Biomedical subjects
Publications and source records attributed to Chao Chen.
The asymmetric addition of phenylacetylene to aldehydes was carried out by using a camphorsulfonamide titanium complex as a catalyst. The reactions proceeded under mild conditions and gave the products with good yields and high ees. This system is very useful for the synthesis of chiral propargylic alcohol. [reaction: see text]
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Reaction of alkynes with Cp2ZrBu2 and chlorophosphate in the presence PR3 to form zircono-alkenylphosphonates, which can be converted into various beta-functionalized alkenylphosphonates.
Gold particles with diameters between 2.5 and 4.5 nm have been introduced in the inner cavity of an icosahedral brome mosaic virus. The optical properties of single gold-marked virions have been tested in-vitro with respect to the characteristic plasmon polariton resonance. The shift in the plasmon polariton resonance of a single Au particle encapsulated in a virus with respect to a free particle in solution indicates a close interaction between the basic residues on the inner wall of the capsid and the negative surface charge of the particle. Incorporation of a pair of Au particles, approximately 4 nm diameter, is shown to be a frequent event. In this case, the dependence of the two-particle surface plasmon spectrum on the interparticle distance and the strong particle/capsid wall interaction suggest that, in the future, it will be possible to use encapsulated Au particles to track changes in the viral capsid volume in real-time and in a physiological environment.
AIM: To describe the incidence of esophageal cancer (EC) in Cixian, a county of Hebei province during 1974-1996. We analyzed the sex and age characteristics as well as the geographic distribution of EC, in order to determine the impact so that methods of preventing and controlling EC in Cixian can be put in place. METHODS: Since the early 1970s, the cancer registry system has been established, which collects the cancer incidence in Cixian county. The malignant tumors were coded according to International Classification of Disease IX (ICD-9). All the data were checked and analyzed using EPIINFO. RESULTS: The trend of the incidence rate of EC from 1974 to 1996 had declined, (229.9/100 000 vs 178.5/100 000, Odds ratio=1.47, 95 % CI:1.32-1.63, chi(2)=52.89. trend chi(2)=26.54, P<0.001). The incidence rate of males declined significantly (281.81/100 000 vs 157.96/100 000, Odds ratio=1.61, 95 % CI: 1.41-1.84, chi(2)=47.85. Trend chi(2)=44.86, P<0.001), whereas, the females remained steady (157.96/100 000 vs 133.41/100 000, odds ratio=1.28, 95 % CI:1.17-1.49, chi(2)=9.26. trend chi(2)=2.69, P>0.05). Male average annual incidence rate was 142.80/100 000 and the female's was 95.18/100 000. The sex ratio (males to females) was 1.50:1. The incidence rate was increasing along with the age. As to the geographic distribution, the incidence rate in mountainous areas and hilly areas showed a significantly declining trend (mountainous areas, trend chi(2)=149.93, P<0.001; hilly areas, trend chi(2)=42.70, P<0.001). The incidence rate of EC in plain areas had increased (trend chi(2)=22.39, P<0.001). CONCLUSION: The incidence rate of EC in Cixian county shows a trend and has declined after two decades, especially in mountainous area. But compared to other regions in the world, Cixian county still had a high incidence rate of EC.
OBJECTIVE: To observe the change of surface active agents of eustachian tube of guinea pigs suffering from secretory otitis media, to explore the effects of surface active agents on secretory otitis media. METHODS: To establish the animal model of guinea pigs suffering from secretory otitis media. To analyse the changes of biochemical component and activity of eustachian tube's surfactant, meanwhile; to observe surfactant change after ectogenic surfactant treatment. RESULTS: The main components of the surfactant decrease in the model group of guinea pigs suffering from secretory otitismedia, phosphatidylcholine (PC) is (19.9 +/- 1.7)%, phosphatidylethanolamine(PE) is (36.8 +/- 2.7)%, minimum surface tension (gamma min) is (18.5 +/- 2.4) mN/m, and PC is (25.7 +/- 2.1)%, PE is (43.7 +/- 3.8)%, (P < 0.001), and gamma min is (7.6 +/- 0.8) mN/m in normal group (P < 0.001). After giving Ectogenic surfactant treatment, PC and PE increase, PC is (23.3 +/- 2.2)%, PE is (42.5 +/- 3.6)%; gamma min reduce, it is (11.8 +/- 2.3) mN/m. CONCLUSIONS: The main biochemical components of the surfactant obviously decrease, the activity of the surfactant weakens in secretory otitis media of guinea pig. This study showed the treatment of Ectogenic surfactant is effective.
The phycobilisomes were isolated from blue-green alga Spirulina platensis, and could form monolayer film at air/water interface. The monolayer film of phycobilisomes was transferred to newly cleaved mica, and coated with gold. Scanning tunneling microscope was used to investigate the structure of the Langmuir-Blodgett film of phycobilisomes. It was shown that phycobilisomes in the monolayer arrayed in rows with core attaching on the substrate surface and rods radiating towards the air phase, this phenomenon was similar to the arrangement of phycobilisomes on cytoplasmic surface of thylakoid membrane in vivo. The possible applications of the Langmuir-Blodgett film of phycobilisomes were also discussed.
OBJECTIVE: To study the effects of hypothermia on cardiac function in neonates after birth asphyxia. METHODS: Fifty term newborns with Apgar score < 5 at 5 minutes were randomly divided into no cooling group (normothermia group, NG; rectal temperature = 36.5 degrees C +/- 0.5 degrees C, n = 27) and cooling group (hypothermia group, HG; rectal temperature = 34.5 degrees C +/- 0.3 degrees C, nasopharyngeal temperature = 34.0 degrees C +/- 0.5 degrees C, n = 23). The selective head cooling was applied to maintain nasopharyngeal temperature at 34 degrees C for 72 h in hypothermia group. Systolic and diastolic function was detected at the end of treatment by echocardiogram. RESULTS: (1) The heart rate was obviously decreased during the hypothermia treatment, and there was a significant difference between HG and NG [(103 +/- 15) bpm vs. (126 +/- 14) bpm, P < 0.05]. No cardiac arrhythmia and hypotension were found in all neonates. (2) There were no significant differences on the ejection fraction, stroke volume and cardiac output of left ventricle between the two groups (P > 0.05). No significant difference was found in the numbers of left and right ventricular diastolic dysfunction, pulmonary hypertension between the two groups (P > 0.05). (3) The level of cardiac troponin T (cTnT) in plasma was (0.47 +/- 0.15) ng/ml in HG, and (0.35 +/- 0.21) ng/ml in NG, and there was no significant difference between the two groups (P > 0.05). CONCLUSION: No significant cardiac dysfunction complication caused by the hypothermia treatment was found in term neonates after birth asphyxia.
BACKGROUND: Cixian county has one of the highest incidence rates of esophageal cancer (EC) in China, as well as the world. In 1974, the Cixian population-based cancer registry system was established, so that there is now information on esophageal cancer cases over almost 30 years. METHODS: Data from Cixian Cancer Registry were checked and analyzed using SPSS 11.5. RESULTS: From 1974 to 2002, a total of 18,471 new esophageal cancer cases were registered in Cixian, 11,068 in males and 7,403 in females. The age standardized incidence rate (ASR) for males was 208.77 per 100,000, while for females it was 120.47 per 100,000. There was a clear trend for decrease overall in the incidence rate of esophageal cancer over the 29 years (X(2)=19.94, P<0.001). As to the geographic distribution, the incidence rate in mountainous and hilly areas showed a significant decline (X(2) = 195.00 and X(2) = 46.08, respectively, both P X(2)0.001). Data for esophageal cancer incidence in level land areas in contrast were relatively steadily, with increase in recent years. CONCLUSION: Esophageal cancer has decreased in Cixian county during the last 29 years, but this is due to change in mountainous and hilly areas. Compared to other regions in the world, Cixian county still has a very high incidence of ECs.
A model is presented to simulate the cooling processes during tumor cryosurgery with different kinds of flows through the cryoprobe. The heat flux between the cryoprobe wall and the tumor, the heat transfer coefficient under different inflow conditions are obtained numerically. The impact of the inlet mass flow rate, gas volume fraction on these parameters is investigated. It is found that the heat transfer coefficient decreased significantly when inflow changed from two-phase annular flow to droplet flow, and to gas flow. The inlet gas volume fraction and flow velocity only significantly affect the freezing ability of the probe when the inflow is gas or in droplet phase. Simulation of the tumor temperature profiles under different flow conditions show that the heat transfer coefficient is a crucial parameter in temperature prediction during cryosurgery. Results indicate that when the cryoprobe wall is assumed at a constant temperature conventionally, the cooling effect could be overestimated. It would be more reasonable to use the constant wall heat transfer coefficient to simulate the cooling progress under a specific flow.