Molecular magnetic resonance imaging.

Molecular MRI (mMRI) is a special implementation of Molecular Imaging for the non-invasive visualisation of biological processes at the cellular and molecular level. More specifically, mMRI comprises the contrast agent-mediated alteration of tissue relaxation times for the detection and localisation of molecular disease markers (such as cell surface receptors, enzymes or signaling molecules), cells (e.g. lymphocytes, stem cells) or therapeutic drugs (e.g. liposomes, viral particles). MRI yields topographical, anatomical maps; functional MRI (fMRI) provides rendering of physiologic functions and magnetic resonance spectroscopy (MRS) reveals the distribution patterns of some specific metabolites. mMRI provides an additional level of information at the molecular or cellular level, thus extending MRI further beyond the anatomical and physiological level. These advances brought by mMRI are mandatory for MRI to be competitive in the age of molecular medicine. mMRI is already today increasingly used for research purposes, e.g. to facilitate the examination of cell migration, angiogenesis, apoptosis or gene expression in living organisms. In medical diagnostics, mMRI will pave the way toward a significant improvement in early detection of disease, therapy planning or monitoring of outcome and will therefore bring significant improvement in the medical treatment for patients.In general, Molecular Imaging demands high sensitivity equipment, capable of quantitative measurements to detect probes that interact with targets at the pico- or nanomolar level. The challenge to detect such sparse targets can be exemplified with cell surface receptors, a common target for molecular imaging. At high expression levels (bigger than 106 per cell) the receptor concentration is approx. 10(15) per ml, i.e. the concentration is in the micromole range. Many targets, however, are expressed in even considerably lower concentrations. Therefore the most sensitive modalities, namely nuclear imaging (PET and SPECT) have always been at the forefront of Molecular Imaging, and many nuclear probes in clinical use today are already designed to detect molecular mechanisms (such as FDG, detecting high glucose metabolism). In recent years however, Molecular Imaging has commanded attention from beyond the field of nuclear medicine. Further imaging modalities to be considered for molecular imaging primarily include optical imaging, MRI and ultrasound.

Safety of pediatric bedside tracheostomy in the intensive care unit.

BACKGROUND: Elective bedside pediatric tracheostomies in the intensive care unit have not been widely reported. Unlike in the adult population, this is not yet considered a safe or routine procedure in the pediatric population. We performed a preliminary study suggesting that bedside pediatric tracheostomies can be done safely and at reduced cost. DESIGN: Retrospective medical chart review. SETTING: Tertiary care referral center at a single university hospital. PATIENTS: Fifty-seven patients, ranging in age from 15 days to 8 years. Thirty operating room tracheostomies and 27 bedside tracheostomies were performed during a 6-year period. The mean age of the patients was 20.5 months, with no significant age difference between the 2 groups. The top 3 diagnoses necessitating tracheostomy were laryngotracheal disorders (18 patients [32%]), bronchopulmonary dysplasia (9 [16%]), and neurologic disorders (6 [11%]). INTERVENTIONS: Tracheostomy. MAIN OUTCOME MEASURES: The initial 48-hour postoperative period was examined to compare complication rates between groups. RESULTS: Overall, the 2 groups had similar complication rates (chi(2) = 0.12; P =.73). The operating room group had 3 complications (10%) related to bleeding, infection, and pneumothorax. The bedside group had 2 complications (7%), both involving pneumothorax. Each operating room tracheostomy incurred charges totaling $1693 vs $235 for each bedside tracheostomy. CONCLUSIONS: Historically, pediatric tracheostomy has been viewed as a technically demanding procedure with a high complication rate, thus encouraging routine operating room use. We found that pediatric tracheostomy performed in the intensive care unit, with attention to prudent patient selection and adherence to consistent, sound techniques, was as safe as operating room tracheostomy.

Lipoinjection augmentation of the soft palate for velopharyngeal stress incompetence.

OBJECTIVES/HYPOTHESIS: Velopharyngeal stress incompetence in professional musicians is an uncommon but potentially career-ending problem. Pharyngeal flaps, V-Y palatal pushback procedures, Teflon or collagen injection of the posterior pharyngeal wall, and speech therapy have all been used to address this problem. The ideal procedure for this subset of patients with velopharyngeal incompetence (VPI) with high-pressure, mild VPI would be one that combines low morbidity and an expedient recovery for the busy musician. We describe an approach of endoscopically assisted autologous lipoinjection of the soft palate. STUDY DESIGN: A retrospective review of our experience treating high-pressure stress VPI in two professional musicians. METHODS: Literature review and retrospective chart review. RESULTS: Two musicians underwent autologous lipoinjection of the soft palate for stress VPI. Patients resumed full play within 2 weeks of the operation with no serious complications. There has been no recurrence of the VPI after 18 and 12 months of follow-up, respectively. CONCLUSIONS: Velopharyngeal stress incompetence in musicians is an uncommon disorder. Velopharyngeal incompetence in these patients may not present as in a typical manner with hypernasality but may go undiagnosed for years mistakenly rationalized as a declining performance ability rather than a curable structural problem. The performance demands of professional musicians necessitate a timely solution to their VPI. More precise and limited contouring of palatal bulk can be achieved through the lipoinjection technique than compared with traditional palatal V-Y pushback or a standard pharyngeal flap. Lipoinjection of the palate can be performed as an outpatient procedure with only minor discomfort and an expedient recovery for the career musician.

Characterization of a human pancreatic secretory trypsin inhibitor mutant binding to Legionella pneumophila as determined by a quartz crystal microbalance.

We describe the isolation from a large phagemid library of a human pancreatic secretory trypsin inhibitor (hPSTI) mutant that binds to Legionella pneumophila. To gain further insight into the binding kinetics of the isolated hPSTI mutant, an immunosensing system based on a quartz crystal microbalance (QCM) was used. In contrast to ELISA procedures, k(on) and k(off) rates could be derived from the QCM sensograms. Thus, it is possible to characterize specific intermolecular interactions between proteins and phages isolated from large phage display libraries by QCM.

Determination of phage antibody affinities to antigen by a microbalance sensor system.

Over the past decade, phage display has maturated to be a frequently used method for the generation of monoclonal antibodies of human origin. The essential step of this method is the "biopanning" of phage carrying functional antibody fragments on their surface on an immobilized antigen. The screening of large combinatorial gene libraries with this method usually leads to a set of diverse clones specifically binding to the antigen that need to be characterized further. Beside its specificity, the key parameter to be determined is the affinity of the recombinant antibody fragment to its antigen. Here, we present a mass sensitive microsensor method that allows the estimation of antibody affinity directly from the phage supernatant. Binding of phage antibodies to the antigen immobilized on a quartz crystal microbalance (QCM) induced a mass dependent decrease in frequency. This principle was used to determine the apparent affinity of a single-chain (sc)Fv antibody against the RNA polymerase of Drosophila melanogaster presented on the surface of a filamentous phage (M13) from its association and dissociation rates. The apparent affinity obtained is in accordance with the affinity of the scFv fragment as determined by conventional equilibrium enzyme-linked immunosorbent assay (ELISA) and plasmon resonance methods.

Quartz crystal microbalance (QCM) as a device for the screening of phage libraries.

An immunosensing system based on a quartz crystal microbalance (QCM) is presented for the selection of both antigen specific recombinant antibodies and antigen specific human pancreatic secretory trypsin inhibitor (hPSTI) mutants isolated from large phage libraries. The QCM was integrated into a flow injection analysis system for the straightforward analysis of large sample numbers. Measurements were performed using a biotinylated antigen immobilized by streptavidin onto the gold surface of the quartz crystal and phages displaying recombinant antibodies or hPSTI mutants. The results obtained by the QCM were in accordance to those of a well established enzyme linked immunosorbent assay (ELISA). Therefore, the QCM is well suited for the detection of single high affinity clones isolated from large phage display libraries.

Subinhibitory concentrations of antimicrobial agents reduce the uptake of Legionella pneumophila into Acanthamoeba castellanii and U937 cells by altering the expression of virulence-associated antigens.

We determined the MICs of ampicillin, ciprofloxacin, erythromycin, imipenem, and rifampin for two clinical isolates of Legionella pneumophila serogroup 1 by 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) reduction assay and by quantitative culture. To test the influence of subinhibitory concentrations (sub-MICs) of antimicrobial agents on Legionella uptake into Acanthamoeba castellanii and U937 macrophage-like cells, both strains were pretreated with 0.25 MICs of the antibiotics for 24 h. In comparison to that for the untreated control, subinhibitory concentrations of antibiotics significantly reduced Legionella uptake into the host cells. Measurement of the binding of monoclonal antibodies against several Legionella antigens by enzyme-linked immunoassays indicated that sub-MIC antibiotic treatment reduced the expression of the macrophage infectivity potentiator protein (Mip), the Hsp 60 protein, the outer membrane protein (OmpM), an as-yet-uncharacterized protein of 55 kDa, and a few lipopolysaccharide (LPS) epitopes. In contrast, the expression of some LPS epitopes recognized by monoclonal antibodies 8/5 and 30/4 as well as a 45-kDa protein, a 58-kDa protein, and the major outer membrane protein (OmpS) remained unaffected.

Unsuspected subglottic stenosis in a two-year-old.

Unsuspected subglottic stenosis was encountered in the operating room in a 23-month-old girl who had been diagnosed having Vater syndrome without the component of tracheooesophageal fistula. Her scheduled elective thumb reconstruction was postponed until tracheal reconstruction was performed. A rational approach to handle this situation is described.

[Eradication of Legionella from warm water systems--documentation of our own experiences with thermal disinfection]. / Sanierung von Warmwassersystemen mit Legionellenbefall--Dokumentation eigener Erfahrungen mit thermischer Desinfektion.

A nosocomial case of Legionellosis in a recently built hospital was the reason for an investigation and thermal disinfection of the complete warm water distribution system. Furthermore weak points in the tubing of the warm water system, which promoted the contamination of potable water, were eliminated as far as technically possible. A lasting reduction of the numbers of Legionella spp. isolated could be measured (factor 10-1000), but a complete decontamination of the warm water distribution system was not possible. As Legionella spp. may cause serious infections in immunodeficient patients, additional measures for the disinfection of the hospital water distribution system must be taken into consideration.

Anatomic and audiologic sequelae after tympanostomy tube insertion or prolonged antibiotic therapy for otitis media.

In this study the anatomic and hearing sequelae are characterized for 43 children (86 ears) with recurrent acute otitis media and/or persistent otitis media with effusion who had received three or more tympanostomy tube placements and 46 children (92 ears) managed medically with repeated courses of therapeutic and/or or prophylactic antibiotics. In the surgical group 311 tympanostomy tube surgeries had been performed and in the medical group 1334 episodes of acute otitis media and/or 186 episodes of otitis media with effusion occurred. Tympanosclerosis was found in 6.5% of the medical group ears and 52.3% of the surgical group ears. Tympanic atrophy occurred in 4.3% of the medical group ears and 40.7% of the surgical group ears. The duration of the presence of the tympanostomy tube significantly influenced the tympanic membrane. The presence of middle ear fluid at the time of tube insertion, particularly high viscosity ("glue") fluid, correlated with persisting sclerosis (P less than 0.00001) and reduced tympanic membrane mobility (P less than 0.00001) but not tympanic membrane atrophy (P = 0.94) later. Abnormal hearing, defined as a hearing threshold greater than 20 dB occurred in 9.3 to 18.7% of the surgical ears and in 3.7 to 9.0% of the medical ears depending on the hearing frequency tested. Medical management consisting of recurrent use of therapeutic and/or prophylactic antibiotics was associated with infrequent anatomic and audiologic sequelae. Repeated placement of tympanostomy tubes may be associated with the frequent occurrence of both anatomic and audiologic sequelae.

New imaging techniques in diagnosis of cerebrospinal fluid fistula.

The localization of a cerebrospinal fluid fistula producing cerebrospinal fluid otorrhea can be very difficult. However, the exact anatomic localization of the bony defect is important when selecting the surgical approach to repair. Case reports of two patients in whom spontaneous cerebrospinal fluid otorrhea occurred following pressure equalization tube placement for middle-ear effusion are presented. Nuclear magnetic imaging supplemented CT scan findings, providing noninvasive localization of the defect. Preoperative impressions were confirmed at surgery. In addition to discussing the use of magnetic resonance imaging in evaluating cerebrospinal fluid otorrhea, the literature will also be reviewed.

Anatomic findings and management of choanal atresia and the CHARGE association.

The CHARGE association is a collection of multisystem congenital anomalies including choanal atresia. A review of the literature failed to identify any specific findings that suggested the need to alter the management of choanal atresia in these patients. Our review of 24 patients with choanal atresia managed between 1974 and 1986 identified nine patients with the CHARGE criteria. These nine patients demonstrated a higher prevalence of surgical failures than the patients without the CHARGE association. The reasons are discussed, and computed tomographic scans demonstrate the anatomic findings of a more contracted nasopharynx and narrowed posterior choanal region. Thus, successful repairs require a more radical resection of the posterior nasal septum and lateral bony walls that can be achieved only with a transpalatal approach. The preoperative airways of CHARGE association patients are also at increased risk of obstruction and may require intubation or tracheotomy during the early life of the patient.

The role of C.T. scans in managing the orbital complications of ethmoiditis.

Thirty-three cases of ethmoidities with orbital complications were reviewed to determine the accuracy of clinical diagnosis and the benefit of CT scans in planning treatment. Patients were classified according to the Schramm et al. 1982 criteria of orbital involvement with ethmoiditis: periorbital cellulitis with chemosis (PCC)-9, and orbital cellulitis (OC)-11, subperiosteal abscess (SPA)-9, and orbital abscess (OA)-4. These patients received CT scans acutely for diagnostic purposes and demonstrated an 84% accuracy with the final clinical groupings. Of 33 patients, 9 had a shift in clinical classification based on the CT scan result interpreted by the Radiology Department or surgical findings. There were no false positives in the periorbital or orbital cellulitis patients, and no false negatives in the subperiosteal and orbital abscess patients. Thus classification changes caused no change from medical to surgical treatment in any of the cases. The conclusion is that a knowledgeable clinical exam established the correct grouping in 70% of the patients versus 82% with the CT scan. An urgent CT scan is advised for patients in clinical groups SPA, OA, or cavernous sinus thrombosis (CST) to determine the imminent need for surgery, as the cases may be underestimated. Patients with PC or PCC can be managed medically with elective CT scans not routinely indicated.