Biomedical subjects

H Duan

Publications and source records attributed to H Duan.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Changes of hepatic energy metabolism following partial hepatopetal blood occlusion].

OBJECTIVE: To evaluate the changes of hepatic energy metabolism by temporary occlusion of partial hepatopetal blood. METHODS: The animal mode of partial hepatopetal blood occlusion (PBO) was established without portal stasis. The hepatic energy metabolism parameters including adenosine triphosphate, respiratory control ratio, P/O ratio, and arterial ketone bodies ratio were studied following 30 min ischemia or 1, 6, and 24 h of reperfusion. The total hepatopetal blood occlusion (TBO) and sham groups served as control. RESULTS: The parameters of hepatic motochondrial function reflecting hepatic damage to ischemia-reperfusion showed different in PBO comparing with TBO group. The functional lesion was restored progressively in PBO-30 min group, but it was maintained low level in TBO-30 min group. CONCLUSION: The results suggest that it is beneficial to restoration of the hepatic energy metabolism in the ischemia-reperfusion injury by partial hepatopetal blood occlusion.

Adenosine Triphosphate↗

PubMed2000

[The effect of polylactide screws on fracture healing].

This experiment aimed at investigating the effect of a kind of home-bred poly-DL-lactide screws on fracture healing. An operation was performed so as to make bilateral lateral condylar fractures of the femur in 8 dogs. The left sides were fixed with 2 home-bred PDLLA(Mv = 43 x 10(4)) screws, and the contralateral sides were fixed with 2 metalic screws to be used as controls. The animals were sacrificed at 2, 4, 8, and 12 weeks after surgery. Optic microscopy and SEM photography were done. The results of optic microscopy showed that fibrous callus formed already in both groups by 2 weeks after surgery, and bilateral fractures united uneventfully by 12 weeks. Although the course of fracture healing in experimental group was slower than that in control group, the osteogenesis in experimental group appeared to be normal. The SEM examination demonstrated that collagenous fibers arranged regularly and calcified normally in both groups at 12 weeks. And many square and rhomboid granules produced from the degradation of PDLLA material were found in experimental group at 12 weeks. Therefore, it is suggested that this kind of home-bred PDLLA screws should be applicable to fractures where the tissues are rich in blood supply.

Animals↗

PubMed1999

Expression, purification, and biochemical characterization of SAG, a ring finger redox-sensitive protein.

We recently reported the cloning and characterization of SAG (sensitive to apoptosis gene), a novel zinc RING finger protein, that is redox responsive and protects mammalian cells from apoptosis. Here we report the expression, purification, and biochemical characterization of SAG. Bacterially expressed SAG is brown in color and dithiothreitol (DTT)-sensitive. SAG forms large oligomers without DTT that can be reduced into a monomer in the presence of DTT. These features help us to purify SAG using the chromatography with or without DTT. Likewise, purified SAG is redox sensitive. Upon H2O2 exposure, SAG forms oligomers as well as monomer doublets due to the formation of the inter- or intramolecular disulfide bonds, respectively. This process can be reversed by DTT or prevented by pretreatment with the alkylating reagent, N-ethylmaleimide (NEM). Although SAG contains two putative heme-binding sites and a RING finger domain, the protein appears not to bind with heme and to lack transcription factor activity as determined in a Gal4-fusion/transactivation assay. Wildtype, but not RING finger domain-disrupted SAG mutants, prevents copper-induced lipid peroxidation. These results, along with our previous observations, suggest that SAG is an intracellular antioxidant molecule that may act as a redox sensor to buffer oxidative-stress induced damage.

Copper↗

PubMed1999

Immunosuppressive diterpenoids from Tripterygium wilfordii.

A clinically used extract of Tripterygium wilfordii afforded three new diterpenoids-3beta,19-dihydroxyabieta-8,11,13-triene (triptobenzene L) (1); 12,19-dihydroxy-3-oxoabieta-8,11,13-triene (triptobenzene M) (2); and 19-hydroxy-3,7-dioxo-abieta-8,11, 13-triene (triptobenzene N) (3)-along with 14 known diterpenoids. The structures of 1-3 were established on the basis of spectroscopic studies. Of the known compounds, the stereochemistry at C-4 of triptonediol (4) was reassigned. Tripterifordin (8) and 13-epi-manoyl oxide-18-oic acid (9) showed significant inhibitory effects on cytokine production.

Abietanes↗

PubMed1999

SAG, a novel zinc RING finger protein that protects cells from apoptosis induced by redox agents.

SAG (sensitive to apoptosis gene) was cloned as an inducible gene by 1,10-phenanthroline (OP), a redox-sensitive compound and an apoptosis inducer. SAG encodes a novel zinc RING finger protein that consists of 113 amino acids with a calculated molecular mass of 12.6 kDa. SAG is highly conserved during evolution, with identities of 70% between human and Caenorhabditis elegans sequences and 55% between human and yeast sequences. In human tissues, SAG is ubiquitously expressed at high levels in skeletal muscles, heart, and testis. SAG is localized in both the cytoplasm and the nucleus of cells, and its gene was mapped to chromosome 3q22-24. Bacterially expressed and purified human SAG binds to zinc and copper metal ions and prevents lipid peroxidation induced by copper or a free radical generator. When overexpressed in several human cell lines, SAG protects cells from apoptosis induced by redox agents (the metal chelator OP and zinc or copper metal ions). Mechanistically, SAG appears to inhibit and/or delay metal ion-induced cytochrome c release and caspase activation. Thus, SAG is a cellular protective molecule that appears to act as an antioxidant to inhibit apoptosis induced by metal ions and reactive oxygen species.

Amino Acid Sequence↗

PubMed1999

An essential role for the Drosophila Pax2 homolog in the differentiation of adult sensory organs.

The adult peripheral nervous system of Drosophila includes a complex array of mechanosensory organs (bristles) that cover much of the body surface of the fly. The four cells (shaft, socket, sheath, and neuron) which compose each of these organs adopt distinct fates as a result of cell-cell signaling via the Notch (N) pathway. However, the specific mechanisms by which these cells execute their conferred fates are not well understood. Here we show that D-Pax2, the Drosophila homolog of the vertebrate Pax2 gene, has an essential role in the differentiation of the shaft cell. In flies bearing strong loss-of-function mutations in the shaven function of D-Pax2, shaft structures specifically fail to develop. Consistent with this, we find that D-Pax2 protein is expressed in all cells of the bristle lineage during the mitotic (cell fate specification) phase of bristle development, but becomes sharply restricted to the shaft and sheath cells in the post-mitotic (differentiative) phase. Two lines of evidence described here indicate that D-Pax2 expression and function is at least in part downstream of cell fate specification mechanisms such as N signaling. First, we find that the lack of late D-Pax2 expression in the socket cell (the sister of the shaft cell) is controlled by N pathway activity; second, we find that loss of D-Pax2 function is epistatic to the socket-to-shaft cell fate transformation caused by reduced N signaling. Finally, we show that misexpression of D-Pax2 is sufficient to induce the production of ectopic shaft structures. From these results, we propose that D-Pax2 is a high-level transcriptional regulator of the shaft cell differentiation program, and acts downstream of the N signaling pathway as a specific link between cell fate determination and cell differentiation in the bristle lineage.

Alleles↗

PubMed1999

Apolipoprotein E-dependent cholesterol efflux from macrophages: kinetic study and divergent mechanisms for endogenous versus exogenous apolipoprotein E.

In these studies, we have utilized a J774 macrophage model in order to compare phospholipid and cholesterol efflux kinetics in macrophage cells that do not express endogenous apoE to cells transfected to express physiologic levels of human apoE. This model was also used to compare the effect of exogenously added versus endogenously expressed apoE on cholesterol efflux kinetics from macrophages. ApoE expression increased free cholesterol and phospholipid efflux into the medium, but did not change the free cholesterol/phospholipid molar ratio of secreted lipids. Kinetic examination showed that free cholesterol and phospholipid appeared simultaneously in the medium, and that cholesterol loading widened the difference in the rate of cholesterol efflux between apoE-expressing and non-expressing macrophages. Addition of exogenous lipid-free apoE added to non-expressing cells, at a >2-fold higher medium concentration than that produced by endogenous expression, produced less cholesterol efflux than that observed from apoE-expressing cells. The addition of phosphatidylcholine liposomes substantially increased cholesterol efflux from apoE-expressing and non-expressing J774 cells. Addition of these liposomes eliminated the enhanced cholesterol efflux produced by addition of exogenous apoE. On the other hand, even in the presence of phosphatidylcholine liposomes, cholesterol efflux rates remained significantly higher from apoE-expressing macrophages than non-expressing cells. Similar results were obtained when efflux was studied in the presence of cyclodextrin. These results suggest that endogenous expression of apoE by macrophages alters cell cholesterol balance via mechanisms distinct from those utilized by the extracellular addition of apoE, and may involve intracellular or pericellular mechanisms.

Animals↗

PubMed1999

[Study on the electrothermal tissue effects during transcervical resection of endometrium].

OBJECTIVE: To investigate the tissue electrothermal effects and to seek the appropriate setting of operative wattage during transcervical resection of endometrium (TCRE). METHODS: The power setting were 60 W, 80 W, 100 W for cutting and 30 W, 60 W, 80 W, 100 W for coagulation when performing endometrial resection in vitro or in vivo with operating time 3-5 seconds or 6-8 seconds respectively. After operation the uterine specimens were stained by hemaloxylin-eosin, and respiratory enzyme dehydronicotinamide adenine dinucleotide phosphate diaphorase methods for evaluating the tissue damage. RESULTS: (1) The depth of endometrial damage under cutting was considerably less severe than those under coagulation with the same power setting. (2) When the power of cutting and coagulation were 80 W, 100 W and 30 W, 60 W respectively and operating time prolonged more than 5 seconds, the thermal damage covered endometrium and 2-3 mm of myometrium in depth. (3) At such wattage and operating time the deepest destruction was only 16.27% of uterine wall. CONCLUSION: (1) There is significant difference in the depth of thermal damage between cutting and coagulation during hysteros copic surgery. (2) The appropriate power setting should be 80-100 W for cutting and 30-60 W for coagulation.

Adult↗

PubMed1999

[Relationship between retinal and glomerular microvascular lesions in experimental diabetes in rat].

OBJECTIVE: To evaluate the relationship between diabetic retinopathy (DR) and diabetic nephropathy (DN). METHODS: The thickness of retinal capillary basement membrane (RBM) and glomerular basement membrane (GBM) and their anionic sites were quantitatively analyzed by electron microscopy and immunohistochemical methods. RESULTS: RBM and GBM became gradually thickened with the development of diabetes. The thickened basement membrane was accompanied with decrease of anionic sites in number. CONCLUSION: DR and DN share partly the pathological process, and there are also some incoordinate phenomena in the microvascular lesion.

Animals↗

PubMed1999

[Implementation of gateway between WWW and DICOM].

This paper discusses the necessity of gateway between WWW and DICOM, shows the method of the implementation and the result. It brings forward a new way in which doctors interact with PACS and medical image device such as CT, MRI, ultrasonic, etc. It points out that the gateway between WWW and DICOM is a kind of transition between appropriative standard and general standard. This kind of transition will bring convenience to telemedicine information system and integrated medical information system.

Internet↗

PubMed1999

[Effect of 15-methyl PGF2 alpha methyl ester combined with tyrosine hydrazide on early pregnancy in mice].

OBJECTIVE: To observe the effect of 15-methyl PGF2 alpha methyl ester (PG05) in combination with tyrosine hydrazide (TH) on early pregnancy in mice. METHODS: The pregnancy rate of mice treated with PG05 and TH was counted and serum progesterone level was measured by RIA. RESULTS: Administration of TH at 90 mg.kg.day-1 to mice on day 7-9 of gestation enhanced significantly the termination of early pregnancy induced by PG05 at 0.2 mg-1.kg-1 for 2 days. Serum progesterone level of mice treated with PG05 combined with TH was found to be markedly lower than that of animals given PG05 or TH alone. TH at 30 micrograms-1.ml-1 inhibited significantly the activity of 3 beta-HSD of luteal cells in rat. However, PG05 at 10 micrograms-1.ml-1 had no influence upon inhibitory effect of 3 beta-HSD activity induced by TH. TH at 150 mg-1.kg-1 for 3 days did not affect the progesterone receptor level of utering cytoplasma in pseudopregnant rats. CONCLUSIONS: The inhibitory effect of TH on the production of progesterone may be the main mechanism to terminate early pregnancy when used synergically with PG05.

3-Hydroxysteroid Dehydrogenases↗

PubMed1998

Solution structure of the RAIDD CARD and model for CARD/CARD interaction in caspase-2 and caspase-9 recruitment.

Apoptosis requires recruitment of caspases by receptor-associated adaptors through homophilic interactions between the CARDs (caspase recruitment domains) of adaptor proteins and prodomains of caspases. We have solved the CARD structure of the RAIDD adaptor protein that recruits ICH-1/caspase-2. It consists of six tightly packed helices arranged in a topology homologous to the Fas death domain. The surface contains a basic and an acidic patch on opposite sides. This polarity is conserved in the ICH-1 CARD as indicated by homology modeling. Mutagenesis data suggest that these patches mediate CARD/CARD interaction between RAIDD and ICH-1. Subsequent modeling of the CARDs of Apaf-1 and caspase-9, as well as Ced-4 and Ced-3, showed that the basic/acidic surface polarity is highly conserved, suggesting a general mode for CARD/CARD interaction.

Amino Acid Sequence↗

PubMed1998

The proliferative properties of tumor cells differentially correlate with the host immune responses in anogenital Bowen's disease.

Bowen's disease is a squamous cell carcinoma in situ that rarely invades into the underlying dermis. In order to evaluate the relationship between the cytological properties of the tumor cells and the host immune response, we have examined the expression of p53 and proliferating cell nuclear antigen (PCNA), and the number of mitotic cells, clumping cells, koilocytes, Langerhans cells (LCs) and dermal lymphoid cell infiltration in 18 cases of anogenital Bowen's disease. When compared with normal anogenital skins (n = 10), a statistically significant number of p53-positive cells, PCNA-positive cells, mitotic cells, clumping cells, koilocytes and dermal lymphoid cells was observed in the cases of Bowen's disease. Importantly, there existed a very strong correlation between the number of PCNA-positive tumor cells and the number of infiltrated dermal lymphoid cells. Moreover, the number of mitotic cells significantly correlated with the number of intratumoral LCs. The in situ hybridization technique for human papilloma virus (HPV) demonstrated that the HPV-infected Bowen's disease showed a similar histological and immunohistological pattern as the HPV-non-infected counterparts, except for increased koilocyte formation and decreased p53 positivity. The present data suggest that the proliferative activity of Bowen's disease significantly correlates with the host immune reaction, and that the host immune system may differentially recognize the different cytological properties of tumor cells in the Bowen's disease.

Adult↗

PubMed1998

shaven and sparkling are mutations in separate enhancers of the Drosophila Pax2 homolog.

We have previously shown that the sparkling gene, which like mammalian Pax2 plays an important role in eye development, is encoded by the Drosophila homolog of Pax2. Here we demonstrate that D-Pax2 also encodes the shaven function, which is crucial during bristle development. Both sv and spa alleles, previously thought to represent different genes, are mutations in two widely separated enhancers of D-Pax2. The sv function of D-Pax2 acts in at least two distinct steps of mechanosensory bristle development: the specification of the alternative fate of shaft as opposed to socket cell, and later the differentiation of the shaft cell.

Alleles↗

PubMed1998

[Internal fixation with mini-titanium plate for midface fractures].

Thirty four patients with midface bone fractures were fixed by rigid internal fixation (RIF) with min-titanium plate. An optimum exposure is provided for the fracture sites of zygomatic, zygomatic arch, orbital floor and maxilla with the coronal incision and adjuvant incisions. The approach was of benefit to accurate anatomic reduction and fixation of the fracture segments. RIF with min-titanium plate provided three-dimensional stability. The fixation of zygomatic-frontal crevice and zygomatic maxillary crevice were the key for obtaining sufficient stability, and at least two fixation screws were required above zygomatic-frontal crevice.

Adult↗

PubMed1998

Combination of hysteroscopy and laparoscopy in gynecologic operation: an analysis of 65 cases.

OBJECTIVE: To introduce the procedures, preliminary experience, and advantages of operation using combination of hysteroscopy and laparoscopy. METHODS: Sixty-five women underwent transcervical resection of endometrium (11), myoma (38), polyp (2), septa (9), adhesion (1) or foreign body (4). All had the indications for simultaneous laparoscopic monitoring and operation. They were first diagnosed laparoscopically to decide the type of laparoscopic operation. Then they were treated hysteroscopically and finally received laparoscopic operation. RESULTS: Laparoscopic examinations confirmed the original diagnoses, revealed the causes of pelvic pain in 8 patients, and detected ovarian cyst, endometriosis, and pelvic adhesion in 5. Two cases of uterine perforation were found by laparoscopic monitoring. Thirty laparoscopic operations included removal or puncture of ovarian cyst, lysis of adhesion, coagulation of endometriosis, Rubin's test, and partial salpingectomy. The postoperative course was smooth and the operative result was satisfactory. CONCLUSIONS: Operations using combination of hysteroscopy and laparoscopy are safe and effective. They also reduce the pain, and save the time and money of patients. Laparoscopic monitoring may detect uterine perforation in time.

Adult↗

PubMed1998

[A 24-hour solid state Holter recording and analyzing system].

The design and functions of a new type of multi-channel solid-state Holter system were introduced in this paper. The flash memory card based recorder can record 24 hours or more of data from up to all 12 leads. The full function scanner software can analysis automatically and archive with complete editing capabilities.

Electrocardiography, Ambulatory↗

PubMed1998

[Studies on analytical method for 10 drugs of abuse in urine using HPLC].

A systematic determination method for 10 drugs of abuse, morphine, codeine, 6-monoacetylmorphine, heroin, levorphanol, pethidine, ethylmorphine, anadol, pentazocine and ethamivan, using high performance liquid chromatography is described. Separation of the 10 drugs was achieved on a 25 cm x 4.6 mm ID, 10 microns Zorbax C8 column, using methanol--0.05 mol.L-1 KH2PO4--diethyl amine (27:73:0.5, pH 4) as mobile phase. Codeine was used as the interal standard. Calibration graphs were linear over the concentration range of 10-200 micrograms.ml-1 and regression equations showed correlation coefficients of greater than 0.999. Precision (RSD) were found to be better than 3% for each compound. Precision and linearity of the method are satisfactory for clinical toxicological applications. The extraction procedure yielded cleaner extracts. The recovery rates from urine were all above 87% without interference. This method is rapid, sensitive and specific.

Chromatography, High Pressure Liquid↗