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Biomedical subjects

L Chen

Publications and source records attributed to L Chen.

At least 1,009 records · Page 56Linked to original sources
PubMed1996

Cardiac cytotoxic mechanism mediated by antibodies against myocardial mitochondrial ADP/ATP carrier in patients with dilated cardiomyopathy.

OBJECTIVE: To investigate mechanism of the antibody-mediated cardiac cytotoxicity and clinical significance in dilated cardiomyopathy (DCM), and study the effects of the antibodies against the myocardial mitochondrial ADP / ATP carrier from sera of patients with dilated cardiomyopathy on the guinea pig ventricular myocytes. PATIENTS AND METHODS: This study included 18 patients with DCM (12 men and 6 women), with mean age of 43 years. Control group included 18 health donors, (9 men and 9 women), with mean age of 32 years. The antibodies against the ADP / ATP carrier and cell membrane 52 000 peptide were examined by immunoblotting. The antibody-mediated cardiac cytotoxicity was studied with the cytotoxic test and whole cell patch-clamp technique. RESULTS: The antibodies against myocardial mitochondrial ADP / ATP carrier and cell membrane 52 000 peptide were positive in 18 patients with DCM, while negative in controls. The antibodies induced cytotoxic damage with time-dependent and enhanced Ca-current in cardiac myocytes. The increasing amplitude of peak Ca(2+)-current was 100 pA-840 pA (n = 8) in different dilution of the antibodies. The effect of the antibodies might be inhibited by verapamil, and were null in controls (n = 4). CONCLUSIONS: The above findings suggest that an increase in the antibody-mediated Ca(2+)-current of cardiac myocytes is related to the cytotoxic damage in dilated cardiomyopathy.

Adult↗
PubMed1996

[Preventive effect of gene therapy with pro-uk gene on the formation of intimal hyperplasia of vascular anastomotic site].

OBJECTIVES: To develop a new way to prevent vascular anastomotic sites from intimal hyperplasia, we applied medical suture which had been soaked in pN2-pro-uk plasmid solution to perform rat carotid artery end-to-end anastomosis and study the effect of gene therapy with pro-uk gene on the formation of intimal hyperplasia of vascular anastomotic sites. METHODS: 11/0 nylon medical suture which had been soaked in pN2-pro-uk plasmid solution was applied to perform rat carotid artery end to end anastomoses. The rats were randomly divided into control and treatment groups. In the control group, medical suture was soaked in the pN2 plasmid solution for 72 hours before use. In the treatment group, medical suture was soaked in the pN2-pro-uk plasmid solution. By means of Northern blot analysis, pro-urokinase activity assay, the number detection of cr-51 labelled platelets accumulating at anastomotic sites, 3H-TDR incorporation detection of anastomotic sites, pathological changes study, the following results were obtained. RESULTS: When isolated RNA was hybridized with the radiolabeled pro-uk probe, band appeared in Northern blot analysis in the treatment group, but band could not be found in the control group. The pro-uk activity could be detected on the 2nd, 7th, 14th, 90th day in the treatment group, but could not be detected in the control group. The number of platelets accumulating at the anastomotic sites, the average intimal area and 3H-TDR incorporation of anastomotic sites were significantly fewer in the treatment group than in the control group (P < 0.01). CONCLUSIONS: When medical suture which has been soaked in pN2-pro-uk plasmid solution is used to perform vascular anastomoses, the foreign gene can produce pro-uk at anastomotic sites and effectively prevent the formation of intimal hyperplasia. The mechanism is probably related to the decrease of platelets accumulating at anastomotic sites. This study provides a new way to prevent vascular anastomotic sites from intimal hyperplasia.

Anastomosis, Surgical↗
PubMed1996

Processing of global and local properties--an analysis with event-related brain potentials.

The different processing of global and local properties of compound visual stimuli was studied with event-related brain potentials (ERPs) in the present experiment. It was found that, compared with the identification of global properties, the discrimination of local properties elicited longer RTs, lower accuracies, increased amplitudes of PI, decreased amplitudes of N1, and longer latencies of N2 and P3. The conflict of global and local properties increased the amplitudes of P2, decreased the amplitudes of P3, and prolonged latencies of N2 and P3. These results indicated that the advantage of global processing occurs at an early perceptual stage, and the attentional mechanisms for global and local processing may be different.

Adolescent↗
PubMed1996

Gene therapy for malignant gliomas using replication incompetent retroviral and adenoviral vectors encoding the cytochrome P450 2B1 gene together with cyclophosphamide.

Cyclophosphamide is an inactive prodrug which is converted by hepatic cytochrome P450 2B1 to cytotoxic metabolites which produce interstrand DNA cross-linking in a cell cycle-independent fashion. The limited ability of these metabolites to cross the blood-brain barrier contributes to the poor activity of cyclophosphamide against brain tumors. In this study we demonstrate that replication deficient retroviral and adenoviral vector-mediated gene transfer of cytochrome P450 2B1 into 9L glioma cells significantly increases the sensitivity of these tumor cells to cyclophosphamide in vitro, and prolongs the survival of animals bearing intracerebral 9L tumors treated with cyclophosphamide in vivo. Attempts to improve the effectiveness of retrovirally mediated transduction of the P450 2B1 gene by increasing the concentration of cyclophosphamide delivered to the tumors using intracarotid and intratumoral injections did not prolong animal survival, although survival was increased when a second treatment with P450-expressing retroviral vectors and cyclophosphamide was administered. These results suggest that in situ transduction of tumor cells with the P450 2B1 gene using retroviral and adenoviral vectors increases their sensitivity to cyclophosphamide and may have a potential role in the therapy of malignant gliomas.

Adenoviridae↗
PubMed1996

Ectopic parathyroid adenoma with severe hungry bone syndrome: a case report.

The presentation rate of ectopic mediastinal parathyroid adenoma is about 5 approximately 22%. Ectopic parathyroid adenoma is a common etiology of failed parathyroid surgery as well as a diagnostic challenge to clinicians. We reported a case of ectopic mediastinal parathyroid adenoma. A 20-year-old girl presented with arthralgia for 2 years before hyperparathyroidism was diagnosed. Parathyroid ultrasonography failed to find the lesion, but a vivid uptake in the superior mediastinum was discovered by thallium-201 (Tl-201) and technetium-99m-sestamibi (Tc-99m-MIBI) images. Removal of the ectopic adenoma resulted in severe Hungry bone syndrome, which required a large amount of calcium and phosphorous supply. Later, the patient suffered from bilateral femoral neck fracture due to marked osteoporosis. Bone mineral density study revealed marked increase of fracture risk. Although bone disorder is rare in cases of hyperparathyroidism nowadays, it still should be considered in patients with arthritis of unknown etiology like our case. Early diagnosis and treatment can reduce the morbidity.

Adenoma↗
PubMed1996

Proteins and bioprosthetic calcification in the rat model.

BACKGROUND AND AIM OF THE STUDY: The mechanism of valvular bioprostheses calcification is still unknown, but early studies showed increased Gla-protein content in calcified valves. Using an experimental model, which reproduces the clinical process, we therefore analyzed the role of minerals and proteins in bioprosthetic valvular calcification. METHODS: Glutaraldehyde pretreated porcine valves were studied before and after implantation in rats by X-ray, calcium (Ca) and phosphorus (P) measurement, Fourier Transform Infrared (FTIR) spectroscopy, SDS-PAGE and 45Ca ligand blotting of the extracted proteins. RESULTS: Before implantation, there was no X-ray calcification with very little Ca and P content. After implantation, X-ray calcifications appeared on day seven with increased Ca and P up to day 35 (p < 0.05, ANOVA). FTIR revealed structural proteins alone before implantation, plus minor proportions of lipids on day two, which always preceded Ca and P appearance. Ca and P increased up to day 35, first as amorphous and changed in carbapatite over time. SDS-PAGE before implantation revealed two proteins (66-kD and 54-kD) alone, which were sustained up to day 35. The 66-kD had 45Ca affinity. On day two, many other proteins appeared on SDS-PAGE, four of which (52, 45, 14 and below 14-kD) with 45Ca affinity. Protein pattern did not change from day two to 35. CONCLUSIONS: Valvular bioprosthesis calcification is associated with progressive increase in Ca and P content and at least five calcium-binding proteins: one intrinsic valvular protein, pre-existing to implantation, plus four other, extrinsic valvular proteins adsorbed within the tissue after implantation.

Animals↗
PubMed1996

Inhibition of capacitative Ca2+ entry into cells by farnesylcysteine analogs.

Capacitative Ca2+ influx, which occurs in response to mobilization of intracellular Ca2+ stores, is a general feature of many cell types. Although the mechanism of capacitative Ca2+ entry is not known, evidence suggests the involvement of small G proteins that are prenylated on a cysteine residue near their carboxyl termini. We have investigated the actions of farnesyl-cysteine analogs on capacitative Ca2+ influx. Using human embryonic kidney 293 cells, we found that S-farnesylthioacetic acid, N-acetyl-S-farnesyl-L-cysteine, N-pivaloyl-S-farnesyl-L-cysteine, and N-acetyl-S-gernylgernyl-L-cysteine blocked the activation of capacitative Ca2+ influx, whereas N-benzoyl-S-farnesyl-S-cysteine had no effect on capacitative Ca2+ entry. Inhibition by S-farnesylthioacetic acid was concentration dependent (5-20 microM) and specific for Ca2+ influx through non-voltage-gated Ca2+ channels. A single protein band of 26-28 kDa was labeled specifically with a photoaffinity analog of farnesylcysteine. GTP binding to the photoaffinity-labeled band was demonstrated. These findings suggest, but do not prove, that a prenylated substrate, possibly a small G protein, is linked functionally to capacitative Ca2+ entry in human embryonic kidney 293 cells.

Affinity Labels↗
PubMed1996

[Expression of transforming growth factor alpha and p53 in non-small cell lung cancer by immunohistochemical study].

Primary non-small cell lung cancer samples were examined for the expression of p53, transforming growth factor alpha (TGF-alpha) and its receptor EGF-R by immunohistochemistry. Accumulation of p53 protein was found in 15 out of 24 carcinomas. Meanwhile, the results of TGF-alpha and p53 expression in 21 carcinomas showed that p53 protein was not detected in 2 out of 2 TGF-alpha negative and 4 out of 5 TGF-alpha low expression cases. However, there was no relationship found between EGF-R and p53 expression in these cases. The results suggest that p53 may have some effects on TGF-alpha expression.

Carcinoma, Non-Small-Cell Lung↗
PubMed1996

Abnormal expressions of hepatocellular proteins and extracellular matrix in CCL4-induced liver injury in rats.

OBJECTIVE: To evaluate the effects of carbon tetrachloride (CCl4) on the expressions of both intracellular proteins and extracellular matrix and the protective role of taurine. METHODS: Forty Sprague-Dawley rats were divided into five groups: 1.5% taurine, CCl4, CCl4 + 0.5% taurine, CCl4 + 1.5% taurine and control. CCl4 was given ig at a dose of 500 mg/kg body weight, twice a week for 5 weeks. The taurine solution or tap water was given to the rats for drinking. The sections (4 microns) of rat liver were stained with haematoxylin and eosin, immunohistochemistry or colloid silver methods. RESULTS: The animals treated with 1.5% taurine and control had normal liver structures. Light microscopic examination of sections of the liver taken 5 weeks after dosing of CCl4 showed hydropic degeneration of hepatocytes around the central veins and lipid vacuolation in mid-zonal and some periportal hepatocytes. Necrotic cells and neutrophil infiltration around most central veins as well as hepatocytes showing various stages of mitosis indicative of regeneration were observed. These histopathological changes in the animals treated with CCl4 alone showed more extensive and severe lesions than those seen in the animals treated with CCl4 plus taurines. The incidences of PCNA and p53 antigen positive hepatocytes, and the numbers of nuclear apoptotic bodies and AgNORs granules were markedly higher in the CCl4-treated animals than in those protected with taurine. Declined and unevenly distributed expressions of LN and FN were seen in the CCl4 treated rats. CONCLUSIONS: Both the damage of hepatocellular DNA and the abnormal expressions of hepatic extracellular matrix were observed in the CCl4-treated rats. Taurine, in this study, not only inhibited hepatocellular degeneration, necrosis and DNA damage, but also inhibited the lesion of extracellular matrix induced by CCl4.

Animals↗
PubMed1996

[Effect of tetrandrine on intraacinar pulmonary arterial structural remodelling and pulmonary hypertension].

Rat's pulmonary hypertension was induced by a single subcutaneous injection of monocrotaline. The influences of tetrandrine (Tet) upon the structure of intraacinar pulmonary arteries (IAPA) was studied by light and electron microscopy. The results indicated that Tet reduced the thickness of IAPA medial membrane, the ratio of the thickness of IAPA medial membrane to the diameter of IAPA, the number of circular muscular artery and partially muscular artery about 16.4%, 30.5%, 24.3% and 16.4% respectively, and Tet increased the number of nonmuscular artery about 24.7%. It also decreased the degeneration of IAPA, collagen of medial membrane, prolife-ration and myoid differentiation of the pericyte, and it increased the number of IAPA. The authors discussed why Tet caused such changes.

Alkaloids↗
PubMed1996

Study on ultrastructural cytochemistry and pathogenic mechanism of Trichomonas vaginalis.

OBJECTIVE: To study the relation among enzymic ultrastructural localizations, cell organelles and functions of Trichomonas vaginalis (T. vaginalis) as well as its pathogenic mechanism. MATERIAL AND METHODS: The specimens were Trichomonas vaginalis cultured purely for several generations. After prefixation, several electron microscopic cytochemical reactions for marker enzymes of lysosome, Golgi body, mitochondrion and microbody as well as Ur-Pb-Cu impregnation were undertaken. Then the specimens were post-fixed and embedded, and the unstained ultrathin sections were observed under a transmission electron microscope. RESULTS: The activities of acid phosphatase and cytidine monophosphatase appeared in the primary and secondary lysosomes of the parasite, and the reaction product of peroxidase was found in the secondary lysosomes. It was found that lysosomes could release hydrolytic enzymes out of the cell. The reaction products of thiamine pyrophosphatase and nicotinamide adenine dinucleotide phosphatase were located within the mature-surface and intermediate saccules of Golgi body respectively. The reactions for succinate dehydrogenase, cytochrome oxidase and catalase were negative. The hydrogenosomes, endoplasmic reticulum and Golgi bodies of the parasite were densely stained by Ur-Pb-Cu impregnation method. CONCLUSIONS: T.vaginalis has lysosomal system which can release hydrolases out of the parasite, causing damage to the vaginal and urethral epithelial cells. This may be an important pathogenic mechanism of vaginitis and urethritis caused by T.vaginalis. This protozoon has well-developed Golgi bodies and rich endoplasmic reticulum. It lacks mitochondrion and microbody, but has abundant hydrogenosomes which are energy producing organelles of anaerobic metabolism and resemble microbody in morphology and mitochondrion in some functions.

Animals↗
PubMed1996

[Three dimensional reconstruction of human endometrial spiral arteries preinsertion and postinsertion of IUD].

OBJECTIVE: To investigate the micro-three dimensional changes of endometrial spiral arteries after insertion of different intrauterine devices (IUD). METHODS: Nine endometrium specimens were obtained from fertile age women, 3 from preinsertion, 3 obtained 3 months after insertion of TCu220C IUD, and 3 specimens obtained 3 months after insertion of gamma Cu IUD (releasing indomethacin 20 micrograms/day). All samples were collected in late secretory phase and were sectioned serially. By a TV camera, the images of sections were sent from a light microscope to a computer and converted into digital data. The spiral arteries of endometrium were reconstructed and visualized on a workstation by means of the software package for the three dimensional reconstruction and visualization. The curvature and torsion of the spiral arteries were calculated. RESULTS: In preinsertion group, the spiral arteries curved regularly in three dimensions, and the average diameter was 22.69 microns, the average curvature was 0.96 and the average torsion was 1.27. The spiral arteries of gamma Cu IUD group had similar appearances as the preinsertion group. However, in TCu220C IUD group, the curves were irregular, and the average diameter was 17.99 microns, the average curvature was 1.48 and average torsion 1.86. CONCLUSION: The three dimensional reconstruction of human endometrial spiral arteries was done by means of computerassisted reconstruction technology for the first time. The endometrium spiral arteries changed in morphology after insertion of copper IUD, and indomethacin may have contrary effects on copper.

Adult↗
PubMed1996

[A comparative morphometric and histologic study of five bone substitute materials].

OBJECTIVE: To investigate and compare the osteogenesis of bone substitute materials. METHODS: 52 Chbb: ch rabbits were divided into 5 groups. Five different porous biomaterials, including natural bovine hydroxyapatite (Bio-OSS, BK V/1), semi-synthetic coral hydroxyapatite interpore 500, synthetic tricalcium phosphate CEROS 82 and glass POROLITH, were implanted together with free periosteum into the muscle of rabbits for up to 3 and 6 weeks. Undecalcified sections were prepared for microradiography, light and UV microscopy, and morphometry. RESULTS: Bone ingrowth was present in all such implantats. Bone formation was limited to the periphery of the Ceros blocks, that are lack of pore interconnection, while the other 4 materials with an interconnected porous system were infiltrated by bone into the centrum. Planimetric analyses showed that the specimens were composed of 6.5%-19.0% new bone at the 3rd week and 14.2%-25% at the 6th week respectively. The difference of bone ingrowth was only significant between Bio-OSS and BK V/1 at the 3rd week. No statistically significant difference of bone volume was found within the 6 week groups. There was a positive correlation between the new bone volume and the porosity of the materials. CONCLUSION: For the bone ingrowth, the structure of the materials, specifically the pore and pore interconnections, is more impatant than the chemical composition.

Animals↗
PubMed1996

[The clinical characteristics and surgical treatment of giant mediastinal tumors: an analysis of 140 cases].

The experience on the diagnosis and treatment of 140 cases of giant mediastinal tumors from Jan. 1978 to Dec. 1994 was summarized in this paper. The mean size of the tumors was 14.6 cm x 11.2 cm x 8.9 cm. Among the 140 cases, teratoma was seen in 58 cases (41.4%), thymoma in 32 cases (22.9%) and neurogenic tumors in 16 cases (11.4%). Correct preoperative diagnosis was made in 96.4% for ultrasongraphy (UG), 89.5% for CT and only 19.5% for thin needle biopsy (TNB). The resection rate was 82.9% (116/140) and the operative mortality was 2.14% (3/140). The authors suggest that for the giant mediastinal tumoor, besides chest X-ray, UG and chest CT should be the main preoperative diagnostic nethods, TNB and fibro-optic bronchoscopy are also helpful to define the border and the invasiveness of the tumor. The choice of incisions and attentions during the operation are discussed.

Adolescent↗
PubMed1996

[The prevention and treatment of complications after esophagogastrostomy by intraluminal elastic circular ligation].

To summarize our experience on the handling of postoperative complications of esophagogastrostomy by elastic circular ligation (IECL), 176 patients with esophageal or cadiac carcinoma underwent esophagogastrostomy by IECL with absorbable supporting tubes were reviewed. There were 7 cases of postoperative complications with an incidence of 3.97%. Of which, anastomotic leakage in 3 patients, recurrent laryngeal nerve paralysis in one and chylothorax in one were cured by conservative measures; one patient with hiatus hernia was treated by reoperation, and another patient died of right tension pneumothorax. After the causes of complications being analysed, improved operative procedures are recommended. (1) The esophagus must be dissociated up to the apex of pleural cavity when anastomosis is performed above the aortic arch, so as to have the lower end of the supporting tube at least 0.5 cm higher than the arch. (2) The supporting tube must be wrapped with the gastric wall and avoid suturing through the esophageal mucosa layer. (3) When the anastomosis is performed below the aortic arch, reconstruction of the hiatus should be done with the esophagus moved forward to prevent the thoracic aorta from eroded by the supporting tube. (4) If the residual gastric volume is less than one-third of normal, the above-mentioned operation procedures can not be employed.

Adult↗
PubMed1996

[Effects of ear acupuncture on beta-adrenoreceptor in lung tissues of guinea-pigs with experimental asthma].

The maximal binding volume (Bmax) of beta-adrenoreceptor in the lung tissues of guinea-pigs in health group, experimental asthma group and ear acupuncture treatment group was determined with radiological ligand binding analysis. The results were as follows: (1) the Bmax of beta-adrenoreceptor in lung tissues of guinea-pigs in asthma group (52.4 +/- 20.1 fmol/mg protein) was significantly lower than that of healthy group (106.8 +/- 14.0 fmol/mg protein) (P < 0.01); (2) the Bmax in the lung tissues of guinea-pigs in ear acupuncture treatment group (84.5 +/- 35.1 fmol/mg protein) was significantly higher than that of asthma group (P < 0.02), and was similar to that of healthy group(P > 0.05). These suggested it was one of the mechanisms of ear acupuncture treatment on asthma to increase the number of beta-adrenorecepor in the lung tissues.

Animals↗