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Dieckmann ME, Ahmed H, Doria D, Sarri G, Walder R, Folini D, Bret A, Ynnerman A, Borghesi M. Thin-shell instability in collisionless plasma. Phys Rev E Stat Nonlin Soft Matter Phys 2015; 92:031101. [PMID: 26465418 DOI: 10.1103/physreve.92.031101] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2015] [Indexed: 06/05/2023]
Abstract
Thin-shell instability is one process which can generate entangled structures in astrophysical plasma on collisional (fluid) scales. It is driven by a spatially varying imbalance between the ram pressure of the inflowing upstream plasma and the downstream's thermal pressure at a nonplanar shock. Here we show by means of a particle-in-cell simulation that an analog process can destabilize a thin shell formed by two interpenetrating, unmagnetized, and collisionless plasma clouds. The amplitude of the shell's spatial modulation grows and saturates after about ten inverse proton plasma frequencies, when the shell consists of connected piecewise linear patches.
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Affiliation(s)
- M E Dieckmann
- Department of Science and Technology, Linköping University, SE-60174 Norrköping, Sweden
| | - H Ahmed
- Centre for Plasma Physics (CPP), Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - D Doria
- Centre for Plasma Physics (CPP), Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - G Sarri
- Centre for Plasma Physics (CPP), Queen's University Belfast, Belfast BT7 1NN, United Kingdom
| | - R Walder
- École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, Lyon, France
| | - D Folini
- École Normale Supérieure, Lyon, CRAL, UMR CNRS 5574, Université de Lyon, Lyon, France
| | - A Bret
- ETSI Industriales, Universidad Castilla La Mancha, E-13 071 Ciudad Real, Spain
| | - A Ynnerman
- Department of Science and Technology, Linköping University, SE-60174 Norrköping, Sweden
| | - M Borghesi
- Centre for Plasma Physics (CPP), Queen's University Belfast, Belfast BT7 1NN, United Kingdom
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Walder R, Mouriquand P, Ruffion A, Rudigoz RC. [Ileocystoplasty, pregnancy and delivery]. ACTA ACUST UNITED AC 2015; 45:380-7. [PMID: 25980901 DOI: 10.1016/j.jgyn.2015.04.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Revised: 02/06/2015] [Accepted: 04/15/2015] [Indexed: 11/25/2022]
Abstract
INTRODUCTION Bladder augmentation is commonly used in neurological and other congenital anomalies of the lower urinary tract. In pregnant women, this reconstructive surgery may affect pregnancy and delivery. The obstetrical consequences of these urological procedures are scarcely reported in literature. MATERIAL AND METHOD Eight pregnancies in 6 pregnant women with ileocystoplasty were followed in our institution between 1998 and 2014. RESULTS Urinary tract infections were the most frequent undesirable record event (5 patients, 7 pregnancies). Obstetrical complications were not more frequent compared to common pregnancies. Delivery was programmed at 37WA. Cesarean section was favoured in this group although natural delivery is possible. CONCLUSION Urological complications were the major problem in this series. The type of delivery depends on the past surgical history and the obstetrical prognosis.
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Affiliation(s)
- R Walder
- Pôle de gynécologie-obstétrique, hôpital de la Croix-Rousse, 103, boulevard de la Croix-Rousse, 69004 Lyon, France.
| | - P Mouriquand
- Service de chirurgie urologique pédiatrique, hôpital Femme-Mère-Enfant, 59, boulevard Pinel, 69500 Bron, France.
| | - A Ruffion
- Service d'urologie, hôpital Lyon-Sud, 165, chemin du Grand-Revoyet, 69495 Pierre-Bénite, France.
| | - R-C Rudigoz
- Pôle de gynécologie-obstétrique, hôpital de la Croix-Rousse, 103, boulevard de la Croix-Rousse, 69004 Lyon, France.
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Moncayo AC, Medina GM, Kalvatchev Z, Brault AC, Barrera R, Boshell J, Ferro C, Freier JE, Navarro JC, Salas R, De Siger J, Vasquez C, Walder R, Weaver SC. Genetic diversity and relationships among Venezuelan equine encephalitis virus field isolates from Colombia and Venezuela. Am J Trop Med Hyg 2001; 65:738-46. [PMID: 11791968 DOI: 10.4269/ajtmh.2001.65.738] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
During field studies of enzootic Venezuelan equine encephalitis (VEE) viruses associated with epizootic emergence, a large number of virus isolates were made in sylvatic foci of Venezuela and Colombia. To rapidly characterize these isolates, antigenic subtypes were determined by means of immunofluorescence and by single-strand conformational polymorphism (SSCP) analysis by use of an 856-bp fragment from the P62 gene, which we used to distinguish genetic variants. Representative isolates were sequenced to assess the sensitivity of SSCP to detect genetic differences. The SSCP analysis distinguished isolates differing by as little as 1 nucleotide; overall, differences of > or = 1 nucleotide were recognized 89% of the time, and the sensitivity to distinguish strains that differed by only 1 or 4 nucleotides was 17 and 57%, respectively. Phylogenetic analyses of representative sequences showed that all recent isolates from the Catatumbo region of western Venezuela and the middle Magdalena Valley of Colombia were closely related to epizootic subtype IAB and IC strains; strains from Yaracuy and Miranda States were more distantly related. Cocirculation of the same virus genotype in both Colombian and Venezuelan foci indicated that these viruses are readily transported between enzootic regions separated by > 300 km. The SSCP analysis appears to be a simple, fast, and relatively efficient method of screening VEE virus isolates to identify meaningful genetic variants.
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Affiliation(s)
- A C Moncayo
- Center for Tropical Disease and Department of Pathology, University of Texas Medical Branch, Galveston 77555-0609, USA
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Kalvatchev Z, Walder R, Garzaro D, Barrios M. Detection of genetic diversity among bovine immunodeficiency virus population by single-strand conformation polymorphism analysis. Viral Immunol 2001; 13:373-81. [PMID: 11016600 DOI: 10.1089/08828240050144680] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Serial virus specimens rescued from rabbits, experimentally infected with bovine immunodeficiency (BIV) strain R29, were monitored for changes in quasispecies population, using the single-strand conformation polymorphism (SSCP) analysis. The generation of characteristic SSCP patterns enables the rapid differentiation of BIV variants derived from the conserved part on the env region of the BIV genome, reducing the need for expensive and time-consuming direct sequencing analyses. Our results showed genetic polymorphism among a number of sampled BIV population in experimentally infected rabbits. At least three SSCP patterns (BIV quasispecies) were detected. The SSCP analysis allows for an easy, sensitive, and rapid screening of genetic variants of the virus and the assessment of variation at a number of tissue target sites. These variations may relate to cell-type targets and/or disease progression, and could be significant to our understanding of lentiviral pathogenesis.
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Affiliation(s)
- Z Kalvatchev
- Laboratorio de Virus Animales, Centro de Microbiología y Biologia Celular, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
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Walder R, Kalvatchev L, Pérez F, Garzaro D, Barrios M. Bovine immunodeficiency virus in experimentally infected rabbit: tropism for lymphoid and nonlymphoid tissues. Comp Immunol Microbiol Infect Dis 2001; 24:1-20. [PMID: 11131038 DOI: 10.1016/s0147-9571(00)00010-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The bovine immunodeficiency virus (BIV)/New Zealand (Oryctolagus cuniculus) rabbit model was used to study events that underlie the early and chronic stages of viral replication, routes and time course of viral dissemination and the distribution of the virus in the lymphoid. nonlymphoid and mucosa associated tissues. The results indicated that BIV, a lentivirus with genetic relatedness to the HIV, induced changes of clinical (anorexia, weight loss, muscular wasting, diarrhea, hypoalgesia, torticollis), immunological (recurrent T- and B-cell dysfunctions) and histopathological (lymphadenopathy, splenomegaly) nature that closely parallels those described for cat (Fly), monkey (SIV) and human (HIV) lentiviral diseases. These findings showing that BIV induces both splenomegaly and lymphadenopathy syndromes with associated fatal immune dysfunctions and the ability of the virus to replicate productively at the mucosal surfaces in rabbits, emphasize the importance of the BIV/rabbit system as a good small-animal model for the study of retrovirus-induced AIDS and offers the opportunity to evaluate prophylactic and therapeutic anti-retroviral agents of relevance to HIV-1 as well as the opportunity to study mechanisms of drug resistance phenomena.
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Affiliation(s)
- R Walder
- Laboratorio Virus Animales, Centro de Microbiología v Biologia Celular, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
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Kalvatchev Z, Walder R, Perez F, Garzaro D, Barrios M. Infection of rabbits with R29 strain of bovine immunodeficiency virus: virulence, immunosuppression, and progressive mesenteric lymphadenopathy. Viral Immunol 1999; 11:159-66. [PMID: 9918407 DOI: 10.1089/vim.1998.11.159] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To assess the value of bovine immunodeficiency virus (BIV) infection as a model for human immunodeficiency virus (HIV) infection in man, we studied the impairment of certain immunologic functions in New Zealand white rabbits experimentally infected with an uncloned virulent isolate of the virus, BIV R29. Serum samples were tested by Western blot for the presence and persistence of antibody production. The T- and B-lymphocyte function was studied by evaluation of the blastogenic responsiveness to concanavalin A (Con A) and to dextran sulfate (DxS). All infected rabbits seroconverted to BIV antigens within 2 to 4 weeks postinfection (p.i.) The BIV was isolated from the peripheral blood lymphocytes (PBLs) of 13 of 17 rabbits (77%) early in the infection and also from 5 of 17 hyperplastic mesenteric lymph nodes (29%) and 10 of 17 spleens (59%) during the chronic stage of infection. Seven of 17 BIV-infected rabbits (41%) developed marked immunodepression 2 to 5 months p.i., and later, 5 exhibited a rapidly progressive disease with anorexia, weight loss, neurologic impairment, splenomegaly, and mesenteric lymphadenopathy. These data underline the value of the BIV model for studying HIV pathogenesis in vivo and the development of interventional strategies for AIDS.
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Affiliation(s)
- Z Kalvatchev
- Laboratorio Virus Animales, Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela
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Walder R, Kalvatchev Z, Apitz-Castro R. Selective in vitro protection of SIVagm-induced cytolysis by ajoene, [(E)-(Z)-4,5,9-trithiadodeca-1,6,11-triene-9 oxide]. Biomed Pharmacother 1998; 52:229-35. [PMID: 9755820 DOI: 10.1016/s0753-3322(98)80021-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
We studied the effect of synthetic ajoene on simian immunodeficiency virus (SIVagm)-mediated cell fusion and subsequent virus-induced cytolysis. Our data indicate that this compound is a strong antifusion agent with a 50% syncytium inhibitory concentration (SIC50%) value of about 2.9 microM. We suggest that ajoene interacts with the cell-specific integrin molecules and sterically hinders the association between fusion (or other co-receptors) and the CD4-gp120 complex at the cell surface of SIV-infected cells. Although ajoene was maximally effective in suppressing syncytium formation during the early period (ie, up to 6 h) of the fusion process, when the compound was recurrently added to the co-cultures, the inhibitory effect was regained and further cell death was markedly delayed. This indicates that ajoene was also effective after the initial cell-to-cell contact stage. These data suggest that ajoene may be a promising approach for the treatment of SIV/human immunodeficiency virus (HIV) infections.
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Affiliation(s)
- R Walder
- Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científica, Caracas, Venezuela
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Garrett MR, Dene H, Walder R, Zhang QY, Cicila GT, Assadnia S, Deng AY, Rapp JP. Genome scan and congenic strains for blood pressure QTL using Dahl salt-sensitive rats. Genome Res 1998; 8:711-23. [PMID: 9685318 DOI: 10.1101/gr.8.7.711] [Citation(s) in RCA: 123] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
An F2 population (n = 151) derived from Dahl salt-sensitive (S) and Lewis rats was raised on a 8% NaCl diet for 9 weeks and analyzed for blood pressure quantitative trait loci (QTL) by use of a whole genome scan. Chromosomes 5 and 10 yielded lod scores for linkage to blood pressure that were significant; chromosomes 1, 2, 3, 8, 16, 17, and 18 gave lod scores suggestive for linkage. Chromosome 7 gave a significant signal for heart weight with a lesser effect on blood pressure. Congenic strains were constructed by introgressing Lewis low-blood-pressure QTL alleles for chromosomes 1, 5, 10, and 17 into the S genetic background. Congenic strains for chromosomes 1, 5, and 10 had significantly lower blood pressure than S, proving the existence of QTL on these chromosomes, but the chromosome 17 congenic strain failed to trap a contrasting QTL allele. The QTL allele increasing blood pressure originated from S rats for all QTL except those on chromosomes 2 and 7 in which the Lewis allele increased blood pressure. Interactions between each QTL and every other locus in the genome scan yielded significant interactions between chromosomes 10 and 4, and between chromosomes 2 and 3.
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Affiliation(s)
- M R Garrett
- Department of Physiology and Molecular Medicine, Medical College of Ohio, Toledo, Ohio 43614-5804 USA
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Walder R, Kalvatchev Z, Garzaro D, Barrios M, Apitz-Castro R. In vitro suppression of HIV-1 replication by ajoene [(e)-(z)-4,5,9-trithiadodeca-1,6,11-triene-9 oxide]. Biomed Pharmacother 1998; 51:397-403. [PMID: 9452790 DOI: 10.1016/s0753-3322(97)89433-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Studies were performed to establish whether synthetic ajoene exhibited differential inhibitory activity against human immunodeficiency virus (HIV)-1 (IIIB) and to clarify the mechanism of its antiviral effects. Our results demonstrate that ajoene protected acutely infected Molt-4 cells against HIV-1 and blocked further destruction of CD4 T-cells in vitro. Ajoene showed dose-dependent inhibition, with 50% cytotoxic concentration (CTC50%) and 50% effective inhibitory concentration (EIC50%) values of 1.88 microM and about 0.35 microM, respectively, when the test compound was added before or after HIV-1 infection and incubation carried out at 37 degrees C for 4 days. Ajoene proved relatively more active than dextran sulfate in blocking HIV-1 virus-cell attachment. The mode of anti-HIV action of ajoene can be ascribed to the inhibition of early events of viral replication, particularly virus adsorption.
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Affiliation(s)
- R Walder
- Centro de Microbiología y Biología Celular, Instituto Venezolano de Investigaciones Científica, Caracas, Venezuela
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Cicila GT, Dukhanina OI, Kurtz TW, Walder R, Garrett MR, Dene H, Rapp JP. Blood pressure and survival of a chromosome 7 congenic strain bred from Dahl rats. Mamm Genome 1997; 8:896-902. [PMID: 9383281 DOI: 10.1007/s003359900607] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
11 beta-hydroxylase (Cyp11b1) mutations were previously linked to altered steroid biosynthesis and blood pressure in Dahl salt-resistant (R) and Dahl salt-sensitive (S) rats. In the present work, interval mapping identified a putative blood pressure quantitative trait locus (QTL) near Cyp11b1 in an F1(SxR)xS population (LOD = 2.0). Congenic rats (Designated S.R-Cyp11b) were constructed by introgressing the R-rat Cyp11b1 allele into the S strain. S.R-Cyp11b rats had significantly lower blood pressure and heart weight compared with S rats, proving the existence of a blood pressure QTL on Chromosome (Chr) 7 despite the fact that QTL linkage analysis of blood pressure never achieved stringent statistical criteria for significance. To test the effects of the introgressed region on blood pressure and survival, S.R.-Cyp11b and S rats were maintained on a 4% NaCl diet until they died or became moribund. Analysis of variance (ANOVA) indicated significant strain differences in blood pressure and days survived (P < 0.0001 for both) as well as gender differences in days survived (P = 0.0003). Kaplan-Meier survival analysis also found significant strain (P < 0.0001) and gender (P = 0.007) differences in days survived. However, when the effects of blood pressure were removed, significant strain differences in survival essentially disappeared. This suggests that the increased survival of S.R-Cyp11b rats was largely due to their decreased blood pressure and thus strongly corroborates the existence of a blood pressure QTL on Chr 7 near or at Cyp11b1.
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Affiliation(s)
- G T Cicila
- Department of Physiology and Molecular Medicine, Medical College of Ohio, Toledo 43699-0008, USA
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Kalvatchev Z, Walder R, Garzaro D. Different effects of phorbol ester derivates on human immunodeficiency virus 1 replication in lymphocytic and monocytic human cells. Acta Virol 1997; 41:289-92. [PMID: 9607083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The mode of action of the phorbol 12,13-dibutyrate (PDBu) and phorbol 12-myristate 13-acetate (PMA) on the human immunodeficiency virus 1 (HIV-1) replication in human lymphocytes and monocytes was studied. PDBu and PMA appear to have similar effects on the regulation of HIV-1 replication in acutely infected cells. Here we show a significantly increased replication of HIV-1 induced by PDBu and PMA in Molt-4 and Jurkat cells, but a reduced replication in THP-1 and U-937 cells. Moreover, quantitatively different activity of the two derivatives in relation to HIV-1 replication was observed. PDBu proved to be a stronger stimulator or suppressor of HIV-1 replication as compared to PMA. Although the precise mechanism of the activation of HIV-1 replication by phorbol ester derivatives is not clear, it can be assumed that the hydrophilycity of PDBu may cause its stronger effect.
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Affiliation(s)
- Z Kalvatchev
- Laboratorio de Virus Animales, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
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Abstract
Extracts of dried flowers from Calendula officinalis were examined for their ability to inhibit the human immunodeficiency virus type 1 (HIV-1) replication. Both organic and aqueous extracts were relatively nontoxic to human lymphocytic Molt-4 cells, but only the organic one exhibited potent anti-HIV activity in an in vitro MTT/tetrazolium-based assay. In addition, in the presence of the organic extract (500 micrograms/mL), the uninfected Molt-4 cells were completely protected for up to 24 h from fusion and subsequent death, caused by cocultivation with persistently infected U-937/HIV-1 cells. It was also found that the organic extract from Calendula officinalis flowers caused a significant dose- and time-dependent reduction of HIV-1 reverse transcription (RT) activity. An 85% RT inhibition was achieved after a 30 min treatment of partially purified enzyme in a cell-free system. These results suggested that organic extract of flowers from Calendula officinalis possesses anti-HIV properties of therapeutic interest.
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Affiliation(s)
- Z Kalvatchev
- Laboratorio de Virus Animales, IVIC, Caracas, Venezuela
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Walder R, Kalvatchev Z, Tobin GJ, Barrios MN, Garzaro DJ, Gonda MA. Possible role of bovine immunodeficiency virus in bovine paraplegic syndrome: evidence from immunochemical, virological and seroprevalence studies. Res Virol 1995; 146:313-23. [PMID: 8578005 DOI: 10.1016/0923-2516(96)80594-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Bovine paraplegic syndrome (BPS) is a debilitating cattle disease of unknown origin that is characterized by leukocytosis, lymphocytopenia and monocytopenia. The major clinical signs are difficulties in locomotion affecting hind limbs, hypoalgesia in the hind quarters, posterior paralysis and death within 72 to 96 hours after recumbency. To investigate the aetiological basis of BPS, we examined a possible association of the syndrome with infection by bovine immunodeficiency virus (BIV), a lentivirus implicated in immune system dysfunction and central nervous system lesions in cattle. Serum samples (n = 1,278) were collected from both healthy and BPS-prevalent cattle herds in Venezuela, and organ extracts were prepared from euthanized animals (n = 11) suspected of having BPS. Sera were analysed for reactivity to recombinant BIV and bovine leukaemia virus gag precursor proteins by immunoblot procedures. Serum reactivity to BIV ranged from 12 to 66% between groups of BPS prevalent herds. The percentage of samples reactive to BLV antigen was much lower (2 to 17%). Rabbits inoculated with extracts from BPS-afflicted animals exhibited an anamnestic immune response to BIV antigens as well as the presence of BIV gag antigens in their tissues. We present evidence for a possible association between BPS disease and a viral agent related to BIV. The role of BIV, in combination with malnutrition, in BPS is discussed.
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Affiliation(s)
- R Walder
- Laboratorio Virus Animales, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas
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Affiliation(s)
- R Walder
- International Planned Parenthood Federation, Regent's College, Regent's Park, London
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Walder R, Kalvatchev Z, Garzaro D, Barrios M. [Natural products from the tropical rain forest of Venezuela as inhibitors of HIV-1 replication]. Acta Cient Venez 1995; 46:110-4. [PMID: 9279026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
More than 100 plant extracts from the Amazonian rain forest of Venezuela were evaluated for their cytotoxicity and inhibitory activity against the human immunodeficiency virus type-1 (HIV-1). Aqueous extracts from Fomitella supina (S # 0389-4), Phellinus rhabarbarinus (S # 0389-7), Trichaptum perrottetti (S # 0389-8) and Trametes cubensis (S # 0389-13), Polyporaceae exhibited strong anti-HIV-1 activity, without toxicity for Molt-4 lymphocytic cells. Our results demonstrated, that the compound(s) acted by mechanism of direct virion inactivation and by inhibition of syncytium formation in an in vitro culture system. These results support the suggestion that the test extracts specifically act at the level of CD4-gp120 binding. The active components of these extracts is at present unknown, but anti-AIDS agents, such as those found in this study, individually or in combination, may be of therapeutic relevance.
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Affiliation(s)
- R Walder
- Instituto Venezolano de Investigaciones Científicas (I.V.I.C.), Centro de Microbiología y Biología Celular, Caracas, Venezuela
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Kalvatchev Z, Walder R, Barrios M, Garzaro D. Acquired immune dysfunction in rabbits experimentally infected with an infectious molecular clone of the bovine immunodeficiency virus (BIV127). Viral Immunol 1995; 8:159-64. [PMID: 8833269 DOI: 10.1089/vim.1995.8.159] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
To investigate the effect of bovine immunodeficiency virus (BIV) infection on the rabbit immune system, we studied the proliferative responses of peripheral blood lymphocytes (PBLs) of rabbits experimentally inoculated with BIV. All BIV127-inoculated rabbits seroconverted after 6 weeks and remained seropositive over a prolonged period of time. Assays for specific lymphocyte reactivity to concanavalin A (Con A) were performed monthly for over 1 year. One-hundred percent of infected rabbits developed abnormally low T cell responses, as measured by Con A stimulation. By 3 months postinoculation, the PBL response to Con A was diminished and remained depressed for 6 months. All animals were clinically asymptomatic within 14 months of BIV inoculation. By 15 and 16 months postinoculation, two of three infected rabbits exhibited recurrent lowering of the T cell responsiveness including a decrease in absolute PBL counts. One of these animals died unexpectedly. Our results further confirmed that a functional impairment of lymphocytes was induced early in the course of BIV infection, prior to clinical disease. These findings suggested that BIV infection may mimic asymptomatic infection of human immunodeficiency virus (HIV) and provided further evidence of the importance of BIV-induced disease in rabbits as a relevant model for the study of AIDS.
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Affiliation(s)
- Z Kalvatchev
- Laboratorio Virus Animales, Centro de Microbiologia y Biologia Celular, Instituto Venezolano de Investigaciones Cientificas (IVIC), Caracas, Venezuela
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Huezo C, Kleinman R, Walder R. Natural family planning. Couples take chances. BMJ 1993; 307:1003. [PMID: 8267777 PMCID: PMC1679169 DOI: 10.1136/bmj.307.6910.1003-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Abstract
In order to evaluate central serotonergic function during viral encephalitis biochemical, behavioural and immunohistofluorescence studies were carried out. Mice were inoculated with the moderate virulent strain of venezuelan equine encephalomyelitis virus, Pixuna. Signs of encephalitis were observed in 50-60% of infected animals. Levels of serotonin and 5-hydroxyindolacetic acid, and the ratio of the indolamine and its metabolite in raphe and cortex did not change with respect to sham-inoculated mice. A differential decrease in turnover rate by pharmacological methods, such as pargyline, p-chlorophenylalanine and probenecid administration, was observed in raphe and cortex. The ratio serotonin turnover rate/steady state concentration of serotonin was only decreased in the raphe of sick animals. The response to 5-methoxy-N,N-dimethyltryptamine was greater in infected animals. The duration of immobility in the swim test was shorter in the infected group. A greater number of viral antigen particles was localized in raphe and periraphe areas than in cortex, brain stem or striatum. The results suggest a serotonin presynaptic deficit, a postsynaptic hyperreactivity of serotonin system, and a region-selective distribution of the virus.
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Affiliation(s)
- L Lima
- Laboratorios de Neuroquímica, Instituto Venezolano de Investigaciones Científicas (IVIC), Caracas, Venezuela
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Weinstock JV, Blum A, Walder J, Walder R. Eosinophils from granulomas in murine schistosomiasis mansoni produce substance P. J Immunol 1988; 141:961-6. [PMID: 2456338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Granulomas are chronic, usually focal, tissue-destructive inflammatory reactions that usually form around slowly degradable, poorly soluble substances. They are dynamic lesions, regulated by complex immune mechanisms. Tachykinins are a family of neuropeptides characterized by the common C-terminal amino acid sequence -Phe-X-Gly-Leu-Met-NH2. One such tachykinin, substance P, has been reported to modulate immunologic responses. In this investigation, granulomas were examined for substance P. Granulomas were isolated from the livers of mice infected with murine schistosomiasis, and substance P was extracted. Immunoreactive substance P was detected by RIA. The authenticity of the molecule was confirmed by elution profile on HPLC. Immunoreactive substance P, identified by immunostaining, localized to eosinophils derived from collagenase-dispersed granulomas. Granulomas were then probed for expression of the gene for substance P (preprotachykinin). Preprotachykinin mRNA was localized to granuloma eosinophils by in situ oligonucleotide hybridization. It is concluded that substance P is present within the granuloma as a result of preprotachykinin production by eosinophils.
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Affiliation(s)
- J V Weinstock
- Department of Medicine, University of Iowa, College of Medicine, Iowa City 52242
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22
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Weinstock JV, Blum A, Walder J, Walder R. Eosinophils from granulomas in murine schistosomiasis mansoni produce substance P. The Journal of Immunology 1988. [DOI: 10.4049/jimmunol.141.3.961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Granulomas are chronic, usually focal, tissue-destructive inflammatory reactions that usually form around slowly degradable, poorly soluble substances. They are dynamic lesions, regulated by complex immune mechanisms. Tachykinins are a family of neuropeptides characterized by the common C-terminal amino acid sequence -Phe-X-Gly-Leu-Met-NH2. One such tachykinin, substance P, has been reported to modulate immunologic responses. In this investigation, granulomas were examined for substance P. Granulomas were isolated from the livers of mice infected with murine schistosomiasis, and substance P was extracted. Immunoreactive substance P was detected by RIA. The authenticity of the molecule was confirmed by elution profile on HPLC. Immunoreactive substance P, identified by immunostaining, localized to eosinophils derived from collagenase-dispersed granulomas. Granulomas were then probed for expression of the gene for substance P (preprotachykinin). Preprotachykinin mRNA was localized to granuloma eosinophils by in situ oligonucleotide hybridization. It is concluded that substance P is present within the granuloma as a result of preprotachykinin production by eosinophils.
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Affiliation(s)
- J V Weinstock
- Department of Medicine, University of Iowa, College of Medicine, Iowa City 52242
| | - A Blum
- Department of Medicine, University of Iowa, College of Medicine, Iowa City 52242
| | - J Walder
- Department of Medicine, University of Iowa, College of Medicine, Iowa City 52242
| | - R Walder
- Department of Medicine, University of Iowa, College of Medicine, Iowa City 52242
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23
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Abstract
Pixuna, a strain of intermediate virulence of venezuelan equine encephalomyelitis virus, was inoculated intracranially to 24-day-old mice. Signs of encephalitis were present in 60% of the animals between 6 and 9 days with a maximum at 7 days postinoculation. The rest of the infected mice did not show clinical signs of encephalitis. In order to study the functional state of serotonergic systems a series of tests susceptible to modifications by serotonin activity were carried out. Locomotor activity was measured in an open field test. Virus-inoculated animals presented a variety of changes in their locomotor behavior at various days postinoculation with respect to the sham-inoculated group, however, they were not significant. Central serotonergic function was examined by the production of the serotonergic syndrome with the receptor agonist, 5-methoxy-N,N-dimethyltryptamine and the precursor, 5-hydroxytryptophan, both administered 4 days after the inoculation. The dose of the agonists was established by a prior drug-response analysis. Intensity of the syndrome was significantly higher in infected mice than in the sham-inoculated group only in 5-methoxy-N,N-dimethyltryptamine-treated animals. The behaviour in the swim test was also measured. Duration of immobility was much shorter in infected than in control mice. The decrease in central serotonin turnover previously reported might be responsible for the modification in locomotor behaviour and for the supersensitivity of serotonin receptors observed in infected mice.
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Affiliation(s)
- L Lima
- Laboratory of Neurochemistry, Instituto Venezolano de Investigaciones Cientificas, Caracas, Venezuela
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24
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Lima L, Walder R, Obregón F, Drujan B. Serotonin turnover rate in raphe and cortex of mice infected with Venezuelan equine encephalomyelitis virus. J Neurosci Res 1987; 17:428-34. [PMID: 2442407 PMCID: PMC7167128 DOI: 10.1002/jnr.490170415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/1986] [Revised: 12/06/1986] [Accepted: 12/10/1986] [Indexed: 12/31/2022]
Abstract
The turnover of serotonin (5HT) was determined in the raphe area and cortex of mice infected with Pixuna, a strain of intermediate virulence of Venezuelan equine encephalomyelitis virus (VEEV). NMRI-mice, 24 days old, were inoculated intracerebrally (ic) with 300 LD50 of the virus. The animals were sacrificed 4, 7, 15, 21, 30, and 60 days postinoculation. 5HT and 5-hydroxyindoleacetic acid (5HIAA) in raphe and cortex were determined by high performance liquid chromatography (HPLC) with electrochemical detection. Turnover rate of 5HT was determined by the administration of pargyline, p-chlorophenylalanine, and probenecid. The content of 5HT or 5HIAA and 5HT/5HIAA ratios were not significantly different in infected compared with control mice. However, a decrease of 5HT turnover rate, determined after pargyline treatment, was observed in the raphe and not in the cortex of infected mice at 4 and 7 days after the inoculation. The turnover rate/(5HT)0 in raphe is decreased in infected mice with signs of illness, suggesting a lower density of 5HT innervation in this brain area. The administration of p-chlorophenylalanine and probenecid showed that the cortex is also affected, but the synthesis is less modified than metabolism or elimination. Cell bodies of 5HT neurons seem to be more susceptible than projections to infection by Pixuna strain of VEEV.
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25
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Abstract
Representative strains of Venezuelan equine encephalitis virus (VEEV) and Eastern equine encephalitis virus (EEEV) were compared for their ability to grow in cultures of unstimulated leucocytes and monocytes derived from donkey peripheral blood. Replication of epizootic and vaccine strains of VEEV, but not of enzootic strains was observed in this system. Only a minority of monocytes supported virus replication as detected by immunofluorescence, electron microscopy and infectious center assays. EEEV did not appear to replicate in this cell system although virus attached to and was internalized by monocytes.
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26
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Walder R, Suarez OM, Calisher CH. Arbovirus studies in the Guajira region of Venezuela: activities of eastern equine encephalitis and Venezuelan equine encephalitis viruses during an interepizootic period. Am J Trop Med Hyg 1984; 33:699-707. [PMID: 6148023 DOI: 10.4269/ajtmh.1984.33.699] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Repeated outbreaks of Venezuelan equine encephalitis (VEE) in humans and equines in the Guajira region of Venezuela suggested a sylvatic focus of an epizootic subtype of VEE virus. A surveillance system was established, and virus isolations were attempted from 67,760 mosquitoes as well as sentinel hamsters. Sixteen isolates of eastern equine encephalitis (EEE) and a strain of Itaqui virus were recovered from mosquitoes, and 60 isolates of EEE, two of VEE, and two of Itaqui viruses were recovered from tissues of sentinel hamsters. The VEE virus isolates were shown to be closely related antigenically to prototype VEE ID and the EEE virus isolates were shown to be more closely related to the South American than the North American variety of EEE virus. Evidence for the presence of VEE and EEE viruses in small wild vertebrates was obtained from serologic testing. This study showed, for the first time, the enzootic presence of both VEE ID and EEE viruses during a nonepizoodemic period in the Guajira region.
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27
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Walder R, Suarez OM, Calisher CH. Arbovirus studies in southwestern Venezuela during 1973-1981. II. Isolations and further studies of Venezuelan and eastern equine encephalitis, Una, Itaqui, and Moju viruses. Am J Trop Med Hyg 1984; 33:483-91. [PMID: 6145366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Increasing utilization of arable land in southwestern Venezuela has led to a potential increase in human exposure to arbovirus infections. Since previous studies in the Catatumbo region of this area documented the presence of eastern equine encephalitis (EEE) and Venezuelan equine encephalitis (VEE) viruses, an attempt was made to study the transmission and maintenance of these viruses from 1973 to 1981. Isolations of EEE, VEE ID strains, Una, Itaqui , and Moju viruses were repeatedly obtained from mosquitoes, mostly Culex ( Melanoconion ) spp. and sentinel hamsters. The results indicate that these viruses constitute a potential hazard to public health in the area. Further, the strategic location of the Catatumbo region, between enzootic tropical foci of arboviruses, may provide circumstances and conditions for study of both enzootic maintenance and movement of these viruses.
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28
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Liprandi F, Walder R. Replication of virulent and attenuated strains of yellow fever virus in human monocytes and macrophage-like cells (U937). Arch Virol 1983; 76:51-61. [PMID: 6860148 DOI: 10.1007/bf01315703] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Virulent and attenuated strains of yellow fever virus were compared for their ability to grow in cultures of unstimulated leucocytes and monocytes derived from human peripheral blood, and of a macrophage-like cell line of human origin, U937. The extent of virus growth in leucocyte cultures varied depending on the strain of virus, multiplicity of infection, presence of diluted antibody in the culture medium but independently of the flavivirus immune status of the donor. The same pattern of differential growth was observed in the three types of cultures used. Although strain related variation in growth occurred within both virulent and attenuated strains, most of the attenuated strains produced higher virus yields than the virulent ones, suggesting that replication in this cell system is not related to the expression of virulence for the host. Replication in human monocytes as an in vitro marker of immunogenity for substrains of 17 D vaccine virus is discussed.
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29
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Lima L, Díaz Borges JM, Walder R. Influence of Venezuelan equine encephalomyelitis virus on catecholamine metabolism in mouse CNS: early changes in turnover rates and content. J Neurosci Res 1983; 10:61-71. [PMID: 6887281 DOI: 10.1002/jnr.490100108] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The influence of two strains of Venezuelan equine encephalomyelitis virus on catecholamine metabolism in the central nervous system (CNS) of the mouse was studied by the intracranial inoculation of NMRI-IVIC mice, 24 days old. Doses of 300 LD50 of the moderately virulent Pixuna strain and 10(4) LD50 of the nonvirulent TC-83 strain were used. The animals were sacrificed 4, 7, 12, and 18 days after the inoculation, and the CNS contents of dopamine, norepinephrine, and adrenaline were determined by a radioenzymatic method. The turnover of these compounds was studied with the aid of the enzymatic inhibitors pargyline and alpha-methyl tyrosine. With the Pixuna strain a decrease in the level and turnover of catecholamines was observed in all eight brain areas studied: cerebellum, pons-medulla, hypothalamus, mesencephalon, striatum, olfactory bulb-tuberculum, hippocampus, and cerebral cortex. In some regions the levels returned to normal in 12-18 days, but in the striatum, mesencephalon, hypothalamus, and olfactory bulb-tuberculum, recovery was slower and required at least 18 days after inoculation. The levels of catecholamines in the brain of mice inoculated with the nonvirulent TC-83 strain were not modified, but there was a decrease in the turnover.
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30
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Walder R, Rosato RR, Eddy GA. Virion polypeptide heterogeneity among virulent and avirulent strains of eastern equine encephalitis (EEE) virus. Arch Virol 1981; 68:229-37. [PMID: 6268022 DOI: 10.1007/bf01314576] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Comparative analysis of structural virion polypeptides of 24 selected EEE virus strains, representing North and South American types, was performed by one-dimensional discontinuous sodium dodecyl sulfate (SDS)-polyacrylamide-gel electrophoresis (PAGE). The structural proteins of different EEE virus isolates, resolved by this method, exhibited mol.wts. values in the range of 57-60 X 10(3) for (E-1), 51-54 X 10(3) for (E-2) and 35-38 X 10(3) daltons for the core (NP) nucleocapsid. The exception was the South American human lethal virus, TRVL-89287 strain, which was shown to possess only a single envelope glycoprotein. The high molecular weight envelope (E-1) glycoprotein species was absent or co-migrated adjacent to the smaller envelope (E-2) glycoprotein. Results indicated similarities in the core (NP) proteins, however greater variability in the envelope (E-/ and/or E-2) glycoproteins. Based on these variations seven distinct profiles could be observed among the EEE virus strain studied. The classification based on the patterns of structural polypeptides obtained by SDS-PAGE of these strains does not correlate well with any other previously reported in vitro characteristics (antigenic subtypes, HTP elution profiles) nor with the in vivo virulence markers.
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31
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Walder R. [Urine analysis with the new Uroton measuring device]. ZFA (Stuttgart) 1980; 56:1839-40. [PMID: 7467746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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32
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Walder R. [The Reflotest system]. ZFA (Stuttgart) 1980; 56:1841-2. [PMID: 7467747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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33
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Walder R. [Family planning]. ZFA (Stuttgart) 1979; 55:5. [PMID: 483985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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34
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Walder R, Bradish CJ. Multi-factorial specification of virus-host interactions: studies with strains of Venezuelan equine encephalomyelitis virus in mice. J Gen Virol 1979; 44:373-82. [PMID: 521796 DOI: 10.1099/0022-1317-44-2-373] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mice of different ages were infected i.p. or i.c. by 23 different strains of VEE virus. The course of the virus host interaction was specified in terms of the efficiency of infection, the outcome of infection as lethality or protection and the survival time. These separately quantifiable features all showed several host-maturation events that combine to provide a multifactorial specification of virus-strains and host-responses. This base-line for correlations with the responses of principal hosts (equidae and man) may be expanded to test correlations with the antigenic or in vitro characteristics of virus-strains.
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35
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Walder R, Suárez OM. Studies of arboviruses in Southwestern Venezuela: I. Isolations of Venezuelan and Eastern Equine Encephalitis viruses from sentinel hamsters in the Catatumbo region. Int J Epidemiol 1976; 5:375-8. [PMID: 1010667 DOI: 10.1093/ije/5.4.375] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The purpose of this report is to describe isolations of Venezuelan (VEE) and Eastern (EEE) Equine Encephalitis virus made in the lowland moist tropical forest of the Catatumbo region on the southwestern part of the State of Zulia, Venezuela. We have isolated four strains of EEEV from sentinel hamsters exposed at Caño Mocho and Madre Vieja sites in 1973 and 1974, and three strains of EEEV in Hacienda (Hda.) Las Nubes in 1975. Both viruses were recovered during silent interepidemic periods and we believe these viruses are maintained in this region in sylvatic conditions. The recovered virus strains were detected within 24 to 48 hours, both in SMB and Vero Cell monolayer cultures and the sentinel hamsters yielded virus infectivities up to 10(4) PFU ml. Our VEEV isolate (IVIC PAn 23645-47), recovered during the silent interepizodemic period had an elution profile on the hydroxylapatite column corresponding to that of a I-D (VEEV-3880) or a I-E (VEEV-63A216) 'enzootic' subtype. However, considering other in vitro criteria (KHI; HA pH 5.8-6.0; small plaque size in Vero monolayers with suitable overlay media), this later and other previous isolates had some very distinct properties of the 'epizootic' strains. Thus, the evidence suggests that in Venezuela the VEEV cycle in nature is maintained either by the so called 'enzootic' and/or 'epizootic' virus types, or the virus population of the isolates have particular in vitro properties which do not correlate to the virulence markers in vivo. We consider this important question must be further clarified, and in addition, the isolation of three strains of EEEV are reported; this is the first report of the presence of this virus in Venezuela. Although the EEEV isolates may be of the South American type, they must be considered as potentially dangerous in the case of outbreaks.
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36
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Abstract
Thermal inactivation of Venezuelan Equine Encephalomyelitis Virus (VEEV) was studied at temperatures from 26 degrees to 55 degrees C. Inactivation of infectivity took place by two thermodynamically different reactions, one of which predominated at temperatures below 44 degrees C and the other at higher temperatures. The presence of 1 or 2 M NaCl stabilized the VEE virus at low temperatures but enhanced the inactivation at high temperatures. This latter effect at temperatures higher than 50 degrees C, is associated with the occurrence of two-component survival curves. The different effects of hypertonic NaCl concentrations at the two ranges of temperature, are related to different mechanisms of inactivation operating at each range (protein denaturation and nucleic acid-RNA breakdown). Different kinetics of thermal inactivation at 55 degrees C were observed between virus strains with different virulence. However, no significant correlations was found between the virulence of the eleven VEE virus strains studied and their thermostability at 37 degres and 55 degrees C.
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37
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Soyano A, Malavé I, Walder R, Layrisse Z, Layrisse M. Hepatitis-B antigen in an isolated Indian population (Yanomama indians) Southern Venezuela. Rev Bras Pesqui Med Biol 1976; 9:247-53. [PMID: 1013404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A high frequency of Hepatitis-B antigen (7%) was found in apparently healthy Yanomama indians living in southern Venezuela. The prevalence in 24 different Yanomama villages varied between 0 and 30%, but only 3 of 938 serum samples showed presence of HB-Ab. The distribution of the HB-Ag was found to be significantly higher in males than in females.
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38
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Walder R. [The female physicians' assistant in current practice]. Z Allgemeinmed 1975; 51:993-9. [PMID: 241162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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39
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Walder R. [Laboratory spectrum of established physicians. Statistical analysis]. Z Allgemeinmed 1975; 51:585-90. [PMID: 1146361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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40
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Walder R. [The utilization of laboratory diagnosis by the established physician]. Z Allgemeinmed 1975; 51:557-568. [PMID: 1146358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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41
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Walder R, Bradish CJ. Venezuelan equine encephalomyelitis virus (VEEV):strain differentiation and specification of virulence markers. J Gen Virol 1975; 26:265-75. [PMID: 804536 DOI: 10.1099/0022-1317-26-3-265] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Fourteen strains of VEEV of diverse origin and antigenicity were classified into five virulence categories according to their efficiency of infection and nature of response in mice. Mice of ages up to 30 days represented distinct levels of responsiveness and were suitable for the differentiation of VEEV strains of highest to lowest virulence. Stepwise changes with age of the susceptibility or responsiveness of mice appeared to determined the type of response as predominantly lethal (D), dual or intermediate (DP) or protective (P).
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43
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Walder R, Dominguez AC, Tamayo JG. Cytomorphological changes during Nariva virus infection. Arch Gesamte Virusforsch 1971; 35:54-61. [PMID: 4108652 DOI: 10.1007/bf01249752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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44
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Walder R. [Diagnosis and the general practitioner. Research task of the Health Insurance Association of Northern Württemberg]. Landarzt 1968; 44:1426-1434. [PMID: 5712709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
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45
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Walder R, Hsiung GD. Biological and antigenic characteristics of an A2 influenza virus isolated in 1965. Public Health Rep (1896) 1967; 82:689-96. [PMID: 4962117 PMCID: PMC1920062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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