[Ultraviolet Mie lidar observations of aerosol extinction in a dust storm case over Macao].

Atmospheric aerosol over Macao was monitored by using a 355 nm Mie scattering lidar during the dust event on March 22nd, 2010. Vertical profiles of aerosol extinction coefficients were obtained and correlated with local PM10 concentration. The near-surface aerosol extinction coefficients have good agreement with PM10 concentration values. The aerosol extinction vertical profiles showed that there were distinct layers of dust aerosol concentration. The source and tracks of dust aerosol were analyzed by back-trajectory simulation. Observations showed that this lidar could run well even in dust storm episode, and it would help to further the study on aerosol properties over Macao.

Prevalence of undiagnosed diabetes and postchallenge hyperglycaemia in Chinese patients with non-alcoholic fatty liver disease.

BACKGROUND: Non-alcoholic fatty liver disease is prevalent in affluent countries and is strongly associated with metabolic syndrome. AIM: To study the prevalence of undiagnosed diabetes and postchallenge hyperglycaemia in Chinese patients with non-alcoholic fatty liver disease. METHODS: 73 consecutive patients with biopsy-proven non-alcoholic fatty liver disease and no history of diabetes underwent comprehensive metabolic screening. Diagnosis of diabetes and impaired glucose regulation was based on the 2006 American Diabetes Association criteria. RESULTS: The prevalence of undiagnosed diabetes and impaired glucose tolerance in non-alcoholic fatty liver disease patients was 33% and 29%, respectively. Among patients with 2-h plasma glucose above 7.8 mm, 47% had normal fasting glucose (below 5.6 mm). Impaired glucose tolerance was more common in patients with non-alcoholic steatohepatitis than those with simple hepatic steatosis (P = 0.036), and 2-h plasma glucose correlated with fibrosis stage (Spearman coefficient: 0.25, P = 0.046). In a binary logistic regression analysis, high fasting glucose and low high-density lipoprotein cholesterol were independent factors associated with diabetes. Nevertheless, if oral glucose tolerance test was only performed in non-alcoholic fatty liver disease patients with impaired fasting glucose, 20.8% of diabetes cases would be missed. CONCLUSIONS: Isolated postchallenge hyperglycaemia is common among Chinese non-alcoholic fatty liver disease patients without history of diabetes. It is associated with histological severe disease, and cannot be accurately predicted by any fasting glucose cut-off.

Chronic hepatitis B viral infection independently predicts renal outcome in type 2 diabetic patients.

AIMS/HYPOTHESIS: We examined the association between chronic hepatitis B virus (HBV) infection and clinical outcomes in a consecutive cohort of Chinese patients with type 2 diabetes. SUBJECTS, MATERIALS AND METHODS: Between 1995 and 1999, 2,838 type 2 diabetes patients underwent comprehensive assessments and blood screening for hepatitis B surface antigen (HBsAg). The risk of occurrence of cardiovascular events and end-stage renal disease (defined as need for dialysis, doubling of serum creatinine or serum creatinine > or =500 micromol/l) was compared between HBsAg-positive and HBsAg-negative groups. RESULTS: At baseline, HBV-infected patients (n=286, 10.1%) were younger (51.0+/-11.5 vs 53.7+/-12.7 years, p=0.004), had earlier onset of diabetes (51.0+/-11.5 vs 53.7+/-12.7 years, p=0.001) and a higher frequency of retinopathy (28 vs 22%, p=0.03) than non-HBV-infected patients. After a median follow-up of 3.5 years (interquartile range: 1.7-5.9 years) and adjustment of age, glycaemic control and other potential confounding factors, HBV-infected patients were more likely to develop end-stage renal disease than non-HBV infected patients (8.7 vs 6.4%) with a hazard ratio of 4.5 (95% CI 1.1-18.6). The difference in the frequency of cardiovascular endpoints was not statistically significant. CONCLUSIONS: In Chinese type 2 diabetes patients, chronic HBV infection was associated with increased risk of end-stage renal disease, and this was independent of other potential confounding factors. Early identification of HBV status and close surveillance of renal function are important in patients with type 2 diabetes who are living in areas where HBV is endemic or who are at risk of chronic HBV infection.

Metabolic syndrome under fire: weighing in on the truth.

In the past two decades, the 'metabolic syndrome' has raised much clinical and research interest and remains a controversial topic. The constellation of commonly coexisting cardiovascular risk factors, now known as the metabolic syndrome, has had many definitions which has added to the confusion surrounding the syndrome. Recently, the controversy has been escalated by a joint statement from the American Diabetes Association and the European Association for the Study of Diabetes calling into question the existence and clinical utility of the metabolic syndrome as a discrete clinical entity. Despite the controversy, there is agreement that the risk factors of abdominal obesity, hypertension, elevated glucose and dyslipidemia commonly coexist in the same patient, and are important to identify when assessing an individual patient's risk. Therefore, whether the 'syndrome' is a distinct clinical entity is not important. By definition, a syndrome is a group of signs or symptoms that commonly group together. It remains a useful clinical tool to raise awareness among health care professionals to look for 'nontraditional' cardiovascular risk factors, such as glucose intolerance or elevated waist circumference, in patients with other components of the syndrome, without negating the importance of identifying and treating the other 'traditional' risk factors not identified in the syndrome. It also reminds clinicians of the importance of lifestyle interventions to treat all of the components of the syndrome. Therefore, the 'metabolic syndrome' continues to serve a useful clinical purpose to raise awareness among health care professionals and aid in identifying high-risk individuals.

Acousto-optic measurements of tropospheric nitrogen dioxide column density by solar spectroscopy.

Measurements of column densities of atmospheric gases can be achieved by a solar spectroscopic method that uses differential optical absorption spectroscopy. Because of the scintillation of sunlight intensity in the atmosphere, the variation in intensity will introduce a low-frequency modification of the measured solar spectrum. A spectral capturing-type CCD spectrometer takes milliseconds to capture a solar spectrum, and the effect of sunlight scintillation is negligible. In contrast, without scintillation correction, a scanning-type spectrometer spending minutes to obtain a complete solar spectrum will introduce some amount of errors. We demonstrate an intensity-compensation technique in a scanning-type spectrometer, based on a solid-state acousto-optic tunable filter, for solar spectroscopic measurements.

The correlation of midline shifts of human brain with large brain haematoma using a finite element approach.

OBJECTIVES: We report on using a computational (finite element) model to simulate a human skull-brain structure to quantify the distortion of brain. METHODS: We simulated various effects of brain haematoma causing the distortion of brain. Midline shifts of the human brain in relation to size and location of haematoma were compared with the theoretical prediction. RESULTS: Prediction of midline shifts in lobar space-occupying lesions was more accurate that in deep-seated ones (such as thalamic lesions). DISCUSSION: More accurate boundary conditions of space-occupying lesions and better knowledge of physical materials properties of brain tissues can improve predictions of brain deformation using mathematical models.

Fluoroscopic frameless computer-assisted navigation for transsphenoidal surgery: a clinical assessment of accuracy in spatial position and trajectory.

OBJECTIVE: Fluoroscopic navigation technique in transsphenoidal surgery on the one hand provides multi-planar (antero-posterior and lateral views) navigation while on the other hand it does not need any preoperative preparation. To assess the clinical accuracy of the above technique in the transsphenoidal surgery, we performed this study. METHODS: 5 patients undergoing transsphenoidal surgery were assessed. Fluoroscopic images were compared with C-arm X-ray images for difference in spatial position and trajectory. RESULTS: 26 sets of data were collected for analysis. Mean pointer tip difference was 0.6 mm. The 95 % confidence interval was 1.3 mm. Mean trajectory difference was 1.2 degree. The 95 % confidence interval was 2.7 degree. CONCLUSION: With a good clinical accuracy, fluoroscopic navigation offers a distinct advantage to replace the traditional fluoroscopic approach for transsphenoidal surgery for its low X-ray exposure and multi-planar (antero-posterior and lateral views) navigation.

Quality of life in long-term survivors of intensive care.

INTRODUCTION: Traditionally, outcome from intensive care has focused on mortality. The cost of intensive care and the limited resources devoted to patients who have a poor prognosis also raises questions about the utilisation of such resources. There is increasing pressure for outcome evaluation of intensive care to incorporate assessment of long-term survival and the quality of life in survivors. The principal objectives of this article were to examine current methods of assessing quality of life measures in critically ill patients surviving intensive care and to determine the quality of life of these survivors. METHODS: Direct and computerised search of published research articles. RESULTS: Measurement of quality of life after intensive care is not common practice. There is a lack of consensus concerning appropriate measuring instruments to be used and how best to interpret results. Despite the availability of general outcome tools and disease specific instruments, there is a paucity of studies in the literature which include assessments of quality of life following intensive care unit (ICU) care. Generic health indices suggest that the quality of life in ICU survivors is acceptable though in certain sub-groups, e.g. adult respiratory distress syndrome and sepsis, quality of life may be moderately impaired. ICU survivors appear to suffer less disability than chronic physical disease patients. CONCLUSIONS: Assessment of outcome after intensive care should include health related quality of life measurements. A unifying framework is required to enhance communication between clinicians, administrators and investigators of quality of life research and also to enable more rational and effective decision making at the bedside. Patients who survive intensive care appear to enjoy a reasonable standard of quality of life. While their health status may not be as good, subjectively patients find this acceptable.

"Paper-clip" type triple helix formation by 5'-d-(TC)3Ta(CT)3Cb(AG)3 (a and b = 0-4) as a function of loop size with and without the pseudoisocytosine base in the Hoogsteen strand.

The formation of a DNA "paper-clip" type triple helix (triplex) with a common sequence 5'-d-(TC)(3)T(a)()(CT)(3)C(b)()(AG)(3) (a and b = 0-4) was studied by UV thermal melting experiments and CD spectra. These DNA oligomers form triplexes and duplexes under slightly acidic and neutral conditions, respectively. The stability of the formed triplexes (at pH 4.5) or duplexes (at pH 7.0 or 8.0) does not vary significantly with the size of the loops (a and b = 1-4). At pH 6.0, the triplex stability is, however, a function of a and b. It is also interesting to note that the oligomer 5'-d-(TC)(3)(CT)(3)(AG)(3) (a and b = 0) forms a stable triplex at pH 4.5 with a slightly lower T(m) value, due to dissociation of a base triad at one end and a distorted base triad at the other, observed by (1)H NMR. Thus, we have here a model system, 5'-d-(TC)(3)T(a)(CT)(3)C(b)(AG)(3), that could form a triplex effectively with (a and b = 1-4) and without (a and b = 0) loops under acidic conditions. In addition, the triplex formation of oligomers with replacement of one, two, or three 2'-deoxycytidine in the Hoogsteen strand by either 2'-deoxypseudoisocytidine (D) or 2'-O-methylpseudoisocytidine (M) was also studied in the sequence 5'-d-(TX)(3)T(2)(CT)(3)C(2)(AG)(3) (where X is C, D, or M). Both CD spectra and UV melting results showed that only D3 [(TX)(3) = (TD)(3)] and M3 [(TX)(3) = (TM)(3)] were able to form the paper-clip structure under both neutral and acidic conditions. This is because the N(3)H of a pseudoisocytosine base can serve as a proton donor without protonation. We hereby proved that the 2'-deoxypseudoisocytidine, similar to 2'-O-methylpseudoisocytidine, could replace 2'-deoxycytidine in the Hoogsteen strand to provide triplex formation at neutral pH.

Developing a quality of life measure for Chinese patients with diabetes.

The objective of this study was to develop a Chinese version of the Diabetes Quality of Life measure (DQOL), appropriate for elderly Chinese immigrants with Type 2 diabetes, and evaluate its reliability and validity through psychometric testing. Using an established diabetes quality of life measure, we employed focus groups to modify the instrument to be appropriate for an elderly Chinese population. The revised version was forward translated and back translated by four individuals independently. A review committee consensus determined the final version, which was pre-tested on five lay people to assess the equivalence of meaning. Elderly Chinese patients with Type 2 diabetes (n = 70) attending either an endocrinology or family practice clinic near Toronto were recruited to complete the Chinese version of the DQOL. Reliability of the instrument was assessed by evaluating internal consistency, item-internal consistency and test-retest reliability. Divergent validity was assessed to show that the instrument could detect worsening quality of life associated with diabetic complications. The Chinese version of the DQOL consists of 42 items and three scales including satisfaction, impact and diabetes-related worry. The DQOL and its three scales had high degrees of internal consistency (Cronbach's alpha = 0.76-0.92) and excellent test-retest reliability (Pearson correlation = 0.94-0.99). All items had high correlation with their hypothesized scale with the exception of three items. Divergent validity of the instrument was demonstrated. This study provides evidence for the reliability and validity of this Chinese version of the DQOL measure for an elderly Chinese population with Type 2 diabetes. This instrument may be used in future studies to better understand the quality of life of the Chinese population with diabetes.

Perioperative management of intra-partum seizure.

A young nulliparous woman previously diagnosed with pregnancy-induced hypertension suffered a seizure during active first stage labour. Pre-seizure blood pressure was borderline high but she did not fulfill other criteria for preeclampsia. She underwent emergency caesarean section for presumed eclampsia. Postoperatively, she deteriorated neurologically. CT scan showed an intracranial haemorrhage requiring neurosurgical intervention. The similarities of presentation of a primary cerebrovascular event and eclampsia following an intra-partum seizure made the differential diagnosis difficult.

Development of a second-generation fiber-optic on-line image verification system.

PURPOSE: We have previously reported the development of a fiber-optic fluoroscopic system for on-line imaging on radiation therapy machines with beam-stops because of space limitation. While the images were adequate for clinical purposes in most cases, an undesirable grid artifact existed and distracted visualization. The resolving power of the system, limited by the 1.6 mm x 1.6 mm dimension of the input fibers, appeared insufficient in some cases. This work identifies solutions to reduce grid artifact and to improve the resolution of the system. METHODS AND MATERIALS: In the clinical system, it was found that the scanning mechanism of the newvicon camera was deflected differently at various gantry positions because of the different orientation of the earth's magnetic field. The small image misregistration produced grid artifact during image normalization, particularly near boundaries of the fiber bundles. One approach taken to reduce magnetic field effects was to shield the camera with mu-metal. Alternatively, a charged-coupled-device camera was used instead of the newvicon camera. As for improving spatial resolution, fibers with smaller input dimension were used. A 20 cm x 20 cm high resolution fiber-optic prototype consisting of 250 x 250 fibers, each with an input dimension of 0.8 mm x 0.8 mm was constructed. Its performance was tested using several phantoms studies. RESULTS: Both shielding the newvicon camera with mu-metal or replacing it with a charge-coupled-device camera reduced grid artifact. However, optimal shielding could not be made for our clinical system because of the space limitation of its housing. High contrast resolution was improved, the 30% value of the modulation transfer function occurred at 0.3 linepairs per mm for the clinical system and at 0.7 linepairs per mm for the high-resolution prototype. However, because of the larger degree of transmission non-uniformity of the prototype, it was less effective using the current setup in detecting low contrast objects. CONCLUSIONS: The results are encouraging and demonstrate successful reduction of grid artifact and improvement of high contrast spatial resolution using the proposed methods. The less effective low contrast detection was related to reduced light collection efficiency due to use of prototype fibers whose productions were not closely monitored. The findings are being considered in our construction of a second generation clinical fiber-optic on-line image verification system.

On-line image verification in radiation therapy: an early USA experience.

The intense effort in the past 5 to 10 years to develop on-line image verification (OLIV) systems is made partly in anticipation of the increased verification demands of complex 3-dimensional (3D) conformal radiation therapy, and partly to improve on the current practice of weekly treatment verification. These systems allow convenient acquisition of daily portal images or many images during one treatment session. Systems based on fluoroscopic and scanning approaches can now be purchased from various vendors and are being evaluated at several radiation therapy centers. The performances of these systems vary, but all appear to be adequate for clinical use. At the Mallinckrodt Institute of Radiology, we have been conducting clinical on-line imaging for the past 3 years using a fiber-optic fluoroscopic system. Daily operation of the system requires coordinated participation of the physics and radiation therapy technology staff. The major consideration is in the management and evaluation of the large amount of verification images about each individual patient. At present, it is not clear whether the technology would be cost-effective in the clinical setting. However, it is clear that OLIV provides a powerful tool in enhancing our knowledge of treatment variation. The information will be invaluable in the development of improved treatment techniques. It is also likely that these systems will play a important part in the verification of 3D conformal radiation therapy.

A method to analyze 2-dimensional daily radiotherapy portal images from an on-line fiber-optic imaging system.

On-line radiotherapy imaging systems allow convenient treatment verification and generate a wealth of data. Quantitative analysis of data will provide important information about the nature of treatment variations. Using an inhouse fiber-optic imaging system to acquire daily portal images for five patients, we have developed a method to analyze the cumulative positional variation of blocks in the 2-dimensional images. For each beam arrangement used to treat a particular patient, a reference portal image was established. All other images for that patient were registered with respect to the anatomical landmarks visible on the reference image. Two-dimensional frequency distributions describing the overlap of the blocks during the course of treatment were then calculated and superimposed on the reference image. Results of the analysis show positional and quantitative information about the daily variation in block placement, and appeared to be site-dependent. Long term verification studies using on-line imaging systems will be important in the understanding of treatment uncertainties.

On-line radiotherapy imaging with an array of fiber-optic image reducers.

In the optical approach for on-line radiotherapy imaging, a large metal sheet-fluorescent screen combination is used to convert the radiation intensity distribution into a visible light image. Data are then captured via a mirror with a camera located out of the beam. Although usable portal images can be acquired, presence of the large mirror renders the system impractical in many treatment geometries. We have overcome this limitation by replacing the mirror with an array of 16 by 16 bundles of plastic fiber-optic image reducers. Each bundle, in turn, is made up of 16 by 16 individual optical fibers. The total of 256 by 256 fibers spans an input area of 40 cm by 40 cm with each individual fiber viewing an area of 1.6 mm by 1.6 mm. Within a height of 12 cm, each fiber is reduced to an area of 0.1 mm by 0.1 mm. The reduced portal image is then turned and "piped" to a final 3.0 cm by 3.0 cm output area. For data acquisition and digitization, the fiber output is directly coupled to the sensor of a TV camera interfaced to a small computer via a 512 by 512 frame grabber. In this initial evaluation, the imaging system has been characterized in terms of its line spread function, noise and resistance to radiation damage. Adequate phantom and patient images are presented.