Ex-utero intrapartum treatment: a controlled approach to the management of anticipated airway problems in the newborn.

Airway problems in an unborn foetus that may cause obstruction can be safely managed using an ex-utero intrapartum technique. Advanced technology now allows many congenital airway problems to be diagnosed in the prenatal period. Careful prenatal planning of an ex-utero intrapartum treatment allows safe airway control while the foetus remains on uteroplacental support. It avoids the need for emergent intervention of an acutely obstructed airway in a neonate that often has disastrous consequences.

Polyotia--a rare external ear anomaly.

A rare case of polyotia in a 7-year old boy associated with first arch syndrome is reported. The accessory auricle formed a well defined helix and conchal bowl located anterior to a normal auricle and an atretic external auditory meatus. Surgical resection and reconstruction resulted in a good cosmetic outcome.

Prevalence of otitis media with effusion in multicultural schools in Hong Kong.

The prevalence of otitis media with effusion (OME) in Asia has only been studied in a limited fashion. This preliminary study forms part of a larger study aiming to establish the prevalence of OME in Hong Kong. One hundred and seventy-seven children (from multicultural schools) between the ages of five and 6.03 years were screened for OME otoscopy and tympanometry. Nine positive screens (5.1 per cent) were obtained for OME. Within this mixed ethnic group, Chinese children had a significantly lower point prevalence (1.3 per cent) than Caucasian children (9.5 per cent) (p < 0.05). Although the point prevalence from this mixed ethnic group of children was significantly higher (p < 0.05) than that of local Chinese school children (1.95 per cent) by the same group of investigators, the point prevalence in the ethnic Chinese children was comparable. The reason for the lower prevalence of OME in the Chinese population needs further research.

Diagnosis of peritonsillar infections: a prospective study of ultrasound, computerized tomography and clinical diagnosis.

Peritonsillar infections include cellulitis and abscess (quinsy). Clinical diagnosis is often supplemented by diagnostic drainage (aspiration or incision) in an effort to distinguish abscess from cellulitis. In a prospective study of 14 patients we have shown that clinical impression alone is unreliable (sensitivity 78 per cent, specificity 50 per cent). Computerized tomography (CT) (sensitivity 100 per cent, specificity 75 per cent) and intraoral ultrasound (sensitivity 89 per cent, specificity 100 per cent) are much more reliable. We propose that intraoral ultrasound could play a useful role in the clinical assessment of peritonsillar infections helping to improve accuracy in distinguishing abscesses from cellulitis.

Double maxillary antrum as a cause of maxillary sinus mucocele.

We report a rare case of a mucocele occurring in a naturally compartmentalized maxillary sinus in a 50-year-old woman. Sinus computerized tomography (CT) showed the antrum to be divided by a vertical bony septum, producing a mucocele within an isolated and non-draining anterolateral compartment. Accidental trauma to the thin bony shell precipitated rapid swelling of the pre-existing mass, leading to her initial consultation. A wide sublabial surgical approach allowed complete excision with a good cosmetic result.

Screening for otitis media with effusion to measure its prevalence in Chinese children in Hong Kong.

In an attempt to gain a better understanding of the prevalence of otitis media with effusion (OME) in the Hong Kong community, and to compare the characteristics of the disease here with OME as it is described in the Western literature, we screened more than 6,000 6- and 7-year-old children with both clinical and audiologic examinations. The initial positive screening rate was 5.3%. Upon further evaluation, we determined that the overall prevalence of persistent OME was 2.2%. We found that the disease pattern and natural history of persistent OME in Hong Kong children are similar to those reported in the Western literature.

Screening for otitis media with effusion in Chinese schoolchildren: a pilot study.

Otitis media with effusion (OME) is a common childhood otological condition. The treatment of OME with myringotomy and grommet insertion is the commonest surgical procedure performed on children worldwide. Although the figure for the prevalence of OME is widely known in Caucasian children, figures are lacking for Chinese children. A pilot study for the prevalence of OME in Hong Kong Chinese schoolchildren was undertaken by the investigators on a group of 255 children with ages ranging from 6 to 7 years old. A point prevalence rate of 1.56% of OME was found. This is noticeably lower than studies in the West where the reported prevalence ranges from 2.3% to 14% in age compatible children. The epidemiology of OME and the methodology for population screening of OME are reviewed and discussed. The preliminary findings of this study would be a useful indicator for the estimation of study group size in a full epidemiological study of OME in Chinese children as well as providing valuable insight into the technical difficulties involved.

Direct experimental evidence for kinetic proofreading in amino acylation of tRNAIle.

Kinetic proofreading is a reaction scheme with a structure more complicated than that of Michaelis kinetics, which leads to a proofreading for errors in the recognition of a correct substrate by an enzyme. We have measured the stoichiometry between ATP hydrolysis and tRNAIle charging, using the enzyme isoleucyl-tRNA synthetase [L-isoleucine:tRNAIle ligase (AMP-forming), EC 6.1.1.5] and the amino acids isoleucine (correct) and valine (incorrect). The enzymatic deacylation of charged tRNA, which would normally prevent meaningful stoichiometry studies, was eliminated by the use of transfer factor Tu-GTP, (which binds strongly to charged tRNA) in the reaction mixture. For isoleucine, 1.5 ATP molecules are hydrolyzed per tRNA charged, but for valine, 270. These stoichiometry ratios are fundamental to kinetic proofreading, for the energy coupling is essential and proofreading is obtained only by departing from 1:1 stoichiometry between energy coupling and product formation. Within the known reaction pathway, these ratios demonstrate that kinetic proofreading induces a reduction in errors by a factor of 1/180. An overall error rate of about 10(-4) for tRNA charging is obtained by a kinetic proofreading using a fundamental discrimination level of about 10(-2), and is compatible with the low in vivo error rate of protein synthesis.

Miniature field-flow fractionation system for analysis of blood cells.

Field-flow fractionation is an analytical tool that has been historically used to separate species, ranging from molecules to particles or cells several micrometers in size. This technology can effect separation by size, density, charge, or other physical properties, depending on the configuration of the field-flow system. We have developed a miniature field-flow system to analyze cell populations in a small, 125-microns-deep channel 19 cm long. Gravity is used as the primary field to effect separation, and cell analysis is performed in < 20 min. Erythrocytes elute as a single peak when diluted blood is fractionated in this system. Analysis of blood samples from several donors (normal controls and patients with sickle cell anemia) yields erythrocyte peaks with slightly different mobilities (elution times). Peak mobility does not directly correlate with mean cell volume or other standard erythrocyte parameters. Cell density appears to be a key factor in determining cell mobility with this system.

Comparative study of human red blood cell analysis with three different field-flow fractionation systems.

An extensive multi-laboratory study was conducted to compare three different field-flow fractionation (FFF) systems for use in the analysis of human erythrocytes. The object of this study was to determine the relationship between the FFF elution properties for each system and the traditional hematological blood cell parameters. One centrifugal system (Utah) and two gravitational systems (Paris and Abbott) were compared. In order to analyze erythrocyte populations with a broad range of hematological indices, blood samples were collected from individuals heterozygous for sickle cell anemia (A/S) and also from normal controls (A/A), and these were analyzed at each site. Identical samples were analyzed by the Abbott and Utah sites. With all three systems, blood samples from each category produced narrow, overlapping distributions of FFF retention ratios, with the Abbott and Utah systems showing slight elevations in the mean retention ratios for the sickle cell samples. Blood cell elution peak characteristics were compared with standard hematological parameters for each of the FFF systems, and negative correlations were consistently found between mean corpuscular volume (MCV) and retention ratios. Positive correlations were found between red cell distribution width (RDW) and retention ratios. Elevated FFF retention ratios were frequently found with blood samples having abnormal hematological profiles. These results demonstrate that the three differently configured systems all produce similar analysis profiles for erythrocytes from the classes studied here. The relationships between FFF parameters and hematological indices were consistent for all systems.

Computed tomography imaging of the temporal bone--normal anatomy.

This review describes the fundamental anatomical structures of the temporal bone as depicted on high-resolution computed tomography, and the clinical significance of these structures. It is not an encyclopaedic atlas, but provides the junior radiology/otorhinolaryngology resident with sufficient knowledge for interpretation of most of the imaging studies encountered in daily clinical practice.

Computed tomography of common congenital lesions of the temporal bone.

This pictorial review describes the application of high-resolution computed tomography to the investigation and pre-operative work-up of the common lesions of congenital hearing loss, including congenital aural dysplasia, various congenital ossicular anomalies, inner ear dysmorphology, large vestibular aqueduct syndrome, and congenital absence of cochlear nerve and labyrinthitis ossificans from previous infection. The aim is to help radiologists to provide a more accurate diagnosis of underlying aetiology and assist in surgical planning.

Multianalyte assay system developed for drugs of abuse.

A simple, 10-min immunoassay system has been developed that simultaneously screens for five different classes of drugs of abuse in a urine sample. This system tests for amphetamines, cannabinoids, cocaine metabolites, opiates, and phencyclidine, and each assay has a specific preset cutoff concentration. Accuracy is > 99% for reporting positive or negative results for samples with 200% or 50%, respectively, of the cutoff concentrations of the drugs. Tests of a panel of 96 compounds yielded only three cases of nonspecific reactivity (at a drug concentration of 100 mg/L). Another panel of 12 compounds that could normally be found in urine samples was also evaluated and no interferences were observed. Concordance was > 95% between this system and the comparable automated immunoassays for detecting drugs of abuse. Greater than 98% of GC/MS-confirmed positive samples gave positive results with this assay system.