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Biomedical subjects

D Chen

Publications and source records attributed to D Chen.

At least 361 records · Page 20Linked to original sources
PubMed1999

[A study on chemical composition of Gardenia sootepensis Hutch--quantitative determination of iridoid compounds by RP-HPLC].

OBJECTIVE: To determine the iridoid contents in Gardenia sootepensis. METHODS: Using RP-HPLC with geniposidic acid, geniposide and scandoside methyl ether as standards. RESULT: According to the selected chromatographic conditions, the linear ranges of geniposidic acid, geniposide and scandoside methyl ether were 0.097-0.606 microgram, 0.0638-3.990 micrograms and 0.198-1.239 micrograms, respectively. The average recoveries of these three compounds were 100.0%, 99.9% and 100.1%, and RSD 1.23%, 1.38% and 1.53% (n = 5) respectively. CONCLUSION: The method is easy, rapid, and reproducible.

Chromatography, High Pressure Liquid↗
PubMed1999

[Pathological morphology of arterioles and main visceal organs in primary hypertension--an analysis of 45 autopsies].

The autopsy materials of 45 cases of primary hypertension were studied retrospectively. The arteriolar lesions were reviewed. The arterioles < 100 microns in diameter were defined as distal arterioles; those > or = 100 microns and < 300 microns in diameter were proximal arterioles. The lesions of arteriolar wall were categorized as plasma infiltration and hyaline degeneration, and according to seriousness, the latter was divided into three degrees: I, II and III. The results revealed that (1) the arteriolar lesions in different areas of the body were at different stages of seriousness; (2) the changes in the distal arterioles were earlier than those in the proximal ones; in brain, the proximal arterioles dilated first, and then occurred the hyline degeneration; (3) hyaline degeneration took place early in the abdominal organs such as kidney, liver and pancreas, but relatively late in brain; (4) different parts of an organ were at different stages of seriousness; and (5) the lesions in different organs led to different consequences. The pathogenesis of arteriolar sclerosis in primary hypertension was also discussed.

Adult↗
PubMed1999

[Study of the carrying of respiratory tract viruses in steroid-responsive and simple nephrotic syndrome].

This study aimed to investigate the relationship between the carrying of respiratory tract viruses and the quantitative change of urinary protein of the steroid-responsive and simple nephrotic syndrome (SRSNS), and to assess the function of respiratory tract viruses in the triggering of the SRSNS, 37 children with nephrotic syndrome underwent the examination of respiratory tract viruses (APAAP method) once a week when they were hospitalized from August 1997 to March 1998. Among them, 17 children had simple nephrotic syndrome and 10 had nephritic nephrosis. Moreover, 18 children with respiratory infection in the same season were chosen as the control and were subjected to the examination of respiratory tract viruses by the same method. In the cases of SRSNS, the percentage for the carrying of respiratory tract viruses increases obviously in the acme, the percentage for the carrying of respiratory tract viruses of SRSNS has close relationship with the quantity of urinary protein (P < 0.05). There is no difference between the constitution of the category of the viruses carried in the acme of SRSNS and that of the viruses in the control (P > 0.05). The most frequently detected respiratory tract viruses in the acme of SRSNS is RNA virus, and that in the control is the same (P > 0.05). In the acme of SRSNS, most children have no symptoms of respiratory infection although respiratory tract viruses were detected. In the SRSNS, the percentage for the carrying of respiratory tract viruses increases obviously in the acme, it has an important relationship with the quantitative change of urinary protein. The category of the respiratory tract viruses detected in the SRSNS has a relationship with the season, this may be the reason why the cases of SRSNS so easily happen and relapse in this season. RNA virus perhaps plays an important role in the triggering of this disease, including the respiratory tract viruses infection and the carrying of respiratory tract viruses without the symptom of respiratory infection.

Carrier State↗
PubMed1999

[An assessment of Helkimo index in 88 orthodontic patients before treatment].

OBJECTIVE: The prevalence of temporomandibular joint disorders(TMJDs) was studied in orthodontic patients before orthodontic treatment. METHODS: The functional examination of the masticatory system was made with Helkimo index in 88 young patients with general malocclusion. RESULTS: According to the dysfunction index, 50 percent of the patients was free of anamnestic dysfunction, and 44.32% and 5.68% of the patients had a mild and a severe anamnestic dysfunction respectively, 32.95 percent of patients was free of clinical dysfunction, and 51.14% and 14.77% of patients had a mild and a moderate clinical dysfunction respectively, only 1.14 percent of patients had a severe clinical dysfunction. The dysfunction of masticatory muscles and sounds of temporomandibular joint were most common in the signs and symptoms of TMJDs. CONCLUSION: There were no significant differences in the distribution of Ai and Di in different gender and between Angle's Class I and II malocclusion, and there was a relationship between Ai and Di.

Adult↗
PubMed1999

[Determination of the aconitine alkaloids in traditional Chinese medicine chuanwu and caowu by high performance capillary electrophoresis(HPCE)].

A simple and rapid method for the simultaneous assay of three aconitine alkaloids (mesaconitine (MA), hypaconitine (HA) and aconitine (A) in the traditional Chinese medicines, Chuanwu and Caowu, by high performance capillary electrophoresis has been established, using tetracaine as an internal standard. The experimental conditions were as follows, the electrophoretic medium was composed of V[70 mmol/L Tris-borate (pH 8.49)]: V(methanol) = 60:40, uncoated capillary used was 50 cm x 50 microns i.d. and detection was carried out with a UV monitor at 235 nm. The separation was achieved by optimizing the cartridge temperature, the applied voltage, and the pH as well as the concentration of the buffer, and organic modifier. The calibration curve showed a good linearity in the mass concentration range of 0.0115-0.8330 g/L (r = 0.9996) for MA, 0.0089-0.6440 g/L (r = 0.9997) for HA, and 0.0083-0.6000 g/L(r = 0.9997) for A. The recoveries ranged from 93.0% to 104.0% with relative standard deviations from 0.68% to 1.7%. The total time for separation and determination was within 23 min. By means of this method, three aconitine alkaloids in Chuanwu and Caowu have been determined.

Aconitine↗
PubMed1999

[Dual window factor analysis for data of hyphenated chromatography].

A new method, dual window factor analysis (DWFA), used for the qualitative and quantitative analysis of target components hidden in chromatographic overlapping peaks of hyphenated methods is proposed in this paper. It's based on the characteristic information of the spectrum of the component. This method can directly be used for the qualitative analysis and the resolution of the spectrum and chromatogram of target components. Therefore, it is appropriate for the qualitative and quantitative analysis of the desired components in multicomponent complex system with hyphenated methods. DWFA is successfully applied to the analysis of the 4 components overlapping peak, and the results show that excellent correlations between resolved chromatographic peak area and mass concentration are kept in each of the 4 components.

Chlorophenols↗
PubMed1999

[Diagnostic value of ENG in occupied lesions of cerbellopontine angle].

OBJECTIVE: To evaluate the diagnostic value of ENG in occupied lesions of cerebellopontine angle. METHOD: Twenty-four cases of pathological confirmed occupied lesions of cerebellopontine angle were examined with ENG before operation. The ENG examination included saccade test, gaze test, ocular pursuit test, optoknetic test, positional test and positioning test. RESULT: ENG tests were compared with the results of operation and pathology. The results showed that abnomal ENG-OKR suggested central lesions. Brun's nystagmus and unilateral canal paresis were of important value in locating the lesions of cerebellopontine angle. The ocular pursuit test and optokinetic test could point out which side the lesions were. CONCLUSION: Patients with cerebellopontine angle lesions smaller than 3 cm in diameter showed unilateral canal paresis in caloric test indicated acoustic neuroma. Patients with cerebellopontine angle lesions showed no canal paresis may be other lesions except acoustic neuroma.

Adult↗
PubMed1999

[Character identification of 12 kinds of pilose antler medicinal materials].

In this paper, commercial medicinal materials of 12 kinds of pilose antler, Cervus nippon, C. elaphus, C. albirostris, C. unicolor, C. eldihainanus, C. timorensis C. porinus, Dama dama, Rangifer farandus, Alces alces, Elaphurus davidianus, Capreolus capreolus were compared and identified. A key and simple character illustration were listed.

Animals↗
PubMed1999

[Spectroscopic study of the 1pig Rydberg states of Na2].

Six highly excited 1pig states of the Na2 molecule have been investigated by optical-optical double resonance (OODR) flourescence excitation spectroscopy. Absolute vibrational numberings are determined and molecular constants and RKR potential curves are obtained. The lowest 10 1pig states have been relabeled according to the hydrogenic nllambda characters of the Rydberg orbital and classified into core-penetrating and core-nonpenetrating Rydberg states.

English Abstract↗
PubMed1999

[The application of ion detection in the study of spectroscopy of Na2].

Ion detection technique has been successfully used in the study of Rydberg states of Na2 by pulse optical-optical double resonance. High-lying Rydberg states near ionization limit have been observed and high sensitive and high gain spectra have been obtained. This technique is very useful for molecular spectroscopy.

English Abstract↗
PubMed1999

[The two-step three-photon resonant ionization of atom Cu].

This paper discusses the process of resonant laser ablation (RLA), where the two-step three-photon resonant ionization of copper is considered as the best scheme. The rate equations of resonant ionization of copper are calculated and the factors that affect the ionization efficiency are discussed. The results prove the potential advantages of RLA especially the low energy threshold.

English Abstract↗
PubMed1999

[Vibration studies of amphetamine and methamphetamine by micro Raman].

For the first time, we obtained and investigated the Raman spectra of amphetamine and methamphetamine by micro Raman with incidence excitation light 514.5 nm under the ambient environment. According to the fact that both molecules belong to single substituted benzene which has the symmetry of Cy2v, the attribution of Raman vibration modes in amphetamine and methamphetamine molecules was carried out by studying the spectral lines in the two spectra. The Raman line that only appeared in methamphetamine but could not be seen in any other drugs we have investigated was most possibly attributed to the stretching vibration between C-N(+)-C.

Amphetamine↗
PubMed1999

[Studies of narcotics by micro Raman spectroscopy].

For the first time, the Raman spectra of eight kinds of narcotics were obtained and investigated by micro Raman. The results indicated that the Raman spectra were affected by the numbers and position of methyl in substituent groups. Under incidence light 514.5 nm and appropriate measurement condition, high quality Raman spectra of drugs with low fluorescence background were obtained. In addition, we discovered that narcotine and thedaine were very sensitive to strong light radiation. Finally, by comparing Raman spectra carefully for all drugs we measured the specific Raman peaks were given for the purpose of distinguishing different kinds of drugs.

Illicit Drugs↗
PubMed1998

Expression of hirudin fusion proteins in mammalian cells: a strategy for prevention of intravascular thrombosis.

BACKGROUND: Intravascular thrombosis occurs in disorders of diverse pathogeneses, including allograft and xenograft rejection. In this in vitro study, we describe an approach for tethering the specific thrombin inhibitor hirudin to plasma membranes as part of a genetic strategy for regulating intravascular coagulation. METHODS AND RESULTS: An HLA class I leader sequence was fused with hirudin linked to domains 3 and 4 of human CD4 and intracytoplasmic sequence from either CD4 or human P-selectin. The constructs were transfected into mouse fibroblasts, Chinese hamster ovary (CHO)-K1 cells, immortalized porcine endothelial cells (IPECs), and a pituitary secretory cell line (D16/16). Thrombin binding to the hirudin fusion proteins expressed on fibroblasts and CHO-K1 cells could be blocked by an anti-hirudin monoclonal antibody and by pretreatment of thrombin with either the synthetic tripeptide thrombin inhibitor PPACK or native hirudin. Hirudin expression significantly modified the procoagulant phenotype of IPECs in human plasma, leading to prolongation of clotting times. Hirudin-CD4-P-selectin fusion proteins accumulated in adrenocorticotropic hormone-containing granules in D16/16 cells, with no cell surface expression except on activation with phorbol ester, when hirudin relocated to the outer membrane. CONCLUSIONS: Hirudin fusion proteins were expressed on mammalian cells, where they reduced local thrombin levels and inhibited fibrin formation. Regulated expression was achieved on activated cells by use of the cytoplasmic sequence from P-selectin. In vivo, these fusion proteins may prove useful transgenic or gene therapy agents for preventing intravascular thrombosis.

Amino Acid Chloromethyl Ketones↗
PubMed1998

Adenovirus vector-based purging of multiple myeloma cells.

Adenoviruses are efficient gene delivery agents for a variety of neoplasms. In the present study, we have investigated the use of adenoviruses for the delivery of the thymidine kinase (tk) gene into multiple myeloma (MM) cells. We first demonstrated that MM cell lines and MM patient cells express both adenovirus receptors as well as the DF3/MUC1 protein, thus providing a rationale for using adenoviruses to selectively deliver genes under the control of the DF3 promoter. By using an adenoviral construct containing beta-galactosidase (beta-gal) gene driven by the DF3 promoter (Ad. DF3-betagal), we demonstrate greater than 80% transduction efficiency in OCI-My5 and RPMI 8226 MM cell lines at a multiplicity of infection of 1 to 100. Importantly, transduction with the tk gene driven by the DF3 promoter (Ad.DF3-tk) followed by treatment with 50 micromol/L ganciclovir (GCV) purged >/=6 log of contaminating OCI-My5 and RPMI 8226 MM cells within bone marrow mononuclear cells. In contrast, normal human hematopoietic progenitor cell number was unaffected under these conditions. Selectivity of DF3/MUC1 promoter was further confirmed, because Ad.DF3-betagal or Ad.DF3-tk did not transduce MUC1-negative HeLa cervical carcinoma cells. In addition, GCV treatment of Ad.DF3-tk-transduced RPMI 8226 MM cells did not induce a significant bystander effect. These findings demonstrate that transduction with Ad vectors using a tumor-selective promoter provides a highly efficient and selective approach for the ex vivo purging of MM cells.

Adenoviridae↗
PubMed1998

Pituitary adenylate cyclase activating peptide (PACAP) in the retinohypothalamic tract: a daytime regulator of the biological clock.

The retinohypothalamic tract (RHT) relays photic information from the eyes to the brain biological clock in the suprachiasmatic nucleus (SCN). Activation of this pathway by light plays a role in adjusting circadian timing to light exposure at night. Here we report a new signaling pathway by which the RHT regulates circadian timing in the daytime as well. Using dual-immunocytochemistry for PACAP and the in vivo tracer Cholera toxin subunit B (ChB), intense PACAP immunoreactivity (PACAP-IR) was observed in retinal afferents at the rat SCN as well as in the intergeniculate leaflet (IGL) of the thalamus. This PACAP-IR was nearly lost upon bilateral eye enucleation. PACAP afferents originated from ganglion cells distributed throughout the retina. The phase of circadian rhythm measured as SCN neuronal activity in vitro was significantly advanced by application of PACAP-38 during the subjective day, but not at night. The effect is channelled to the clock via a PACAP 1 receptor-cAMP signaling mechanism. Thus, in addition to its role in nocturnal regulation by glutamatergic neurotransmission, the RHT can adjust the biological clock by a PACAP-cAMP-dependent mechanism during the daytime.

Animals↗
PubMed1998

Optimal selection and preparation of fresh frozen corticocancellous allografts for cervical interbody spinal fusion.

STUDY DESIGN: Iliac crest corticocancellous allografts for anterior interbody fusion were harvested from six cadavers. The grafts were cut sequentially from left and right crests and randomly assigned to tricortical or bicortical preparations. Their compression strengths then were determined and compared by matched pair analysis. OBJECTIVES: To quantify the failure strength of the grafts from different iliac locations and determine the optimal type of preparation of the grafts for anterior interbody fusion. SUMMARY OF BACKGROUND DATA: Iliac crest corticocancellous autografts and allografts commonly are used for interbody cervical fusions. However, graft strengths for specific sites have not been determined fully. METHODS: Six paired, fresh frozen, iliac crests were sectioned using a customized miter box into multiple 1-cm-thick grafts 1.5 cm in depth to simulate cervical interbody grafts. The left and right sides of each pair were randomly assigned to tricortical and bicortical preparations. The samples were tested by applying a compressive load to failure using a specialized fixture to simulate vertebral body loading. RESULTS: The grafts closer to the anterosuperior iliac spine had significantly higher failure loads and failure strengths than those closer to the posterosuperior iliac spine. The strengths of the bicortical grafts were 72 +/- 14% of the strengths of the tricortical grafts (P < 0.001). CONCLUSIONS: Anterior iliac crest grafts were stronger in compression, even after removal of one cortical surface, than posterior iliac crest grafts.

Adult↗