Radiological conference. Rickets

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Reconstruction after craniofacial trauma

Management of craniofacial trauma has became a sophisticated branch of reconstructive surgery in the last 20 years. New operative techniques and advanced technologies have evolved to allow much better treatment results to be achieved. The general principles of diagnosis and management of craniofacial trauma are discussed. The approach to individual fractures is also highlighted.published_or_final_versio

Fast detection of venous air embolism in Doppler heart sound using the wavelet transform

The introduction of air bubbles into the systemic circulation can result in significant morbidity. Real-time monitoring of continuous heart sound in patients detected by precordial Doppler ultrasound is, thus, vital for early detection of venous air embolism (VAE) during surgery. In this study, the multiscale feature of wavelet transforms (WT's) is exploited to examine the embolic Doppler heart sound (DHS) during intravenous air injections in dogs. As both humans and dogs share similar physiological conditions, the authors' methods and results for dogs are expected to be applicable to humans. The WT of DHS at scale 2 j(j=1,2) selectively magnified the power of embolic, but not the normal, heart sound. Statistically, the enhanced embolic power was found to be sensitive (P<0.01 at 0.01 ml of injected air) and correlated significantly (P<0.0005, τ=0.83) with the volume of injected air from 0.01 to 0.10 ml. A fast detection algorithm of O(N) complexity with unit complexity constant for VAE was developed (processing speed=8 ms per heartbeat), which confirmed the feasibility of real-time processing for both humans and dogs.published_or_final_versio

Volume Estimation by Wavelet Transform of Doppler Heart Sound During Venous Air-Embolism in Dogs

The Doppler heart sound signals detected by the precordial Doppler ultrasound method under simulated sub clinical and clinically significant venous air embolism were studied in anesthetized dogs. Signal processing using wavelet transform enhanced the contrast of embolic to normal signal, facilitating automatic detection and extraction of embolic signal simply by thresholding. Linear relationship of good correlation coefficient was obtained in log-log scale between the subclinical volume of injected air and the corresponding embolic signal power in all dogs. The calibration curve was found to be good estimate of the volume of embolic air during simulated clinically significant venous air embolism. Hence, we overcame the need of constant human attention for detecting venous air embolism and the lack of quantitative information on the volume of embolic air in the traditional precordial Doppler ultrasound method by the present approach.published_or_final_versio

The efficacy of surgery for recurrent nasopharyngeal carcinoma

Conference Theme: Challenges to specialists in the 21st centurypublished_or_final_versio

Cervical lymph node metastatic patterns of squamous carcinomas in the upper aerodigestive tract

The radical neck dissection specimens of 384 ethnically Chinese patients with different primary squamous carcinomas in the head and neck region were studied. Over 50 per cent of the specimens showed metastatic disease at one level in the neck. For oral cavity carcinoma, the levels of metastasis frequently involved were I, II and III while for carcinoma of the oropharynx, hypopharynx and larynx, the levels were II, III and IV. Extracapsular spread was present in 112/384 of patients (29 per cent) and this increased with advancing N-stages. Based on these findings, different selective neck dissections could be used for patients harbouring different primary head and neck carcinomas with limited neck disease.published_or_final_versio

Fully Automatable Two-dimensional HILIC–RP Liquid Chromatography with Online Tandem Mass Spectrometry for Shotgun Proteomics

Poster PresentationConference theme: Proteomics: Better for lifeMultidimensional liquid chromatography (MDLC) which multiples the resolution power of individual dimension with high orthogonality is a very efficient front-end separation method for analyzing the digests of complex biological samples. Among the existing two dimensional liquid chromatography (2DLC) systems, the combination of hydrophilic interaction liquid chromatography (HILIC) followed by low-pH reversed-phase (RP)LC (HILIC-RP) has very high orthogonality and is a very promising 2DLC method. Herein, a fully automatable two-dimensional (2D) liquid chromatography system was developed for shotgun proteomics analyses, which coupling the hydrophilic interaction liquid chromatography (HILIC) TSKgel Amide 80 (a non-ionic type) with the low-pH reversedphase (RP) chromatography. The performance of the 2D HILIC-RP LC platform was investigated at both pH 6.8 (neutral pH) and pH 2.7 (acidic pH) of the first dimension HILIC column by duplicate analyses of a Rat pheochromocytoma lysates.Online coupling of the neutral-pH HILIC and RP systems outperformedthe acidic HILIC–RP combination,resulting in 18.4% (1914 versus 1617 nonredundant proteins) and 41.6% (12,989 versus 9172unique peptides) increases in the number of identified proteins and peptides. To further test the established 2D HILIC-RP platform, we identified 2648 non-redundant proteins from triplicate analyses of a Saccharomyces cerevisiae lysate, with the detected protein abundances spanning from approximately41 to 106 copies per cell, which contained up to 2164 different validated protein species with a dynamic range of concentrations up to approximately 104. Herein, this studyestablished a fully automated 2D liquid chromatography platform to enable onlinecoupling of different HILIC and RP chromatography systems, thereby expanding the choice and application of multidimensional liquid chromatography for shotgun proteomics.published_or_final_versio

Consensus statement on ischaemic stroke care in Hong Kong

Objective. To issue guidelines for the care of acute stroke in Hong Kong, with the target audience of all health care professionals who are involved in acute stroke care. Participants. The Hong Kong Neurological Society and the Hong Kong Stroke Society. Evidence. The panel applied the 'rule of evidence' used by the United States Agency for Health Care Policy and Research. When there is insufficient evidence, the recommendation was based on customary practice and was circulated among the members and fellows of the two societies before coming to a consensus. Consensus process. Group meetings were held in 2002 to review the literature about acute care for patients with ischaemic stroke and to issue a consensus statement with reference to the local health care system. Participants of the meetings were appointed by the councils of The Hong Kong Neurological Society and the Hong Kong Stroke Society. The draft statement was circulated among the members and fellows of the two societies for comments before it was finalised. Conclusions. Ischaemic stroke is a heavy health care burden to Hong Kong. The current consensus statement provides a framework to establish a multidisciplinary approach towards its acute management.published_or_final_versio

Detection and quantification of venous air embolism by wavelet analysis of Doppler heart sound

The wavelet analysis of the Doppler heart sound detected under controlled venous air embolism at sub-clinically and clinically significant volumes was studied in anaesthetized dogs. Signal processing with wavelet enhances the Dower of embolic signal and facilitates the simple detection and extraction of embolic heart beats by thresholding. The cumulative power of the extracted embolic heart beats is found to be linearly related to the volume of embolic air on the log-log scale, suggesting that it is feasible to estimate clinically significant volume of embolic air in human subjects by linearly extrapolating from sub-clinical embolic volumes.published_or_final_versio