ABSTRACT
BACKGROUND: In the past 10 years, the use of support personnel in Canada has generated significant interest from occupational therapists, professional associations, regulatory bodies, employers, educational institutions, and government agencies. PURPOSE: The purpose of this study was to explore the impact of a combined collaborative fieldwork placement and weekly tutorial as a teaching strategy for intraprofessional education. METHODS: Seven pairs of student occupational therapists and occupational therapist assistants were assigned to fieldwork placements. Tutorials were scheduled during the placements to discuss intraprofessional issues and provision of occupational therapy services in the clinical setting. Journaling and focus groups were used to collect data from students, tutors, and preceptors. FINDINGS: Three key themes emerged from the data: (1) developing the relationship, (2) understanding roles, and (3) recognizing environmental influences on learning. IMPLICATIONS: Intraprofessional learning experiences prior to graduation can help prepare occupational therapy and occupational therapist assistant students for future collaborative practice.
Subject(s)
Allied Health Personnel/education , Interprofessional Relations , Occupational Therapy/education , Preceptorship/organization & administration , HumansABSTRACT
Lipopolysaccharide (LPS) is a virulence determinant of Haemophilus influenzae and exhibits substantial heterogeneity in structure within and between strains. Key factors contributing to this heterogeneity are the genes required to add the first glycose to each of the three heptose residues of the LPS inner core. In each case this addition can facilitate further oligosaccharide extension. lgtF is invariably present in strains and the product has a function in adding the glucose to the first heptose. lic2C is present in half the strains and was found to add a glucose to the second heptose. Insertion of lic2C into a strain that does not naturally contain it resulted in hexose incorporation from the second heptose of the LPS. The product of the lpsA gene can add a glucose or galactose to the third heptose. By allelic replacement of lpsA between strains it is shown that the sequence of the gene can be the sole determinant of this specificity. Thus, lgtF, lic2C and lpsA make significant but very distinct contributions to the conservation and variable patterns of oligosaccharide extensions seen in H. influenzae LPS.
Subject(s)
Bacterial Proteins/genetics , Gene Expression Regulation, Bacterial , Glucosyltransferases/genetics , Haemophilus influenzae/metabolism , Lipopolysaccharides/biosynthesis , Oligosaccharides/biosynthesis , Bacterial Proteins/metabolism , Blood Bactericidal Activity , Carbohydrate Conformation , Carbohydrate Sequence , Glucosyltransferases/metabolism , Haemophilus influenzae/genetics , Humans , Lipopolysaccharides/chemistry , Spectrometry, Mass, Electrospray IonizationABSTRACT
Otitis media, a common and often recurrent bacterial infection of childhood, is a major reason for physician visits and the prescription of antimicrobials. Haemophilus influenzae is the cause of approximately 20% of episodes of bacterial otitis media, but most strains lack the capsule, a factor known to play a critical role in the virulence of strains causing invasive H. influenzae disease. Here we show that in capsule-deficient (nontypeable) strains, sialic acid, a terminal residue of the core sugars of H. influenzae lipopolysaccharide (LPS), is a critical virulence factor in the pathogenesis of experimental otitis media in chinchillas. We used five epidemiologically distinct H. influenzae isolates, representative of the genetic diversity of strains causing otitis media, to inoculate the middle ear of chinchillas. All animals developed acute bacterial otitis media that persisted for up to 3 wk, whereas isogenic sialic acid-deficient mutants (disrupted sialyltransferase or CMP-acetylneuraminic acid synthetase genes) were profoundly attenuated. MS analysis indicated that WT bacteria used to inoculate animals lacked any sialylated LPS glycoforms. In contrast, LPS of ex vivo organisms recovered from chinchilla middle ear exudates was sialylated. We conclude that sialylated LPS glycoforms play a key role in pathogenicity of nontypeable H. influenzae and depend on scavenging the essential precursors from the host during the infection.
Subject(s)
Haemophilus Infections/etiology , Haemophilus influenzae/metabolism , Haemophilus influenzae/pathogenicity , Lipopolysaccharides/metabolism , N-Acetylneuraminic Acid/metabolism , Otitis Media/etiology , Animals , Base Sequence , Carbohydrate Sequence , Chinchilla , DNA, Bacterial/genetics , Disease Models, Animal , Haemophilus Infections/microbiology , Haemophilus influenzae/genetics , Humans , Lipopolysaccharides/chemistry , Lipopolysaccharides/toxicity , Models, Molecular , Molecular Sequence Data , Mutation , Otitis Media/microbiology , Phylogeny , Spectrometry, Mass, Electrospray Ionization , VirulenceABSTRACT
The structure of the lipopolysaccharide (LPS) from three Neisseria meningitidis strains was elucidated. These strains were nonreactive with mAbs that recognize common inner-core epitopes from meningococcal LPS. It is well established that the inner core of meningococcal LPS consists of a diheptosyl-N-acetylglucosamine unit, in which the distal heptose unit (Hep II) can carry PEtn at the 3 or 6 position or not at all, and the proximal heptose residue (Hep I) is substituted at the 4 position by a glucose residue. Additional substitution at the 3 position of Hep II with a glucose residue is also a common structural feature in some strains. The structures of the O-deacylated LPSs and core oligosaccharides of the three chosen strains were deduced by a combination of monosaccharide analysis, NMR spectroscopy and MS. These analyses revealed the presence of a structure not previously identified in meningococcal LPS, in which an additional beta-configured glucose residue was found to substitute Hep I at the 2 position. This provided the structural basis for the nonreactivity of LPS with these mAbs. The determination of this novel structural feature identified a further degree of variability within the inner-core oligosaccharide of meningococcal LPS which may contribute to the interaction of meningococcal strains with their host.
Subject(s)
Lipopolysaccharides/chemistry , Lipopolysaccharides/isolation & purification , Neisseria meningitidis/chemistry , Oligosaccharides/chemistry , Carbohydrate Conformation , Carbohydrate Sequence , Magnetic Resonance Spectroscopy , Molecular Sequence Data , Neisseria meningitidis/growth & development , Neisseria meningitidis/immunology , Oligosaccharides/isolation & purification , Spectrometry, Mass, Electrospray IonizationABSTRACT
Lipopolysaccharide (LPS) is a major virulence determinant of the human bacterial pathogen Haemophilus influenzae. Structural elucidation of the LPS from H. influenzae type b strain RM7004 was achieved by using electrospray ionization mass spectrometry (ESI-MS) and high-field NMR techniques on delipidated LPS and core oligosaccharide samples of LPS. It was found that the organism elaborates a series of related LPS glycoforms having a common inner-core structure, but differing in the number and position of attached hexose residues. LPS glycoforms containing between four and nine hexose residues were structurally characterized. The inner-core element was determined to be L-alpha-D-Hepp-(1-->2)-[PEA-->6]-L-alpha-D-Hepp-(1-->3)-[beta-D-Glcp-(1-->4)]-L-alpha-D-Hepp-(1-->5)-[P-->4]-alpha-KDOp-(2-->, a structural feature which has been identified in every H. influenzae strain investigated to date. Two major groups of isomeric glycoforms were characterized in which the terminal Hepp residue of the inner-core element was either substituted at the O-2 position with a beta-D-Galp residue or not. The structures of the major LPS glycoforms were found to have oligosaccharide chain extensions from O-3 of the middle Hepp residue. Glycoforms containing five and six hexose residues were most abundant and were shown to carry the tetrasaccharide unit alpha-D-Galp-(1-->4)-beta-D-Galp-(1-->4)-beta-D-Glcp-(1-->4)-alpha-D-Glcp at the O-3 position of the middle heptose. This tetrasaccharide displays the globoside trisaccharide (globotriose) as a terminal epitope, a structure that is found on many human cells (P(k) blood group antigen) and which is thought to be an important virulence determinant for H. influenzae. LPS glycoforms were characterized that had further chain extension from the beta-D-Glcp-(1--> residue of the proximal Hepp. In the fully extended LPS (Hex9/Hex8' glycoforms), both the proximal and middle heptose residues carried tetrasaccharide chains displaying terminal globotriose epitopes. In addition, the LPS was found to carry phosphorylcholine and O-acetyl groups.
Subject(s)
Haemophilus influenzae type b/chemistry , Lipopolysaccharides/chemistry , Trisaccharides/chemistry , Electrophoresis, Capillary , Lipopolysaccharides/isolation & purification , Oligosaccharides/chemistry , Spectrometry, Mass, Electrospray IonizationSubject(s)
Bacteria/chemistry , Glycolipids/chemistry , Lipopolysaccharides/chemistry , Oligosaccharides/chemistry , Carbohydrate Conformation , Carbohydrate Sequence , Cell Wall/chemistry , Conserved Sequence , Electrophoresis, Capillary/methods , Glycolipids/analysis , Glycolipids/isolation & purification , Haemophilus influenzae/chemistry , Indicators and Reagents , Lipopolysaccharides/analysis , Lipopolysaccharides/isolation & purification , Molecular Sequence Data , Oligosaccharides/isolation & purification , Spectrometry, Mass, Electrospray Ionization/methodsABSTRACT
A sialylated lacto-N-neotetraose (Sial-lNnT) structural unit was identified and structurally characterized in the lipopolysaccharide (LPS) from the genome-sequenced strain Rd [corrected] (RM118) of the human pathogen Haemophilus influenzae grown in the presence of sialic acid. A combination of molecular genetics, MS and NMR spectroscopy techniques showed that this structural unit extended from the proximal heptose residue of the inner core region of the LPS molecule. The structure of the Sial-lNnT unit was identical to that found in meningococcal LPS, but glycoforms containing truncations of the Sial-lNnT unit, comprising fewer residues than the complete oligosaccharide component, were not detected. The finding of sialylated glycoforms that were either fully extended or absent suggests a novel biosynthetic feature for adding the terminal tetrasaccharide unit of the Sial-lNnT to the glycose acceptor at the proximal inner core heptose.