A S Ramírez

Publications (18)29.01 Total impact

• Source

  Available from: Chris J Morrow

  Article: Development and evaluation of an improved diagnostic PCR for Mycoplasma synoviae using primers located in the haemagglutinin encoding gene vlhA and its value for strain typing.

  P P Hammond, A S Ramírez, C J Morrow, J M Bradbury
  [show abstract] [hide abstract]
  ABSTRACT: Using published primers, detection of Mycoplasma synoviae and strain identification using the vlhA gene sequence was attempted. However, of 21 M. synoviae strains examined, three could not be amplified, so a new reverse primer was designed with a target in the conserved region of the vlhA gene. This allowed all 21 M. synoviae strains, a further nine strains and also material from 11 swab samples from M. synoviae-positive birds, to produce a PCR product, suggesting that the method could also be suitable for clinical specimens. The protocol was then tested on the type strains of M. synoviae and the other 22 recognised avian Mycoplasma species, with amplification of M. synoviae only. Further testing demonstrated that this PCR was equally or more sensitive than other PCR tests used to detect M. synoviae. Subsequent DNA sequence analysis of the PCR product based on percent similarity and evolutionary relationship appeared to be a useful tool for strain differentiation.
  Veterinary Microbiology 12/2008; 136(1-2):61-8. · 3.33 Impact Factor
• Source

  Available from: cnrs.fr

  Article: High inter-species and low intra-species variation in 16S-23S rDNA spacer sequences of pathogenic avian mycoplasmas offers potential use as a diagnostic tool.

  A S Ramírez, C J Naylor, D G Pitcher, J M Bradbury
  [show abstract] [hide abstract]
  ABSTRACT: In order to investigate its value for phylogenetic analysis, species characterisation and diagnosis, the 16S-23S rDNA intergenic spacer regions (ISRs) of the type strain of 23 avian Mycoplasma species were amplified and the sequences determined. Also sequenced were the reference strains of Mycoplasma iowae serotypes J, K, N, Q and R and a number of field strains of Mycoplasma synoviae, Mycoplasma gallisepticum, Mycoplasma meleagridis and M. iowae. The ISRs demonstrated a high level of size variation (178-2488bp) between species and did not include tRNA genes. Phylogenetic analysis performed using the information conflicted with that based on the 16S rDNA and was therefore not helpful for phylogenetic studies. However, the ISR did appear to be of value for determining species since there was high inter-species variation between all 23 avian Mycoplasma species, and in addition there was low intra-species variation, at least in the four pathogenic species. It could also be very useful as additional information in the description of a new species and as a target for species-specific PCRs.
  Veterinary Microbiology 05/2008; 128(3-4):279-87. · 3.33 Impact Factor
• Article: First isolation of Mycoplasma capricolum subsp. capricolum, one of the causal agents of caprine contagious agalactia, on the island of Lanzarote (Spain).

  C De la Fe, A Gutiérrez, J B Poveda, P Assunção, A S Ramírez, F Fabelo
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  ABSTRACT: During an unusually long period of bad weather, several outbreaks of caprine contagious agalactia (CCA) were reported in a number of flocks on the island of Lanzarote (Canary Islands, Spain). Clinical and subclinical mastitis in lactating goats and some cases of arthritis and pneumonia in kids were observed in the affected flocks. Mycoplasma capricolum subsp. capricolum was isolated as the main causal agent of the outbreaks, associated with M. mycoides subsp. mycoides "large colony type" (Mmm LC) in two flocks. This is the first report of an isolation of M. capricolum subsp. capricolum on the island of Lanzarote. The finding is of epidemiological importance and could complicate plans to control the disease. The significance of this mycoplasma species in association with CCA must now be studied in detail.
  The Veterinary Journal 04/2007; 173(2):440-2. · 2.24 Impact Factor
• Article: Protein and antigenic variability among Mycoplasma hyopneumoniae strains by SDS-PAGE and immunoblot.

  P Assunção, C De la Fe, A S Ramírez, O González Llamazares, J B Poveda
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  ABSTRACT: Porcine enzootic pneumonia (PEP), with Mycoplasma hyopneumoniae as the primary agent, is a chronic respiratory disease that causes major economic losses to the pig industry worldwide. The aim of this work was to analyse 18 field strains of M. hyopneumoniae isolated in Gran Canaria (Spain) and the reference M. hyopneumoniae strain by SDS-PAGE and immunoblot. A monoclonal antibody (MAb) against the membrane protein p46 reacted with all the strains in this study. In contrast, a purified polyclonal antibody (PAb) against the cytoplasmic protein p36 reacted with this protein in only 10 strains. A MAb against the adhesin protein p97 stained multiple proteins of different sizes and with different intensities. Different antigenic patterns in the same M. hyopneumoniae strains were also observed after different numbers of passages in culture medium. Furthermore, variability in the staining of the 36 kDa protein was observed, depending on whether the p36 PAb or the antiserum against M. hyopneumoniae reference strain was used. It is concluded that local M. hyopneumoniae field isolates in Gran Canaria are characterized by protein diversity.
  Veterinary Research Communications 11/2005; 29(7):563-74. · 0.82 Impact Factor
• Article: Relationship between rheumatoid arthritis and Mycoplasma pneumoniae: a case-control study.

  A S Ramírez, A Rosas, J A Hernández-Beriain, J C Orengo, P Saavedra, C de la Fe, A Fernández, J B Poveda
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  ABSTRACT: Rheumatoid arthritis (RA) has a complex and multifactorial aetiology. Infectious agents could start this disease. The majority of the characteristics of this infirmity can be observed in chronic arthritis produced by mycoplasmas in animals. In this study the association between Mycoplasma pneumoniae and RA has been evaluated. A case-control study was performed. Sera taken from 78 RA patients and from 156 controls were analysed to ascertain the levels of immunoglobulin G (IgG) against M. pneumoniae. Other variables, like age, gender, work status, history of pneumonia, etc., were recorded in a questionnaire. The presence of antibodies against M. pneumoniae was associated with RA (odds ratio=2.34, P<0.001). The results suggest that M. pneumoniae could be a cofactor in the pathogenesis of RA; however, more studies need to be done.
  Rheumatology 07/2005; 44(7):912-4. · 4.06 Impact Factor
• Article: A morphologic and immunohistochemical study of the bronchus-associated lymphoid tissue of pigs naturally infected with Mycoplasma hyopneumoniae.

  J Sarradell, M Andrada, A S Ramírez, A Fernández, J C Gómez-Villamandos, A Jover, H Lorenzo, P Herráez, F Rodríguez
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  ABSTRACT: Porcine enzootic pneumonia (PEN), caused by Mycoplasma hyopneumoniae (Mh), has been described in pigs in all geographic areas. The disease is characterized by high morbidity and low mortality rates in intensive swine production systems. A morphologic and immunohistochemical study was done to determine the cellular populations present in lung parenchyma of infected pigs, with special attention to the bronchus-associated lymphoid tissue (BALT). Polyclonal and monoclonal antibodies were used for the detection of antigens of Mh, T lymphocytes (CD3+, CD4+, and CD8+), IgG+ or IgA+ lymphocytes, and cells containing lysozyme, S-100 protein, major histocompatibility complex class II antigen or myeloid-histiocyte antigen. Findings in lung tissues associated with Mh infection were catarrhal bronchointerstitial pneumonia, with infiltration of inflammatory cells in the lamina propria of bronchi and bronchioles and alveolar septa. Hyperplasia of mononuclear cells in the BALT areas was the most significant histologic change. The BALT showed a high morphologic and cellular organization. Macrophages and B lymphocytes were the main cellular components of germinal centers. T lymphocytes were primarily located in perifollicular areas of the BALT, lamina propria and within the airway epithelium, and plasma cells containing IgG or IgA at the periphery of the BALT, in the lamina propria of bronchi and bronchioles, in alveolar septa, and around bronchial submucosal glands. The hyperplastic BALT in PEN cases consisted of macrophages, dendritic cells, T and B lymphocytes, and IgG+ and IgA+ plasma cells. CD4+ cells predominated over CD8+ cells. Local humoral immunity appears to play an important role in the infection.
  Veterinary Pathology 08/2003; 40(4):395-404. · 1.95 Impact Factor
• Article: J. Sarradell, M. Andrada, A. S. Ramírez, A. Fernández, J. C. Gómez-Villamandos, A. Jover, H. Lorenzo, P. Herráez, F. Rodríguez. A morphologic and immunohistochemical study of the bronchus-associated lymphoid tissue of pigs naturally infected with Micoplasma hyopneumoniae. Veterinary Pathology 40: 395-404 (2003).

  J. Sarradell, M. Andrada, A. S. Ramírez, A. Fernández, J. C. Gómez-Villamandos, A. Jover, H. Lorenzo, P. Herráez, F. Rodríguez
  Veterinary Pathology 05/2003; · 1.95 Impact Factor
• Article: Immunohistochemical detection of Mycoplasma agalactiae in formalin-fixed, paraffin-embedded tissues from naturally and experimentally infected goats.

  F Rodríguez, G A Ramírez, A S Ramírez, H J Ball, A Espinosa de los Monteros, A Fernandez
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  ABSTRACT: Samples from the mammary tissue of 14 lactating goats (12 naturally infected and two experimentally infected) were examined for the presence of Mycoplasma agalactiae. A monoclonal antibody (5G12) was applied to formalin-fixed, paraffin-wax-embedded sections and labelled by the avidin-biotin peroxidase complex (ABC) method. Histological examination of tissue sections revealed strong immunoreactivity in all animals included in the study. Mycoplasma agalactiae antigen was mainly detected in the cellular debris at the periphery of purulent exudates present within lactiferous sinuses, and lactiferous and interlobular ducts. In addition, M. agalactiae organisms appeared in the cytoplasm of the epithelium of ducts, and in infiltrating macrophages and neutrophils within the ducts, alveoli, interstitial tissue and regional lymph node sinuses. It is concluded that this monoclonal antibody-based immunohistochemical technique is an efficient and specific method for the post-mortem detection of M. agalactiae in cases of clinical mastitis as well as being a useful tool for the study of the route of infection and cellular types involved during mastitis caused by this organism.
  Journal of Veterinary Medicine Series B 07/2002; 49(5):226-9. · 1.48 Impact Factor
• Article: F. Rodríguez, G.A. Ramírez, A.S. Ramírez, H.J. Ball, A. Espinosa de los Monteros, A. Fernández.Immunohistochemical detection of mycoplasma agalactiae in formalin-fixed, paraffin-embedded tissues from naturally and experimentally infected goats.Journal of Veterinary Medicine, B 49: 226-229 (2002).

  F. Rodríguez, G.A. Ramírez, A.S. Ramírez, H.J. Ball, A. Espinosa de los Monteros, A. Fernández
  Journal of Veterinary Medicine Series B 04/2002; · 1.48 Impact Factor
• Article: Changes in lymphocyte subsets in the bronchus-associated lymphoid tissue of goats naturally infected with different Mycoplasma species.

  F Rodríguez, A Fernández, J Orós, A S Ramírez, R Luque, H J Ball, J Sarradell
  [show abstract] [hide abstract]
  ABSTRACT: The distribution of cells containing lysozyme, S-100 protein, CD3, CD4, CD8, major histocompatibility complex class II antigen and immunoglobulin G (IgG) was analysed in the bronchus-associated lymphoid tissue (BALT) of goats naturally infected with three Mycoplasma species. This study included the immunohistochemical characterization of the pneumonic lesions of 18 goats (3-5 months old) infected with one of the following Mycoplasma species: M. mycoides ssp. mycoides, Large Colony type (goats no. 1-6), M. mycoides ssp. capri (goats no. 7-12) and M. capricolum ssp. capricolum (goats no. 13-18). Microscopically, infected animals showed a moderate broncho-interstitial pneumonia, characterized by lymphoid hyperplasia of the BALT and infiltration of mononuclear cells in the alveolar walls and airways. The main cellular type in the BALT was represented by CD3+ T lymphocytes, and the ratio of CD4+:CD8+ cells was > 2. The BALT showed large germinal centres mainly composed of IgG+ B lymphocytes, with numerous S-100+ follicular dendritic cells. The presence of follicular dendritic cells confirmed the high degree of organization of this lymphoid tissue. The immunohistochemical results showed that activated T lymphocytes, particularly in the CD4 subset, and IgG+ B cells, play a major role in the immune response of the caprine lung infected with these species of mycoplasmas.
  Journal of Veterinary Medicine Series B 06/2001; 48(4):259-66. · 1.48 Impact Factor
• Article: F. Rodríguez, A. Fernández, J. Orós, A.S. Ramírez, R. Luque, H.J. Ball, J. Sarradell.Changes in the lymphocyte subsets in the bronchus-associated lymphoid tissue of goats naturally infected with different mycoplasma species.Journal of Veterinary Medicine, B, 48: 259-266 (2001).

  F. Rodríguez, A. Fernández, J. Orós, A.S. Ramírez, R. Luque, H.J. Ball, J. Sarradell
  Journal of Veterinary Medicine Series B 03/2001; · 1.48 Impact Factor
• Article: J. Orós, A. Fernández, J.L. Rodríguez, S. Matsushita, A.S. Ramírez and J.B. Poveda.Association of cilia-associated respiratory (CAR) bacillus with natural chronic tracheitis in goats.Journal of Comparative Pathology. Oct. 117(3):289-94. (1997).

  J. Orós, A. Fernández, J.L. Rodríguez, S. Matsushita, A.S. Ramírez, J.B. Poveda
  Journal of Comparative Pathology 03/1997; · 1.65 Impact Factor
• Article: Systemic mycosis caused by Penicillium griseofulvum in a Seychelles giant tortoise (Megalochelys gigantea).

  J Orós, A S Ramírez, J B Poveda, J L Rodríguez, A Fernández
  The Veterinary record 10/1996; 139(12):295-6. · 1.25 Impact Factor
• Article: J.L. Rodríguez, J.B. Poveda, F. Rodríguez, A. Espinosa de los Monteros, A.S. Ramírez and A. Fernández.Ovine infectious keratoconjunctivitis caused by Mycoplasma agalactiae.Small Ruminant Research, Vol. 22, 93-96 (1996).

  J.L. Rodríguez, J.B. Poveda, F. Rodríguez, A. Espinosa de los Monteros, A.S. Ramírez, A. Fernández
  Small Ruminant Research 09/1996; · 1.29 Impact Factor
• Article: J. Orós, A.S. Ramírez, J.B. Poveda, J.L. Rodríguez, A. Fernández.Systemic mycoisis caused by Penicillium griseofulvum in a sechelles giant tortoise (Megalochelys gigantea).Veterinary Record, Vol. 139, 295-296 (1996).

  J. Orós, A.S. Ramírez, J.B. Poveda, J.L. Rodríguez, A. Fernández
  The Veterinary record 01/1996; · 1.25 Impact Factor
• Article: Survey of antibodies to Mycoplasma agalactiae and Mycoplasma mycoides subsp. mycoides (large colony type) in dromedaries (Camelus dromedarius) in close contact with an infected goat population

  C. De la Fe, P. Assunçao, C. Gutiérrez, A.S. Ramírez, C. Poveda, F. Fabelo, J.B. Poveda
  [show abstract] [hide abstract]
  ABSTRACT: Given recent evidence of a possible role of camelids in the epidemiology of diseases caused by mycoplasma species in other ruminants, we examined the prevalence of the mycoplasmas most commonly responsible for contagious agalactia (CA) in small ruminants among the dromedaries (Camelus dromedarius) of Lanzarote. On this island, one of the most arid regions of Spain in which CA is considered endemic, dromedaries and infected small ruminants such as goats and sheep, live in close contact. Specific IgG antibodies against Mycoplasma agalactiae and Mycoplasma mycoides subsp. mycoides (large colony biotype) were determined using two indirect enzyme immunoassays in 28% of the island's dromedary population. None of the serum samples tested were found to have antibodies against the two mycoplasma species, suggesting that the camels are not potential carriers of the main causative agents of CA.
  Journal of Arid Environments.
• Source

  Available from: Chris J Morrow

  Article: Development and evaluation of an improved diagnostic PCR for Mycoplasma synoviae using primers located in the haemagglutinin encoding gene vlhA and its value for strain typing

  P.P. Hammond, A.S. Ramírez, C.J. Morrow, J.M. Bradbury
  [show abstract] [hide abstract]
  ABSTRACT: Using published primers, detection of Mycoplasma synoviae and strain identification using the vlhA gene sequence was attempted. However, of 21 M. synoviae strains examined, three could not be amplified, so a new reverse primer was designed with a target in the conserved region of the vlhA gene. This allowed all 21 M. synoviae strains, a further nine strains and also material from 11 swab samples from M. synoviae-positive birds, to produce a PCR product, suggesting that the method could also be suitable for clinical specimens. The protocol was then tested on the type strains of M. synoviae and the other 22 recognised avian Mycoplasma species, with amplification of M. synoviae only. Further testing demonstrated that this PCR was equally or more sensitive than other PCR tests used to detect M. synoviae. Subsequent DNA sequence analysis of the PCR product based on percent similarity and evolutionary relationship appeared to be a useful tool for strain differentiation.
  Veterinary Microbiology.
• Article: High inter-species and low intra-species variation in 16S–23S rDNA spacer sequences of pathogenic avian mycoplasmas offers potential use as a diagnostic tool

  A.S. Ramírez, C.J. Naylor, D.G. Pitcher, J.M. Bradbury
  [show abstract] [hide abstract]
  ABSTRACT: In order to investigate its value for phylogenetic analysis, species characterisation and diagnosis, the 16S–23S rDNA intergenic spacer regions (ISRs) of the type strain of 23 avian Mycoplasma species were amplified and the sequences determined. Also sequenced were the reference strains of Mycoplasma iowae serotypes J, K, N, Q and R and a number of field strains of Mycoplasma synoviae, Mycoplasma gallisepticum, Mycoplasma meleagridis and M. iowae. The ISRs demonstrated a high level of size variation (178–2488 bp) between species and did not include tRNA genes. Phylogenetic analysis performed using the information conflicted with that based on the 16S rDNA and was therefore not helpful for phylogenetic studies. However, the ISR did appear to be of value for determining species since there was high inter-species variation between all 23 avian Mycoplasma species, and in addition there was low intra-species variation, at least in the four pathogenic species. It could also be very useful as additional information in the description of a new species and as a target for species-specific PCRs.
  Veterinary Microbiology.