Biomedical subjects

Lei Dong

Publications and source records attributed to Lei Dong.

93 records · Page 6Linked to original sources

PubMed2002

[Correlationship between body mass index and mortality in the middle-aged and elderly population of Beijing City].

OBJECTIVE: To explore the association between body mass index (BMI) and mortality in the middle-aged and elderly population of Beijing. METHODS: A prospective cohort study was carried out in a natural population (aged 40 and over) in September 1991, totaling 6 209 subjects. After a baseline survey for risk factors, all the subjects were followed-up throughout December 1999. All deaths occurred during the follow-up period were registered and encoded according to ICD-9. Proportional hazard regression was used to examine the relationship between BMI (body weight in kilograms/height in square meters) and overall and cause-specific mortality. RESULTS: During the past ten years, five leading causes of death in the middle-aged and elderly population of Beijing were cardiovascular disease (CVD), cor pulmonale, digestive malignant tumor, sudden death without definite cause and lung cancer, which accounting for 33.3%, 13.8%, 11.2%, 7.4% and 5.6% of the total deaths, respectively. The minimum overall mortality in all population and in non-smokers were seen in those with BMI of 23.6 - 26.2. Compared with those with BMI of 23.6 - 26.2, the relative risks (RR) for all-cause mortality in all population and non-smokers with BMI less than 21.2 and equal to or greater than 26.2 were 1.7, 1.3, 1.9 and 1.5, respectively after adjusted for age, gender, smoking and alcohol drinking. BMI correlated positively with death risk due to CVD in non-smokers, with an RR of 1.2 for those with BMI > 26.2 to non-smokers with BMI < 21.2 after adjusted for age, gender and alcohol drinking. A U-shaped correlationship between BMI and deaths due to other specific causes, including cor pulmonale, digestive malignant tumor, lung cancer, pneumonia and sudden death without definite causes. With the minimum cause-specific death rates all at BMI of 23.6 - 26.2. In comparison with those with BMI of 23.6 - 26.2, RRs for these five cause-specific mortality were 14.8, 1.1, 5.6, 2.4 and 2.6, respectively for non-smokers with BMI < 21.2 and 3.0, 1.9, 3.7, 2.2 and 1.5, respectively for non-smokers with BMI >/= 26.2 after adjusted for age, gender, and alcohol drinking. The proportion of deaths due to CVD was the highest in each BMI group, with a range of 28.0% - 54.8%. CONCLUSIONS: There exists a U-shaped correlationship between BMI and overall mortality in the middle-aged and elderly population in Beijing. CVD remains the top leading cause of death in natural population, and its death risk increased with BMI.

Adult↗

PubMed2002

[Effect of different infusion volume on hemodynamics of portal hypertension canines after hemorrhagic shock].

OBJECTIVE: To examine the effect of different infusion volume on hemodynamics of portal hypertension (PHT) canines after hemorrhagic shock (HS). METHODS: PHT canine models were made by coarctating a half main portal vein with silk line chronic embolization. Two weeks later, the canine models were assigned to hemorrhagic shock by femoral artery venesection quickly. They were divided into two groups: large volume infusion group (n=6) and small volume infusion group (n=6). Hemodynamics indexes of PHT canines after HS were monitored continuously. We also examined the effect of different infusion volume on hemodynamics. RESULTS: PHT canines showed a series of hemodynamics changes in hemorrhagic shock stage, which aggravated hemodynamics disorder in PHT. After quick infusion, MAP, IVCP, PVP, PVPG, PVBF, HABF, and HBF increased significantly. These indexes in large volume infusion group were higher than those in small volume infusion group. PVR, SVR, HAR decreased significantly. PVP, PVPG, PVBF, HABF, and HBF showed a rebound increase above baseline values in large volume infusion group. The changes of PVP, PVPG, PVBF, HABF, and HBF were parallel with MAP and IVCP and without rebound increase in small volume infusion group. In large volume infusion group PVPG increased earlier and more significant than PVP and exceeded baseline by 13% (2.58 0.37) kPa, so the danger of rebleeding rose greatly. In small volume infusion group PVPG was over 22% (1.67 0.27) kPa lower than baseline, which infers that the danger of rebleeding reduced greatly. SVR and HAR were lower in large volume infusion group. PVP, PVPG, PVBF, HABF, and HBF showed a positive correlation with accumulated vein infusion volume. PVR showed a positive correlation with accumulated vein infusion volume in small volume infusion group. HAR showed a negative correlation with accumulated vein infusion volume in large volume infusion group. CONCLUSIONS: PHT canines after HS show a rebound increase of PVP, PVPG, PVBF, HABF, and HBF above baseline values in large volume infusion group. In small volume infusion group, however, no rebound increase is noticed. Large volume infusion may cause PVP, PVPG, PVBF, HABF, and HBF increase higher than small volume infusion.

Animals↗

PubMedDate not supplied

The use of rectal balloon during the delivery of intensity modulated radiotherapy (IMRT) for prostate cancer: more than just a prostate gland immobilization device?

PURPOSE: The purpose of this study was to investigate the role of a rectal balloon for prostate immobilization and rectal toxicity reduction in patients receiving dose-escalated intensity-modulated radiotherapy for prostate cancer. PATIENTS AND METHODS: Patients with localized prostate cancer who were undergoing intensity-modulated radiotherapy were treated in a prone position, immobilized with a customized Vac-Lok bag (MED-TEC, Orange City, IA). A rectal balloon with 100 cc of air was used to immobilize the prostate. The prostate displacements were measured using computed tomography (CT)-CT fusion on 10 patients who received radioactive seed implant before intensity-modulated radiotherapy. They were scanned twice weekly during 5 weeks of intensity-modulated radiotherapy, and breathing studies were also performed. Rectal toxicity was evaluated by use of Radiation Therapy Oncology Group scoring in 100 patients. They were treated to a mean dose of 76 Gy over 35 fractions (2.17-Gy fraction size). Dose-volume histogram of the rectum was assessed. A film phantom was constructed to simulate the 4-cm diameter air cavity that was created by the rectal balloon. Kodak XV2 films (Rochester NY) were used to measure and compare dose distribution with and without the air cavity. A fraction of 1.25 Gy was delivered to the phantom at isocenter with 15-MV photons by use of the NOMOS Peacock system and the MIMiC treatment delivery system (Sewickley, PA). RESULTS: The anterior-posterior and lateral prostate displacements were minimal, on the order of measurement uncertainty (approximately 1 mm). The standard deviation of superior-inferior displacement was 1.78 mm. Breathing studies showed no organ displacement during normal breathing when the rectal balloon was in place. The rectal toxicity profile was very favorable: 83% (83/100) patients had no rectal complaint, and 11% and 6% had grade 1 and 2 toxicity, respectively. Dose-volume histogram analysis revealed that in all of the patients, no more than 25% of the rectum received 70 Gy or greater. As visualized by film dosimetry, the dose at air-tissue interface was approximately 15% lower than that without an air cavity. The dose built up rapidly so that at 1 and 2 mm, the differential was approximately 8% and 5%, respectively. The dosimetric coverage at the depth of the posterior prostate wall was essentially equal, with or without the air cavity. DISCUSSION: The use of a rectal balloon during intensity-modulated radiotherapy significantly reduces prostate motion. Prostate immobilization thus allows a safer and smaller planning target volume margin. It has also helped spare the anterior rectal wall (by its dosimetric effects) and reduced the rectal volume that received high-dose radiation (by rectal wall distension). All these factors may have further contributed to the decreased rectal toxicity achieved by intensity-modulated radiotherapy, despite dose escalation and higher-than-conventional fraction size.

Catheterization↗