Clinical practice guideline: Tympanostomy tubes in children Rosenfeld, Richard M; Schwartz, Seth R; Pynnonen, Melissa A ...
Otolaryngology and head and neck surgery/Otolaryngology--head and neck surgery,
July 2013, Letnik:
149, Številka:
1 Suppl
Journal Article
Recenzirano
Odprti dostop
Insertion of tympanostomy tubes is the most common ambulatory surgery performed on children in the United States. Tympanostomy tubes are most often inserted because of persistent middle ear fluid, ...frequent ear infections, or ear infections that persist after antibiotic therapy. Despite the frequency of tympanostomy tube insertion, there are currently no clinical practice guidelines in the United States that address specific indications for surgery. This guideline is intended for any clinician involved in managing children, aged 6 months to 12 years, with tympanostomy tubes or being considered for tympanostomy tubes in any care setting, as an intervention for otitis media of any type.
The primary purpose of this clinical practice guideline is to provide clinicians with evidence-based recommendations on patient selection and surgical indications for and management of tympanostomy tubes in children. The development group broadly discussed indications for tube placement, perioperative management, care of children with indwelling tubes, and outcomes of tympanostomy tube surgery. Given the lack of current published guidance on surgical indications, the group focused on situations in which tube insertion would be optional, recommended, or not recommended. Additional emphasis was placed on opportunities for quality improvement, particularly regarding shared decision making and care of children with existing tubes. ACTION STATEMENTS: The development group made a strong recommendation that clinicians should prescribe topical antibiotic eardrops only, without oral antibiotics, for children with uncomplicated acute tympanostomy tube otorrhea. The panel made recommendations that (1) clinicians should not perform tympanostomy tube insertion in children with a single episode of otitis media with effusion (OME) of less than 3 months' duration; (2) clinicians should obtain an age-appropriate hearing test if OME persists for 3 months or longer (chronic OME) or prior to surgery when a child becomes a candidate for tympanostomy tube insertion; (3) clinicians should offer bilateral tympanostomy tube insertion to children with bilateral OME for 3 months or longer (chronic OME) and documented hearing difficulties; (4) clinicians should reevaluate, at 3- to 6-month intervals, children with chronic OME who did not receive tympanostomy tubes until the effusion is no longer present, significant hearing loss is detected, or structural abnormalities of the tympanic membrane or middle ear are suspected; (5) clinicians should not perform tympanostomy tube insertion in children with recurrent acute otitis media (AOM) who do not have middle ear effusion in either ear at the time of assessment for tube candidacy; (6) clinicians should offer bilateral tympanostomy tube insertion to children with recurrent AOM who have unilateral or bilateral middle ear effusion at the time of assessment for tube candidacy; (7) clinicians should determine if a child with recurrent AOM or with OME of any duration is at increased risk for speech, language, or learning problems from otitis media because of baseline sensory, physical, cognitive, or behavioral factors; (8) in the perioperative period, clinicians should educate caregivers of children with tympanostomy tubes regarding the expected duration of tube function, recommended follow-up schedule, and detection of complications; (9) clinicians should not encourage routine, prophylactic water precautions (use of earplugs, headbands; avoidance of swimming or water sports) for children with tympanostomy tubes. The development group provided the following options: (1) clinicians may perform tympanostomy tube insertion in children with unilateral or bilateral OME for 3 months or longer (chronic OME) and symptoms that are likely attributable to OME including, but not limited to, vestibular problems, poor school performance, behavioral problems, ear discomfort, or reduced quality of life and (2) clinicians may perform tympanostomy tube insertion in at-risk children with unilateral or bilateral OME that is unlikely to resolve quickly as reflected by a type B (flat) tympanogram or persistence of effusion for 3 months or longer (chronic OME).
The near universality of otitis media with effusion (OME) in children makes a comparative review of treatment modalities important. This study's objective was to compare the effectiveness of surgical ...strategies currently used for managing OME.
We identified 3 recent systematic reviews and searched 4 major electronic databases. Eligible studies included randomized controlled trials, nonrandomized trials, and cohort studies that compared myringotomy, adenoidectomy, tympanostomy tubes (tubes), and watchful waiting. Using established criteria, pairs of reviewers independently selected, extracted data, rated risk of bias, and graded strength of evidence of relevant studies. We incorporated meta-analyses from the earlier reviews and synthesized additional evidence qualitatively.
We identified 41 unique studies through the earlier reviews and our independent searches. In comparison with watchful waiting or myringotomy (or both), tubes decreased time with OME and improved hearing; no specific tube type was superior. Adenoidectomy alone, as an adjunct to myringotomy, or combined with tubes, reduced OME and improved hearing in comparison with either myringotomy or watchful waiting. Tubes and watchful waiting did not differ in language, cognitive, or academic outcomes. Otorrhea and tympanosclerosis were more common in ears with tubes. Adenoidectomy increased the risk of postsurgical hemorrhage.
Tubes and adenoidectomy reduce time with OME and improve hearing in the short-term. Both treatments have associated harms. Large, well-controlled studies could help resolve the risk-benefit ratio by measuring acute otitis media recurrence, functional outcomes, quality of life, and long-term outcomes. Research is needed to support treatment decisions in subpopulations, particularly in patients with comorbidities.
The American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF) has published a supplement to this issue featuring the new Clinical Practice Guideline: Tympanostomy Tubes in ...Children. To assist in implementing the guideline recommendations, this article summarizes the rationale, purpose, and key action statements. The 12 recommendations developed address patient selection, surgical indications for and management of tympanostomy tubes in children. The development group broadly discussed indications for tube placement, perioperative management, care of children with indwelling tubes, and outcomes of tympanostomy tube surgery. Given the lack of current published guidance on surgical indications, the group focused on situations in which tube insertion would be optional, recommended, or not recommended. Additional emphasis was placed on opportunities for quality improvement, particularly regarding shared decision making and care of children with existing tubes.
Hepatitis C virus NS3 helicase can unwind double-stranded DNA and RNA and has been proposed to form oligomeric structures. Here we examine the DNA unwinding activity of monomeric NS3. Oligomerization ...was measured by preparing a fluorescently labeled form of NS3, which was titrated with unlabeled NS3, resulting in a hyperbolic increase in fluorescence anisotropy and providing an apparent equilibrium dissociation constant of 236 nm. To evaluate the DNA binding activity of individual subunits within NS3 oligomers, two oligonucleotides were labeled with fluorescent donor or acceptor molecules and then titrated with NS3. Upon the addition of increasing concentrations of NS3, fluorescence energy transfer was observed, which reached a plateau at a 1:1 ratio of NS3 to oligonucleotides, indicating that each subunit within the oligomeric form of NS3 binds to DNA. DNA unwinding was measured under multiple turnover conditions with increasing concentrations of NS3; however, no increase in specific activity was observed, even at enzyme concentrations greater than the apparent dissociation constant for oligomerization. An ATPase-deficient form of NS3, NS3(D290A), was prepared to explore the functional consequences of oligomerization. Under single turnover conditions in the presence of excess concentration of NS3 relative to DNA, NS3(D290A) exhibited a dominant negative effect. However, under multiple turnover conditions in which DNA concentration was in excess to enzyme concentration, NS3(D290A) did not exhibit a dominant negative effect. Taken together, these data support a model in which monomeric forms of NS3 are active. Oligomerization of NS3 occurs, but subunits can function independently or cooperatively, dependent upon the relative concentration of the DNA.
Binding of NS3 helicase to DNA was investigated by footprinting with KMnO4, which reacts preferentially with thymidine residues in single-stranded DNA (ssDNA) compared to those in double-stranded DNA ...(dsDNA). A distinct pattern of reactivity was observed on ssDNA, which repeated every 8 nucleotides (nt) and is consistent with the known binding site size of NS3. Binding to a DNA substrate containing a partial duplex was also investigated. The DNA contained a 15 nt overhang made entirely of thymidine residues adjacent to a 22 bp duplex that contained thymidine at every other position. Surprisingly, the KMnO4 reactivity pattern extended from the ssDNA into the dsDNA region of the substrate. Lengthening the partial duplex to 30 bp revealed a similar pattern extending from the ssDNA into the dsDNA, indicating that NS3 binds within the duplex region. Increasing the length of the ssDNA portion of the partial duplex by 4 nt resulted in a shift in the footprinting pattern for the ssDNA by 4 nt, which is consistent with binding to the 3′-end of the ssDNA. However, the footprinting pattern in the dsDNA region was shifted by only 1–2 bp, indicating that binding to the ssDNA–dsDNA region was preferred. Footprinting performed as a function of time indicated that NS3 binds to the ssDNA rapidly, followed by slower binding to the duplex. Hence, multiple molecules of NS3 can bind along a ssDNA–dsDNA partial duplex by interacting with the ssDNA as well as the duplex DNA.
The hepatitis C virus (HCV) nonstructural protein 3 (NS3) is a multifunctional enzyme with serine protease and DEXH/D-box helicase domains. A crystal structure of the NS3 helicase domain (NS3h) was ...generated in the presence of a single-stranded oligonucleotide long enough to accommodate binding of two molecules of enzyme. Several amino acid residues at the interface of the two NS3h molecules were identified that appear to mediate a protein-protein interaction between domains 2 and 3 of adjacent molecules. Mutations were introduced into domain 3 to disrupt the putative interface and subsequently examined using an HCV subgenomic replicon, resulting in significant reduction in replication capacity. The mutations in domain 3 were then examined using recombinant NS3h in biochemical assays. The mutant enzyme showed RNA binding and RNA-stimulated ATPase activity that mirrored wild type NS3h. In DNA unwinding assays under single turnover conditions, the mutant NS3h exhibited a similar unwinding rate and only ∼2-fold lower processivity than wild type NS3h. Overall biochemical activities of the mutant NS3h were similar to the wild type enzyme, which was not reflective of the large reduction in HCV replicative capacity observed in the biological experiment. Hence, the biological results suggest that the known biochemical properties associated with the helicase activity of NS3h do not reveal all of the likely biological roles of NS3 during HCV replication. Domain 3 of NS3 is implicated in protein-protein interactions that are necessary for HCV replication.
HCV NS3 helicase exhibits activity toward DNA and RNA substrates. The DNA helicase activity of NS3 has been proposed to be optimal when multiple NS3 molecules are bound to the same substrate ...molecule. NS3 catalyzes little or no measurable DNA unwinding under single cycle conditions in which the concentration of substrate exceeds the concentration of enzyme by 5-fold. However, when NS3 (100 nm) is equimolar with the substrate, a small burst amplitude of ∼8 nm is observed. The burst amplitude increases as the enzyme concentration increases, consistent with the idea that multiple molecules are needed for optimal unwinding. Protein-protein interactions may facilitate optimal activity, so the oligomeric properties of the enzyme were investigated. Chemical cross-linking indicates that full-length NS3 forms higher order oligomers much more readily than the NS3 helicase domain. Dynamic light scattering indicates that full-length NS3 exists as an oligomer, whereas NS3 helicase domain exists in a monomeric form in solution. Size exclusion chromatography also indicates that full-length NS3 behaves as an oligomer in solution, whereas the NS3 helicase domain behaves as a monomer. When NS3 was passed through a small pore filter capable of removing protein aggregates, greater than 95% of the protein and the DNA unwinding activity was removed from solution. In contrast, only ∼10% of NS3 helicase domain and ∼20% of the associated DNA unwinding activity was removed from solution after passage through the small pore filter. The results indicate that the optimally active form of full-length NS3 is part of an oligomeric species in vitro.
Hepatitis C virus (HCV) infects over 170 million persons worldwide. It is the leading cause of liver disease in the U.S. and is responsible for most liver transplants. Current treatments for this ...infectious disease are inadequate; therefore, new therapies must be developed. Several labs have obtained evidence for a protein complex that involves many of the nonstructural (NS) proteins encoded by the virus. NS3, NS4A, NS4B, NS5A, and NS5B appear to interact structurally and functionally. In this study, we investigated the interaction between the helicase, NS3, and the RNA polymerase, NS5B. Pull-down experiments and surface plasmon resonance data indicate a direct interaction between NS3 and NS5B that is primarily mediated through the protease domain of NS3. This interaction reduces the basal ATPase activity of NS3. However, NS5B stimulates product formation in RNA unwinding experiments under conditions of excess nucleic acid substrate. When the concentrations of NS3 and NS5B are in excess of nucleic acid substrate, NS5B reduces the rate of NS3-catalyzed unwinding. Under pre-steady-state conditions, in which NS3 and substrate concentrations are similar, product formation increased in the presence of NS5B. The increase was consistent with 1:1 complex formed between the two proteins. A fluorescently labeled form of NS3 was used to investigate this interaction through fluorescence polarization binding assays. Results from this assay support interactions that include a 1:1 complex formed between NS3 and NS5B. The modulation of NS3 by NS5B suggests that these proteins may function together during replication of the HCV genome.
Scedosporium apiospermum, the asexual stage of Pseudoallescheria boydii, is a fungus ubiquitous in soil as well as organically polluted areas, where nitrogen‐containing compounds are abundant. It is ...an emerging opportunistic pathogen that can range from cutaneous to disseminated infection and can be fatal within months of diagnosis. Here we present a case of disseminated S. apiospermum infection with cutaneous manifestations in a 59‐year‐old woman with myelodysplastic syndrome, in remission from chronic lymphocytic leukemia, presented with pneumonia and deteriorating mental status. An X‐ray computed tomography scan showed three non‐contrast‐enhancing hypodensities affecting the brain. Many erythematous, indurated skin lesions, measuring 3–5 mm in diameter, were noted on her chest, shoulders and arms. Biopsies were submitted for culture and histology. Histopathologic examination revealed superficial and deep perivascular and periadnexal inflammatory infiltrates of lymphocytes and neutrophils. Scattered collections of fungal organisms were noted near the eccrine glands. The periodic acid Schiff with diastase stain showed the presence of variable sized spores and hyphae with some acute angle branching. Both tissue and blood cultures were positive for a single Scedosporium species. Histologically, eccrine or peri‐eccrine involvement by fungi may be an important finding for Scedosporium infection of the skin.
Harrison MK, Hiatt KH, Smoller BR, Cheung WL. A case of cutaneous Scedosporium infection in an immunocompromised patient.
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