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Biomedical subjects

D C Liang

Publications and source records attributed to D C Liang.

At least 73 records · Page 4Linked to original sources
PubMed1990

Post-hepatitic aplastic anaemia in children in Taiwan, a hepatitis prevalent area.

Aplastic anaemia is a rare but serious complication of hepatitis, and hepatitis is an unusual cause of aplastic anaemia in children in the West. However, the relative frequencies of acquired aplastic anaemia in children in Taiwan, a hepatitis prevalent area, differ from those in the West, in the very high frequency of post-hepatitic aplastic anaemia (23.9% of all cases of aplastic anaemia). This may account for the higher incidence of aplastic anaemia in children in Taiwan. Although the prognosis of post-hepatitic severe aplastic anaemia was very poor, the present study using bone marrow transplantation, antithymocyte (or antilymphocyte) globulin, high-dose methylprednisolone and cyclosporin, etc., has improved the response rate and the survival.

Adolescent↗
PubMed1990

Extralobar pulmonary sequestration of the left retroperitoneum.

This paper presents an extralobar pulmonary sequestration in the left retroperitoneum in an eight year old girl. The clinical and diagnostic features included abdominal pain, an abdominal mass, elevated VMA, and radiological manifestations simulating a left adrenal mass. A laparatomy was performed. Extralobar pulmonary sequestration of the left retroperitoneum is fairly uncommon. An eight year old girl was admitted with abdominal pain, elevated urinary VMA and an abdominal mass. The radiological manifestations simulated a left adrenal mass. At surgery an extralobar pulmonary sequestration was detected.

Bronchopulmonary Sequestration↗
PubMed1990

Preliminary crystallographic analysis of deshexapeptide (B25-B30) insulin.

Satisfactory single crystals of deshexapeptide (B25-B30) insulin for X-ray crystal structure analysis have been grown in citrate buffer by the method of hanging-drop gas phase diffusion. The crystal belongs to the monoclinic system with space group C2. The unit cell constants are a = 42.6 A, b = 37.9 A, c = 27.2 A, beta = 125.4 degrees and there is only one molecule of deshexapeptide insulin in an asymmetric unit.

Crystallography↗
PubMed1990

Studies on the crystal structure of A1-(D-Tryptophan) insulin.

We have determined the crystal structure of A1-(D-Trp) insulin and discovered that it belongs to the trigonal system with space group R3. The parameters of the unit cell are a = b = 78.6 A, c = 50.0 A. A set of data for half a sphere reciprocal space to a spacing of 2.2 A were collected. The model was adjusted and refined by using a step-by-step approach and a stereochemically-restrained least squares program, assisted by manual revision based on the difference Fourier maps, to a final R-factor of 0.218. The main and side chains of both A1-D-Trp residues in the asymmetric unit are well ordered. The packing of A1-(D-Trp) insulin in the unit cell, the conformational differences with other insulin structures and its structure and function relationship have also been discussed.

Crystallization↗
PubMed1990

O2-dependent hepatotoxicity due to ethylhexanol in the perfused rat liver: mitochondria as a site of action.

Toxicity of 2-ethylhexanol, a metabolite of diethylhexyl phthalate, was assessed in the perfused rat liver. Livers from starved rats were perfused with ethylhexanol (3 mM) dissolved in Krebs-Henseleit buffer (pH 7.4, 37 degrees C) saturated with 95% O2-5% CO2 in both the anterograde and retrograde direction. Following infusion of ethylhexanol, O2 uptake and ketone body formation were diminished by 50 and 80%, respectively, and cell damage, as assessed by the appearance of lactate dehydrogenase in the effluent perfusate, was apparent. Both inhibition of O2 uptake by ethylhexanol and the appearance of lactate dehydrogenase in the perfusate were dose-dependent. Only O2-rich upstream regions of the liver lobule were damaged as reflected by trypan blue uptake. Inhibition of O2 uptake by ethylhexanol was also reflected by a 60% decrease in the ATP/ADP ratio. Local rates of O2 uptake, measured using miniature electrodes placed on the liver surface, indicated that ethylhexanol only diminished O2 uptake in O2-rich upstream regions of the liver lobule regardless of the direction of flow. This phenomenon apparently can be explained by a direct effect of ethylhexanol on mitochondria in upstream regions since active state 3 rates of respiration were inhibited by ethylhexanol in isolated mitochondria. Ethylhexanol also caused a dose-dependent decrease in the mitochondrial membrane potential and an increase in the beta-hydroxybutyrate/acetoacetate (B/A) ratio. However, infusion of radical scavengers such as allopurinol, cianidanol and uric acid did not alter lactate dehydrogenase release due to ethylhexanol. Thus, the toxicity of ethylhexanol in the liver is dependent on local O2 tension and mitochondrial are primary targets.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenine Nucleotides↗
PubMed1989

Crystal structure determination of desheptapeptide (B24--B30)-insulin.

Desheptapeptide (B24--B30)-insulin (DHPI), an essentially inactive insulin analog, is crystallized in space group P212121 with two molecules in an asymmetric unit. The orientations of the molecules in the crystal cell have been determined by using Patterson search method at 6 A resolution and the positions of the molecules are deduced from translation function calculation and R search at 3 A resolution. After using the rigid body refinement (CORELS) further to refine the orientational and positional parameters as well as the initial energy restrained refinement (EREF) for the model, the crystallographic R value is reduced to 0.384 at 3 A resolution. The initial Fourier map shows that the B-chain N-terminal (B1-B8) and C-terminal (B20-B22) segments, compared with the native 2 zinc insulin, exhibit drastic conformational changes, but the three helices of B- and A-chains and their relative arrangement are essentially kept in DHPI.

Crystallography↗
PubMed1989

Studies on the crystal structure of (D-Ala)-B0 porcine insulin at 1.9 A resolution.

The crystal structure of (D-Ala)-B0 porcine insulin has been determined, using data to 1.9 A and atomic parameters of 2 Zn porcine insulin as a starting model, and through the use of the difference method and the restrained least square method, to a final R-factor of 0.211 and r.m.s. deviation of 0.057 A for the bond lengths. The electron densities of B0 residues were very clear. Introduction of B0 residues into the molecules had reduced the thermal vibration of the N-terminus of B-chain for both molecules I and II and made the molecules pack closer in the crystal. The obvious differences between the crystal structures of 2 Zn and (D-Ala)-B0 porcine insulin were the conformations of partial polar groups around the possible receptor binding surface and the assembly mode of two helixes of A-chain in molecule I. In the local environment of the N-terminus of B-chain there were great differences between the crystal structures of (D-Ala)-B0 porcine insulin, (Trp)-B1 porcine insulin and Des B1(Phe) bovine insulin. In this paper the structure-immunoactivity relationships of insulin molecule have also been discussed briefly.

Animals↗
PubMed1989

Crystal structure determination of 4-zinc bovine insulin at 1.9 A resolution.

With the isomorphous difference Fourier method and the restrained least-squares refinement technique, the crystal structure of 4-zinc bovine insulin in space group R3 was determined. The final crystallographic residual is 0.19 at 1.9 A resolution. Based on the refined model, the structural mechanism for prolonged action of 4-zinc insulin is discussed.

Animals↗
PubMed1988

A simple and rapid in situ staining method for granulocyte-macrophage colonies in agar culture.

This report describes a very simple, quick and effective method for in situ staining of granulocyte-macrophage colonies in agar cultures and for classifying various colony types. The procedure takes only one minute to fix and a few minutes to stain; a few additional minutes are required for preparation of the permanent whole plate. In this process the Riu stain, a modified Romanowsky stain, is used. Besides the ease and rapidity of this procedure, the identification of colony types appears to be enhanced. Thus, the method seems to be very beneficial in routine observations of colony types.

Agar↗
PubMed1988

Granulocyte/macrophage colony-forming units from cord blood of premature and full-term neonates: its role in ontogeny of human hemopoiesis.

It is still uncertain whether the yolk sac is the only origin of hemopoietic stem cells during fetal development. We studied the level of circulating granulocyte/macrophage colony-forming unit (CFU-GM) from the 23rd week of gestation to fullterm, trying to delineate its role in the ontogeny of human hemopoiesis. Cord blood samples were collected from 45 healthy premature neonates and 91 healthy full-term neonates. CFU-GM assays were performed using a single agar layer system with human placental conditioned medium as a source of colony stimulating activity. The mean numbers of colonies produced from the cord blood samples of the premature and full-term neonates were 116 +/- 185 (SD) and 96 +/- 113/2 x 10(5) mononuclear cells, respectively. There was no statistical difference between the numbers of colonies of the two groups (Mann-Whitney test, p greater than 0.05). These results indicate that the level of circulating CFU-GM from the 23rd week of gestation to full term is constantly high and add credence to the assumption that CFU-GM are produced not only from the yolk sac but also from other hemopoietic sites.

Colony-Forming Units Assay↗
PubMed1988

Studies on the crystal structure of A1-(L-tryptophan) insulin at 2.1 A resolution.

In order to study the biological effect of alterations to the N-terminus of the insulin A-chain, we have determined the crystal structure of A1-(L-Trp) insulin and discovered that it belongs to the trigonal system with space group R3. The parameters of the unit cell are a = b = 80.3A, c = 37.5A. The model was adjusted and refined by using a stereochemically-restrained least squares program, assisted by manual revision of the model based on the difference Fourier map, to a final R-factor of 0.195. The main and side chains of both A1-(L-Trp) residues in the asymmetric unit are well ordered. It was found that the A1-Trp residue of molecule I occupied two distinct positions. We have proposed from the results of the three-dimensional structure that the 4-zinc insulin hexameric form is a stored state of insulin molecules in a conformation of low activity. The structural details of the insulin molecule and its structure and function relationship have also been discussed.

Insulin↗
PubMed1986

Reactive histiocytosis in acute lymphoblastic leukemia and non-Hodgkin's lymphoma.

An extensive hemophagocytic syndrome in the termination of one case of pre-T acute lymphoblastic leukemia (ALL) and another case of non-Hodgkin's lymphoma (NHL), are described. Since most of the proliferating cells were mature macrophages and these cells were limited in the mononuclear phagocytic system (MPS), it was determined to be a reactive histiocytosis rather than histiocytic medullary reticulosis (HMR) or malignant histiocytosis (MH). The pathogenesis of the HMR or MH-like syndrome in these patients is discussed, and it is considered that this might be a reaction of the bacterial sepsis related to their immunosuppressed state secondary to the pre-existing malignancies and/or the cytotoxic therapy. The literature was reviewed. Based on a proposal for differential diagnosis between reactive histiocytosis and MH (or HMR), the heterogeneity of HMR-like syndrome complicating the malignancies are clarified.

Autopsy↗
PubMed1986

To early distinguish neonatal transient leukemoid proliferation from congenital leukemia by in vitro cell growth.

To differentiate neonatal transient leukemoid proliferation from congenital leukemia at an early stage is often difficult. Bone marrow culture is found to be helpful in this aspect. A normal in vitro growth pattern suggests transient leukemoid proliferation, while an abnormal growth pattern indicates congenital leukemia. A neonate who manifested with pictures mimicking acute myeloblastic leukemia (M1), had a karyotype of 46, XY/46, XY, i(21 q). However, the in vitro growth pattern was normal and so only supportive treatment was given. All the leukemoid manifestations disappeared several months later and he is now a healthy 2 year old boy remaining in complete remission. A second neonate who also displayed features of acute myeloblastic leukemia (M2), had a karyotype of 46, XY/47, XY, + 21 and abnormal in vitro growth pattern. This neonate died at 18 days of age.

Cell Division↗
PubMed1986

Molecular structure and absolute configuration of suberogorgin.

In the present paper it is reported that the molecular structure and absolute configuration of poisonous suberogorgin are determined by using X-ray diffraction method. The crystal of suberogorgin belongs to orthogonal system with space group D4(2)-P2(1)2(1)2(1). The crystallographic parameters are: a = 16.135A, b = 13.189A, c = 12.901A, Z = 8. The initial model of the crystal structure was solved by the direct method. The refinement of the structure parameters was carried out by using the least square method and led to a final R-factor of 0.056. In accordance with the molecular structure of suberogorgin mentioned above, the solvent effect of NMR has been further discussed and the relationship between the molecular structure of suberogorgin and its toxicity has also been preliminarily investigated.

Animals↗
PubMed1985

Molecular structure and absolute configuration of the diterpene lactone, praelolide.

Praelolide is a new compound which was isolated out from the gorgonian, Menella praelonga (Ridley), collected from the South Sea of China at Zhanjiang, Guangdong. The molecular formula is C28H35O12Cl. The research result by X-ray diffraction method on the crystal structure is presented. The compound is orthorhombic with space group P2(1)2(1)2, cell dimensions a = 16.936, b = 16.709, c = 10.333 A, and Z = 4. The structure has been solved by direct method and refined to R = 0.055 for 2257 unique observable reflexions by least-squares. The molecule is composed of the major conformational isomer in which the three main rings (a six-membered ring, an eight-membered ring, a six-membered ring) take separately the form of chair-chairboat-chair, a five-membered actone ring, a C1 substitution, 4 acetate groups, and a three-membered epoxide ring. The absolute configuration of the molecule has also been determined by statistics (R factor ratio R = 1.012) and Bijvoet pairs observation. For 30 pairs of the greatest anomalous contributions the residuals are R'(+) = 0.057 for the first enantiomorph and R'(-) = 0.005 for the second one, so the latter should unambiguously correspond to the absolute configuration of the molecule.

Animals↗
PubMed1985

The growth of single crystal and the determination of crystallographic parameters of (L-tryptophan)A1-insulin and (D-tryptophan)A1-insulin.

The crystal-growing conditions and the results of preliminary X-ray crystallographic analysis of (L-Try)A1-insulin and (D-Try)A1-insulin are reported. The single crystals of this pair of insulin analogue suitable for X-ray diffraction analysis have been grown in the citrate buffer system by still-setting method. They both belong to the trigonal system with space group R3. The parameters of the unit cell (L-Trp)A1-insulin are aH = 80.31A, cH = 37.45A and those of (D-Trp)A1-insulin aH = 79.48A, cH = 43.81A. There are two molecules in an asymmetric unit. The obtained results are discussed.

Crystallography↗