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S Soares

Publications and source records attributed to S Soares.

11 recordsLinked to original sources
PubMed1998

Induction of MAP1B phosphorylation in target-deprived afferent fibers after kainic acid lesion in the adult rat.

We have previously shown that the phosphorylated form of microtubule-associated protein 1B (MAP1B-P), which is located in growing axons during development and regeneration, remains detectable in the adult central nervous system only in areas that undergo morphologic plasticity (Nothias et al. [1996] J. Comp. Neurol. 368:317-334). Our objective in the present study was to determine whether lesion-induced axonal remodeling, in the adult rat, is associated with reinduction of MAP1B phosphorylation. MAP1B-P was not detectable in intact adult thalamic ventrobasal complex (VB), although low levels of MAP1B and its mRNA were present. A neuron-depletion of VB by in situ injection of kainic acid was followed by an induction of MAP1B phosphorylation by 24 hours postlesion. MAP1B-P was detected in fibers originating from undamaged neurons that were not located in the lesion, as demonstrated by the absence of hybridized MAP1B-mRNA. Ultrastructural analysis confirmed the exclusive location of MAP1B-P in axons in a proximodistal gradient. MAP1B phosphorylation appeared to be regulated by posttranslational modification of existing protein because the levels of MAP1B-mRNA did not change. The number of MAP1B-P-labeled fibers increased during the first month postlesion and remained high for a long period. Double staining by using axonal tracing with dextran-biotin and tyrosine hydroxylase immunohistochemistry, showed the presence of MAP1B-P in VB afferents from somatosensory relays and the locus coeruleus. This study supports the hypothesis that MAP1B, at a particular state of phosphorylation, is correlated with axonal remodeling in the adult central nervous system (CNS). We suggest that the interaction of MAP1B-P with microtubules allows the modulation of their dynamic properties during periods of increased axonal plasticity.

Afferent Pathways↗
PubMed1997

Mycobacterium bovis BCG genes involved in the biosynthesis of cyclopropyl keto- and hydroxy-mycolic acids.

The resurgence of tuberculosis and the emergence of multidrug-resistant mycobacteria necessitate the development of new antituberculosis drugs. The biosynthesis of mycolic acids, essential elements of the mycobacterial envelope, is a good target for chemotherapy. Species of the Mycobacterium tuberculosis complex synthesize oxygenated mycolic acids with keto and methoxy functions. In contrast, the fast-growing Mycobacterium smegmatis synthesizes oxygenated mycolic acids with an epoxy function. We describe the isolation and sequencing of a cluster of four genes from Mycobacterium bovis bacillus Calmette-Guerin (BCG), coding for methyl transferases, and which, when transferred into M. smegmatis, allow the synthesis of ketomycolic acid, in addition to an as yet undescribed mycolic acid, hydroxymycolic acid. These oxygenated mycolic acids, unlike the regular mycolic acids of M. smegmatis, and similar to the mycolic acids of M. bovis, are highly cyclopropanated. Furthermore, there is a perfect match between the structures of the keto- and the hydroxy-mycolic acids. We propose a biosynthetic model in which there is a direct relationship between these two types of mycolic acid.

Amino Acid Sequence↗
PubMed1996

Overproduction of mycobacterial ribosomal protein S13 induces catalase/peroxidase activity and hypersensitivity to isoniazid in Mycobacterium smegmatis.

A Bacillus Calmette Guerlin (BCG) DNA fragment was identified which conferred hypersensitivity to isoniazid (INH) upon Mycobacterium smegmatis (Ms) when present on a multicopy plasmid. The gene cluster present on this fragment contains the genes encoding ribosomal proteins L36 (rpmJ), S13 (rpsM), S11 (rpsK) and S4 (rpsD), as well as the gene encoding initiation factor-1 (infA), an open reading frame of unknown function (ORFX) and a putative promoter region. The rpsM gene, from either BCG or Ms is necessary and sufficient to produce the INH-hypersensitive phenotype in Ms, but the gene cluster has no effect on INH sensitivity when introduced into BCG on a multicopy plasmid. The presence of rpsM on a multicopy plasmid also causes an increase in catalase/peroxidase (Kat/Prx) activity in Ms. The overproduction of S13 may induce a stress response, resulting in increased expression of katG (encoding Kat/Prx) in Ms, thereby causing hypersensitivity to INH.

Amino Acid Sequence↗
PubMed1995

Transmission of multidrug-resistant serotype 23F Streptococcus pneumoniae in group day care: evidence suggesting capsular transformation of the resistant strain in vivo.

Surveillance for nasopharyngeal colonization with Streptococcus pneumoniae was maintained in a research day care center between 1985 and 1992. An outbreak of nasal carriage of a multi-drug-resistant (MDR) serotype 23F organism occurred between May 1990 and December 1991 involving 14 of 52 children. Electrophoresis of penicillin-binding proteins (PBP) and pulsed-field gel electrophoresis (PFGE) of chromosomal DNA indicated that the MDR serotype 23F organism was closely related to a serotype 23F MDR clone that has been prevalent in Spain since the early 1980s. In June 1991, an MDR serotype 14 organism was isolated from a child who had previously carried the MDR serotype 23F strain. PFGE and PBP typing revealed that the MDR serotype 14 organism was very similar to the circulating MDR serotype 23F strain, suggesting serotype transformation. Dissemination of MDR pneumococcal strains and possibly spread of the MDR phenotype to additional serotypes may be facilitated in group day care.

Anti-Bacterial Agents↗
PubMed1994

Human-engineered monoclonal antibodies retain full specific binding activity by preserving non-CDR complementarity-modulating residues.

Humanization of murine monoclonal antibodies for human therapy has commonly been achieved by complementarity-determining region (CDR) grafting, in which murine CDR loops are grafted onto human framework regions. Difficulties with that method have revealed the importance of certain framework residues in determining both the 3-D structure of CDR loops and the overall affinity of the molecule for its specific ligand. In the general model of structure-function relationships presented here, each amino acid position in the variable region is classified according to the benefit of achieving a more human-like antibody versus the risk of decreasing or abolishing specific binding affinity. Substitutions of human residues at low-risk positions (exposed to solvent but not contributing to antigen binding or antibody structure) are likely to decrease immunogenicity with little or no effect on binding affinity. Changes at high-risk positions (directly involved in antigen binding, CDR stabilization or internal packing) are avoided to preserve the biological activity of the antibody. Moderate-risk changes are made with caution. This model has been tested experimentally using H65, an anti-CD5 murine monoclonal antibody, whose binding activity had been greatly reduced by two previous attempts at humanization by conventional CDR grafting. The new 'human-engineered' H65 antibody containing 20 low-risk human consensus substitutions (expressed as either IgG or Fab) retains the full binding avidity of parental murine and chimeric H65 antibodies. A human-engineered antibody with an additional 14 moderate-risk substitutions has unexpectedly enhanced avidity (3- to 7-fold). This method is generally applicable to the design of other human-engineered antibodies with therapeutic potential.

Amino Acid Sequence↗
PubMed1993

Evidence for the introduction of a multiresistant clone of serotype 6B Streptococcus pneumoniae from Spain to Iceland in the late 1980s.

Almost all of the multiresistant pneumococci that appeared suddenly in clinical specimens in Iceland between 1989 and 1992 belonged to serogroup 6. Fifty-seven of these isolates were analyzed for serotype, penicillin-binding protein pattern, multilocus enzyme genotype, and fragmentation pattern obtained by pulsed-field electrophoretic separation of restriction enzyme digests of chromosomal DNA. All isolates were of serotype 6B and had similar or identical patterns in each molecular test. The Icelandic isolates were indistinguishable from a subgroup of multiresistant serotype 6B pneumococci that has been present with high incidence in Spain during the past two decades. The data suggest the import to Iceland of a single multiresistant clone of pneumococcus, most likely from Spain.

Bacterial Proteins↗
PubMedDate not supplied

[Serving in Macao].

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Education, Nursing↗