Frederick K. Kozak

Apolipoprotein-mediated lipid antigen presentation in B cells provides a pathway for innate help by NKT cells

Natural killer T (NKT) cells are innate-like lymphocytes that recognize lipid antigens and have been shown to enhance B-cell activation and antibody production. B cells typically recruit T-cell help by presenting internalized antigens recognized by their surface antigen receptor. Here, we demonstrate a highly efficient means whereby human B cells present lipid antigens to NKT cells, capturing the antigen using apolipoprotein E (apoE) and the low-density lipoprotein receptor (LDL-R). ApoE dramatically enhances B-cell presentation of alpha-galactosylceramide (alphaGalCer), an exogenous CD1d presented antigen, inducing activation of NKT cells and the subsequent activation of B cells. B cells express the LDL-R on activation, and the activation of NKT cells by B cells is completely LDL-R dependent, as shown by blocking experiments and the complete lack of presentation when using apoE2, an isoform of apoE incapable of LDL-R binding. The dependence on apoE and the LDL-R is much more pronounced in B cells than we had previously seen in dendritic cells, which can apparently use alternate pathways of lipid antigen uptake. Thus, B cells use an apolipoprotein-mediated pathway of lipid antigen presentation, which constitutes a form of innate help for B cells by NKT cells.

Innate immune control of EBV-infected B cells by invariant natural killer T cells

Individuals with X-linked lymphoproliferative disease lack invariant natural killer T (iNKT) cells and are exquisitely susceptible to Epstein-Barr virus (EBV) infection. To determine whether iNKT cells recognize or regulate EBV, resting B cells were infected with EBV in the presence or absence of iNKT cells. The depletion of iNKT cells increased both viral titers and the frequency of EBV-infected B cells. However, EBV-infected B cells rapidly lost expression of the iNKT cell receptor ligand CD1d, abrogating iNKT cell recognition. To determine whether induced CD1d expression could restore iNKT recognition in EBV-infected cells, lymphoblastoid cell lines (LCL) were treated with AM580, a synthetic retinoic acid receptor-α agonist that upregulates CD1d expression via the nuclear protein, lymphoid enhancer-binding factor 1 (LEF-1). AM580 significantly reduced LEF-1 association at the CD1d promoter region, induced CD1d expression on LCL, and restored iNKT recognition of LCL. CD1d-expressing LCL elicited interferon γ secretion and cytotoxicity by iNKT cells even in the absence of exogenous antigen, suggesting an endogenous iNKT antigen is expressed during EBV infection. These data indicate that iNKT cells may be important for early, innate control of B cell infection by EBV and that downregulation of CD1d may allow EBV to circumvent iNKT cell-mediated immune recognition.

Wideband reflectance in normal Caucasian and Chinese school-aged children and in children with otitis media with effusion.

Objectives: Wideband reflectance (WBR) is a middle ear analysis technique that quantifies frequency-specific sound conduction over a wide range of frequencies. One shortcoming of WBR is that there is limited normative data, particularly for pediatric populations and children with middle ear pathology. The goals of this study were to establish normative WBR data for early school-aged children; to determine whether WBR differs significantly between Caucasian and Chinese children, male and female children, and children and adults (experiment 1); and to compare the normative pediatric WBR data with the WBR data obtained from children with abnormal middle ear conditions (experiment 2). Design: WBR was measured from 78 children with normal middle ear status with an average age of 6.15 yrs and 64 children with abnormal middle ear status with an average age of 6.34 yrs. Control group subjects and subjects without previously diagnosed middle ear pathology were recruited from eight elementary schools in the Greater Vancouver Area. Subjects with known middle ear pathology were recruited through the British Columbia Childrens Hospital Otolaryngology department. Middle ear effusion (MEE) was identified in one of the two ways. In the British Columbia Childrens Hospital group, MEE was diagnosed by a pediatric otolaryngologist (OTL) using pneumatic otoscopy and video otomicroscopy. These cases (21 ears) were classified as OTL confirmed. Subjects who were assessed through screenings at their elementary schools and suspected to have MEE based on audiological test battery results including elevated air conduction thresholds, flat low- and high-frequency tympanograms, and absent transient-evoked otoacoustic emissions were classified as not OTL confirmed (21 ears). Data were statistically analyzed for effects of gender, ethnicity (Caucasian versus Chinese), age (child versus adult), and middle ear condition. WBR equipment used for this study was from Mimosa Acoustics (RMS-system, version 4.03). Data were averaged in one-third octave bands collected from 248 frequencies ranging from 211 to 6000 Hz. Results: Control group subject data (experiment 1) revealed no effects of gender or ear, and their interactions with frequency were not significant. There was a significant interaction between ethnicity (Caucasian versus Chinese) and frequency. Chinese children had lower energy reflectance (ER) values over the mid-frequency range. ER was significantly different between pediatric data and previously collected adult data. Diseased group ER was significantly different among all four middle ear conditions (normal, mild negative middle ear pressure, severe negative middle ear pressure, and MEE) (experiment 2). The overall test performance of ER was objectively evaluated using receiver operating characteristic (ROC) curve analyses; it was compared across frequencies averaged in one-third octave bands. Statistical comparison of the area under ROC (AUROC) plots revealed that ER above 800 Hz (except for ER at 6300 Hz) had better test performance in distinguishing normal middle ear status from MEE compared with ER at 630 and 800 Hz. Although not statistically different from other frequencies between 800 and 5000 Hz, ER at 1250 Hz had the largest AUROC curve (sensitivity of 96% and specificity of 95%) and was selected for further analysis. Comparison of AUROC curves between WBR at 1250 Hz and static admittance at 226-Hz probe tone frequency revealed significantly better test performance for WBR in distinguishing between healthy ears and MEE. Conclusions: A preliminary set of normative ER data have been generated for a pediatric population between the ages of 5 and 7 yrs, which were significantly different from previously gathered normative adult ER data. In this study, pediatric normative data were warranted for testing children, but ethnic-specific norms were not required to detect middle ear pathology and changes in middle ear status. WBR shows promise as a clinical diagnostic tool for measuring the mechanoacoustic properties of the middle ear and the changes that result in the presence of negative middle ear pressure or MEE.

A systematic review of neonatal toxoplasmosis exposure and sensorineural hearing loss

INTRODUCTION The Joint Committee on Infant Hearing 2007 Position Statement includes in utero toxoplasmosis infection as a risk indicator for delayed-onset or progressive sensorineural hearing loss. It is recommended that children with congenital toxoplasmosis infection undergo audiologic monitoring to identify congenital and delayed-onset sensorineural hearing loss. OBJECTIVE To determine the prevalence of sensorineural hearing loss and to develop evidence-based guidelines for audiologic monitoring of children born with congenital toxoplasmosis infection. DATA SOURCES Systematic search of Medline, EMBASE and Cochrane databases and manual search of references. STUDY SELECTION Longitudinal studies reporting an inception cohort identified at birth, with serologic confirmation of toxoplasmosis infection, and long-term serial audiometric evaluation. DATA EXTRACTION Independent extraction of patient and audiometric data. DATA SYNTHESIS Descriptive statistics. CONCLUSION The five studies meeting our inclusion criteria report a prevalence of toxoplasmosis-associated hearing loss from 0% to 26%. Improved treatment regimens for toxoplasmosis may account for this range. Three treatment groups were identified and a subgroup analysis of the compiled data was performed. In children receiving limited or no treatment, the prevalence of toxoplasmosis-associated SNHL was found to be 28%. In children prescribed 12 months of antiparasitic treatment but in whom treatment was not confirmed to have started prior to 2.5 months of age and in whom compliance was not ensured, the prevalence of SNHL was 12%. In children treated with 12 months of antiparasitical therapy initiated prior to 2.5 months of age with serologically-confirmed compliance, the prevalence of SNHL was 0%. Only two longitudinal studies were identified and neither reported any cases of delayed-onset or progressive toxoplasmosis-associated SNHL. Children who have received a 12-month course of antiparasitical therapy initiated prior to 2.5 months with serologically-confirmed compliance should have repeat audiometric evaluation at 24-30 months of age. Children with congenital toxoplasmosis that had no treatment, partial treatment, delayed onset of treatment, or compliance issues should undergo annual audiologic monitoring until able to reliably self-report hearing loss.

Familial breast cancer in males. A case report and review of the literature.

The occurrence of breast cancer in two related males, an uncle and nephew is reported. A review of previously reported cases of male breast cancer occurring in families and the association with other cancers in other family members is included. In previous reports on breast cancer in males, familial or hereditary factors have not generally been recognized as a major contributing factor. Of ten families reported (including our own) where there is sufficient information given, six families (60%) had females with breast cancer. It appears there are some families in which males as well as females have an increased risk of developing breast cancer.

Pediatric lateral sinus thrombosis: retrospective case series and literature review.

OBJECTIVE A comparison between the literature and our management of pediatric patients presenting with otogenic lateral sinus thrombosis. DESIGN A retrospective case series of five pediatric patients. SETTING Four patients were treated at BC Childrens Hospital, whereas the fifth patient was treated in New Westminster, BC. All were treated between 1994 and 2001. METHODS A retrospective chart review was conducted with a literature review for otogenic lateral sinus thrombosis. MAIN OUTCOME MEASURES Treatment success was based on resolution of acute infection and neurologic symptoms. RESULTS Five patients, four males and one female, aged 2 to 14 years were reviewed. Three patients were treated successfully without mastoidectomy. One patient received a mastoidectomy that yielded no pus or granulation tissue within the mastoid cavity. One patient required a mastoidectomy after failure to respond to bilateral myringotomy and tympanostomy tube insertion. Although no pus was seen in the mastoid cavity, perisinus pus was found after unroofing the sigmoid sinus plate; free flow of blood was obtained on needle aspiration of the sinus, and the sinus was not surgically opened. CONCLUSION The current literature states that the management of otogenic lateral sinus thrombosis includes high-dose intravenous antibiotics with a mastoidectomy and possible opening of the sinus. In our retrospective case series, three of five patients recovered completely without mastoidectomy, and a fourth had a mastoidectomy deemed to have been unnecessary. We conclude that intravenous antibiotics and insertion of a tympanostomy tube are sufficient treatment for selected cases of otogenic lateral sinus thrombosis. Mastoidectomy with possible opening of the sinus should be reserved for patients refractory to the above conservative treatment.

Changes in pediatric tracheostomy 1982–2011: a Canadian tertiary children's hospital review

BACKGROUND Pediatric tracheostomy has undergone notable changes in frequency and indication over the past 30 years. This study investigates pediatric tracheostomy at British Columbia Childrens Hospital (BCCH) over a 30-year period. METHODS A retrospective chart review of tracheostomy cases at BCCH from 1982 to 2011 was conducted. Charts were reviewed for demographics, date of tracheostomy, indication, complications, mortality and date of decannulation. Data from three 10-year time periods were compared using Fishers Exact test to examine changes over time. RESULTS 251 procedures (154 males) performed on 231 patients were reviewed. Mean age at tracheostomy was 3.74 years with 48% of procedures undertaken before the age of one year. Frequency of procedure by year has generally declined into the early 2000s. Upper airway obstruction was the most common indication accounting for 33% of procedures. The rate of complication across the entire cohort was 22% with 63% of patients being decannulated. Tracheostomy related mortality occurred in 2.0% of cases reviewed. CONCLUSIONS Changes occurred in primary indications with infections indicating less procedures and neurological impairments indicating more procedures over time. Complications increased and the decannulation rate decreased over this 30-year review. Pediatric tracheostomy is considered a safe and effective procedure at BCCH.

Foreign body aspiration in infants and toddlers: recent trends in British Columbia.

OBJECTIVES The objectives of this study were to (1) examine recent trends in the demographics and presentation of children with foreign body aspiration at British Columbias Childrens Hospital and (2) develop safety guidelines regarding feeding nuts and other hard, crunchy foods to infants and toddlers. METHODS The methods used were a retrospective chart review and a review of swallowing mechanics in early childhood. RESULTS Between July 1997 and July 2001, 51 children under 3 years of age underwent rigid bronchoscopy for suspected foreign body aspiration. Of these patients, 27 (53%) were 18 months of age or younger. Of these 27 infants and toddlers, 24 (89%) had a witnessed choking event and 22 (81%) had an airway foreign body. Nuts, raw carrots, and popcorn kernels accounted for 14 (64%) of the foreign bodies aspirated by these infants and toddlers. Before 2 years of age, children are poorly equipped to grind and swallow hard, crunchy food because they lack second molars and are still adjusting to the descent of the larynx. CONCLUSIONS Infants and toddlers in British Columbia have been aspirating foreign bodies at an alarmingly high rate. Most cases would have been prevented with better public awareness. Caregivers should be informed that children under 3 years of age should never be fed nuts or other hard, crunchy foods. A public awareness campaign is warranted.

Repair of a laryngotracheoesophageal cleft in an infant by means of extracorporeal membrane oxygenation.

Few survivors have been reported following attempted repair of laryngotracheoesophageal clefts (LTECs). The major challenge is maintaining oxygenation, both during the surgical repair and during the postoperative period of healing. We report a neonate with an LTEC extending to the carina whose successful repair was facilitated by extracorporeal membrane oxygenation (ECMO) begun intraoperatively and continued postoperatively for 11 days. The intraoperative surgical exposure of the defect was excellent. Postoperative trauma to the fresh tracheal repair from ventilatory pressures and endotracheal tube motion was eliminated through the use of ECMO. The patient was discharged without a tracheotomy and with a normal voice, cry, and swallow. According to this result, the use of ECMO may represent a significant advance in facilitating the correction of major laryngotracheoesophageal anomalies. The rationale, advantages, disadvantages, and potential pitfalls of this approach are presented, as well as preoperative and postoperative documentation of our results.

Assessment of Vocal Fold Mobility Before and After Cardiothoracic Surgery in Children

OBJECTIVES To assess the incidence of vocal fold immobility (VFI) after cardiothoracic surgery in children and to determine the factors potentially associated with this outcome. METHODS Flexible laryngoscopy to assess vocal fold mobility was performed before surgery and within 72 hours after extubation in 100 pediatric patients who underwent cardiothoracic procedures. The 2 operating surgeons recorded the surgical technique and their impression of possible injury to the recurrent laryngeal nerve. The presence of laryngeal symptoms, such as stridor, hoarseness, and strength of cry, after extubation was documented. RESULTS Of 100 children included in this study, 8 had VFI after surgery. Univariate analyses showed that these 8 patients were younger and weighed less than the patients with normal vocal fold movement. Monopolar cautery was used in all patients with VFI. On univariate analysis, factors statistically significantly associated with VFI were circulatory arrest and dissection or ligation of the patent ductus arteriosus, left pulmonary artery, right pulmonary artery, or descending aorta. However, multivariate analyses failed to show these associations. CONCLUSIONS The incidence of VFI after cardiothoracic surgery in our population of children was 8.0% (8 of 100). Of several factors found to be potentially associated with VFI on univariate analysis, none were significant on multivariate analysis. This may be a result of the few patients with VFI. A larger multicenter prospective study would be needed to definitively identify factors associated with the outcome of VFI.