bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of the Toll-Like Receptor 9 Signaling Pathway in the Induction of Innate Immunity by Baculovirus
Authors: Abe Takayuki , Hemmi Hiroaki , Miyamoto Hironobu , Moriishi Kohji , Tamura Shinichi , Takaku Hiroshi , Akira Shizuo , Matsuura Yoshiharu
Published: February 2005

We have previously shown that mice inoculated intranasally with a wild-type baculovirus (Autographa californicanuclear polyhedrosis virus [AcNPV]) are protected from a lethal challenge by influenza virus. However, the precise mechanism of induction of this protective immune response by the AcNPV treatment remained unclear. Here we show that AcNPV activates immune cells via the Toll-like receptor 9 (TLR9)/MyD88-dependent signaling pathway. The production of inflammatory cytokines was severely reduced in peritoneal macrophages (PECs) and splenic CD11c+dendritic cells (DCs) derived from mice deficient in MyD88 or TLR9 after cultivation with AcNPV. In contrast, a significant amount of alpha interferon (IFN-α) was still detectable in the PECs and DCs of these mice after stimulation with AcNPV, suggesting that a TLR9/MyD88-independent signaling pathway might also participate in the production of IFN-α by AcNPV. Since previous work showed that TLR9 ligands include bacterial DNA and certain oligonucleotides containing unmethylated CpG dinucleotides, we also examined the effect of baculoviral DNA on the induction of innate immunity. Transfection of the murine macrophage cell line RAW264.7 with baculoviral DNA resulted in the production of the inflammatory cytokine, while the removal of envelope glycoproteins from viral particles, UV irradiation of the virus, and pretreatment with purified baculovirus envelope proteins or endosomal maturation inhibitors diminished the induction of the immune response by AcNPV. Together, these results indicate that the internalization of viral DNA via membrane fusion mediated by the viral envelope glycoprotein, as well as endosomal maturation, which releases the viral genome into TLR9-expressing cellular compartments, is necessary for the induction of the innate immune response by AcNPV.
Interferon Induction and/or Production and Its Suppression by Influenza A Viruses
Authors: Marcus Philip I. , Rojek Jillian M. , Sekellick Margaret J.
Published: February 2005

Developmentally aged chicken embryo cells which hyperproduce interferon (IFN) when induced were used to quantify IFN production and its suppression by eight strains of type A influenza viruses (AIV). Over 90% of the IFN-inducing or IFN induction-suppressing activity of AIV populations resided in noninfectious particles. The IFN-inducer moiety of AIV appears to preexist in, or be generated by, virions termed IFN-inducing particles (IFP) and was detectable under conditions in which a single molecule of double-stranded RNA introduced into a cell via endocytosis induced IFN, whereas single-stranded RNA did not. Some AIV strains suppressed IFN production, an activity that resided in a noninfectious virion termed an IFN induction-suppressing particle (ISP). The ISP phenotype was dominant over the IFP phenotype. Strains of AIV varied 100-fold in their capacity to induce IFN. AIV genetically compromised in NS1 expression induced about 20 times more IFN than NS1-competent parental strains. UV irradiation further enhanced the IFN-inducing capacity of AIV up to 100-fold, converting ISP into IFP and IFP into more efficient IFP. AIV is known to prevent IFN induction and/or production by expressing NS1 from a small UV target (gene NS). Evidence is presented for an additional downregulator of IFN production, identified as a large UV target postulated to consist of AIV polymerase genes PB1 + PB2 + PA, through the ensuing action of their cap-snatching endonuclease on pre-IFN-mRNA. The products of both the small and large UV targets act in concert to regulate IFN induction and/or production. Knowledge of the IFP/ISP phenotype may be useful in the development of attenuated AIV strains that maximally induce cytokines favorable to the immune response.
Synthetic Double-Stranded RNA Poly(I:C) Combined with Mucosal Vaccine Protects against Influenza Virus Infection
Authors: Ichinohe Takeshi , Watanabe Izumi , Ito Satoshi , Fujii Hideki , Moriyama Masami , Tamura Shin-ichi , Takahashi Hidehiro , Sawa Hirofumi , Chiba Joe , Kurata Takeshi , Sata Tetsutaro , Hasegawa Hideki
Published: February 2005

The mucosal adjuvant effect of synthetic double-stranded RNA polyriboinosinic polyribocytidylic acid [poly(I:C)] against influenza virus was examined under intranasal coadministration with inactivated hemagglutinin (HA) vaccine in BALB/c mice and was shown to have a protective effect against both nasal-restricted infection and lethal lung infection. Intranasal administration of vaccine from PR8 (H1N1) with poly(I:C) induced a high anti-HA immunoglobulin A (IgA) response in the nasal wash and IgG antibody response in the serum, while vaccination without poly(I:C) induced little response. Intracerebral injection confirmed the safety of poly(I:C). In addition, we demonstrated that administration of poly(I:C) with either A/Beijing (H1N1) or A/Yamagata (H1N1) vaccine conferred complete protection against PR8 challenge in this mouse nasal infection model, suggesting that poly(I:C) possessed cross-protection ability against variant viruses. To investigate the mechanism of the protective effect of poly(I:C), mRNA levels of Toll-like receptors and cytokines were examined in the nasal-associated lymphoid tissue after vaccination or virus challenge. Intranasal administration of HA vaccine with poly(I:C) up-regulated expression of Toll-like receptor 3 and alpha/beta interferons as well as Th1- and Th2-related cytokines. We propose that poly(I:C) is a new effective intranasal adjuvant for influenza virus vaccine.
Multiclade Human Immunodeficiency Virus Type 1 Envelope Immunogens Elicit Broad Cellular and Humoral Immunity in Rhesus Monkeys
Authors: Seaman Michael S. , Xu Ling , Beaudry Kristin , Martin Kristi L. , Beddall Margaret H. , Miura Ayako , Sambor Anna , Chakrabarti Bimal K. , Huang Yue , Bailer Robert , Koup Richard A. , Mascola John R. , Nabel Gary J. , Letvin Norman L.
Published: February 2005

The development of a human immunodeficiency virus type 1 (HIV-1) vaccine that elicits potent cellular and humoral immune responses recognizing divergent strains of HIV-1 will be critical for combating the global AIDS epidemic. The present studies were initiated to examine the magnitude and breadth of envelope (Env)-specific T-lymphocyte and antibody responses generated by vaccines containing either a single or multiple genetically distant HIV-1 Env immunogens. Rhesus monkeys were immunized with DNA prime-recombinant adenovirus boost vaccines encoding a Gag-Pol-Nef polyprotein in combination with either a single Env or a mixture of clade-A, clade-B, and clade-C Envs. Monkeys receiving the multiclade Env immunization developed robust immune responses to all vaccine antigens and, importantly, a greater breadth of Env recognition than monkeys immunized with vaccines including a single Env immunogen. All groups of vaccinated monkeys demonstrated equivalent immune protection following challenge with the pathogenic simian-human immunodeficiency virus 89.6P. These data suggest that a multicomponent vaccine encoding Env proteins from multiple clades of HIV-1 can generate broad Env-specific T-lymphocyte and antibody responses without antigenic interference. This study demonstrates that it is possible to generate protective immune responses by vaccination with genetically diverse isolates of HIV-1.
DNA Damage Sensors ATM, ATR, DNA-PKcs, and PARP-1 Are Dispensable for Human Immunodeficiency Virus Type 1 Integration
Authors: Ariumi Yasuo , Turelli Priscilla , Masutani Mitsuko , Trono Didier
Published: February 2005

Integration of a DNA copy of the viral RNA genome is a crucial step in the life cycle of human immunodeficiency virus type 1 (HIV-1) and other retroviruses. While the virally encoded integrase is key to this process, cellular factors yet to be characterized are suspected to participate in its completion. DNA damage sensors such as ATM (ataxia-telangiectasia mutated), ATR (ATM- and Rad3-related), DNA-PK (DNA-dependent protein kinase), and PARP-1 [poly(ADP-ribose) polymerase 1] play central roles in responses to various forms of DNA injury and as such could facilitate HIV integration. To test this hypothesis, we examined the susceptibility to infection with wild-type HIV-1 and to transduction with a vesicular stomatitis virus G protein (VSV-G)-pseudotyped HIV-1-derived lentiviral vector of human cells stably expressing small interfering RNAs against ATM, ATR, and PARP-1. We found that integration normally occurred in these knockdown cells. Similarly, the VSV-G-pseudotyped HIV-1-based vector could effectively transduce ATM and PARP-1 knockout mouse cells as well as human cells deficient for DNA-PK. Finally, treatment of target cells with the ATM and ATR inhibitors caffeine and wortmannin was without effect in these infectivity assays. We conclude that the DNA repair enzymes ATM, ATR, DNA-PKcs, and PARP-1 are not essential for HIV-1 integration.
Evidence for a New Viral Late-Domain Core Sequence, FPIV, Necessary for Budding of a Paramyxovirus
Authors: Schmitt Anthony P. , Leser George P. , Morita Eiji , Sundquist Wesley I. , Lamb Robert A.
Published: February 2005

Enveloped virus budding has been linked to both the ubiquitin-proteasome pathway and the vacuolar protein-sorting pathway of cells. We show here for the paramyxovirus SV5 that proteasome inhibitors and expression of dominant-negative VPS4(E228Q) ATPase blocks budding. The SV5 matrix (M) protein lacks previously defined late domains (e.g., P[T/S]AP, PPxY, YPDL) that recruit cellular factors. We identified a new motif for budding (core sequence FPIV) that can compensate functionally for lack of a PTAP late domain in budding human immunodeficiency virus type 1 virus-like particles (VLPs). Mutagenesis experiments suggest the more general sequence Ø-P-x-V. The proline residue was found to be critically important for function of this sequence, as substitution of this proline in the SV5 M protein resulted in poor budding of SV5 VLPs and failure of recombinant SV5 virus to replicate normally. Adaptation of mutant virus occurred rapidly, resulting in new proline residues elsewhere in the M protein. We hypothesize that these proline residues act to partially restore virus budding by generation of new motifs that act as suboptimal late domains.
Use of a Murine Cytomegalovirus K181-Derived Bacterial Artificial Chromosome as a Vaccine Vector for Immunocontraception
Authors: Redwood Alec J. , Messerle Martin , Harvey Nicole L. , Hardy Christopher M. , Koszinowski Ulrich H. , Lawson Malcolm A. , Shellam Geoffrey R.
Published: February 2005

Cytomegaloviruses (CMVs) are members of theBetaherpesvirinaesubfamily of theHerpesviridae, and their properties of latency, large DNA size, gene redundancy, and ability to be cloned as bacterial artificial chromosomes (BACs) suggest their utility as vaccine vectors. While the K181 strain of murine CMV (MCMV) is widely used to study MCMV biology, a BAC clone of this virus had not previously been produced. We report here the construction of a BAC clone of the K181Perthstrain of MCMV. The in vivo and in vitro growth characteristics of virus derived from the K181 BAC were similar to those of wild-type K181. The utility of the K181 BAC as a method for the rapid production of vaccine vectors was assessed. A vaccine strain of BAC virus, expressing the self-fertility antigen, murine zona pellucida 3, was produced rapidly using standard bacterial genetics techniques and rendered female BALB/c mice infertile with a single intraperitoneal inoculation. In addition, attenuated vaccine strains lacking the open reading framesm07tom12exhibited no reduction in efficacy compared to the full-length vaccine strain. In conclusion, we describe the production of a K181-based BAC virus which behaved essentially as wild-type K181 and allowed the rapid production of effective viral vaccine vectors.
Estradiol Regulates Susceptibility following Primary Exposure to Genital Herpes Simplex Virus Type 2, while Progesterone Induces Inflammation
Authors: Gillgrass Amy E. , Fernandez Sherie A. , Rosenthal Kenneth L. , Kaushic Charu
Published: February 2005

We report here that sex hormones modulate susceptibility to a sexually transmitted viral agent, herpes simplex virus type 2 (HSV-2), in a mouse model. Ovariectomized mice were administered either saline (control), estradiol (E2), progesterone (P4), or a combination of both estradiol and progesterone (E+P) and infected intravaginally with HSV-2. With an inoculation dose of 105PFU, the saline- and P4-treated mice were found to be highly susceptible to genital HSV-2 infection. Both groups had extensive pathology and high viral titers in vaginal secretions, and 100% of mice succumbed by day 4 postinfection. E2-treated mice were protected from HSV-2 infection at the same dose and did not display any vaginal pathology or viral shedding. There was a slow progression of genital pathology in the combination hormone-treated group, along with prolonged viral shedding; 80% of animals succumbed by day 13. With lower inoculation doses of 103and 102PFU, 50 and 100%, respectively, of the combination hormone-treated mice survived. Localization of HSV-2 infection showed extensive infection in the vaginal epithelium of P4- and saline-treated animals within 24 h of inoculation. E2-treated animals were clear of infection, while the E+P-treated group had focal infection at 24 h that had progressed extensively by day 3. Infection was accompanied by persistent inflammation and infiltration of neutrophils in the P4-treated group. An analysis of the genes in the vaginal tissue showed that inflammation in the P4-treated group correlated with local induction of chemokines and chemokine receptors that were absent in the E2-treated mice and in uninfected P4-treated mice. The results show that sex hormones regulate initiation of infection and immune responses to genital HSV-2 infection.
Protection against Genital Herpes Infection in Mice Immunized under Different Hormonal Conditions Correlates with Induction of Vagina-Associated Lymphoid Tissue
Authors: Gillgrass Amy E. , Tang Vera A. , Towarnicki Kate M. , Rosenthal Kenneth L. , Kaushic Charu
Published: February 2005

The present study was undertaken to examine the effect of the hormonal environment on immunization with an attenuated strain of herpes simplex virus type 2 (HSV-2 TK−) and subsequent protection against challenge. Ovariectomized mice were administered saline (S; control), estradiol (E2), progesterone (P4), or a combination of estradiol and progesterone (E+P) and immunized intravaginally (IVAG) with HSV-2 TK−. Three weeks later, the immunized mice were challenged IVAG with wild-type HSV-2. Mice that were immunized following E treatment were not protected, whereas complete protection against the challenge was seen in mice from the S- and P4-treated groups. In the P4-treated group, 15% of mice developed chronic pathology following TK−immunization. Interestingly, about 40% of the E+P-treated mice were also protected. Upon examination of viral shedding in the vaginal secretions, it was clear that protection against challenge was dependent on the ability of the TK−virus to cause productive genital infection under different hormonal conditions. In the protected mice (the S and P groups and part of the E+P group), induced vagina-associated lymphoid tissues composed of CD11c+dendritic cells and CD3+and CD4+T cells were formed transiently in the vaginal lamina propria from day 2 to day 5 postchallenge. These aggregates were absent in the unprotected mice (the E group and part of the E+P group). Significant HSV-2-specific activation of lymphocytes was observed in the local draining lymph nodes of protected mice. This response was absent in the unprotected groups. High titers of gB-specific local immunoglobulin A (IgA) antibodies were present in the vaginal secretions of S- and P4-treated immunized mice following HSV-2 challenge. The S-treated group of mice also had high gB-specific IgG titers. These studies show that sex hormones modify the induction of protective immune responses following IVAG immunization.
Transfer of the Full-Length Dystrophin-Coding Sequence into Muscle Cells by a Dual High-Capacity Hybrid Viral Vector with Site-Specific Integration Ability
Authors: Gonçalves Manuel A. F. V. , van Nierop Gijsbert P. , Tijssen Marloes R. , Lefesvre Pierre , Knaän-Shanzer Shoshan , van der Velde Ietje , van Bekkum Dirk W. , Valerio Dinko , de Vries Antoine A. F.
Published: February 2005

Duchenne muscular dystrophy (DMD) is caused by mutations in the
DMD
gene, making it a potential target for gene therapy. There is, however, a scarcity of vectors that can accommodate the 14-kb
DMD
cDNA and permanently genetically correct muscle tissue in vivo or proliferating myogenic progenitors in vitro for use in autologous transplantation. Here, a dual high-capacity adenovirus-adeno-associated virus (hcAd/AAV) vector with two full-length human dystrophin-coding sequences flanked by AAV integration-enhancing elements is presented. These vectors are generated from input linear monomeric DNA molecules consisting of the Ad origin of replication and packaging signal followed by the recently identified AAV DNA integration efficiency element (p5IEE), the transgene(s) of interest, and the AAV inverted terminal repeat (ITR). After infection of producer cells with a helper Ad vector, the Ad DNA replication machinery, in concert with the AAV ITR-dependent dimerization, leads to the assembly of vector genomes with a tail-to-tail configuration that are efficiently amplified and packaged into Ad capsids. These dual hcAd/AAV hybrid vectors were used to express the dystrophin-coding sequence in rat cardiomyocytes in vitro and to restore dystrophin synthesis in the muscle tissues of
mdx
mice in vivo. Introduction into human cells of chimeric genomes, which contain a structure reminiscent of AAV proviral DNA, resulted in AAV Rep-dependent targeted DNA integration into the
AAVS1
locus on chromosome 19. Dual hcAd/AAV hybrid vectors may thus be particularly useful to develop safe treatment modalities for diseases such as DMD that rely on efficient transfer and stable expression of large genes.
THE EARLY HISTORY OF ATMOSPHERIC OXYGEN: Homage to Robert M. Garrels
Authors: Canfield D.E.
Published: February 2005

▪ Abstract  This paper reviews the Precambrian history of atmospheric oxygen, beginning with a brief discussion of the possible nature and magnitude of life before the evolution of oxygenic photosynthesis. This is followed by a summary of the various lines of evidence constraining oxygen levels through time, resulting in a suggested history of atmospheric oxygen concentrations. Also reviewed are the various processes regulating oxygen concentrations, and several models of Precambrian oxygen evolution are presented. A sparse geologic record, combined with uncertainties as to its interpretation, yields only a fragmentary and imprecise reading of atmospheric oxygen evolution. Nevertheless, oxygen levels have increased through time, but not monotonically, with major and fascinating swings to both lower and higher levels.
MAST CELLS AS “TUNABLE” EFFECTOR AND IMMUNOREGULATORY CELLS: Recent Advances
Authors: Galli Stephen J. , Kalesnikoff Janet , Grimbaldeston Michele A. , Piliponsky Adrian M. , Williams Cara M.M. , Tsai Mindy
Published: February 2005

▪ Abstract  This review focuses on recent progress in our understanding of how mast cells can contribute to the initiation, development, expression, and regulation of acquired immune responses, both those associated with IgE and those that are apparently expressed independently of this class of Ig. We emphasize findings derived from in vivo studies in mice, particularly those employing genetic approaches to influence mast cell numbers and/or to alter or delete components of pathways that can regulate mast cell development, signaling, or function. We advance the hypothesis that mast cells not only can function as proinflammatory effector cells and drivers of tissue remodeling in established acquired immune responses, but also may contribute to the initiation and regulation of such responses. That is, we propose that mast cells can also function as immunoregulatory cells. Finally, we show that the notion that mast cells have primarily two functional configurations, off (or resting) or on (or activated for extensive mediator release), markedly oversimplifies reality. Instead, we propose that mast cells are “tunable,” by both genetic and environmental factors, such that, depending on the circumstances, the cell can be positioned phenotypically to express a wide spectrum of variation in the types, kinetics, and/or magnitude of its secretory functions.
REGULATION OF VITAMIN C TRANSPORT
Authors: Wilson John X.
Published: February 2005

▪ Abstract  Ascorbic acid and dehydroascorbic acid (DHAA, oxidized vitamin C) are dietary sources of vitamin C in humans. Both nutrients are absorbed from the lumen of the intestine and renal tubules by, respectively, enterocytes and renal epithelial cells. Subsequently vitamin C circulates in the blood and enters all of the other cells of the body. Concerning flux across the plasma membrane, simple diffusion of ascorbic acid plays only a small or negligible role. More important are specific mechanisms of transport and metabolism that concentrate vitamin C intracellularly to enhance its function as an enzyme cofactor and antioxidant. The known transport mechanisms are facilitated diffusion of DHAA through glucose-sensitive and -insensitive transporters, facilitated diffusion of ascorbate through channels, exocytosis of ascorbate in secretory vesicles, and secondary active transport of ascorbate through the sodium-dependent vitamin C transporters SVCT1 and SVCT2 proteins that are encoded by the genes Slc23a1 and Slc23a2, respectively. Evidence is reviewed indicating that these transport pathways are regulated under physiological conditions and altered by aging and disease.
Trypsin secretion and turnover in patients with acute pancreatitis
Authors: O'Keefe Stephen J. D. , Lee Ronzo B. , Li Jing , Stevens Stacie , Abou-Assi Souheil , Zhou Wen
Published: February 2005

Studies in humans have shown that pancreatic enzyme secretion is reduced during acute pancreatitis. It is not known, however, whether the reduction is due to impaired synthesis or disruption of the secretory pathway. The rate of secretion and turnover of trypsin was measured in 12 patients with acute pancreatitis of variable etiology and severity (median Ranson's score 2.5, range 0–5, 4 with severe necrotizing disease) and eight healthy volunteers by 4-h primed/continuous intravenous infusions of 1-13C-labeled l-leucine, and collection of pancreatic secretions by duodenal perfusion and sampling. Trypsin secretion was reduced from 476 ± 73 to 153 ± 60 U/h (means ± SE, P = 0.005) in acute pancreatitis, with the greatest reductions being observed in patients with necrotizing disease (32 ± 7 U/h, P = 0.003). The time for newly labeled trypsin to first appear in digestive juice was not, however, delayed in pancreatitis patients (87.2 ± 11.1 vs. 94.7 ± 4.9 min); on the contrary, there was an early appearance of newly labeled trypsin at 30 min in patients with severe necrotizing pancreatitis ( P < 0.05). Calculated zymogen pool turnover was unchanged, but pool size was decreased ( P = 0.01). Despite low rates of luminal secretion, trypsin continues to be synthesized in patients with acute pancreatitis. Our findings could be explained by post-Golgi leakage of enzymes from acinar cells or by loss of synthetic function in some cells with preservation in others.
A 14-kDa cathepsin L-derived carboxyl IGFBP-2 fragment is sequestered by cultured rat ileal crypt cells
Authors: Gordon Phillip V. , Paxton Jessica B. , Kuemmerle John F. , Fox Nena S.
Published: February 2005

IGF-II gut drives mucosal growth during gestation. IGF binding protein-2 (IGFBP-2) has a high affinity for IGF-II and tightly regulates IGF-II availability during fetal and early neonatal growth. We have previously demonstrated that glucocorticoids alter IGF homeostasis in the neonatal ileum, but the mechanism(s) by which this occurs is poorly understood. We hypothesized that dexamethasone alters proteolytic regulation of IGFBP-2 in ileal crypt cells. To test this, ileal crypt [ileal epithelial (IEC)-18] cells were cultured in serum-free media and used to study IGFBP-2 catabolism by immunochemistry, gene array analysis, and pharmacological perturbation with dexamethasone. In addition, isolated human IGFBP-2, IGF-II, and cathepsins B, D, and L were utilized for in vitro protease assays. We found IGFBP-2 to be highly abundant in IEC-18 culture, and sequestration of carboxyl IGFBP-2 antigen was seen within vesicular bodies of some cells. Dexamethasone significantly decreased the number of these cells and decreased IGFBP-2 in the media. On gene array analysis, cathepsin L's message abundance was significantly increased by dexamethasone, and, by in vitro assay, cathepsin L created a 14-kDa carboxyl fragment that corresponded to the sole antigen detected in IEC-18 cell lysates as well as a 16.5-kDa fragment found in the media. The sequestered fragment size was formed preferentially when IGF-II was present, whereas the larger fragment size was formed preferentially when IGF-II was absent. Cathepsins B and D did not produce these fragments in vitro and were not detected in IEC-18 media. We conclude that dexamethasone alters IGFBP-2 catabolism through its effects on cathepsin L.
Adaptive regulation of intestinal thiamin uptake: molecular mechanism using wild-type and transgenic mice carrying hTHTR-1 and -2 promoters
Authors: Reidling Jack C. , Said Hamid M.
Published: February 2005

Thiamin participates in metabolic pathways contributing to normal cellular functions, growth, and development. The molecular mechanism of the human intestinal thiamin absorption process involves the thiamin transporters-1 (hTHTR-1) and -2 (hTHTR-2), products of the SLC19A2 and SLC19A3 genes. Little is known about adaptive regulation of the intestinal thiamin uptake process or the molecular mechanism(s) involved during thiamin deficiency. In these studies, we addressed these issues using wild-type mice and transgenic animals carrying the promoters of the hTHTR-1 and -2. We show that, in thiamin deficiency, a significant and specific upregulation in intestinal carrier-mediated thiamin uptake occurs and that this increase is associated with an induction in protein and mRNA levels of mTHTR-2 but not mTHTR-1; in addition, an increase in the activity of the SLC19A3, but not the SLC19A2, promoter was observed in the intestine of transgenic mice. Similar findings were detected in the kidney; however, expression of both thiamin transporters and activity of both human promoters were upregulated in this organ in thiamin deficiency. We also examined the effect of thiamin deficiency on the level of expression of mTHTR-1 and mTHTR-2 messages and activity of the human promoters in the heart and brain of transgenic mice and found an increase in mTHTR-1 mRNA and a rise in activity of the SLC19A2 promoter in thiamin-deficient mice. These results show that the intestinal and renal thiamin uptake processes are adaptively upregulated during dietary thiamin deficiency, that expression of mTHTR-1 and mTHTR-2 is regulated in a tissue-specific manner, and that this upregulation is mediated via transcriptional regulatory mechanism(s).
Effects of supplemental oxygen administration on coronary blood flow in patients undergoing cardiac catheterization
Authors: McNulty Patrick H. , King Nicholas , Scott Sofia , Hartman Gretchen , McCann Jennifer , Kozak Mark , Chambers Charles E. , Demers Laurence M. , Sinoway Lawrence I.
Published: February 2005

Patients with heart disease are frequently treated with supplemental oxygen. Although oxygen can exhibit vasoactive properties in many vascular beds, its effects on the coronary circulation have not been fully characterized. To examine whether supplemental oxygen administration affects coronary blood flow (CBF) in a clinical setting, we measured in 18 patients with stable coronary heart disease the effects of breathing 100% oxygen by face mask for 15 min on CBF (via coronary Doppler flow wire), conduit coronary diameter, CBF response to intracoronary infusion of the endothelium-dependent dilator ACh and to the endothelium-independent dilator adenosine, as well as arterial and coronary venous concentrations of the nitric oxide (NO) metabolites nitrotyrosine, NO2−, and NO3−. Relative to breathing room air, breathing of 100% oxygen increased coronary resistance by ∼40%, decreased CBF by ∼30%, increased the appearance of nitrotyrosine in coronary venous plasma, and significantly blunted the CBF response to ACh. Oxygen breathing elicited these changes without affecting the diameter of large-conduit coronary arteries, coronary venous concentrations of NO2−and NO3−, or the coronary vasodilator response to adenosine. Administering supplemental oxygen to patients undergoing cardiac catheterization substantially increases coronary vascular resistance by a mechanism that may involve oxidative quenching of NO within the coronary microcirculation.
Control of blood vessel structure: insights from theoretical models
Authors: Pries A. R. , Secomb T. W.
Published: February 2005

Blood vessels are capable of continuous structural adaptation in response to changing local conditions and functional requirements. Theoretical modeling approaches have stimulated the development of new concepts in this area and have allowed investigation of the complex relations between adaptive responses to multiple stimuli and resulting functional properties of vascular networks. Early analyses based on a minimum-work principle predicted uniform wall shear stress in all segments of vascular networks and led to the concept that vessel diameter is controlled by a feedback system based on responses to wall shear stress. Vascular reactions to changes in transmural pressure suggested feedback control of circumferential wall stress. However, theoretical simulations of network adaptation showed that these two mechanisms cannot, by themselves, lead to stable and realistic network structures. Models combining reactions to fluid shear stress, circumferential stress, and metabolic status of tissue, with propagation of stimuli upstream and downstream along vascular segments, are needed to explain stable and functionally adequate adaptation of vascular structure. Such models provide a basis for predicting the response of vascular segments exposed to altered conditions, as, for example, in vascular grafts.
Marriage of resistance and conduit arteries breeds critical limb ischemia
Authors: Coats Paul , Wadsworth Roger
Published: February 2005

Atherosclerosis in a major leg artery leads to impaired blood supply, which normally progresses to critical limb ischemia. Atherosclerosis produces substantial alterations of structure and endothelial function in the large conduit arteries. Pressure unloading and ischemia in the distal vasculature bring about alterations in microvascular function. Resistance arteries undergo significant wall thinning and changes in their contractile regulation. Optimization of large artery dimensions by the small arteries through flow-mediated vasodilation is impaired. Angiogenesis is stimulated, which can result in the formation of major collateral feeder vessels in addition to small nutritive blood vessels. However, angiogenesis can also contribute to instability of atherosclerotic plaques, which ultimately leads to further deterioration in blood supply. Surgical bypass grafting to restore blood supply to the distal leg generates a sudden increase of pressure in the weakened resistance vasculature, leading to uncontrolled changes in capillary hydrostatic pressure, extravasation of fluid, and tissue edema. This review aims to highlight the importance of the resistance vasculature in critical limb ischemia and the interdependence of pathophysiological changes in the large conduit and small resistance arteries. The major unresolved question is why the physiological mechanisms that regulate vascular structure and function ultimately break down, leading to circulatory failure within the distal limb.
Cold weather exercise and airway cytokine expression
Authors: Davis Michael S. , Malayer Jerry R. , Vandeventer Lori , Royer Christopher M. , McKenzie Erica C. , Williamson Katherine K.
Published: February 2005

Athletes who perform repeated exercise while breathing cold air have a high prevalence of asthmalike chronic airway disease, but the mechanism linking such activity to airway inflammation is unknown. We used a novel animal model (exercising horses) to test the hypothesis that exercise-induced chronic airway disease is caused by exposure of intrapulmonary airways to unconditioned air, resulting in the upregulation of cytokine expression. Bronchoalveolar lavage fluid (BALF) was obtained from eight horses 5 h after submaximal exercise while they breathed room temperature or subfreezing air in a random crossover design. BALF total and differential nucleated cell counts were determined, and relative cytokine mRNA expression in BALF nucleated cells was quantified by real-time RT-PCR using primer and probe sequences specific for equine targets. There were no significant changes in total or differential cell concentrations between BALF recovered after warm and cold air exercise, although there was a strong trend toward increased concentrations of airway epithelial cells after cold air exercise ( P = 0.0625). TH2 cytokines IL-4, IL-5, and IL-10 were preferentially upregulated after cold air exercise 12-, 9-, and 10-fold, respectively, compared with warm air exercise. Other cytokines (IL-2 and IL-6) were upregulated to a lesser extent (6- and 3-fold, respectively) or not at all (IL-1, IL-8, IFN-γ, and TNF-α). These results suggest that cold weather exercise can lead to asthmalike airway disease through the local induction of cytokines typical of the TH2 phenotype.
Aging does not affect voluntary activation of the ankle dorsiflexors during isometric, concentric, and eccentric contractions
Authors: Klass Malgorzata , Baudry Stéphane , Duchateau Jacques
Published: February 2005

This study examines the age-related deficit in force of the ankle dorsiflexors during isometric (Iso), concentric (Con), and eccentric (Ecc) contractions. More specifically, the contribution of neural and muscular mechanisms to the loss of voluntary force was investigated in men and women. The torque produced by the dorsiflexors and the surface electromyogram (EMG) from the tibialis anterior and the soleus were recorded during maximal Iso contractions and during Con and Ecc contractions performed at constant angular velocities (5–100°/s). Central activation was tested by the superimposed electrical stimulation method during maximal voluntary contraction and by computing the ratio between voluntary average EMG and compound muscle action potential (M wave) induced by electrical stimulation (average EMG/M wave). Contractile properties of the dorsiflexor muscles were investigated by recording the mechanical responses to single and paired maximal stimuli. The results showed that the age-related deficit in force (collapsed across genders and velocities) was greater for Iso (20.5%; P < 0.05) and Con (38.6%; P < 0.001) contractions compared with Ecc contractions (6.5%; P > 0.05). When the torque produced during Con and Ecc contractions was expressed relative to the maximal Iso torque, it was significantly reduced in Con contractions and increased in Ecc contractions with aging, with the latter effect being more pronounced for women. In both genders, voluntary activation was not significantly impaired in elderly adults and did not differ from young subjects. Similarly, coactivation was not changed with aging. In contrast, the mechanical responses to single and paired stimuli showed a general slowing of the muscle contractile kinetics with a slightly greater effect in women. It is concluded that the force deficit during Con and Iso contractions of the ankle dorsiflexors in advanced age cannot be explained by impaired voluntary activation or changes in coactivation. Instead, this age-related adaptation and the mechanisms that preserve force in Ecc contractions appeared to be located at the muscular level.
Basic Fibroblast Growth Factor Exhibits Dual and Rapid Regulation of Cyclin D1 and p27KIP1 to Stimulate Proliferation of Rat Cerebral Cortical Precursors
Authors: Li Baogang , DiCicco-Bloom Emanuel
Published: February 2005

While extracellular signals play a major role in brain neurogenesis, little is known about the cell cycle machinery underlying mitogen stimulation of precursor proliferation. Current models suggest that the D cyclins function as primary sensors of extracellular mitogens. Here we define the mechanisms by which basic fibroblast growth factor (bFGF) stimulates cortical precursors, with particular attention to the responses of cell cycle promitogenic and antimitogenic regulators. bFGF produced a 4-fold increase in DNA synthesis and a 3-fold rise in bromodeoxyuridine labeling, suggesting that the factor promotes the G1/S transition. There was also a 3-fold increase in cyclin-dependent kinase 2 (CDK2) kinase activity, which is critical for S phase entry. CDK2 activation was apparently cyclin E dependent, since only its protein and mRNA levels were elevated at 24 h, whereas CDK2, p27KIP1 and p57KIP2 levels were unaltered. Late G1 phase CDK2/cyclin E activity depends on early G1 D cyclin function. Indeed, cyclin D1, but not cyclin D3, was upregulated selectively at 8 h after bFGF treatment, a time when cyclin E was unchanged. The sequential activation of cyclin D1 and cyclin E supports the idea that cyclin E gene transcription is regulated by cyclin-D/CDK4/6-mediated pRb phosphorylation and subsequent E2F transcription factor release. However, in addition to increased D1 cyclin, we unexpectedly detected a 75% reduction in p27KIP1 protein at 8 h, suggesting that both pro- and antimitogenic regulators are targets of extracellular mitogens during brain development.
Perinatal Hypoxia/Ischemia Damages and Depletes Progenitors from the Mouse Subventricular Zone
Authors: Brazel Christine Y. , Rosti III Robert T. , Boyce Sheri , Rothstein Raymond P. , Levison Steven W.
Published: February 2005

Hypoxia-ischemia (H/I) as a result of asphyxia at term remains a major cause of neurologic disability. Our previous studies in the P7 rat model of perinatal H/I have shown that progenitors within the subventricular zone (SVZ) are vulnerable to this insult. Since many investigators are using transgenic and knockout mice to determine the importance of specific molecules in the evolution of damage after a stroke, there is a need to perform comparative studies on the relative vulnerability of the mouse SVZ. Here we assess damage to the SVZ of 5-, 7- and 10-day-old C57BL/6 mice after unilateral common carotid artery cauterization followed by 70 min of H/I (10% O2). Whereas 5- and 7-day-old mice sustained little SVZ damage as assessed by hematoxylin and eosin staining, there was a 16% reduction of cellularity in 10-day-old animals by 18 h of recovery. Additionally, swollen cells were observed in the medial region of the SVZ of 10-day-old mice. However, few caspase-3+ and TUNEL+ cells were observed in this region, which contains the putative neural stem cells. Rather, the majority of the dying cells were situated in the mediolateral and lateral tail of the SVZ. At 18 h of recovery, there was a 2-fold increase in the frequency of TUNEL+ cells in the ipsilateral SVZ as well as a 3-fold increase in the frequency of active-caspase-3+ cells. We conclude that progenitors within the neonatal mouse SVZ are vulnerable to hypoxic/ischemic insult. The demise of these early progenitors likely leads to depletion of neuronal and late oligodendrocyte progenitors, contributing to cerebral dysgenesis.
Comparison between Fetal Spinal-Cord- and Forebrain-Derived Neural Stem/Progenitor Cells as a Source of Transplantation for Spinal Cord Injury
Authors: Watanabe Kota , Nakamura Masaya , Iwanami Akio , Fujita Yuko , Kanemura Yonehiro , Toyama Yoshiaki , Okano Hideyuki
Published: February 2005

Recently, we have shown that the transplantation of spinal-cord-derived neural stem/progenitor cells (NSPCs) can contribute to the repair of injured spinal cords in adult rats, which may correspond to a behavioral recovery. To apply these results to clinical practice, a system for supplying human NSPCs on a large scale must be established. However, human spinal-cord-derived NSPCs are known to have a low proliferation rate, compared with forebrain-derived NSPCs. This low proliferative potency limits the feasibility of large-scale spinal cord-derived NSPC use. Thus, forebrain-derived NSPCs should be examined as an alternative to spinal-cord-derived NSPCs for the treatment of spinal cord injuries. In this study, we compared spinal-cord- and forebrain-derived NSPCs transplanted into injured spinal cords with respect to their fates in vivo as well as the animals’ functional recovery. Both spinal-cord- and forebrain-derived NSPCs promoted functional recovery in rats with spinal cord injuries. While both spinal-cord- and forebrain-derived NSPCs survived, migrated and differentiated into neurons, astrocytes and oligodendrocytes in response to the microenvironment within the injured spinal cord after transplantation, forebrain-derived NSPCs differentiated into more neurons and fewer oligodendrocytes, compared to spinal-cord-derived NSPCs. Neurons that had differentiated from the transplanted forebrain-derived NSPCs were shown to be positive for neurotransmitters like GABA, glutamate and glycine, although authentic glycinergic neurons are not normally present within the forebrain. Thus, at least a subpopulation of the transplanted forebrain-derived NSPCs differentiated into spinal-cord-type neurons. In conclusion, forebrain-derived NSPCs could be used as an alternative to spinal-cord-derived NSPCs as a potential therapeutic agent for spinal cord injuries.
Two Breeding Females within Free-Living Groups May Not Always Indicate Polygyny: Alternative Subordinate Female Strategies in Common Marmosets (Callithrix jacchus)
Authors: Arruda M.F. , Araújo A. , Sousa M.B.C. , Albuquerque F.S. , Albuquerque A.C.S.R. , Yamamoto M.E.
Published: February 2005

The mating system of callitrichids has been reported to be monogamous, polygynous and polyandrous. In Callithrix jacchus, groups with 2 breeding females and groups with 1 breeding female have been reported. Our purpose was to evaluate the occurrence of occasional reproduction by subordinate females in free-ranging C. jacchus groups characterized as monogamous. Four groups were monitored at a field site of IBAMA-Brazil for between 20 and 72 months. We recorded the birth of 7 sets of twins to subordinate females that had never reproduced before. Sexual activities were recorded opportunistically: dominant females copulated with only the resident male, while subordinates copulated with extra-group males. We suggest these were essentially monogamous groups that occasionally had 2 reproductive females. Between-group copulations seem to be an alternative strategy used by the subordinates. Despite the costs, there would probably be benefits as a result of scanning for vacancies for reproductive positionsin neighbouring groups and the establishment of ties with extra-group males that might become a reproductive partner in the future.
Prenatal Testing Guidelines:
Authors: Kuppermann Miriam , Norton Mary E.
Published: February 2005

Numerous advances over the past 15 years have led to a much wider array of prenatal testing options for pregnant women who are interested in obtaining information regarding the chromosomal status of their fetus. However, despite recent data calling into question the assumptions underlying current testing guidelines, including those inherent in the risk-based threshold for offering invasive testing, chorionic villus sampling and amniocentesis are still typically offered only to women whose likelihood of carrying a fetus affected by a chromosomal disorder such as Down syndrome is at least as high as that of the average 35-year-old. In this paper, we summarize the evidence suggesting that this aspect of prenatal testing guidelines should be revisited, and that women should be allowed to make informed decisions regarding the use of invasive testing that are reflective of their own values and preferences.
Cost-Effectiveness Analysis of Prenatal Diagnosis: Methodological Issues and Concerns
Authors: Caughey Aaron B.
Published: February 2005

With increasing concerns regarding rapidly expanding health care costs, cost-effectiveness analysis (CEA) provides a methodology to assess whether marginal gains from new technology are worth the increased costs. In the arena of prenatal diagnosis, particular methodological and ethical concerns include whether the effects of such testing on individuals other than the patient are included, how termination of pregnancy is included in the models, redundancy of screening and diagnostic methods, and how screening may reassure or cause anxiety in patients depending on their results. The existing literature has demonstrated cost-effectiveness of screening and diagnosis of neural tube defects, Down syndrome, and cystic fibrosis in the general population. Screening for genetic disorders which have a higher prevalence among particular groups has also been shown to be cost effective, including diseases such as hemoglobinopathies and Tay-Sachs disease. Understanding the methodology and salient issues of CEA is critical for researchers, editors and clinicians to accurately interpret results of the growing body of cost-effectiveness studies in prenatal diagnosis.