Biomedical subjects

D Chen

Publications and source records attributed to D Chen.

At least 451 records · Page 25Linked to original sources

PubMed1998

[Influence of compensatory hepatocyte proliferation on the carcinogenesis of N-nitrosodimethylamine].

OBJECTIVE: To study the influence of compensatory hepatocyte proliferation on the N-nitrosodimethylamine (NDMA) carcinogenesis in rats. METHODS: NDMA was given to animals of the experimental group 24 hours after partial hepatectomy, and the control group was only treated with NDMA. Expression of gamma-glutamyltransferase (GGT), glutathione S-transferase placental form (GSTP), proliferating cell nuclear antigen (PCNA), insulin-like growth factor-II (IGF-II) and oncogenes was detected. RESULTS: The numbers and areas of GGT- and GSTP-foci in the experimental group were significantly increased in comparing with the control groups. The expression of GSTP was higher than that of GGT. The total tumor incidence of the experimental group was higher than that of the control by the end of the 56th week. Up to week 71, the incidences of liver and other tumors were higher respectively in the experimental group. The amount of PCNA positive cells were corresponding with proliferative condition of the hepatic lesions. The expression of IGF-II, c-myc and H-ras mRNA increased in the altered hepatocyte foci and nodules, but markedly decreased in hepatocellular carcinoma and adenoma. No c-jun mRNA expression was detected in all the normal and abnormal tissues of liver. CONCLUSIONS: The results suggest that compensatory hepatocyte proliferation enhances the carcinogenesis induced by multiple doses of NDMA, and the over expression of IGF-II, c-myc, H-ras may play a synergetic role in NDMA-induced hepatocarcinogenesis.

Animals↗

PubMed1998

[Detection of T-cell receptor gamma chain gene rearrangement in midline T-cell lymphomas by PCR method].

OBJECTIVE: To investigate the clonality of midline T-cell lymphoma. METHODS: Using polymerase chain reaction method and a panel of family specific primers for the variable regions of TCR-gamma gene, and totally 11 cases (22 samples) of midline T-cell lymphoma (midline malignant reticulosis) were studied. RESULTS: Family specific monoclonal TCR-gamma gene rearrangements were found in 21 out of 22 samples (94.45%). There was no change of clonality during the course of disease. CONCLUSION: There is monoclonal T-cell proliferation in midline T-cell lymphoma and the clonality is not transformed with the advance of the disease. This finding provides an evidence to support the hypothesis of monoclonal origin of neoplasm.

Adult↗

PubMed1998

[Enhancement of apoptotic sensitivity induced by UV irradiation on the p53-transducted K562 cells].

OBJECTIVE: To answer whether wild-type p53 can sensitize K562 cell apoptosis induced by UV irradiation. METHODS: K562 cells transducted with retrovirus encoding wild-type p53 were irradiated by ultraviolet for different time and then cultured for different time. Apoptosis was detected by TDT end labelling technique, DNA fragmentation and MTT assay. RESULTS: TDT end labelling and DNA fragmentation showed that apoptosis induced by 8 min UV-irradiation differed significantly between K562-neo and K562-p53 cells. CONCLUSION: Wild-type p53 can enhance apoptosis induced by UV-irradiation on K562 cells.

Apoptosis↗

PubMed1998

[Effects in tetramethylpyrazine on TXA2 and PGI2 by cardio-pulmonary bypass in congenital heart diseases with pulmonary hypertension patients].

OBJECTIVE: To study protective effects of tetramethylpyrazine (TMP) on the imbalance of TXA2/PGI2 during cardiopulmomary bypass (CPB) in congenital heart disease (CHD) with pulmonary hypertension (PH) patients. METHODS: Thirty patients suffered from non-cyanotic CHD-PH were randomly divided into control group (n = 15) and treatment group (n = 15). 3 mg/kg of TMP was dripped intravenously after anesthesia and 1 mg/kg of TMP was infused into oxygenator after CPB individually. Blood samples were collected and TXA2 as well as PGI2 were measured after anesthesia induction, 15 min during CPB, 5 min after release of the aortic cross-clamp, and 20 min, 6 hrs and 24 hrs after CPB. RESULTS: There was significant difference between treatment group and control group except before operation and 24 hrs after CPB. CONCLUSIONS: The imbalance of TXA2 and PGI2 in patients with CHD-PH during CPB could correct by TMP.

6-Ketoprostaglandin F1 alpha↗

PubMed1998

[Study on efficacy of Chinese Kidney-Tonifying Recipe in male rats with osteoporosis induced by dexamethasone and its mechanism].

OBJECTIVE: To study the efficacy of traditional Chinese Kidney-Tonifying Recipe (KTR) in male rats with osteoporosis induced by dexamethasone (DM) and its mechanism. METHODS: Forty-six male Sprague-Dawley rats at 12 months of age were chosen: they were divided into four groups and KTR and DM were administered appropriately for 18 weeks. General bone mineral density, femur bending strength, serum-BGP, serum-PTH and serum-E2 were measured. RESULTS: General bone mineral density, femur bending strength in KTR prevention group were significantly higher than those in DM group (P < 0.01) and the same with those in normal control group (P > 0.05). General bone mineral density, femur bending strength in KTR treatment group were higher than those in DM group (P < 0.05), and lower than those in normal control group. Compared with DM group, level of serum-T in KTR prevention group and KTR treatment group increased (P < 0.05) and level of serum-PTH in those two groups decreased (P < 0.05). But in comparison with DM group, level of serum-E2 and serum-BGP in the above-mentioned two groups was unchanged (P > 0.05). CONCLUSIONS: The data indicated that traditional Chinese Kidney-Tonifying Recipe could prevent and treat osteoporosis in male rats induced by DM.

Animals↗

PubMed1998

[The powder X-ray diffraction analysis with Fourier spectrum of Chinese material medica Cortex Cinnamomi].

OBJECTIVE: To develop a method for the identification of Chinese medicinal materials in diffraction space. METHOD: Using powder X-ray diffraction analysis to obtain the Fourier spectrum of 10 samples of Cortex Cinnamomi. RESULTS: The analysis shows that each of the 10 samples has its own Fourier pattern topology and characteristic peaks which are connected with its chemical composition. CONCLUSION: Cortex Cinnamomi can be identified successfully according to its topology and characteristic peaks.

Cinnamomum↗

PubMed1998

[Chemical constituents of the leaves of Crataegus scabrifolia (Franch.) Rehd].

OBJECTIVE: To explore the medicinal resources of Crataegus and seek compounds with pharmaceutical effects. METHOD: Column chromatography was employed for the isolation and purification of constituents and the structures were elucidated by spectral analysis and chemical evidence. RESULT: Six compounds were obtained and identified as rutin, hyperoside, vitexin, ursolic acid, daucosterol, and nonacosanol. CONCLUSION: The main constituents of the leaves of Crataegus scabrifolia are flavonoids.

Crataegus↗

PubMed1998

[Clinical diagnostic standard of mediopatellar plica syndrome].

OBJECTIVE: To increase the level of clinical diagnosis of mediopatellar plica syndrome. METHOD: We reviewed the preoperative clinical symptoms of 67 knee joints that were proved to have pathologic mediopatellar plica by arthroscopy. RESULT: Mediopatellar plica syndrome had the following clinical symptoms: painful knee and mediopatellar tenderness in all patients; tender bands in 56.7% patients; positive test of flexion or extension with internal femoral condyle pressed in 62.7% patients; positive Mcmarry's sign in 31.3% patients. CONCLUSION: The clinical diagnostic standard of mediopatellar plica syndrome is that the first above-mentioned clinical symptom plus one of other three symptoms could suggest the diagnosis, while the first clinical symptom plus two or three of other three symptoms could define the diagnosis.

Adult↗

PubMed1998

[The influence of side-to-side portacaval shunt plus enhancement of perfusion of hepatic artery on cirrhotic liver: an experimental study].

OBJECTIVE: To for improving the perfusion of liver, we designed an operation of portacaval shunt (PCS) plus enhancement of perfusion of hepatic artery (EPHA). METHOD: 48 wistar rats were divided into 4 groups randomly. group I (normal control), group II (liver cirrhotic control), group III (PCS on liver cirrhosis), and group IV (PCS + EPHA on liver cirrhosis). The EPHA was performed by the ligation of the left gastric and splenic artery. Liver function tests, liver biopsy, and nuclide hepatobiliary dynamic imaging (NHDI) were performed on the 2nd week and the 6th month after operation. RESULT: In NHDI, the peak time was short (P < 0.05) and the excretive rate was high (P < 0.01). The liver function and the proliferative degree of the fibrotic tissue of the liver were perfected significantly (P < 0.05) in the group IV compared with the group III after operation. CONCLUSION: PCS + EPHA can increase the perfusion of the hepatic artery, maintain the liver function and delay liver cirrhosis, and overcome the side effects of PCS. It is a new surgical technique in treating portal hypertension.

Alanine Transaminase↗

PubMed1998

[Anatomical study and clinical observation of thoracic outlet syndrome].

OBJECTIVE: To investigate the etiology of thoracic outlet syndrome (TOS) from the point of anatomical and clinical view. METHOD: Anatomical study was made on both sides of 30 cadavers. The minimus scalene muscle and the insertions of anterior and middle scalene muscle were dissected and observed. Clinically, 45 cases of thoracic outlet syndrome (TOS) were treated and followed up. RESULT: The minimus scalene muscle was found in 88.3% of the cadavers. T(1) nerve root or the lower trunk of brachial plexus crossed the first rib just over the proximal tendinous part of minimus scalene muscle. Of 45 cases of TOS 34 presented neck-shoulder-pain 17 had. Unchanged symptoms postoperatively, and 7 had aggravated symptoms. Of the recent 8 cases of TOS, 7 presented neck-shoulder-pain. However, the symptom remained in only case after the resection of the tendinous tissue around 5, 6 nerve root from anterior and middle scalene muscle. CONCLUSION: The tendinous tissue of minimus muscle is the cause of the compression of T(1) nerve root or the lower trunk of the brachial plexus. The crossed tendinous origins from the anterior and posterior tubercle of C(4,5) transverse process is the cause of the compression of C(5,6) nerve root or the upper trunk of brachial plexus.

Adolescent↗

PubMed1998

[Relationship between dental severe attrition and the temporomandibular glenoid morphology].

This study used the indices of the temporomandibular glenoid and posterior slope of the eminence by tomography to determine the effect of severe dental attrition on temporomandibular glenoid morphology. The results showed: the temporomandibular glenoid indexes in the group with dental severe attrition and in the control group were respectively 91.49 +/- 8.20 and 92.54 +/- 8.38 (P > 0.05), and the indices of posterior slope of the eminence were 49.79 +/- 5.84 and 50.38 +/- 4.58 (P > 0.05), the difference was not statistical. It was concluded that severe dental attrition would not certainly cause abnormal temporomandibular glenoid.

Cephalometry↗

PubMed1998

[Measurements of Ar(I) excitation temperatures and electron number densities in an ICP with and without the presence of Freon 12--the development of ICP technology for hazardous waste management].

For the management of refractory hazardous wastes, an innovative technology emerging recently is the application of ultra high temperature plasma. The preliminary study on destruction of Freon 12 by ICP (1-2kW) under a joint program between Xiamen Univ. and Hong Kong Baptist Univ. showed that the ICP technology indeed holds a great potential for hazardous wastes management. The destruction efficiency is more than 99.9999%. With and without the presence of Freon 12, Ar(I) excitation temperatures were measured by Boltzmann plot method and electron number densities the by H (beta) line broadening method. It was found that above the load coil, the excitation temperatures and electron number densities decrease with increasing the amount of Freon 12 presented in the central channel of the ICP, but inside the load coil region, the excitation temperatures are affected little by Freon 12. The conclusion of thermal pinch could be expected from this phenomenon.

Argon↗

PubMed1998

[A multiexponential model in cavity ring-down absorption spectroscopy].

A multiexponential model of cavity ring-down absorption spectroscopy is established for taking into account the laser linewidth effects. It is demonstrated that by fitting the logarithmic ring-down function to a truncated polynomial, absorption coefficent can be extracted from coefficients of the first as well as higher order terms of the fitted polynomial. The new fit model results in higher accuracy and broader dynamic range than the previous single exponential model.

English Abstract↗

PubMed1998

[Influences of Freon-12 (CF2CCl2) on the electron number densities in an inductively coupled plasma (ICP) measured with Halpha line--the applications of ICP in the disposal of hazardous waste].

The inductively coupled plasma was applied to decompose Freon 12 (CF2CCl2). The efficiency of the decomposition was indirectly evaluated by comparing the electron number densities in the central channel of the ICP with the addition of different amounts of Freon-12. Halpha line (656.3nm) was used to measure the electron number density due to Hbeta line (486.1nm) is seriously interfered with the addition of Freon-12 under the selected operating conditions. The "thermal pinch" effect was found with the addition of Freon-12, which is beneficial to the complete decomposition of the compound.

English Abstract↗

PubMed1998

[Survey on recent progresses in glow discharge mass spectrometry].

Glow discharge mass spectrometry as a sensitive method for direct solid sample analysis has gained rapid development in recent years. In this paper, the progresses of glow discharge mass spectrometry in the designment of new types of discharge lamp and the achievement in the diagnostic study of the atomization and ionization in the discharge process have been reviewed. Also the analytical characteristics of this method in practical application have been described.

English Abstract↗

PubMed1998

[Experimental research on laser-induced single-molecule detection].

Single-molecule detection is a kind of ultra-high sensitive detection technique. It is widely used in biology, medicine, environment and so on. Here we report briefly the principle and device of our laser-induced single-molecule detection spectrum instrument. We also report the experimental results on the instrument by using C445 dye, including the affection of sample velocity, energy characteristic, consistence linearity and detection limit. We discuss the effect of photon bleach on experimental results. These results are the base of our future work.

Chemistry Techniques, Analytical↗

PubMed1998

[Ultrasensitive analysis of R6G and R110 in solution].

This paper describes the ultrasensitive detection of R6G and R110 in a flowing aqueous sample, based on laser-induced fluorescence (LIF) combined with mode-locked pulsed excitation and time-correlated single-photon counting. A high repetition rate mode-locked argon ion laser operated at 514.5 nm was used as the excitation source. The laser beam was found tightly into a thin wall capillary flow cell. The probe volume was about 12.6 x 10(-12)L. Fluorescence was collected at 90 degrees using a x 40 microscope objective, and was detected by a fast response PMT detector. A time-gate was used to discriminate Raman scattering light background. Using the criterion of 3 standard deviations above background, the detection limits obtained for R6G and R110 were 3.8 x 10(-14) mol/L and 1 x 10(-13) mol/L respectively, and the average probability was lower than 1 in the presence of a R6G or a R110 molecule in the detection volume.

Lasers↗

PubMed1998

[Analysis of trace Pd in marine deposit samples using laser-excited atomic fluorescence spectrometry].

Laser-excited atomic fluorescence spectrometry and its experimental set-up are introduced in this paper. Using this spectrometer, Pd contents in 36 marine deposit samples of the East-sea continental shelf were analyzed. The results show that the detection limit and the precision of this spectrometer are 50 pg/mL and 6% respectively, and the measurements of Pd in marine deposit samples are reliable.

English Abstract↗