title: (1→3)-β-D-glucan aptamers labeled with technetium-99m: Biodistribution and imaging in experimental models of bacterial and fungal infection.
abstract: BACKGROUND
  Acid nucleic aptamers are RNA or DNA oligonucleotides capable of binding to a target molecule with high affinity and selectivity. These molecules are promising tools in nuclear medicine. Many aptamers have been used as targeting molecule of radiopharmaceuticals in preclinical studies. (1→3)-β-D-glucans are the main structural cell wall components of fungi and some bacteria. In the present study two radiolabeled (1→3)-β-D-glucan aptamers (seq6 and seq30) were evaluated to identity infectious foci caused by fungal or bacterial cells.
  
  
  METHODS
  Aptamer labeling with99mTc was performed by the direct method and biodistribution studies were accomplished in Swiss mice (n=6) infected in the right thigh muscle with Staphylococcus aureus or Candida albicans. A99mTc radiolabeled library consisting of oligonucleotides with random sequences was used as control.
  
  
  RESULTS
  There was a higher uptake of99mTc radiolabeled aptamers in the infected thigh than in the left thigh muscle (non-infected) in the S. aureus infected animals. The target/non-target ratios were 3.17±0.22 for seq6 and 2.66±0.10 for seq30. These ratios were statistically higher than the value (1.54±0.05) found for the radiolabeled library (control). With regard to biodistribution, no statistical difference was verified between aptamers and control uptakes in the infection foci in the C. albicans infected animals. The target/non-target ratios were 1.53±0.03, 1.64±0.12 and 1.08±0.02 for radiolabeled library, seq6 and seq30, respectively. Scintigraphic imaging of infected foci using radiolabeled aptamers was possible only for S. aureus infected mice.
  
  
  CONCLUSIONS
  Seq6 and seq30 aptamers proved to be inefficient for diagnosis of C. albicans infection. Nevertheless, their applicability for diagnosis of S. aureus and other bacterial infections by scintigraphy should be further explored.
authors.affiliation: Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Rua Professor Mário Werneck S/N°, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31120-970, Brazil. Electronic address: cmslacerda@gmail.com.
authors.forename: Camila Maria
authors.initials: CM
authors.lastname: de Sousa Lacerda
authors.affiliation: Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Rua Professor Mário Werneck S/N°, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31120-970, Brazil. Electronic address: imendesf@yahoo.com.br.
authors.forename: Iêda Mendes
authors.initials: IM
authors.lastname: Ferreira
authors.affiliation: Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Rua Professor Mário Werneck S/N°, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31120-970, Brazil. Electronic address: sararoberta7@hotmail.com.
authors.forename: Sara Roberta
authors.initials: SR
authors.lastname: Dos Santos
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas-Faculdade de Farmácia, Universidade Federal de Minas Gerais, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31270-091, Brazil. Electronic address: brancodebarros@yahoo.com.br.
authors.forename: André Luís Branco
authors.initials: AL
authors.lastname: de Barros
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas-Faculdade de Farmácia, Universidade Federal de Minas Gerais, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31270-091, Brazil. Electronic address: simone@farmacia.ufmg.br.
authors.forename: Simone Odília
authors.initials: SO
authors.lastname: Fernandes
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas-Faculdade de Farmácia, Universidade Federal de Minas Gerais, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31270-091, Brazil. Electronic address: cardosov@farmacia.ufmg.br.
authors.forename: Valbert Nascimento
authors.initials: VN
authors.lastname: Cardoso
authors.affiliation: Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Rua Professor Mário Werneck S/N°, Cidade Universitária-Campus da UFMG, Belo Horizonte, MG 31120-970, Brazil. Electronic address: antero@cdtn.br.
authors.forename: Antero Silva Ribeiro
authors.initials: AS
authors.lastname: de Andrade
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000378:metabolism* / Q000493:pharmacokinetics; D002176:Candida albicans / Q000502:physiology; D004195:Disease Models, Animal; D004355:Drug Stability; D007553:Isotope Labeling; D051379:Mice; D009181:Mycoses / Q000000981:diagnostic imaging*; D011509:Proteoglycans; D013203:Staphylococcal Infections / Q000000981:diagnostic imaging*; D013211:Staphylococcus aureus / Q000502:physiology; D013667:Technetium / Q000737:chemistry*; D014018:Tissue Distribution; D047071:beta-Glucans / Q000378:metabolism*
chemical_list: D052157:Aptamers, Nucleotide; D011509:Proteoglycans; D047071:beta-Glucans; C010770:polysaccharide-K; D013667:Technetium
keywords: (1→3)-β-D-glucans; Aptamer; Biodistribution, Infection Diagnosis; Radiopharmaceutical; Technetium-99m