An outbreak of Salmonella Paratyphi A in a boarding school: a community-acquired enteric fever and carriage investigation.

Salmonella Paratyphi A (SPA) is rapidly becoming a common cause of enteric fever in South East Asia. A large outbreak of SPA occurred in a boarding middle school in China in 2004. There were 394 suspected cases; 95·5% were students. The highest incidence was in the youngest children (7th grade). Forty-four of 151 (29%) blood cultures and 4/54 (7·4%) rectal swabs were positive for SPA; three were from kitchen workers. The geometric mean levels of serum IgG anti-lipopolysaccharide (anti-LPS) from patients was higher than from healthy individuals [35·25 vs. 5·20 ELISA units (EU), P<0·001]. A kitchen worker with a positive rectal swab, negative blood culture and a high level of serum IgG anti-LPS (529·65 EU), was identified as a possible SPA carrier. No SPA was isolated from water or food samples. A survey of students' habits indicated drinking unboiled water as being the main reason for contracting the disease. Hand washing was the second most important factor. A food handler with possible SPA carriage could also have been a risk factor. Attention to maintaining a safe water supply, enhancing food-handler hygiene and proper hand washing can help to prevent similar outbreaks in the future.

Transport properties of warm dense neon and krypton at high pressures.

The transport properties of warm dense neon (Ne) and krypton (Kr) are studied by combining self-consistent fluid variational theory (SFVT) with linear response theory (LRT). The components are determined using the SFVT, and the transport parameters, including the electrical conductivity, thermal conductivity, and thermopower, are calculated with the LRT. The relevant scattering mechanisms, including electron-ion, electron-electron, and electron-atom scatterings, are taken into account. An effective potential model in combination with the Muffin-tin model is introduced to further improve the description for electron-atom scattering, which not only includes static, exchange, and polarization interactions but also considers the plasma environmental effects. It is found that for electron-atom scattering, the influence of the plasma density is significant at lower scattering energies but the effects are different for electron-Ne and electron-Kr scattering. For electron-Kr scattering, a plasma density-dependent Ramsauer-Townsend minimum is observed. The obtained transport parameters are compared with the available experiments and other simulations. The plasma phase transition of warm dense Kr is revisited from multiple perspectives based on the numerical simulation results for the electrical conductivity and thermopower. These observations may help one to better understand the transport properties of warm dense noble gases and are an important guide for future experimental designs and theoretical developments.

Safety of endoscopical procedures during pregnancy.

INTRODUCTION: Data on safety issues and therapeutic outcomes of endoscopy in pregnancy remains limited especially in the local context. The concerns are that of safety in sedation and radiation to the foetus, effects on the pregnancy, the need for special precautions on mother and foetus during the procedure and long-term foetal outcome. We report a case series on four pregnant women to address these concerns and outline their therapeutic approaches. METHODS: We reviewed four patients who underwent oral gastroduodenoscopy (OGD) or endoscopic retrograde cholangiopancreatography (ERCP) during their pregnancies. Lead aprons were used to shield the foetuses in all patients that underwent ERCP. Sedation was given when necessary, and an anaesthetist was employed in one case for close patient monitoring. Fluoroscopy was minimised and radiographs were taken only when essential. RESULTS: The mean patient age was 27.8 years (range 23-35 years). The mean gestation was 21.5 weeks (range 14-32 weeks), with two patients each being in their second and third trimesters. The indications for ERCP were cholangitis and pancreatitis (one), choledocholithiasis on ultrasonography (two), and that for OGD was persistent vomiting (one). Two patients underwent sphincterotomy and one had a biliary stent inserted. One patient was lost to follow-up. The other three had a full-term normal delivery and all babies were healthy at birth with good birth weight and normal Apgar scores. CONCLUSION: Our series showed that endoscopic procedures in pregnancy are safe for both mother and foetus. However, these procedures should be restricted to cases with definite. indications and radiation exposure should be minimised with additional safety precautions such as minimal radiation exposure and the use of lead shield when applicable.

Equations of state, transport properties, and compositions of argon plasma: combination of self-consistent fluid variation theory and linear response theory.

A consistent theoretical model that can be applied in a wide range of densities and temperatures is necessary for understanding the variation of a material's properties during compression and heating. Taking argon as an example, we show that the combination of self-consistent fluid variational theory and linear response theory is a promising route for studying warm dense matter. Following this route, the compositions, equations of state, and transport properties of argon plasma are calculated in a wide range of densities (0.001-20 g/cm(3)) and temperatures (5-100 kK). The obtained equations of state and electrical conductivities are found in good agreement with available experimental data. The plasma phase transition of argon is observed at temperatures below 30 kK and density about 2-6g/cm(3). The minimum density for the metallization of argon is found to be about 5.8 g/cm(3), occurring at 30-40 kK. The effects of many-particle correlations and dynamic screening on the electrical conductivity are also discussed through the effective potentials.

Development and validation of a disease-specific quality of life questionnaire for gastro-oesophageal reflux disease: the GERD-QOL questionnaire.

BACKGROUND: A simple and meaningful health-related quality of life (HRQoL) questionnaire for gastro-oesophageal reflux disease (GERD) patients is lacking. AIM: To develop and validate a disease-specific HRQoL instrument (GERD-QOL) for GERD patients. METHODS: An 18-item questionnaire was generated to measure the impact of GERD on sleep, exercise, diet, need for medication, sex life, work, social activity and psychological well-being. GERD patients were invited to complete the GERD-QOL, a visual analogue scale (VAS) and a validated Chinese generic QoL (SF-36) questionnaire before and after esomeprazole treatment. Factor analysis was performed for item selection and psychometric properties were measured. An English version was developed by a forward-backward translation process. RESULTS: A final 16-item GERD-QOL questionnaire was developed. The items were grouped into four subscales (Daily activity, Treatment effect, Diet, and Psychological well-being) after factor analysis. GERD-QOL had good item-internal consistency (Cronbach's alpha: 0.64-0.88), high test-retest reliability (intraclass correlation coefficient: 0.73-0.94, P < 0.001). Its subscale scores were correlated with SF-36 and VAS, which demonstrated high construct validity (P < 0.001). Discriminant validity was verified by correlating GERD-QOL scores with symptom severity (P < 0.001). Responsiveness after esomeprazole treatment was significant (paired-t-test P < 0.001). An English version of GERD-QOL was developed. CONCLUSION: The instrument, GERD-QOL, is valid and reliable.

Termination of reentrant propagation by a single stimulus: a model study.

A computer model of a ring-shaped one-dimensional cardiac fiber was used to examine responses of reentrant propagation to premature stimuli applied under different degrees of head-tail interaction. Two different types (type I and type II) of termination window (TW) were identified. The type I TW was generated by functional inhomogeneity created by reentrant propagation. The width of the type I TW was proportional to the degree of cellular uncoupling. In contrast, uniform reduction in sodium channel conductance decreased the width of type I TW. The type II TW was generated by electrical alternans created by the head-tail interaction of the reentrant action potential. It was demonstrated that electrical alternans were most significant in medium degree head-tail interaction. For stronger or weaker head-tail interaction, the electrical alternans tended to decrease. The type II TW was located in excitable gaps following reentrant action potentials of short duration. Its size was proportional to the degree of electrical alternans. The type II TW was usually much larger than the type I TW. A premature conditioning stimulus induced alternans and created a type II TW. This response implies that a conditioning stimulus could facilitate greatly the termination of clinical reentrant arrhythmias by programmed electrical stimulation.

A model study of the effects of the discrete cellular structure on electrical propagation in cardiac tissue.

The effects of the discrete cellular structure on propagation of electrical excitation in cardiac muscle were studied in a one-dimensional fiber model containing a periodic intercalated disk structure. Globally, the macroscopic velocity of propagation follows the behavior associated with propagation in a continuous tissue (except for high values of disk resistance). In addition, the computed spatial extracellular potential along the fiber is a smooth biphasic waveform and does not reflect the underlying discrete cellular structure of the tissue. Other results of the simulations demonstrate the discontinuous nature of propagation and the importance of the structure in arrhythmogenesis. Vmax displays a biphasic behavior as a function of increasing intercalated disk resistance. An initial "paradoxical" increase in Vmax (with a simultaneous decrease in conduction velocity) is followed by a decrease that leads to decremental propagation and conduction block. The time constant of the foot of the action potential (tau foot) increases monotonically with increasing intercalated disk resistance. An increase in the leakage current to extracellular space brings about a significant decrease in the action potential duration and a loss of the plateau. This major effect is accompanied by a relatively smaller decrease in conduction velocity. Collision of two activation wavefronts results in a significant (100%) increase in Vmax and a very small (0.6%) decrease in tau foot.

A new DNA immune adsorbent for hemoperfusion in SLE therapy: a clinical trial.

This investigation studied the preparation and clinical trial of DNA immunoadsorbent for hemoperfusion in systemic lupus erythematosus (SLE) therapy. DNA was complexed with blue tetrazolium (BT), then mixed with collodion, and finally adsorbed on macroporous spherical polymeric adsorbent. The percentage of DNA thus immobilized was 98-98.5%, and no release was detected during hemoperfusion. A patient with severe SLE was treated with the above adsorbent in hemoperfusion. The patient was in coma, with high anti-DNA antibody and abnormal immune complex levels, which fell sharply from 56.34% to 0.8% after 2.5 h of whole-blood hemo perfusion. There were no major clinical complications, and 2 weeks later, her proteinuria level became normal and immune complex levels were sustained. She was then discharged from the hospital and has been in good health for more than 1 year.