutaneous nerve in cats while applying carefully graded stimuli to the skin (Bessou P, Perl ER. Response of cutaneous sensory units with unmyelinated fibers to noxious stimuli. J Neurophysiol 32: 1025–1043, 1969). They discovered polymodal nociceptors, which responded to mechanical, thermal, and chemical stimuli in the noxious range, and differentiated them from low-threshold thermoreceptors. Their classic findings form the basis of the present method that undergraduate medical students experience during laboratory exercises of sensory physiology, namely, quantitative testing of the thermal detection and pain thresholds. This diagnostic method examines the function of thin afferent nerve fibers. We collected data from nearly 300 students that showed that 1) women are more sensitive to thermal detection and thermal pain at the thenar than men, 2) habituation shifts thermal pain thresholds during repetititve testing, 3) the cold pain threshold is rather variable and lower when tested after heat pain than in the reverse case (order effect), and 4) ratings of pain intensity on a visual analog scale are correlated with the threshold temperature for heat pain but not for cold pain. Median group results could be reproduced in a retest. Quantitative sensory testing of thermal thresholds is feasible and instructive in the setting of a laboratory exercise and is appreciated by the students as a relevant and interesting technique.
Case studies in a physiology course on the autonomic nervous system: design, implementation, and evaluation
Authors: Zimmermann Martina
Published: June 2010

The introduction of case studies on the autonomic nervous system in a fourth-semester physiology course unit for Pharmacy students is described in this article. This article considers how these case studies were developed and presents their content. Moreover, it reflects on their implementation and, finally, the reception of such a transformation among the students as well as the tutor's perception. Specifically, the following issues were addressed. First, how were the course unit and, within the course unit, case study components organized? Second, how was the transformation of the course unit from an originally interactive but rather teacher-centered lecture to an interactive course module achieved? Third, how were the case studies structured, what questions were asked, and what were the answers expected from the students; what additional information was provided by the tutor? Fourth, how did the implementation of these case studies work out in the actual course, i.e., how did the tutor guide the students in this interactive session and how did the students tackle the problems? Finally, how was the integration of interactive modules received by the students and what was their learning experience (as assessed by questionnaires) and learning success (as assessed through the final course exam)? Equally, the tutor's perception of this transformation and its implementation is described.
Outcome assessment of a computer-animated model for learning about the regulation of glomerular filtration rate
Authors: Gookin Jody L. , McWhorter Dan , Vaden Shelly , Posner Lysa
Published: June 2010

The regulation of the glomerular filtration rate (GFR) is a particularly important and challenging concept for students to integrate into a memorable framework for building further knowledge and solving clinical problems. In this study, 76 first-year veterinary students and 19 veterinarians in clinical specialty training (house officers) participated in separate online exercises to evaluate the use of a computer-animated model of GFR regulation ( www.aamc.org/mededportal ) on learning outcome. Students were randomly allocated to study either the animated model or written materials before completion of a 10-question multiple-choice quiz. House officers completed a 35-question test before and after study of the animated model. Both groups completed a survey about the learning exercise. The ability of the model to enhance learning was demonstrated by a significant improvement ( P < 0.001) in the test performance of house officers after studying the model. The model performed similarly to written materials alone in affecting the subsequent quiz performance of the students. The majority of students and house officers agreed or strongly agreed that the animated model was easy to understand, improved their knowledge and appreciation of the importance of GFR regulation, and that they would recommend the model to peers. Most students [63 of 76 students (83%)] responded that they would prefer the use of the animated model alone over the study of written materials but acknowledged that a combination of hardcopy written notes and the animated model would be ideal. A greater applicability of the model to more advanced students and an introduction in a didactic setting before individual study were suggested by the house officers. The results of this study suggest that the animated model is a useful, effective, and well-received tool for learning and creating a visual memory of the regulatory mechanisms of GFR.
Singing greeting card beeper as a finger pulse sensor
Authors: Belušič Gregor , Zupančič Gregor
Published: June 2010

We constructed a robust and low-priced finger pulse sensor from a singing greeting card beeper. The beeper outputs the plethysmographic signal, which is indistinguishable from that of commercial grade sensors. The sensor can be used in school for a number of experiments in human cardiovascular physiology.
A comparison of student performance in multiple-choice and long essay questions in the MBBS stage I physiology examination at the University of the West Indies (Mona Campus)
Authors: Pepple Dagogo J. , Young Lauriann E. , Carroll Robert G.
Published: June 2010

This retrospective study compared the performance of preclinical medical students in the multiple-choice question (MCQ) and long essay question components of a comprehensive physiology final examination. During the 3 yr analyzed, 307 students had an average score of 47% (SD 9.9) in the long essay questions and 64% (SD 9.9) in the MCQs. Regression analysis showed a significant correlation ( r = 0.62, P < 0.01) between MCQs and long essay questions. When student performance was grouped by final course grade, a statistically significant correlation between MCQ and long essay scores existed only for the 210 students who received a passing grade ( r = 0.20, P < 0.01). The MCQ and long essay question scores were not correlated for the 57 students who failed ( r = 0.25, P = 0.06) or for the 40 students who achieved honors and distinctions ( r = −0.27, P = 0.11). MCQ scores were significantly higher ( P < 0.01) than essay scores for each of the groups when analyzed by two-way ANOVA. The results of this study suggest that for most students, the strong correlation between scores on MCQs and essay questions indicates that student performance was independent of testing format. For students at either end on the performance spectrum, the lack of correlation suggests that the performance in one of the testing formats had a strong influence on the final course grade. In addition, those students who failed the course were likely to be weak in both testing modalities, whereas students in all grade groups were more likely to perform better in the MCQs than in the long essay questions.
Insights into digestion and absorption of major nutrients in humans
Authors: Goodman Barbara E.
Published: June 2010

Nutrient digestion and absorption is necessary for the survival of living organisms and has evolved into the complex and specific task of the gastrointestinal (GI) system. While most people simply assume that their GI tract will work properly to use nutrients, provide energy, and release wastes, few nonscientists know the details about how various nutrients are digested and how the breakdown products traverse the cells lining the small intestine to reach the blood stream and to be used by the other cells of the body. There have been several recent discoveries of new transporters that likely contribute to the absorption of oligopeptides and fatty acids. In addition, details are being clarified about how transporters work and in what forms nutrients can be absorbed. The enzymes that digest basic carbohydrates, proteins, and fats have been identified in various segments of the GI tract, and details are becoming clearer about what types of bonds they hydrolyze. Usually, detailed information about the digestion of basic nutrients is presented and learned in biochemistry courses and detailed information about absorption via transepithelial transport of the breakdown products of digestion is studied in physiology courses. The goal of this Staying Current article is to combine the details of the biochemistry of digestion with the updated information about the physiology of nutrient absorption into one source for teachers of physiology. Insights are included about some of the diseases and conditions that can bring about malabsorption of food in the GI tract and their consequences.
Student perceptions of the use of presentations as a method of learning endocrine and gastrointestinal pathophysiology
Authors: Higgins-Opitz Susan B. , Tufts Mark
Published: June 2010

Second-year medical students at the Nelson R. Mandela School of Medicine (Durban, South Africa) were given a brief to prepare oral presentations on topics related to disorders of the gastrointestinal tract and endocrine system in the form of “patient-doctor” role play and to submit written documents about their topics. This initiative was introduced to assist medical students in their application and understanding of physiology to clinical situations. The aims of the student presentations were to improve the understanding of the physiological basis of diseases; promote independent research, active, and group-based learning; encourage social interactions; and develop presentation and peer review skills. Students rose to the challenge, producing a variety of presentations reflecting a wealth of creativity, humour, sensitivity to local cultural issues, and analytic thinking skills. The quality of the supporting posters and computer-generated slides was outstanding. Numerous “fun” prizes for specific individual and group performances were given based on peer and staff evaluations. This exercise ran over a 5-yr period before the introduction of a problem-based learning medical curriculum. Student feedback obtained over these years is reported here. Students were asked to complete semistructured questionnaires, which elicited feedback on various aspects of the learning exercise, including whether it should be continued and how it could be improved upon, especially if they were in groups that did not function well. The feedback obtained revealed that most students perceived the presentations to be fun, informative, creative/innovative, and, most importantly, beneficial to their learning. The majority of students felt that this exercise improved their understanding of pathophysiology, taught them to research independently, and encouraged better class interactions and group learning. The inclusion of such initiatives is beneficial not only to students' understanding and their experience in studying physiology but also for the development of skills useful in their future careers.
Mitochondrial depolarization underlies delay in permeability transition by preconditioning with isoflurane: roles of ROS and Ca2+
Authors: Sedlic Filip , Sepac Ana , Pravdic Danijel , Camara Amadou K. S. , Bienengraeber Martin , Brzezinska Anna K. , Wakatsuki Tetsuro , Bosnjak Zeljko J.
Published: June 2010

During reperfusion, the interplay between excess reactive oxygen species (ROS) production, mitochondrial Ca2+ overload, and mitochondrial permeability transition pore (mPTP) opening, as the crucial mechanism of cardiomyocyte injury, remains intriguing. Here, we investigated whether an induction of a partial decrease in mitochondrial membrane potential (ΔΨm) is an underlying mechanism of protection by anesthetic-induced preconditioning (APC) with isoflurane, specifically addressing the interplay between ROS, Ca2+, and mPTP opening. The magnitude of APC-induced decrease in ΔΨm was mimicked with the protonophore 2,4-dinitrophenol (DNP), and the addition of pyruvate was used to reverse APC- and DNP-induced decrease in ΔΨm. In cardiomyocytes, ΔΨm, ROS, mPTP opening, and cytosolic and mitochondrial Ca2+ were measured using confocal microscope, and cardiomyocyte survival was assessed by Trypan blue exclusion. In isolated cardiac mitochondria, antimycin A-induced ROS production and Ca2+ uptake were determined spectrofluorometrically. In cells exposed to oxidative stress, APC and DNP increased cell survival, delayed mPTP opening, and attenuated ROS production, which was reversed by mitochondrial repolarization with pyruvate. In isolated mitochondria, depolarization by APC and DNP attenuated ROS production, but not Ca2+ uptake. However, in stressed cardiomyocytes, a similar decrease in ΔΨm attenuated both cytosolic and mitochondrial Ca2+ accumulation. In conclusion, a partial decrease in ΔΨm underlies cardioprotective effects of APC by attenuating excess ROS production, resulting in a delay in mPTP opening and an increase in cell survival. Such decrease in ΔΨm primarily attenuates mitochondrial ROS production, with consequential decrease in mitochondrial Ca2+ uptake.
Sphingomyelinase stimulates oxidant signaling to weaken skeletal muscle and promote fatigue
Authors: Ferreira Leonardo F. , Moylan Jennifer S. , Gilliam Laura A. A. , Smith Jeffrey D. , Nikolova-Karakashian Mariana , Reid Michael B.
Published: June 2010

Sphingomyelinase (SMase) hydrolyzes membrane sphingomyelin into ceramide, which increases oxidants in nonmuscle cells. Serum SMase activity is elevated in sepsis and heart failure, conditions where muscle oxidants are increased, maximal muscle force is diminished, and fatigue is accelerated. We tested the hypotheses that exogenous SMase and accumulation of ceramide in muscle increases oxidants in muscle cells, depresses specific force of unfatigued muscle, and accelerates the fatigue process. We also anticipated that the antioxidant N-acetylcysteine (NAC) would prevent SMase effects on muscle function. We studied the responses of C2C12 myotubes and mouse diaphragm to SMase treatment in vitro. We observed that SMase caused a 2.8-fold increase in total ceramide levels in myotubes. Exogenous ceramide and SMase elevated oxidant activity in C2C12 myotubes by 15–35% ( P < 0.05) and in diaphragm muscle fiber bundles by 58–120% ( P < 0.05). The SMase-induced increase in diaphragm oxidant activity was prevented by NAC. Exogenous ceramide depressed diaphragm force by 55% ( P < 0.05), while SMase depressed maximal force by 30% ( P < 0.05) and accelerated fatigue—effects opposed by treatment with NAC. In conclusion, our findings suggest that SMase stimulates a ceramide-oxidant signaling pathway that results in muscle weakness and fatigue.
Systemic IGF-I administration attenuates the inhibitory effect of chronic arthritis on gastrocnemius mass and decreases atrogin-1 and IGFBP-3
Authors: López-Menduiña María , Martín Ana Isabel , Castillero Estíbaliz , Villanúa María Angeles , López-Calderón Asunción
Published: June 2010

Adjuvant arthritis is an animal model of rheumatoid arthritis that decreases liver and circulating IGF-I as well as skeletal muscle mass. The aim of this work was to elucidate whether IGF-I administration was able to prevent the effect of arthritis on body weight and on two skeletal muscles, gastrocnemius and soleus. On day 4 after adjuvant injection, control and arthritic rats were treated with IGF-I (100 μg/kg sc) two times a day, until day 15 when all rats were killed. Arthritis decreased body weight gain and gastrocnemius weight. In arthritic rats, IGF-I treatment increased body weight gain and gastrocnemius weight, without modifying food intake or the external signs of arthritis. Arthritis increased atrogin-1 and muscle ring finger 1 (MuRF1) gene expression in the gastrocnemius and to a lesser extent in the soleus muscle. IGF-I attenuated the arthritis-induced increase in atrogin-1 and MuRF1 expression in the gastrocnemius, whereas it did not modify the expression of these genes in the soleus muscle. Arthritis also increased IGF-binding protein (IGBP)-3 and IGFBP-5 gene expression in gastrocnemius and soleus, whereas IGF-I administration decreased IGFBP-3, but not IGFBP-5, gene expression in both muscles. In both groups of arthritic rats and in control rats treated with IGF-I, proliferating cell nuclear antigen and myogenic differentiation proteins were increased in the gastrocnemius. These data suggest that the inhibitory effect of chronic arthritis on skeletal muscle is higher in fast glycolytic than in slow oxidative muscle and that IGF-I administration attenuates this effect and decreases atrogin-1 and IGFBP-3 gene expression.
Regulation of the renin expression in the retinal pigment epithelium by systemic stimuli
Authors: Milenkovic Vladimir M. , Brockmann Marisa , Meyer Christian , Desch Michael , Schweda Frank , Kurtz Armin , Todorov Vladimir , Strauss Olaf
Published: June 2010

The retina expresses a local renin-angiotensin system (RAS). This study aimed to investigate the influence of systemic modulation of renin synthesis on the expression of renin in the retinal pigment epithelium (RPE), which forms part of the blood/retina barrier. Freshly isolated RPE cells showed expression of renin 1A, which is the secreted isoform of renin. Systemic administration of the angiotensin-converting enzyme inhibitor enalapril in mice increased the renin expression in both the kidney and the retina. Systemic infusion of ANG II led to a decrease in the renin expression in the kidney and in the retina and RPE. The ANG II-dependent down-regulation of renin expression in the RPE was prevented by systemic application of the AT1receptor blocker losartan. However, water deprivation lead to an increase of the renin expression in the kidney but unexpectedly to a decrease of the renin expression in the retina. In sections of the mouse retina, the ANG II receptor AT1was found in the RPE and localized at the blood side of the epithelium. Short-time cultured RPE cells showed increases in intracellular free Ca2+in response to stimulation by ANG II that were sensitive to losartan. In summary, we conclude that the renin expression in cells of the blood/retina barrier is influenced by the systemic RAS. ANG II circulating in the plasma is likely a mediator of this influence.
Nitric oxide and superoxide transport in a cross section of the rat outer medulla. II. Reciprocal interactions and tubulovascular cross talk
Authors: Edwards Aurélie , Layton Anita T.
Published: June 2010

In a companion study (Edwards A and Layton AT. Am J Physiol Renal Physiol. doi:10.1152/ajprenal.00680.2009), we developed a mathematical model of nitric oxide (NO), superoxide (O2−), and total peroxynitrite (ONOO) transport in mid-outer stripe and mid-inner stripe cross sections of the rat outer medulla (OM). We examined how the three-dimensional architecture of the rat OM, together with low medullary oxygen tension (Po2), affects the distribution of NO, O2−, and ONOO in the rat OM. In the current study, we sought to determine generation rate and permeability values that are compatible with measurements of medullary NO concentrations and to assess the importance of tubulovascular cross talk and NO-O2− interactions under physiological conditions. Our results suggest that the main determinants of NO concentrations in the rat OM are the rate of vascular and tubular NO synthesis under hypoxic conditions, and the red blood cell (RBC) permeability to NO ( PNORBC). The lower the PNORBC, the lower the amount of NO that is scavenged by hemoglobin species, and the higher the extra-erythrocyte NO concentrations. In addition, our results indicate that basal endothelial NO production acts to significantly limit NaCl reabsorption across medullary thick ascending limbs and to sustain medullary perfusion, whereas basal epithelial NO production has a smaller impact on NaCl transport and a negligible effect on vascular tone. Our model also predicts that O2− consumption by NO significantly reduces medullary O2− concentrations, but that O2− , when present at subnanomolar concentrations, has a small impact on medullary NO bioavailability.
Effects of erythropoietin administration on cerebral metabolism and exercise capacity in men
Authors: Rasmussen P. , Foged E. M. , Krogh-Madsen R. , Nielsen J. , Nielsen T. R. , Olsen N. V. , Petersen N. C. , Sørensen T. A. , Secher N. H. , Lundby C.
Published: June 2010

Recombinant human erythropoietin (EPO) increases exercise capacity by stimulating erythropoiesis and subsequently enhancing oxygen delivery to the working muscles. In a large dose, EPO crosses the BBB and may reduce central fatigue and improve cognition. In turn, this would augment exercise capacity independent of erythropoiesis. To test this hypothesis, 15 healthy young men (18–34 years old, 74 ± 7 kg) received either 3 days of high-dose (30,000 IU/day; n = 7) double-blinded placebo controlled or 3 mo of low-dose (5,000 IU/wk; n = 8) counter-balanced open but controlled administration of EPO. We recorded exercise capacity, transcranial ultrasonography-derived middle cerebral artery blood velocity, and arterial-internal jugular venous concentration differences of glucose and lactate. In addition, cognitive function, ratings of perceived exertion, ventilation, and voluntary activation by transcranial magnetic stimulation-induced twitch force were evaluated. Although EPO in a high dose increased cerebrospinal fluid EPO concentration ∼20-fold and affected ventilation and cerebral glucose and lactate metabolism ( P < 0.05), 3 days of high-dose EPO administration had no effect on cognition, voluntary activation, or exercise capacity, but ratings of perceived exertion increased ( P < 0.05). We confirmed that 3 mo of administration of EPO increases exercise capacity, but the improvement could not be accounted for by other mechanisms than enhanced oxygen delivery. In conclusion, EPO does not attenuate central fatigue or change cognitive performance strategy, suggesting that EPO enhances exercise capacity exclusively by increased oxygen delivery to the working muscles.
Community Structure and Biodiversity of Soil Ciliates at Dongzhaigang Mangrove Forest in Hainan Island, China
Authors: Li Jing , Liao Qingyu , Li Mei , Zhang Jinhong , Tam Nora Fungyee , Xu Runlin
Published: June 2010

The distribution of soil ciliates in three different habitats within a typical mangrove forest in Dongzhaigang, Hainan, China was investigated. The abundance, biodiversity, and community similarity of ciliates in fresh and air-dried soil with different, physical/chemical properties were analyzed. Three Classes, 11 Orders, 34 Genera, and 70 species of ciliates were found with the first dominant group being Hypotrichida. Ciliate biodiversities followed Site B < Site A < Site C in both fresh and dried samples. Ciliate abundance was positively correlated with soil moisture, salinity, organic matter (OM), total nitrogen (TN), total phosphorus (TP), and sulfate (SO42−), but negatively with pH and total potassium (TK). Site A and Site B and Site B and Site C showed the highest similarity in fresh and dried samples, respectively. The ubiquitous characteristics of ciliate distribution suggested their important role in food webs and nutrient cycling. The presence of Colpodida was linked with mangrove plants.