Biomedical subjects

C X Duan

Publications and source records attributed to C X Duan.

14 recordsLinked to original sources

PubMed2001

Membrane activity of (Cys48Ser) lung surfactant protein B increases with dimerisation.

One of the possible functions of lung surfactant protein B (SP-B), an hydrophobic membrane-associated saposin-like protein, is to reduce the alveolar surface tension by promoting insertion of phospholipids into the air/liquid interface of the lung. SP-B is a covalent homodimer; Cys48 of two polypeptides form an intermolecular disulphide bond. In order to test whether dimerisation of SP-B is important for surfactant function, transgenic mice which express (Cys48Ser) human SP-B in a mouse SP-B null background were generated. In previous studies (Cys48Ser)SP-B showed a concentration-dependent in vitro activity, suggesting that it may form non-covalent dimers. Here (Cys48Ser)SP-B isolated from bronchoalveolar lavage of transgenic mice was studied at different concentrations by circular dichroism (CD) spectroscopy, pulsating bubble surfactometry, mass spectrometry and reversed-phase HPLC. The results indicate that (Cys48Ser)SP-B, both in a phospholipid environment and in organic solvents, is largely monomeric and exhibits low activity at concentrations lower than 1 -2 microM, while at higher concentrations it forms non-covalent dimers, which are nearly functionally equivalent to native SP-B in vitro. Furthermore, electrospray mass spectrometry showed that more dimers were found relative to the monomer when the polarity of the solvent was decreased, and when the concentration of SP-B increased. (Cys48Ser)SP-B also eluted earlier than native SP-B in reversed-phase HPLC. Taken together, these results indicate that a polar surface is buried upon dimerisation, thereby promoting formation of interchain ion pairs between Glu51-Arg52' and Glu51'-Arg52.

Amino Acid Substitution↗

PubMed2001

[Computer-assisted acquisition and analysis of high-resolution spectrum].

Based on the unique characteristic of spectral line center in the whole spectrum and noise threshold, a computer approach and program for the determination of spectral line position and relative intensity automatically are presented in this paper. Exploring this approach and computer program, we pre-analyzed the partially overlapped 16 line TuFIR experiment spectra of CHF3. The results of line positions and intensities for these TuFIR spectra are in excellent agreement with the results by least-square fit with heavily manual inference. The accuracy and efficiency of this method and program will ensure their wide application in complex high-resolution molecular spectrum.

Algorithms↗

PubMed1998

Removal of a dimeric form of surfactant protein C from mouse lungs: its acceleration by reduction.

Clearance of hydrophobic surfactant-associated protein C (SP-C) and its dimeric form ([SP-C]2) was investigated. SP-C and [SP-C]2 obtained from proteinosis patients were fluorescently labeled and were instilled into mouse lungs as lipid-protein complexes. [SP-C]2 was removed more slowly than SP-C, with apparent half-lives of 30 and 18 h, respectively. A significant amount of [SP-C]2 was removed as SP-C, and the conversion rate was 0.22 micrograms.h-1.mouse-1. By correcting the removal as SP-C, we obtained 38 h for a possible half-life of [SP-C]2. Conversion from SP-C to [SP-C]2 seemed very slow. Decrease in glutathione (GSH) in the lung inhibited the conversion of [SP-C]2 to SP-C and GSH-treatment of liposomes accelerated clearance of [SP-C]2. These results suggest that the removal of [SP-C]2 from lung is accelerated by reduction and that GSH acts as a reducing agent in the lung.

Animals↗

PubMed1997

Effects of proteinosis surfactant proteins on the viability of rat alveolar macrophages.

Pulmonary alveolar proteinosis (PAP) is a disease of unknown etiology that is characterized by the accumulation of protein- and lipid-rich insoluble material in alveoli and terminal bronchioles of the lung. Alveolar macrophages (AM) in PAP are reportedly extremely large and have low viability. We investigated substances in lavaged lung material from patients with PAP that induced these cellular changes in rat AM. Rat AM were incubated for various periods with liposomes prepared from lipids and isolated hydrophobic surfactant apoproteins, and cell size, viability, and lactate dehydrogenase release were determined. Of the hydrophobic apoproteins, a dimeric form of surfactant-associated protein-C ([SP-C]2) had the most marked effects. In addition, [SP-C]2 induced increased superoxide anion release at an early phase (6 to 12 h) and an increase in glutathione content at 24 h of incubation. At 3 d after incubation, cellular glutathione and adenosine triphosphate (ATP) content were significantly decreased in cells treated with [SP-C]2, [SP-C]2 was presumed to cause early cell death through increased formation of superoxide anion and the subsequent derangement of cellular metabolism. [SP-C]2 was not removed from cells, and SP-B and SP-C were removed at slower rates than lipids. The changes in macrophages induced by [SP-C]2 may contribute to establishing PAP.

Adenosine Diphosphate↗

PubMed1992

Hepatic cavernous hemangioma. CT findings and pathological basis.

CT findings in 113 cases of hepatic hemangioma confirmed pathologically including 52 resected specimens and 8 autopsies were studied in correlation with the typical CT scan of 506 cases of the same disease. Mottling enhancement in the surrounding hepatic parenchyma of hemangioma which never appeared in other kinds of tumor was considered as a pathognomonic sign for diagnosis. It was correlated with the presence of dilated vascular spaces or sinusoids communicating with the tumor itself in the surrounding tissue. The thick wall and thin wall types of hemangioma were discussed.

Hemangioma, Cavernous↗

PubMed1991

Radiographic manifestations and pathologic basis of parosteal osteosarcoma. Analysis of 17 cases.

The authors reviewed the radiographic manifestations of 17 cases of parosteal osteosarcoma, with pathologic correlation in 15. There were two types of parosteal osteosarcoma radiologically. The majority of cases were type I with uniformly dense masses which had regular borders. They often adhered to the cortex and showed no evidence of soft-tissue invasion which correlated with low-grade pathologic malignancy and a relatively benign clinical course. Type II involved the bone, soft-tissue and the medullary cavity. These lesions were poorly differentiated and frequently accompanied by metastatic lesions.

Adult↗

PubMed1989

[The roentgen findings and pathological basis of parosteal osteosarcoma].

The roentgen findings of 17 cases of parosteal osteosarcoma were analyzed. In 13 of them, a patho-radiologic correlative study was conducted. The results showed that there was an obvious relationship between the radiologic pattern and the degree of malignancy. On roentgenogram, tumor with dense ivory bone as the main manifestation is mostly lower in malignancy, while cotton-like and spiculate tumor bone usually denotes higher degree of malignancy. The pathological basis of the radiolucent area inside the tumor, the satellite nodules in the vicinity of the tumor as well as the differential diagnosis were discussed.

Adult↗

PubMed1989

Short-term multidrug therapy in multibacillary leprosy--review of 80 cases in two provinces of China (1983-1988).

Thirty-three active multibacillary patients from nine counties of Weifang Prefecture, Shandong Province, and 47 active cases from Menla County, Yunnan Province, People's Republic of China, were treated with 24 and 27 months of multidrug therapy (MDT), respectively, in 1983. Clinical assessments, smears, and histopathologic examinations were carried out independently by study teams from the Institutes of Dermatology of these two provinces. Reexaminations at 12-14 months and at termination of therapy showed marked improvement, and there was continued improvement at 12-18 and 33 months on follow up. Conversion of the bacterial index to negativity was 0/33, 5/47 for the patients from Shandong and Yunnan provinces, respectively, at the end of MDT and 2/33 at 12 months' and 17/47 at 18 months' follow up, which increased to 21/33 and 26/44 at 33 months' follow up. Regression of specific infiltration was about 21%-100% after 24-27 months of MDT; further regression to 95%-100% occurred at 33 months' follow up.

Adult↗

PubMed1985