Assessment of the degree of arterial stenosis in intracranial atherosclerosis using 3D high-resolution MRI: comparison with time-of-flight MRA, contrast-enhanced MRA, and DSA.

AIM: To compare the accuracy of three-dimensional (3D) high-resolution (HR) magnetic resonance imaging (MRI), time-of-flight magnetic resonance angiography (TOF-MRA), contrast-enhanced magnetic resonance angiography (CE-MRA), and digital subtraction angiography (DSA) in measuring the degree of stenosis in intracranial atherosclerosis. MATERIALS AND METHODS: All patients with intracranial artery ischaemic events underwent HR-MRI, TOF-MRA, and CE-MRA analysis, and some of these patients underwent DSA examination. The correlation between different methods for measuring the degree of lumen stenosis was analysed. The accuracy of HR-MRI, TOF-MRA, and CE-MRA was evaluated and compared with that of DSA. RESULTS: A total of 189 arterial stenoses were identified in 93 patients. Of these, 72 patients with 142 arterial stenoses underwent DSA examination. A very strong correlation between HR-MRI and CE-MRA measurements was shown (r=0.839, p<0.0001). The correlation between HR-MRI and TOF-MRA measurements was strong (r=0.720, p<0.0001). A very strong correlation between HR-MRI and DSA measurements was found (r=0.864, p<0.0001), and a similar correlation was observed between CE-MRA, and DSA measurements (r=0.843, p<0.0001). The correlation between TOF-MRA and DSA measurements was strong (r=0.686, p<0.0001). There was substantial agreement between HR-MRI and DSA measurements (K = 0.772) and between CE-MRA, and DSA measurements (K = 0.734) that was slightly higher than the agreement between TOF-MRA and DSA measurements (K = 0.636). CONCLUSION: HR-MRI can accurately measure stenosis (especially for moderate and severe stenosis) in intracranial atherosclerosis by direct visualisation of the vessel lumen and steno-occlusive plaque.

[Current status of thromboembolism risk assessment in patients hospitalized with non-valvular atrial fibrillation in tertiary hospitals in China].

Objective: To analyze the current status, trend and predictors of thromboembolism risk assessment in patients hospitalized with non-valvular atrial fibrillation (NVAF) in tertiary hospitals in China. Methods: The study was based on data from the Improving Care for Cardiovascular disease in China (CCC)-Atrial Fibrillation (AF) project. About 10% of the tertiary hospitals in each geographic-economic stratum were recruited. Participating hospitals reported the first 10 to 20 patients with a discharge diagnosis of atrial fibrillation monthly. From February 2015 to December 2019, a total of 49 104 NVAF patients from 151 tertiary hospitals in 30 provinces, municipalities and autonomous regions were enrolled. Clinical data of the patients was collected. The proportion of NVAF patients receiving thromboembolism risk assessment, variations in the proportion between different hospitals, the time trend of the application of thromboembolism risk assessment, and the predictors of the application of thromboembolism risk assessment were analyzed. Results: The age of the NVAF patients was (68.7±12.1) years, 27 709 patients (56.4%) were male. Only 17 251 patients (35.1%) received thromboembolism risk assessment. The proportion varied substantially between hospitals with the lowest value of 0 and the highest value of 100%. Among the hospitals, which enrolled more than 30 patients, no patients received thromboembolism risk assessment in 18.4% (26/141) of the hospitals, more than 50% of the patients received thromboembolism risk assessment in 21.3% (30/141) of the hospitals, and all the patients received thromboembolism risk assessment in only 1 hospital. The proportion of NVAF patients receiving thromboembolism risk assessment was 16.2% (220/1 362) in the first quarter of 2015, and significantly increased to 67.1% (1 054/1 572) in the last quarter of 2019 (P<0.001). Patients' characteristics were associated with the application of thromboembolism risk assessment. The odds of receiving thromboembolism risk assessment was lower in male patients compared to female patients(OR=0.94,95%CI 0.89-0.99), lower in patients with acute coronary syndrome or other cardiovascular diseases compared to those with AF as the primary admission reason (OR=0.59, 95%CI 0.55-0.63, OR=0.52, 95%CI 0.45-0.61, respectively), and lower in patients with paroxysmal, persistent and long-standing/permanent AF compared to those with first detected AF (OR=0.62, 95%CI 0.57-0.67, OR=0.72, 95%CI 0.66-0.79, OR=0.57, 95%CI 0.52-0.64, respectively). The odds was higher in patients with a history of hypertension, heart failure, stroke/TIA, and previous anticoagulant therapy compared to those without the above conditions (OR=1.17, 95%CI 1.11-1.23, OR=1.18, 95%CI 1.07-1.30, OR=1.17, 95%CI 1.08-1.27, OR=1.28, 95%CI 1.19-1.37, respectively) (P all<0.05). Conclusion: Thromboembolism risk assessment was underused in patients hospitalized with NVAF in tertiary hospitals in China, and there were substantial variations between hospitals in the application of thromboembolism risk assessment. The application of thromboembolism risk assessment in tertiary hospitals has been improved in recent years, but there is still plenty of room for future improvement. Patients' characteristics could affect the application of thromboembolism risk assessment in China.

[Systematic reviews and evidence quality assessment on effectiveness of 1 dose varicella attenuated live vaccine for healthy children aged 1-12 years in China].

Objective: To assess the effectiveness of 1 dose varicella attenuated live vaccine (VarV) for healthy children aged 1-12 years in China and explore the application of the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) framework in observational studies of vaccine effectiveness (VE). Methods: We searched studies about the VE of 1-dose VarV for children aged 1-12 years in China which published before 2019 and evaluated the quality of the studies by the Newcastle Ottawa Scale (NOS) table. We used Meta-analysis models to obtain the pooled 1-dose VE and that in subgroups by study design, outbreak or not, study quality and age of subjects. The evidences of VEs were rated by means of the GRADE system. Results: Thirty-two studies were included and the pooled 1-dose VE was 75% [95% confidence interval (CI): 68%-80%]. The VE of outbreak studies [VE=66% (95%CI: 57%-73%)] was lower than non-outbreak studies [VE=85% (95%CI: 78%-89%)], and the VE in <6 years old children [VE=84% (95%CI:77%-89%)] was higher than that in ≥6 years old children [VE=60% (95%CI: 51%-68%)]. There was no significant difference in VE among studies with different design and quality. The quality of the evidences of pooled 1-dose VE was"very low", which was downgraded in bias risk and inconsistency and not downgraded in indirectness, imprecision and publication bias. Conclusions: The 1-dose VarV can provide medium level protection for 1-12 years old children in China, but it will decrease significantly for ≥6 years old children, so it is suggested to implement the strategies of two-dose vaccination of VarV in children <6 years old. The GRADE framework can be used in the observational studies of VE and it is suggested that the technical guidelines of observational study should be worked out to improve the overall quality of evidence.

[Analysis of herpes zoster incidence and hospitalization in three areas of Beijing in 2015 based on health information system of medical institutions].

Objective: Using data of health information system (HIS) of medical institutions to study the incidence and hospitalization of herpes zoster in three districts of Beijing. Methods: According to the different level of economic development and geographical features in Beijing, 3 districts of Xicheng, Changping and Miyun were chosen and all 110 medical institutions of the first level and above in the 3 districts are included in the survey. All the outpatient and inpatient herpes zoster cases in 2015 were retrospectively reviewed by HIS system. After distinguishing the reduplicated cases, Using the first outpatient case as a molecule and the resident population as denominator to estimate the annual incidence rate, as well as the annual hospitalization rate was estimated based on primary diagnostic hospitalized cases as molecule and the resident population as denominator. Results: A total of 32 313 primary visit outpatient cases were investigated, of which 18 360 cases (56.8%) were women and 20 923 cases (64.8%) were ≥50 years old. The overall estimated incidence of the 3 districts was 8.8‰ with an increase trends with age and reached to the highest in ≥80 years old (30.5/1 000). The incidence of Xicheng, Changping and Miyun districts are respectively 16.2‰, 4.0‰ and 5.7‰. A total of 701 primary visit inpatient cases were identified, of which 366 cases (52.2%) were women and 651 cases (92.9%) were ≥50 years old. The estimated annual hospitalization rate was 19.4/100 000, with the primary and secondary diagnostic hospitalization rate are respectively 5.9/100 000 (212 cases) and 13.5/100 000 (489 cases). The disease types of secondary diagnostic inpatient herpes zoster cases were as follows: cardiovascular disease (19.0%, 93 cases), stroke (14.5%, 71 cases), pneumonia/chronic obstructive pulmonary disease (14.1%, 69 cases), tumor (12.5%, 61 cases) and diabetes (5.7%, 28 cases). Conclusion: Most of the herpes zoster cases in Beijing are over 50 years old, and the incidence of female is slightly higher than male. This disease should become a public health issue of great concern.

[Current status of national free antiretroviral therapy in interprovincial migrating people living with HIV/AIDS and influencing factors, China, 2011-2015].

Objective: To understand the current status of national free antiretroviral therapy in interprovincial migrating people living with HIV/AIDS (PLWHA) and influencing factors in China. Methods: Descriptive and trend test analyses were performed to evaluate the historical characteristics and trends of main descriptive indicators on national free antiretroviral therapy for the interprovincial migrating PLWHA by using the data collected from National Comprehensive HIV/AIDS Information System from 2011 to 2015. Logistic regression model was used to explore the main factors that influencing the coverage of national free antiretroviral therapy among the interprovincial migrating PLWHA in China. Results: The proportion of interprovincial migrating PLWHA gradually increased in last 5 years from 7.1% (17 784/250 645) in 2011 to 10.3% (54 596/528 226) in 2015 (Z=51.38, P<0.000 1) in China. The coverage rate of free antiretroviral therapy in interprovincial migrating PLWHA increased from 37.3% (6 641/17 784) in 2011 to 71.0% (38 783/54 596) in 2015, showing a significant rising tendency (Z=96.23, P<0.000 1), but it was slightly lower than that in non-interprovincial migrating PLWHA in 2015 (71.5%, 338 654/473 630). Multivariate logistic regression analysis showed that the PLWHA who were females, aged ≥50 years, of Han ethnic group, married or had spouse, had the educational level of high school or above, infected through homosexual intercourse, with CD(4)(+)T cells counts ≤500 cells/µl at the first visit, identified to be infected with HIV in medical setting, living in urban areas et al, were more likely to receive free antiretroviral therapy. Conclusions: The coverage rate of free antiretroviral therapy varied among the interprovincial migrating PLWHA with different characteristics. It is still necessary to take effective measures to further increase the coverage of free antiretroviral therapy in interprovincial migrating PLWHA and to include the free antiretroviral therapy in interprovincial migrating PLWHA into standardized management system as soon as possible.

[Establishment and application effect appraisement of community chronic obstructive pulmonary disease integrated management system].

Objective: To establish the COPD community integrated management system suitable for our national situation and assess its effects in the prevention and treatment for COPD. Methods: The COPD community integrated management system based on the electronic management system was established, including the functional modules of preliminary screening for COPD, electronic health record, grading management and dual referral system, ect. Two townships were randomly selected from the rural areas in north Guangdong as Observational Community and Control Community, respectively. Resident families were randomly selected from the two communities. One resident aged 40 or higher who was selected randomly from each family was enrolled in the trial and followed up for 2 years.Of a total of 460 participants from the Observational Community, 340 participants accomplished the two-years the follow-up, among whom there were 45 COPD patients, 117 high risk population, 178 common population. Of a total of 380 participants from the Control Community, 212 participants accomplished the follow-up, among whom there were 39 COPD patients, 68 high risk population, 105 common population.According to the COPD community integrated management system, the health cares including preliminary screening for COPD, grading management and dual referral, ect. were implemented in the Observational Community. Essential diagnosis and treatment services were performed in the Control Community. The effects of the system were appraised by comparisons of the pulmonary function change, acute exacerbation, quality of life and change of risk factors, ect. between the two communities. Results: After the intervention, the follow-up rate, smoking-quitting rate, the proportions of decline in current smoking, passive smoking and switching to clean energy for cooking in the Observational Community were significantly greater than those in the Control Community(73.9% vs. 55.8%, 70.8% vs. 9.1%, 24.2% vs. 7.1%, 32.6% vs. 3.5%, 67.8% vs. 3.2%, respectively, P<0.05). COPD knowledge rates of residents in the Observational Community, including "knowing about COPD" , "knowing about the symptoms of COPD" , "Whether COPD can be prevented and treated" and "lung function test" were significantly greater than before (84.7% vs.30.0%, 76.4% vs.7.6%, 71.5% vs.6.8%, 72.1% vs.27.4%, respectively, P<0.05) and greater than those in the Control Community(84.7% vs.73.6%, 76.4% vs.9.4%, 71.5% vs.7.1%, 72.1% vs.32.5%, P<0.05). In the Observational Community, FEV(1) and FEV(1) %Pred were significantly greater than before (1.88±0.71 vs. 1.74±0.64, 75.6±25.0 vs. 69.4±20.5, respectively, P<0.05). The values of the difference before and after the experiment in the patients of GOLD 1 grade COPD in the Observational Community were greater than those in the Control Community(P<0.05). In the Control Community, FEV(1)、FEV(1) %Pred had no significant difference before and after experiment(P>0.05). In the Observational Community, 6MWD, standard treatment rate and exercises>3 days per week were significantly greater than before(550.5±76.0 vs. 474.7±75.9, 64.4% vs. 8.9%, 100% vs. 22.2%, respectively, P<0.05) and greater than those in the Control Community(550.5±76.0 vs. 404.5±56.7, 64.4% vs. 10.3%, 100% vs. 30.8%, respectively, P<0.05), acute exacerbation was significantly less than before (4.4% vs. 17.8%, P<0.05). In the Control Unit, 6MWD was significantly less than before (404.5±56.7 vs. 469.8±58.5, P<0.05). Conclusions: The COPD community integrated management system can play a great role in community integrated prevention for COPD.

[An epidemiological investigation of pediatric patients under 14 with large area burns: a multicenter study].

Objective: To investigate and evaluate the epidemiological characteristics of patients under 14 with large area burns in China. Methods: Data of pediatric patients aged 0-14yr with ≥30% total body surface area (TBSA) burned admitted into 106 burn centers in the mainland of China in 2014 were retrieved. The children were divided into three age groups: 0-3, 4-6 and 7-14 years according to the age. Information of age, gender, time of burn injury, causes of burns, admission time, prehospital emergency care of burn wound, burn area, inhalation injuries, the case fatality rate and length of hospital stay were collected for analysis. Results: Of the 486 cases included, 285 (58.6%) were boys and 201 (41.4%) were girls. The mean age of the children was (3.4±2.8) years. Children under 3 years old accounted for 67.5% of all the cases. 271 of the burn injuries (55.8%) occurred from April through August. Scalds and flames were the main causes of burns, which were the causes of 394 cases (81.1%) and 71 cases (14.6%), respectively. The burn injuries resulted from scalds and flames accounted for 89.6% and 7.3%, 70.8% and 21.9%, 51.6% and 41.9% in the age group of 0-3, 4-6 and 7-14 years respectively. The distribution of burn etiology in different age groups differed significantly (χ(2)=21.239, 59.442, 7.333, all P<0.01). Most of the patients (57.8%) were admitted within 2 hours after injury. However, when it came to the pre-hospital emergency management of burn wound, 164 patients (33.7%) did not use any drug or wound dressing, whereas the wound area of 236 patients (48.6%) were treated improperly with toothpaste, soy sauce, eggs or other non-standard disposal. The mean TBSA area of the patients was (42.1±14.5)%, while 288 (59.3%) of the patients suffered full thickness burns with mean TBSA of (24.5±17.9)%. The case fatality rate (CFR) was 4.1%, and the CFR of patients complicated with inhalation injury was significantly higher than those without (P<0.01). The average length of stay for pediatric burn patients was (52.3±40.2) days. Conclusions: Children under 3 years old are important target population of severe burns. Scald is the most common type of burns, while the proportion of flames increases as age goes up. Most patients are likely to get clinical treatment in time, however, the pre-hospital emergency burn care is not satisfying at present.

Risk assessment of recent Egyptian H5N1 influenza viruses.

Highly pathogenic avian influenza (HPAI) viruses of the H5N1 subtype are enzootic in poultry populations in different parts of the world, and have caused numerous human infections in recent years, particularly in Egypt. However, no sustained human-to-human transmission of these viruses has yet been reported. We tested nine naturally occurring Egyptian H5N1 viruses (isolated in 2014-2015) in ferrets and found that three of them transmitted via respiratory droplets, causing a fatal infection in one of the exposed animals. All isolates were sensitive to neuraminidase inhibitors. However, these viruses were not transmitted via respiratory droplets in three additional transmission experiments in ferrets. Currently, we do not know if the efficiency of transmission is very low or if subtle differences in experimental parameters contributed to these inconsistent results. Nonetheless, our findings heighten concern regarding the pandemic potential of recent Egyptian H5N1 influenza viruses.

[Why dentists need to learn the epidemiological status and prevention strategy of coronary heart disease in China].

Coronary heart disease(CHD) is the leading cause of death among 235 causes of death in human currently and kills more than 7 million peoples annually worldwide and will continuously be ranked as the top cause of death in next 20 years according the prediction. As the population aging and epidemics of major risk factors of CHD, there are remarkable raising incidence and mortality of CHD in Chinese population with increasing numbers of CHD patients. The CHD patients may visit dental clinics to seek help because of their oral or dental diseases. Some of those CHD patients may not be even aware of that they have CHD or the severity of their disease, and some of them may not know well for the medications they are taking. All of those situations may increase the risk of acute CHD event or other complications during clinical processes either for diagnosis or treatment in dental clinics. Therefore, it is important for dentists to learn basic knowledge of CHD including epidemiology and clinical characteristics and treatments of CHD.

Environmental assessment of three egg production systems - Part III: Airborne bacteria concentrations and emissions.

Airborne microorganism level is an important indoor air quality indicator, yet it has not been well documented for laying-hen houses in the United States. As a part of the Coalition for Sustainable Egg Supply (CSES) environmental monitoring project, this study comparatively monitored the concentrations and emissions of airborne total and Gram-negative (Gram(-)) bacteria in three types of commercial laying-hen houses, i.e., conventional cage (CC), aviary (AV), and enriched colony (EC) houses, over a period of eight months covering the mid and late stages of the flock cycle. It also delineated the relationship between airborne total bacteria and particulate matter smaller than 10 µm in aerodynamic diameter (PM10). The results showed airborne total bacteria concentrations (log CFU/m(3)) of 4.7 ± 0.3 in CC, 6.0 ± 0.8 in AV, and 4.8 ± 0.3 in EC, all being higher than the level recommended for human environment (3.0 log CFU/m(3)). The much higher concentrations in AV arose from the presence of floor litter and hen activities on it, as evidenced by the higher concentrations in the afternoon (with litter access) than in the morning (without litter access). The overall means and standard deviation of airborne total bacteria emission rates, in log CFU/[h-hen] (or log CFU/[h-AU], AU = animal unit or 500 kg live weight) were 4.8 ± 0.4 (or 7.3 ± 0.4) for CC, 6.1 ± 0.7 (or 8.6 ± 0.7) for AV, and 4.8 ± 0.5 (or 7.3 ± 0.5) for EC. Both concentration and emission rate of airborne total bacteria were positively related to PM10 Gram(-) bacteria were present at low concentrations in all houses; and only 2 samples (6%) in CC, 7 (22%) samples in AV, and 2 (6%) samples in EC out of 32 air samples collected in each house were found positive with Gram(-) bacteria. The concentration of airborne Gram(-) bacteria was estimated to be <2% of the total bacteria. Total bacteria counts in manure on belt (in all houses) and floor litter (only in AV) were similar; however, the manure had much more Gram(-) bacteria than the litter. The results point out the need to mitigate airborne total bacteria in laying-hen houses, especially in AV houses.

Anthropogenic atmospheric nickel emissions and its distribution characteristics in China.

Nickel and its compounds are considered as potential human carcinogens, and atmospheric nickel is one of the major routes for human exposure. By applying the best available fuel-based or product-based emission factors and annual activity levels, a multiple-year comprehensive inventory of anthropogenic atmospheric nickel emissions in China is presented with temporal trend and spatial resolutions for the period of 1980-2009 from both fuels combustion sources and industrial producing processes. We estimate that the total atmospheric nickel emissions from all the sources have increased from 1096.07 t in 1980 to 3933.71 t in 2009, at an average annual growth rate of 4.5%. Therein, coal combustion is the leading source, attributing 63.4% of the national total nickel emissions in 2009; liquid fuels consumption ranks the second, contributing 12.4% of the totals; biofuels burning accounts for 8.4% and the remaining sources together contribute 15.8% of the totals. Significant spatial variations are demonstrated among provincial emissions and the most concentrated regions are the highly industrialized and densely populated areas like the Yangtze River Delta, the Pearl River Delta and the Beijing-Tianjin-Hebei region. Moreover, the overall uncertainties are estimated at -32.6%-37.7% by using Monte Carlo simulation, most of which come from non-ferrous metals smelting category, implying the urgent need for further investigation and field tests. This article may help to combat the increasing stress on air heavy metals pollution in China and provide useful information to calculate global mass balance models for hazardous trace elements.

Development of rapid immunoassays for the detection of ractopamine in swine urine.

The monoclonal antibodies (mAbs) against ractopamine (Rac) were prepared and their properties identified by indirect competitive enzyme-linked immunoabsorbant assay (ELISA). The IC(50) of mAbs was 2.7 ng ml(-1) towards Rac or 9.3 ng ml(-1) towards Rac-glucuronides and no cross-reactivity (CR) towards other competitors except dobutamine (CR: 3.76%). Based on the mAbs, the Rac-kit (kit) and Rac-strip (strip) were developed to detect Rac residues in swine urine. The strip and kit assay could be performed within 5-10 min and 2 h, respectively, allowing the analysis of urine samples without the need for sample clean-up. The detection limits were 1 ng ml(-1) for kit and 3 ng ml(-1) with the unaided eye, and 0.2 ng ml(-1) with the Strip Reader for strip. The correlation coefficients (R(2)) were 0.988 for kit in the range 0-128.0 ng ml(-1), and 0.987 for strip in the range 0-10.8 ng ml(-1). Comparing the gas chromatography-mass spectrometry (GC-MS) with the kit or strip in swine urine spiked with Rac standards, the differences ranged from 1.4% to 4.5% for kit and 1.0% to 4.7% for strip. However, the differences were greater than 54% for the kit and 55% for the strip test for the analysis of urine from swine treated with Rac. The results obtained from GC-MS using hydrolysed urine samples were generally in good agreement with those obtained from strip or kit using non-hydrolysed urine samples.

Preliminary risk assessment of trace metal pollution in surface water from Yangtze River in Nanjing Section, China.

In order to investigate the contamination levels of trace metals, surface water samples were collected from six regions along Yangtze River in Nanjing Section. The concentrations of trace metals (As, B, Ba, Be, Cd, Cr, Cu, Fe, Pb, Li, Mn, Mo, Ni, Sb, Se, Sn, Sr, V and Zn) were determined using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Total concentrations of the metals in the water samples ranged from 825.1 to 950.4 microg/L. The result was compared with international water quality guidelines. Seven metals levels were above the permissible limit as prescribed by guidelines. A preliminary risk assessment was then carried out to determine the human health risk via calculating Hazard Quotient and carcinogenic risk of the metals. Hazard Quotients of all metals were lower than unity, except As. The carcinogenic risk of As and Cd was higher than 10(-6), suggesting that those two metals have potential adverse effects on local residents.

Integrated assessment of urban drainage system under the framework of uncertainty analysis.

Due to a rapid urbanization as well as the presence of large number of aging urban infrastructures in China, the urban drainage system is facing a dual pressure of construction and renovation nationwide. This leads to the need for an integrated assessment when an urban drainage system is under planning or re-design. In this paper, an integrated assessment methodology is proposed based upon the approaches of analytic hierarchy process (AHP), uncertainty analysis, mathematical simulation of urban drainage system and fuzzy assessment. To illustrate this methodology, a case study in Shenzhen City of south China has been implemented to evaluate and compare two different urban drainage system renovation plans, i.e., the distributed plan and the centralized plan. By comparing their water quality impacts, ecological impacts, technological feasibility and economic costs, the integrated performance of the distributed plan is found to be both better and robust. The proposed methodology is also found to be both effective and practical.

HIV/AIDS prevention: knowledge, attitudes and education practices of secondary school health personnel in 14 cities of China.

This study assessed the preparedness of school health personnel to develop and deliver HIV/AIDS prevention education programmes for young people in China. A survey of 653 personnel working in secondary schools in 14 cities was conducted. More than 90% had basic knowledge of ways in which HIV can be transmitted, but knowledge of ways in which the virus is not transmitted needs improvement. Substantial numbers of teachers were not sure whether there was an effective preventive vaccine (42%) or did not know whether AIDS was a curable illness or not (32%). The great majority approved of AIDS prevention programmes in universities (98%) and secondary schools (91%), although fewer (58%) agreed that the topic was appropriate for primary schools. Currently, most classroom activities focuses on teaching facts about HIV/AIDS transmission, while less than half are taught about HIV/AIDS related discrimination and life skills to reduce peer pressure. Personnel with some prior training on HIV/ AIDS education (53%) had better factual knowledge, more tolerant attitudes and more confidence in teaching about HIV/AIDS than those without training. The majority of teachers indicated a need for more resource books, audiovisual products, expert guidance, school principal support and dissemination of national AIDS prevention education guidelines to schools.

Prognostic radiology: quantitative assessment of tumor oxygen dynamics by MRI.

It is generally recognized that tumor hypoxia has a strong influence over therapeutic outcome in the clinic. The authors have developed an oximetry approach using 19F echo planar magnetic resonance imaging-FREDOM (Fluorocarbon Relaxometry using Echoplanar imaging for Dynamic Oxygen Mapping), which reveals dynamic changes based on sequential maps of regional tumor PO2. Preclinical investigations focused on diverse sublines of the Dunning prostate R3327 tumor. As expected, intratumoral heterogeneity was considerable. However, large tumors (>3.5 cm3) were significantly less well oxygenated than smaller tumors (<2 cm3). Faster growing, less differentiated tumors were less well oxygenated than size-matched tumors of slower growing sublines. The greatest potential of this technique is the ability to follow the fate of individual tumor regions with respect to interventions. For each subline, there was a significant response to respiratory challenge with oxygen for initially well-oxygenated regions (baseline PO2 > 10 mm Hg). More interestingly, subline dependent behavior was found for initially hypoxic regions that correlated with rate of growth. The authors believe the FREDOM approach is essentially ripe for translation to the clinic. This approach could help to identify patients with hypoxic tumors and indicate the feasibility of manipulating tumor characteristics through adjuvant interventions to improve therapeutic response.

Biochemical and structural assessment of the 1-N-azasugar GalNAc-isofagomine as a potent family 20 beta-N-acetylhexosaminidase inhibitor.

Azasugar inhibitors of the isofagomine class are potent competitive inhibitors of configuration-retaining beta-glycosidases. This potency results from the formation of a strong electrostatic interaction between a protonated endocyclic nitrogen at the "anomeric" center of the inhibitor and the catalytic nucleophile of the enzyme. Although the majority of retaining beta-glycosidases use a mechanism involving a carboxylate residue as a nucleophile, Streptomyces plicatus beta-N-acetylhexos-aminidase (SpHEX) and related family 20 glycosidases lack such a catalytic residue and use instead the carbonyl oxygen of the 2-acetamido group of the substrate as a nucleophile to "attack" the anomeric center. Thus, a strong electrostatic interaction between the inhibitor and enzyme is not expected to occur; nonetheless, the 1-N-azasugar (2R,3R,4S,5R)-2-acetamido-3,4-dihydroxy-5-hydroxymethyl-piperidinium hydrochloride (GalNAc-isofagomine.HCl), which was synthesized and assayed for its ability to inhibit SpHEX, was found to be a potent competitive inhibitor of the enzyme (K(i) = 2.7 microm). A crystallographic complex of GalNAc-isofagomine bound to SpHEX was solved and refined to 1.75 A and revealed that the lack of a strong electrostatic interaction between the "anomeric" center of GalNAc-isofagomine and SpHEX is compensated for by a novel 2.8-A hydrogen bond formed between the equatorial proton of the endocyclic nitrogen of the azasugar ring and the carboxylate of the general acid-base residue Glu-314 of SpHEX. This interaction appears to contribute to the unexpected potency of GalNAc-isofagomine toward SpHEX.

Assessment of damage and recovery of sinusoidal endothelial cell function by in vivo hyaluronic acid uptake in cold-preserved and transplanted rat livers.

We sought to evaluate the significance of endogenous hyaluronic acid levels and in vivo uptake of exogenous hyaluronic acid as markers of liver endothelial cell damage and correlate these findings to graft survival/function in a rat orthotopic liver transplant model. Endogenous hyaluronic acid levels were measured after orthotopic liver transplantation performed with freshly explanted livers, with livers preserved for 30 hr, and after sham operation. Exogenous hyaluronic acid uptake was evaluated in six study groups: fresh liver grafts, livers preserved for 12 hr, 24 hr, 30 hr and 48 hr, and sham-operated livers. Endogenous hyaluronic acid levels fell after orthotopic liver transplantation with freshly harvested livers and after sham operation, but rose in animals transplanted with livers preserved for 30 hr (P<0.01 vs. sham operation). In the preserved group, there was no difference in endogenous hyaluronic acid levels between survivors and nonsurvivors. Uptake of exogenous hyaluronic acid was significantly lower after orthotopic liver transplant with grafts preserved for 12 hr than after sham operation or orthotopic liver transplant with nonpreserved livers (P<0.05). Hyaluronic acid uptake further deteriorated in the 24-, 30-, and 48-hr groups. No significant difference in hyaluronic acid elimination rate was found when results obtained from livers preserved for extended periods (>12 hr) were compared in survivors and nonsurvivors. Hyaluronic acid uptake was reevaluated in surviving animals after 2 weeks. Completely restored function was observed in all survivors, indicating recovery of endothelial cells. We conclude that endogenous hyaluronic acid levels and exogenous hyaluronic acid uptake are reliable markers of liver sinusoidal endothelial cell function and that normal or moderately compromised hyaluronic acid uptake is associated with good graft function. On the other hand, endothelial cell dysfunction suggested by poor hyaluronic acid elimination is not a completely reliable predictor of subsequent deterioration of graft function in rat liver transplantation.

An assessment of the precision and accuracy of protein structures determined by NMR. Dependence on distance errors.

We tested the dependence of the accuracy and precision of calculated NMR structures on the errors of the distance constraints using sequential simulated annealing and found that: (1) the accuracy of the family of structures depends mainly on the quality of the data, but is no better than about 1 A even if the errors in distance constraints are smaller than +/- 1 A. (2) The precision of the calculated structures, on the other hand, is nearly insensitive to the quality of the data. With present methods, the accuracy of NMR structures is at best of the order of 1 to 2 A, although a precision of 0.4 to 0.7 A is readily attainable. Comparisons with recent studies of this problem also brought out the importance of distinguishing between correct and incorrect definitions of accuracy when reporting numerical estimates. Using an incorrect definition of the term accuracy can lead to an artificially favorable estimate of its numerical value.