First Experience with an Automatic Sensing Algorithm in Single-Lead VDD Stimulation

An "Autosensing" algorithm available in SSI(B) and DDD(R) pacemakers automatically adapts the device's sensitivity to changing intracardiac signals. The atrial sensing function of this algorithm was tested for the first time with a VDD pacing system in which large variations of the atrial signal may occur because the atrial electrodes float in the atrial blood pool. Methods: 15 patients with a VDD pacing system were studied (Unity 292–07, lead 425; Sulzer Intermedics). The atrial sensing threshold was measured, and the atrial sensitivity was programmed with a 2:1 safety margin. The autosensing algorithm and sensitivity profile were temporarily activated, and an ambulatory ECG with continuous marker annotation was recorded. All patients underwent a 30-minute daily life activities protocol. A beat-to-beat analysis of the ambulatory ECG was correlated with the changes in atrial sensitivity. Results: The algorithm changed the baseline sensitivity from 0.57 ± 0.23 mV during the test to 0.39 ± 0.20 mV after the final rest period (P < 0.05). During the test 12.6 ± 10.2 adaptations of the sensitivity occurred (range 0–33). In eight patients atrial undersensing occurred in 4.4%± 7.5% of the cycles (4–458 unsensed P waves]. In these patients, the algorithm continuously adjusted the sensitivity towards more sensitive values, operating 19.1 ± 18.3 changes compared with 5.4 ± 7.3 changes in patients without undersensing (P = 0.009). Oversensing did not occur. Conclusion: The autosensing algorithm effectively optimized atrial sensitivity in VDD pacing. In patients with atrial undersensing the algorithm continuously remained near the most sensitive settings, thus reacting as intended. A faster sensitivity adjustment of the system would be desirable.     

Assessment of cancer cost at the international level : challenges and methodological approaches

Historically health care data and especially health care cost rigid were not collected by disease. This is due on one side to a lack of readily available information on the diagnosis that lend to the health care given and on the other side to the diversity of actors and organizations taking charge of patients. This results in a major difficulty of linking together incompatible and separate data. A few countries have tried to desegregate their global health cost data in a top-down approach. The limits of such undertakings appeared however quickly, not the least because of the difficulties in allocating the expenditures by sector and disease. Other approaches, probably more fecund in the long run, such as the one used by the SEER-Medicare database in the U.S. favour the linkage of individual patient clinical and cost data in a bottom-up approach. However one should not ignore the potential bias problems raised, by the use of even large databases such as this one. A major advantage of clinical trials for costing purposes it that they include homogeneous groups of patients randomly allocated to several treatments for comparative purposes. They are therefore potentially better adapted for comparing new treatments with standard reference care.     

灵芝多糖对混合淋巴细胞培养反应中白细胞介素2生成和T细胞亚类的影响(英文)

利用混合淋巴细胞培养反应研究了灵芝多糖的免疫作用机理。结果表明培养12h,灵芝多糖(25,50,100,200μg/ml)可促进白细胞介素2的分泌,且具有剂量依赖关系。培养4d后,可增加总的细胞回收量以及Lyt 2⁺和L3T4⁺细胞的回收量。灵芝多糖还明显增强细胞毒T细胞的功能,在浓度为200μg/ml时,其杀伤活性增加100%。     

MR imaging of rat brain glioma: Gd-DTPA versus Gd-DOTA

The enhancement properties of gadolinium diethylenetriaminepentaacetic acid (DTPA) and gadolinium tetraazacyclododecanetetraacetic acid (DOTA) were compared using a rat glioma model. In vitro analysis included the calculation of T1 relaxivity and determination of characteristic curves. Enhancement of the intracerebral glioma was studied in 23 rats approximately 2 weeks after glioma implantation with Gd-DTPA in 12 rats and Gd-DOTA in 11 rats. Six rats were also studied 1 week after implantation. Gd-DTPA exhibited a slightly greater T1 relaxivity in vitro than Gd-DOTA. Enhancement of the glioma was also greater with Gd-DTPA than with Gd-DOTA (P less than .05).     

Prevalence and persistence of stomach ache and headache among children. Follow-up of a cohort of Norwegian children from 4 to 10 years of age

Results from a prospective cohort of 136 children, from 4 to 10 years of age, indicated that stomach ache was almost as prevalent among preschool children as children of school age. Headache was almost absent among 4-year-olds but prevalent at 10 years of age. Generally, early pain complaints were persistent. The co-occurrence of stomach ache and headache increased from 4% of children at 4 years of age to 20% when they reached 10 years of age.     

Fragment E1 labeled with I-123 in the detection of venous thrombosis

Fragment E1, which has been shown to have specific binding affinity for thrombi in an animal model, was investigated in humans for its safety and ability to bind to venous thrombi. Human Fragment E1 was labeled with I-123 and administered intravenously to patients with proved or suspected deep vein thrombosis. The vascular distribution of radioactivity was documented by obtaining gamma camera images of the patients' legs for 30 minutes following administration of I-123-Fragment E1. All patients (n = 5) with documented venous thrombi had rapid localization of labeled Fragment E1 in the area of thrombus. Patients without evidence of thrombi (n = 5) showed no focal localization, although two of these patients showed diffuse uptake along the length of the veins, due to superficial phlebitis. Analysis of blood samples in four patients indicated that disappearance of Fragment E1 from the circulation was more rapid in individuals with thrombosis (t 1/2 = 20 min) than in individuals without thrombosis (t 1/2 = 90 min), and a radiolabeled species of high molecular weight was found in patients with thrombosis but was absent from patients without thrombosis. These early results suggest that radiolabeled Fragment E1 is a safe and potentially valuable agent for the rapid detection of venous thrombosis.     

Is there a threshold level of fetal hemoglobin that ameliorates morbidity in sickle cell anemia?

When the clinical manifestations of 272 patients with sickle cell anemia are compared with their level of fetal hemoglobin (HbF), the results suggest that there may be a threshold above which HbF is effective in ameliorating the morbidity of this disease. The age of entry of these SS patients into the study ranged from birth to 56 yr; the average length of follow-up was 11 yr for a total of 3,011 patient- years of clinic observation. HbF was determined quantitatively by microchromatographic procedures; the mean for HbF was 10% +/- 6% with a range from 2% to 32%. For major organ failure, analyzed as termination events of morbidity, such as stroke or aseptic necrosis, the threshold appears to be 10%, whereas for recurrent clinical events, such as crisis or pulmonary disorders, it is 20%. No linear trend was found between HbF levels and morbidity. If a threshold exists, it is important to recognize this fact when attempts are made to raise the level of HbF in patients with sickle cell disease.     

Expression and characterization of Gag protein of HIV-1 （CN） in Pichia pastoris

To express the core protein of HIV-1 of Chinese prevalent strata （HIV-1[CN]） in Pichia pastoris, the fulllength gag gene was inserted into the secretory expression vector pHILS1. Linearized recombinant plasmid pHILGAG by Sal I was electrotransformed into the yeast strain GS115, and the yeast transformants were identified by PCR. To induce the interest protein to be expressed, the PCR positive transformants were inoculated in the medium of BMGY and BMMY, mRNA of the strain was detected by RT-PCR, and the expressed protein was analyzed by SDS-PAGE, Western blotting and thin layer scanning. mRNA （1.3 kb） was amplified by RT-PCR. SDS-PAGE and Western blotting analysis showed that the molecular mass of the expressed protein was 55 kDa, which was similar to the expected value, and the expressed protein could react with McAb to HIV-1 p24. Thin layer scanning analysis demonstrated that the whole amount of the expressed protein was approximately 13% of the soluble protein in the supernatant. The recombinant yeast had good genetic stability. The optimal expression conditions of the engineering yeast were as follows： BMMY medium, 80%-90% of dissolved oxygen, 1% methanol, and 3-day-cultivation course. Gag proteins were expressed under the optimal expression condition and purified via gel filtration chromatography. The purity of the interest protein was up to 85%. After the purified proteins were inoculated into BALB/c mice, the anti-HIV-1 antibodies in the immunized mice could be detected by Western blotting.     

Mobile phones,mobile phone base stations and cancer: a review

There have been reports in the media and claims in the courts that radiofrequency (RF) emissions from mobile phones are a cause of cancer, and there have been numerous public objections to the siting of mobile phone base antennas because of a fear of cancer. This review summarizes the current state of evidence concerning whether the RF energy used for wireless communication might be carcinogenic. Relevant studies were identified by searching MedLine with a combination of exposure and endpoint terms. This was supplemented by a review of the over 1700 citations assembled by the Institute of Electrical and Electronics Engineers (IEEE) International Committee on Electromagnetic Safety as part of their updating of the IEEE C95.1 RF energy safety guidelines. Where there were multiple studies, preference was given to recent reports, to positive reports of effects and to attempts to confirm such positive reports. Biophysical considerations indicate that there is little theoretical basis for anticipating that RF energy would have significant biological effects at the power levels used by modern mobile phones and their base station antennas. The epidemiological evidence for a causal association between cancer and RF energy is weak and limited. Animal studies have provided no consistent evidence that exposure to RF energy at non-thermal intensities causes or promotes cancer. Extensive in vitro studies have found no consistent evidence of genotoxic potential, but in vitro studies assessing the epigenetic potential of RF energy are limited. Overall, a weight-of-evidence evaluation shows that the current evidence for a causal association between cancer and exposure to RF energy is weak and unconvincing. However, the existing epidemiology is limited and the possibility of epigenetic effects has not been thoroughly evaluated, so that additional research in those areas will be required for a more thorough assessment of the possibility of a causal connection between cancer and the RF energy from mobile telecommunications.