Transcriptomic analysis identifies growth rate modulation as a component of the adaptation of mycobacteria to survival inside the macrophage.

The adaptation of the tubercle bacillus to the host environment is likely to involve a complex set of gene regulatory events and physiological switches in response to environmental signals. In order to deconstruct the physiological state of Mycobacterium tuberculosis in vivo, we used a chemostat model to study a single aspect of the organism's in vivo state, slow growth. Mycobacterium bovis BCG was cultivated at high and low growth rates in a carbon-limited chemostat, and transcriptomic analysis was performed to identify the gene regulation events associated with slow growth. The results demonstrated that slow growth was associated with the induction of expression of several genes of the dormancy survival regulon. There was also a striking overlap between the transcriptomic profile of BCG in the chemostat model and the response of M. tuberculosis to growth in the macrophage, implying that a significant component of the response of the pathogen to the macrophage environment is the response to slow growth in carbon-limited conditions. This demonstrated the importance of adaptation to a low growth rate to the virulence strategy of M. tuberculosis and also the value of the chemostat model for deconstructing components of the in vivo state of this important pathogen.

Compiling a molecular inventory for Mycobacterium bovis BCG at two growth rates: evidence for growth rate-mediated regulation of ribosome biosynthesis and lipid metabolism.

An experimental system of Mycobacterium tuberculosis growth in a carbon-limited chemostat has been established by the use of Mycobacterium bovis BCG as a model organism. For this model, carbon-limited chemostats with low concentrations of glycerol were used to simulate possible growth rates during different stages of tuberculosis. A doubling time of 23 h (D = 0.03 h(-1)) was adopted to represent cells during the acute phase of infection, whereas a lower dilution rate equivalent to a doubling time of 69 h (D = 0.01 h(-1)) was used to model mycobacterial persistence. This chemostat model allowed the specific response of the mycobacterial cell to carbon limitation at different growth rates to be elucidated. The macromolecular (RNA, DNA, carbohydrate, and lipid) and elemental (C, H, and N) compositions of the biomass were determined for steady-state cultures, revealing that carbohydrates and lipids comprised more than half of the dry mass of the BCG cell, with only a quarter of the dry weight consisting of protein and RNA. Consistent with studies of other bacteria, the specific growth rate impacts on the macromolecular content of BCG and the proportions of lipid, RNA, and protein increased significantly with the growth rate. The correlation of RNA content with the growth rate indicates that ribosome production in carbon-limited M. bovis BCG cells is subject to growth rate-dependent control. The results also clearly show that the proportion of lipids in the mycobacterial cell is very sensitive to changes in the growth rate, probably reflecting changes in the amounts of storage lipids. Finally, this study demonstrates the utility of the chemostat model of mycobacterial growth for functional genomic, physiology, and systems biology studies.

Mediastinitis associated with foreign body erosion of the esophagus in children.

OBJECTIVE: Timely and experienced intervention for esophageal foreign bodies generally allows for removal with minimal morbidity. However, esophageal foreign bodies present a risk for esophageal perforation and subsequent mediastinitis, especially if the diagnosis of the foreign body is delayed. Although much has been written about the management of esophageal foreign bodies and their complications, little has been mentioned in recent literature about the specific complication of mediastinitis. This review was performed to examine our experience with this uncommon complication of esophageal foreign bodies. METHODS: A retrospective review of the esophageal foreign body database at Children's Hospital of Wisconsin from 1987 to 1997 was performed to identify patients with esophageal foreign bodies and subsequent mediastinitis. RESULTS: Four patients with esophageal perforation with associated mediastinitis secondary to retained esophageal foreign bodies were identified. Three of the four patients were treated with conservative measures consisting of foreign body removal, intravenous antibiotics and discontinuing of oral nutrition. These patients all achieved resolution of their mediastinitis and esophageal perforation with subsequent return to normal diets and no significant morbidity. One patient, with vascular erosion, required aggressive, invasive therapy. CONCLUSION: From review of this limited number of patients, in the absence of major vascular erosion, conservative methods of treating children with foreign body esophageal perforation and subsequent mediastinitis appears to be effective.

Computed tomography vs. magnetic resonance imaging of acute bacterial sinusitis: a rabbit model.

PURPOSE: Computed topography (CT) and magnetic resonance imaging (MRI) are important, both clinically and in a research setting, in assessing bacterial sinusitis (BS). The use of CT scanning to evaluate sinus opacification in a reversible model of rabbit acute sinusitis has been reported. MRI offers the potential for better visualization of soft tissue and fluid changes within the paranasal sinuses. MRI has potential as a research tool in animal models of sinusitis. This article compares the use of CT and MRI in measuring maxillary sinus opacification in rabbits during experimental, reversible BS. MATERIALS AND METHODS: In 2 independent trials, New Zealand White rabbits were imaged for baseline anatomy, and BS was generated by sinus inoculation with Staphylococcus aureus. Serial imaging was performed as a measure of the progression and resolution of BS during the trials. Two experienced, independent reviewers then scored each CT and MRI for percent opacification of the maxillary sinus. These scores were analyzed to assess the degree of agreement between the reviewers. RESULTS: The correlation coefficients for CT and MRI were 0.6816 and 0.3584, respectively. The Z-statistic comparing these correlation coefficients was significant (P < .0001), indicating that CT is a more precise measure of reversible BS in this rabbit model. Differences in mean scan time and cost per scan were also significantly different (P < .0001), with CT being both quicker and less expensive. CONCLUSIONS: Greater interobserver consistency of scan interpretation, with less time and cost, make CT the preferred tool for measuring BS in this rabbit model. Attributes of MRI such as better resolution of fluid-tissue interfaces and custom surface coil design for visualization of specific anatomic structures are discussed as they may increase the effectiveness of MRI as an imaging modality in future sinusitis research.

Interleukin-1 receptor antagonist as an adjunct in the treatment of Haemophilus influenzae otitis media in the chinchilla.

OBJECTIVES: This purpose of this study was to investigate the effect of blockade of the inflammatory cytokine pathway on experimentally induced otitis media in the chinchilla model. STUDY DESIGN: Pilot, randomized placebo-controlled trial. METHODS: Ampicillin-sensitive Haemophilus influenzae otitis media was induced in 45 adult chinchillas. The animals were randomly assigned to the following treatment groups: 1) transbullar injections (TBI) of interleukin-1 receptor antagonist (IL-1ra) and intramuscular ampicillin, 2) TBI of saline and intramuscular ampicillin, 3) TBI of IL-1ra and intramuscular sa-1 line or 4) TBI of saline and intramuscular saline. Blinded investigators measured resolution of otitis media by otomicroscopy, tympanogram, and culture results. RESULTS: Comparisons were made between the treatment groups to assess the ability of IL-1ra to assist with resolution of otitis media using exact two-group binomial tests with the StatXact statistical program. The group with TBI of IL-1ra and intramuscular ampicillin as a treatment demonstrated trends suggesting more rapid resolution of positive cultures and more rapid and complete return to normal results on tympanograms and otomicroscopic findings compared with the group treated with TBI of saline and intramuscular ampicillin. These trends did not achieve statistical significance with the relatively small sample sizes used in this pilot study. CONCLUSIONS: This investigation provides further evidence that the inflammatory cytokine cascade plays a significant role in the pathophysiology of otitis media and that modulation of this inflammatory pathway may provide novel and efficacious treatments for otitis media Further studies with larger groups of animals are warranted to determine whether the trends identified in this pilot study are reproducible and achieve statistical significance.

Pierre Robin sequences: secondary respiratory difficulties and intrinsic feeding abnormalities.

OBJECTIVE: There is considerable variation in opinion regarding the optimal management of patients with Pierre Robin sequence (PRS). No single method of airway intervention or feeding strategy is universally appropriate and effective. This study was performed to examine methods used for airway and feeding management and to identify specific problems encountered. STUDY DESIGN: A retrospective study of 252 patient charts between 1989 and 1997 at Children's Hospital of Wisconsin. METHODS: Patient information was collected regarding perinatal history, genetics evaluation, and airway and feeding evaluations and intervention. A group of 47 patients was determined as having PRS. RESULTS: Secondary respiratory difficulties, defined as respiratory abnormalities in addition to the expected PRS obstruction, were identified in 23% of patients. Also, intrinsic feeding abnormalities not associated with airway obstruction were identified in 11% of patients. Analysis by Fisher's Exact Test revealed patients with a syndromic diagnosis to have a significantly higher rate for tracheotomies and gastrostomy tube placement (P = .041, and P = .0004, respectively). Syndromic patients were also found to have significantly lower Apgar scores and longer hospital stays. Positioning techniques, tongue-lip adhesion, and tracheotomy were also employed effectively with specific indications and specific difficulties that need to be considered. CONCLUSION: Patients with PRS require thorough airway and feeding evaluation. Those with additional syndromic diagnoses demonstrate higher rates of more invasive interventions. Patients with PRS must undergo individualized approaches with consideration of multiple factors for successful management.

Prevalence of chronic otitis media with effusion in a pediatric tracheotomy population: a retrospective review.

The prevalence of chronic otitis media with effusion (COME) was investigated in a 4-year retrospective study of a pediatric tracheotomy population followed in the outpatient Tracheotomy-Ventilation Clinic of Children's Hospital of Wisconsin. After exclusions, 83 patients comprised the study population. In a given patient, COME was defined by the presence of middle ear effusion in more than 50% of ear evaluations during the 4-year study period, or tympanostomy tube placement. The prevalence of COME was 60% in the study population as a whole. Special population groups had prevalence as follows: 90% in craniofacial anomaly patients, 79% in chronically ventilated patients, and 48% in nonventilated patients. Chronically ventilated patients had a statistically significant higher prevalence of COME than the nonventilated group (P < 0.025). These data indicate that COME is a prevalent condition in the pediatric tracheotomy population.

Pediatric fibromyalgia and dizziness: evaluation of vestibular function.

Twelve children with fibromyalgia and complaints of chronic dizziness were evaluated with both clinical office maneuvers of vestibular function and laboratory tests composed of electronystagmography and sinusoidal harmonic acceleration rotary chair testing. All test results were normal for spontaneous nystagmus with or without visual fixation, oculocephalic reflex, dynamic visual acuity, head-shaking nystagmus, Quix test, and Dix-Hallpike maneuver. Electronystagmography test results were essentially normal for saccades, gaze, Dix-Hallpike, pendular tracking, and caloric evaluation. Rotary chair testing was normal in all 12 patients. These findings suggest that central (brainstem) and peripheral vestibular (inner ear) mechanisms do not account for the complaints of dizziness in the pediatric patient with fibromyalgia. The common musculoskeletal abnormalities of fibromyalgia may affect their proprioceptive orientation, therefore giving them a sense of imbalance.

Otitis media in infants aged 0-8 weeks: frequency of associated serious bacterial disease.

OBJECTIVE: To determine the frequency of serious bacterial infection in well appearing infants aged 0-8 weeks with isolated otitis media (OM). METHODS: Infants with confirmed OM underwent tympanocentesis with middle ear fluid (MEF) culture and complete sepsis evaluation. Enrolled infants were admitted to the hospital for parenteral antibiotics until blood, urine, and CSF cultures were negative for 48 hours. RESULTS: Forty non-toxic appearing infants were enrolled between January 1994 and April 1995, of whom 15 (38%) had a documented rectal temperature > or =38 degrees C. Bacterial pathogens were isolated from MEF cultures in 25 (62.5%) infants. All afebrile infants had negative blood, urine, and cerebrospinal fluid cultures (upper limit (UL) 95% CI 0.11). Only two febrile infants had positive cultures from sites other than the MEF (UL 95% CI 0.36). CONCLUSION: In our study population, previously healthy, non-toxic appearing afebrile infants aged 2-8 weeks and having isolated OM infrequently have an associated serious bacterial infection, suggesting that outpatient treatment with oral antibiotics and close follow-up may be an option. Further studies with large numbers of infants are necessary to confirm this conclusion.

Kimura's disease: an unusual cause of cervical tumour.

An 11 year old Chinese boy developed a unilateral cervical mass associated with pronounced eosinophilia and a marked increase in IgE concentrations. A biopsy sample showed massive eosinophilic tissue infiltration consistent with Kimura's disease. This disorder should be suspected when the clinical triad of painless unilateral cervical adenopathy, hypereosinophilia, and hyper-IgE is present, particularly in male Asian patients.

Massive blood loss during tonsillectomy in a child with congenital venous malformation.

Tonsillectomy and adenoidectomy have become frequently performed outpatient procedures and are generally considered to have a low morbidity profile. Postoperative haemorrhage remains a rare but important complication, while intraoperative uncontrollable bleeding is extremely uncommon. A child with congenital vascular malformation of the lip and oropharynx undergoing tonsillectomy experienced massive blood loss, subsequent resuscitation and significant perioperative morbidity including a prolonged intensive care unit stay. Preoperative/preanaesthetic nasopharyngoscopic exam and magnetic resonance imaging did not reveal vascular prominence of the tonsils. Preoperative consideration of angiography or magnetic resonance angiography may be prudent to avoid this potentially fatal complication.

Antimicrobial effect on rabbit sinusitis after temporary ostial occlusion.

A key precipitating factor in the pathogenesis of acute bacterial sinusitis (ABS) is ostiomeatal obstruction. It has been postulated that ABS cannot resolve until the sinus ostium is patent. The primary purpose of this study is to quantify sinusitis resolution after temporary ostial occlusion in a rabbit model. A secondary aim is to quantify bacterial clearance with and without antimicrobial therapy in Staphylococcus aureus infected sinuses. A blinded, placebo controlled study in 10 New Zealand white rabbits was performed using Merocel as a temporary maxillary sinus ostial obstruction. Computerized tomography (CT) of the maxillary sinuses was obtained before and after bilateral ostial occlusion; sinuses were cultured and then the left sinus was injected with approximately 10(8) cfu/mL S. aureus. CT imaging and sinus cultures were obtained and then the ostial plugs were removed. Serial CT and cultures were done until sinusitis resolved and cultures were negative for S. aureus. Mean CT sinusitis scores increased with ostial obstruction and decreased with ostial plug removal (P < 0.0001 and P < 0.001). Injection of S. aureus did not significantly change mean CT sinusitis scores despite being cultured from 45% of sinuses. Antimicrobial therapy was not significant in reducing mean CT scan sinusitis scores or positive cultures. Resolution of mucosal swelling is more dependent on relief of ostial obstruction rather than antimicrobial therapy in this rabbit model.

Pediatric sensorineural hearing loss after temporal bone radiation.

In adults, sensorineural hearing loss (SNHL) resulting from megavoltage temporal bone radiation therapy (RT) is dose dependent. A review of the literature reveals only two cases of pediatric SNHL after RT without chemotherapy. This report presents four cases of late onset, asymmetric SNHL after RT in children treated for posterior fossa tumors. The children were treated with surgical resection of the tumor, followed by RT of 50 to 54 gray and no chemotherapy. These children, without evidence of tumor recurrence, developed severe SNHL 18 to 36 months after the completion of RT. Although no definite audiometric pattern was seen, most of the patients had a predominately high frequency SNHL in the poorer hearing ear, and fluctuant hearing in the better ear, without evidence of osteoradionecrosis or otitic infection. A review of the literature suggests that injury to the outer hair cells and cochlear neurons of the basal turn of the cochlea are possible sources for the hearing loss. Pretreatment audiologic evaluation as well as a minimum of 3 years of evaluations following RT would be prudent.

Proximal pH-metry for diagnosis of upper airway complications of gastroesophageal reflux.

Otolaryngologic complications of gastroesophageal reflux (GER) are well described in adults, but this relationship has not been as carefully studied in children. We reviewed 26 dual pH-probe studies performed on 22 children with upper airway symptoms. The proximal probe was placed in the nasopharynx or hypopharynx. The distal probe was placed in the mid-proximal oesophagus. The proximal recording was considered normal if no episodes of pH < 4 were recorded. Indications for the studies were upper airway obstruction (UAO) and congenital choanal atresia (CCA). The age range was from 2 weeks to 47 months. The distal pH probe study was normal in 13 of 22 patients overall. Seventeen UAO patients had abnormal proximal pH probe studies. After treatment, 16 of 17 had improved airways. Twelve with UAO (67%) were premature and/or had developmental delay. Three CCA patients had abnormal proximal pH-probe studies and all improved after treatment. Four follow-up pH studies were normal or improved. GER-induced UAO is more frequent in infants or children with a history of prematurity or developmental delay. Proximal pH-metry is a useful technique to document the relationship between upper airway symptoms and GER. Patients with GER-induced UAO should undergo endoscopy to rule out simultaneous airway lesions.

Gastroesophageal reflux complicating choanal atresia repair.

Four infants with bilateral congenital choanal atresia (CCA) underwent transpalatal (3) or transnasal (1) repairs. Postoperatively all four infants experienced gastroesophageal reflux (GER) with intermittent nasal reflux. GER was documented by GER radionuclide scanning in one patient and by dual nasopharyngeal and esophageal pH probe studies in the remaining three patients. The infants with documented GER required prolonged stenting and dilations for choanal restenosis and granulations. The literature emphasizes the importance of the technical repair for prevention of these complications; GER can be a significant complicating factor.

Pediatric laryngeal granular cell tumor.

Granular cell tumor of the larynx is an uncommon, benign tumor which has rarely been described in the pediatric population. Fewer than 10 cases in children under the age of 10 years have been reported. This paper describes two pediatric patients: An eight-year-old boy with a seven-year history of hoarseness due to an anterior subglottic tumor, and an 11-year-old boy with a one-year history of hoarseness due to a left true vocal cord tumor. Subglottic involvement by laryngeal granular cell tumor is rare in adults, but has been seen in half of the reported cases in the pediatric population. The clinical course of granular cell tumor and its pathology are reviewed.

Microtrapdoor flap repair of laryngeal and tracheal stenosis.

Twenty patients have undergone repair of laryngeal and tracheal stenosis by microtrapdoor accessing of scar or soft tissue and removal with the carbon dioxide laser. A total of 34 flap procedures were performed in the 20 patients. Follow-up ranged from 8 months to 4 years, and 30 of these flaps were considered successful on the basis of improvement of the airway. The only complications were postoperative granulation tissue in 2 patients that responded to endoscopic removal.