Growth mechanism and the order of appearance of diamond (111) and (100) facets.
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Journal Article↗
Biomedical subjects
B Sun
Publications and source records attributed to B Sun.
An analysis of antigenic polypeptides of dengue viruses and their specificity with western blotting.
Dengue virus (DV) samples which harvested after having been either propagated in C6/36 cells or passaged by murine intracerebral inoculation were investigated by Western blotting. Two different denaturing methods with the same solution were selected before electrophoresis, one at 60 degrees C for 20 min; the other at 100 degrees C for 5 min. After the samples were heated at 60 degrees C for 20 min, 3 bands of sizes 46 ku, 70 ku and 98 ku were positively recognized by rabbit immunized sera. The peptide of 98 ku was DV group specific; While that of 46 ku could also react with the sera against both heterologous DV serotype and Japanese B encephalitis virus (JEV). After the samples were heated at 100 degrees C for 5 min, 3 peptides in size of 20 ku, 46 ku and 57 ku were recognized by the rabbit sera against both homologous and heterologous DV serotypes, while the peptide of 57 ku could also be recognized by anti-JEV serum. There was no significant difference in the results of Western blot between the DV antigens harvested from cellular culture and those from intra-cerebral inoculation.
Animals↗
Quantitative autoradiography reveals higher densities of specific calcitonin-gene-related peptide receptors in small intramyocardial compared with large epicardial coronary arteries.
1. Binding sites for calcitonin-gene-related peptide were localized and characterized in porcine coronary arteries using quantitative autoradiography, and the density of binding sites was compared between large epicardial and small intramyocardial coronary arteries. 2. A single class of binding sites for calcitonin-gene-related peptide with a dissociation constant of 2.1 +/- 0.2 nmol/l was detected in both the large and small coronary arteries. The density of specific binding sites was higher (maximum binding site density 231 +/- 14 fmol/mg of protein) in the small coronary arteries than in the large epicardial coronary arteries (maximum binding site density 108 +/- 5 fmol/mg of protein). beta-Human calcitonin-gene-related peptide showed higher affinity than alpha-human calcitonin-gene-related peptide for the binding sites. Most of the specific binding sites for both peptides in the large coronary artery were localized in the intima and media. 3. In coronary artery from patients with coronary heart disease, there were more binding sites for calcitonin-gene-related peptide in the smooth muscle layer of atheromatous segments (7.2 +/- 0.7 amol/mm2) than in that of normal segments (3.0 +/- 0.3 amol/mm2, P < 0.002). 4. The present findings lend further support to the theory of regional variation in the vasodilator response to calcitonin-gene-related peptide in porcine coronary arteries, which seems to be due to different densities of a single type of receptor for calcitonin-gene-related peptide.
Animals↗
Surfactant inhibition in experimental meconium aspiration.
Human meconium components were separated into a water-methanol soluble phase containing mainly proteins and bilirubin and a chloroform soluble phase containing free fatty acids, triglycerides and cholesterol. Various amounts of original meconium, the water-methanol soluble fraction or the chloroform soluble fraction were added to standard suspensions of porcine surfactant (Curosurf). In a pulsating-bubble or Wilhelmy-balance system, meconium and its subfractions inhibited surfactant activity, but the chloroform soluble fraction had the highest specific inhibitory activity. Original meconium in saline (130 or 65 mg/ml) was instilled into the airways of ventilated near-term newborn rabbits (dose 6 ml/kg). Lung-thorax compliance was reduced by 38% in animals aspirating the higher dose and by 27% in the low-dose group. Histological sections showed intra-alveolar accumulation of fine meconium particles in experimental animals, but no plugging of larger airways. We conclude that respiratory failure from meconium aspiration may be mediated, in part, by inactivation of surfactant.
Adsorption↗
Immunochemical analysis of the gp120 surface glycoprotein of human immunodeficiency virus type 1: probing the structure of the C4 and V4 domains and the interaction of the C4 domain with the V3 loop.
We have probed the structure of the C4 and V3 domains of human immunodeficiency virus type 1 gp120 by immunochemical techniques. Monoclonal antibodies (MAbs) recognizing an exposed gp120 sequence, (E/K)VGKAMYAPP, in C4 were differentially sensitive to denaturation of gp120, implying a conformational component to some of the epitopes. The MAbs recognizing conformation-sensitive C4 structures failed to bind to a gp120 mutant with an alteration in the sequence of the V3 loop, and their binding to gp120 was inhibited by both V3 and C4 MAbs. This implies an interaction between the V3 and C4 regions of gp120, which is supported by the observation that the binding of some MAbs to the V3 loop was often enhanced by amino acid changes in an around the C4 region.
Amino Acid Sequence↗
Effects of acute hypoxia on intracranial dynamics in unanesthetized goats.
The effects of acute hypoxia on intracranial dynamics were studied in six unanesthetized goats that were subjected to hypobaric hypoxia at a simulated 4,000-m high altitude for 2 h. Another six nonhypoxic goats served as control group for cerebral water content (CWC). In this study, we measured cerebral blood flow (CBF) by electromagnetic flowmeter, intracranial pressure (ICP) through an intraventricular catheter, and CWC by a wet-to-dry weight technique for a given volume of brain tissue. Intracranial compliance was calculated from a pressure-volume index derived from the change in intraventricular pressure after a subarachnoid injection of saline. During acute hypoxia CBF increased from 146.0 +/- 10.60 to 185.3 +/- 7.83 ml x min-1.100 g-1, ICP increased from 15.4 +/- 1.82 to 27.4 +/- 3.84 cmH2O, and CWC increased from 78.7 +/- 0.30 to 79.5 +/- 0.16%, but intracranial compliance decreased from 0.65 +/- 0.28 to 0.36 +/- 0.19 ml/cmH2O. The data suggest that acute hypoxia results in a significant disturbance of intracranial dynamics, which may be one of the important pathophysiological mechanisms of high-altitude cerebral edema and acute mountain sickness.
Acute Disease↗
Surfactant improves lung function and morphology in newborn rabbits with meconium aspiration.
Nearly mature newborn rabbits (gestational age 29.5 days) were tracheotomized at birth and received, via the tracheal cannula, 6 ml/kg body weight of a filtered saline suspension of human meconium, 65 or 130 mg/ml. Animals were kept in body plethysmographs and ventilated for 60 min with standardized tidal volume (8-10 ml/kg). Aspiration of meconium caused, in both groups, a statistically significant reduction in lung-thorax compliance, elevated PCO2 in heart blood and reduced alveolar volume density (VV) in histological sections. Both groups responded to treatment with exogenous surfactant (Curosurf, 200 mg/kg) with a moderate, statistically significant improvement in lung-thorax compliance, PCO2 and alveolar VV. Our data indicate that respiratory failure after neonatal meconium aspiration may be influenced favorably by treatment with exogenous surfactant.
Animals↗
Changes of pulmonary glucocorticoid receptor and phospholipase A2 in sheep with acute lung injury after high dose endotoxin infusion.
In a sheep model of acute lung injury induced by an Escherichia coli endotoxin (5 micrograms/kg) with chronic lung lymph fistula (n = 15), we measured the changes in glucocorticoid receptor (GCR) binding capacity in lung tissue by means of radioligand binding assay. The content of cortisol and the activity of phospholipase A2 (PLA2) were also measured. The results showed that the maximal binding capacity (Bmax) of GCR in lung cytoplasma decreased continuously 2 h (113 +/- 3 versus 66 +/- 2 fmol/mg protein, p < 0.01), 4 h (105 +/- 6 versus 52 +/- 3 fmol/mg protein, p < 0.01), and 6 h (105 +/- 5 versus 37 +/- 2 fmol/mg protein, p < 0.01) after endotoxin infusion. Its affinity decreased markedly (p < 0.05) at 6 h after the infusion. The contents of cortisol in plasma elevated at 0.5 h and remained at a high level until 4 h after the infusion. PLA2 activity rose from 97 +/- 25 to 188 +/- 12 U (p < 0.05), 99 +/- 13 to 285 +/- 25 U (p < 0.01), and 106 +/- 14 to 354 +/- 32 U (p < 0.01) at 2, 4, and 6 h after endotoxin infusion, respectively. There was a negative correlation between the Bmax of GCR and PLA2 activity (r = -0.87, p < 0.01). The findings indicate that there was a secondary GCR abnormality and a higher PLA2 activity during endotoxin-induced lung injury. The glucocorticoid hypofunction caused by reduced GCR binding capacity may accelerate the pathologic response of acute lung injury.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Single dose versus two doses of betamethasone for lung maturation in preterm rabbits.
Most previous studies of induced lung maturation have used fetal exposures to multiple doses of hormones, and such treatments are associated with fetal growth retardation in rodents and rabbits. This study was designed to evaluate whether single-dose maternal corticosteroid treatments could induce lung maturation without causing fetal growth retardation. Lung maturation was evaluated in 27-d gestational age rabbits by measurements of lung function after preterm delivery and ventilation. Lung function was assessed by measurements of ventilatory requirements, responses to exogenous surfactant, measurements of the recovery of intravascular albumin in the lungs, and surfactant pool sizes. As demonstrated previously, 0.1 mg/kg betamethasone (1 mg = 2.13 mumol betamethasone) given 48 and 24 h before delivery caused both growth retardation (birth weight 20% lower than controls, p < 0.01) and lung maturation (improved compliance, decreased radiolabeled albumin recoveries) despite lower alveolar saturated phosphatidylcholine pool sizes (p < 0.05 versus controls). A single dose of 0.2 mg/kg betamethasone given 48 h before delivery had an equivalent effect on birth weight as the divided doses of 0.1 mg/kg betamethasone, with the only lung maturational effect being a decrease in recovery of labeled albumin in alveolar washes (p < 0.01). A single dose of 0.1 mg/kg betamethasone given 48 h before delivery decreased birth weight by 9.4% (p < 0.01 versus control) but had no effect on any of the lung maturation indicators. Fetal lung maturation caused by maternal corticosteroid is associated with global fetal growth retardation, and a single low dose of corticosteroid can cause growth retardation without inducing lung maturation.(ABSTRACT TRUNCATED AT 250 WORDS)
Albumins↗
Transformation of wheat protoplasts mediated by cationic liposome and regeneration of transgenic plantlets.
E. coli plasmid pCGN1055 containing the hygromycin phosphotransferase (Hpt) gene under the control of the plant promoter was introduced into wheat protoplasts by cationic liposome (lipofectin)-mediated transformation, and transgenic albino plantlets were obtained. The transformation frequencies were 6.0% and 8.8% according to hygromycin resistance and DNA molecular hybridization. The assay of Hpt enzyme activity and Southern blot indicated the foreign gene existed and expressed in transgenic plantlets.
Cations↗
Normocalcemic blood or crystalloid cardioplegia provides better neonatal myocardial protection than does low-calcium cardioplegia.
Although standard blood cardioplegia provides good myocardial protection for cardiac operations in adults, protection of the cyanotic, immature myocardium remains suboptimal. Calcium, which has been implicated in reperfusion injury and in the development of "stone heart" in mature myocardium, is routinely lowered in standard cardioplegic solutions. Immature, neonatal myocardium has lower intracellular calcium stores and is more reliant on extracellular calcium for contraction. To determine if normocalcemic cardioplegia would result in improved cardiac function in the neonatal heart, we conducted a series of experiments using an isolated, blood-perfused working heart model. Thirty-two neonatal piglet hearts (24 to 48 hours) were excised without intervening ischemia and were placed directly on a blood-perfused circuit. Baseline stroke work index was assessed. Hearts were then arrested with cold cardioplegic solution delivered at 45 mm Hg for 2 minutes: group I, low-calcium blood cardioplegic solution (Ca = 0.6 mmol/L); group II, normal-calcium blood cardioplegic solution (Ca = 1.1 mmol/L); group III, University of Wisconsin solution; and group IV, University of Wisconsin solution with added calcium (Ca = 1.0 mmol/L). Cardioplegic solution was administered every 20 minutes for 2 hours and topical hypothermia was used. Hearts were then reperfused with warm whole blood. Functional recovery, expressed as a percentage of control stroke work index, was determined minutes after reperfusion. Hearts preserved with normocalcemic cardioplegic solution (groups II and IV) had complete functional recovery at 60 minutes, whereas hearts preserved with low-calcium cardioplegic solution (groups I and III) achieved functional recoveries of only 80% and 65%, respectively, at a left atrial pressure of 9 mm Hg. Electron micrographs taken 1 hour after reperfusion showed minimal edema and only mild myofibrillar changes. They were identical in both the low-calcium and normocalcemic groups. Complete functional recovery is possible in immature myocardium when calcium is added to either blood or an intracellular crystalloid cardioplegic solution. The addition of calcium does not result in ultrastructural damage and does result in good functional recovery.
Adenosine Triphosphate↗
Different ventilation strategies alter surfactant responses in preterm rabbits.
The effect of ventilation strategy on in vivo function of different surfactants was evaluated in preterm rabbits delivered at 27 days gestational age and ventilated with either 0 cmH2O positive end-expiratory pressure (PEEP) at tidal volumes of 10-11 ml/kg or 3 cmH2O PEEP at tidal volumes of 7-8 ml/kg after treatment with one of four different surfactants: sheep surfactant, the lipids of sheep surfactant stripped of protein (LH-20 lipid), Exosurf, and Survanta. The use of 3 cmH2O PEEP decreased pneumothoraces in all groups except for the sheep surfactant group where pneumothoraces increased (P < 0.01). Ventilatory pressures (peak pressures - PEEP) decreased more with the 3 cmH2O PEEP, low-tidal-volume ventilation strategy for Exosurf-, Survanta-, and sheep surfactant-treated rabbits (P < 0.05), whereas ventilation efficiency indexes (VEI) improved only for Survanta- and sheep surfactant-treated rabbits with 3 cmH2O PEEP (P < 0.01). Pressure-volume curves for sheep surfactant-treated rabbits were better than for all other treated groups (P < 0.01), although Exosurf and Survanta increased lung volumes above those in control rabbits (P < 0.05). The recovery of intravascular radiolabeled albumin in the lungs and alveolar washes was used as an indicator of pulmonary edema. Only Survanta and sheep surfactant decreased protein leaks in the absence of PEEP, whereas all treatments decreased labeled albumin recoveries when 3 cmH2O PEEP was used (P < 0.05). These experiments demonstrate that ventilation style will alter a number of measurements of surfactant function, and the effects differ for different surfactants.
Air Pressure↗
Antenatal ambroxol effects on surfactant pool size and postnatal lung function in preterm ventilated rabbits.
Following maternal treatments with 50 mg/kg/day ambroxol for 2 or 3 days before delivery at 28 days gestation, preterm rabbits were ventilated to evaluate lung function. Subsequently, surfactant saturated phosphatidylcholine (SatPC) pool sizes were measured. One half of the ambroxol treated and control rabbits were given surfactant at delivery. Although surfactant improved lung function comparably for control and ambroxol treated rabbits, ambroxol treatments did not change ventilatory pressure requirements, compliances, or the recovery of intravascular labeled albumin in the lungs. Ambroxol treatments tended to increase lung volumes as evaluated by pressure-volume curves. The ambroxol treatments significantly increased lung tissue SatPC by 22%, but there were no changes in alveolar SatPC pool values. These results do not indicate a large effect of ambroxol on lung function in preterm rabbits.
Ambroxol↗
[Allergen-stimulated release of prostaglandin E, F2 alpha by alveolar macrophages from patients with allergic asthma].
Bronchoalveolar lavage (BAL) was performed in healthy subjects (n = 12) and patients with bronchial asthma (n = 11). Between the two groups there was no significant difference in the total number of cells and the percentage of alveolar macrophages (AM), lymphocytes (L), neutrophils (N) and eosinophils (E) in BAL fluids. When AM were cultured in vitro and stimulated with dermatophagoides farinae (DPF) antigen, the amount of PGE released by AM was significantly increased in the asthmatics. When the asthmatics, AM were sensitized with specific IgE positive serum and stimulated with DPF, they released more PGE and PGF2 alpha than those when specific IgE negative serum was used (P < 0.01). The PGE/PGF2 alpha ratio was significantly decreased. There was positive correlation between the decreased value of PGE/PGF2 alpha and patients, MCH-PC20. The increase in the amount of PGE and PGF2 alpha released and the decrease of PGE/PGF2 alpha ratio might play an important role in the pathogenesis of allergic asthma.
Animals↗
[Morphological changes in experimental atherosclerotic stenosis and intramural balloon angioplasty].
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Angioplasty, Balloon↗
Improved method of human umbilical arterial endothelial cell culture.
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Cell Separation↗
Neutrophil-specific antigen NB1 is anchored via a glycosyl-phosphatidylinositol linkage.
Neutrophil-specific alloantibodies and the antigens they recognize are important in clinical medicine but little is known about the structure of these antigens. Alloimmunization to the antigen NB1 is a clinically important cause of neonatal neutropenia and leukocyte-mediated transfusion reactions. A novel mechanism of protein attachment to cell membranes involving the covalent linkage of the protein through an oligosaccharide to phosphatidylinositol has recently been defined. Many proteins which are anchored to the cell membrane by this mechanism can be released by treatment with phosphatidylinositol-specific phospholipase C (PI-PLC). The 58-64-kDa human neutrophil surface protein which contains the NB1 antigen was labeled with 125I by using lactoperoxidase and examined for PI-PLC sensitivity. The 58-64-kDa protein was specifically released from the cell by treatment with PI-PLC, and the mobility of the protein under non-denaturing conditions using non-ionic detergent was increased by treatment with PI-PLC. Surface expression of the NB1 antigen was slightly up-regulated by treatment with the chemotactic peptide f-met-leu-phe. Removal of N-linked carbohydrates with endoglycosidase-F decreased the apparent molecular weight of the protein to approximately 45-kDa. The data suggest that most of the 58-64-kDa protein bearing the neutrophil-specific antigen NB1 is anchored to the membrane through a glycosyl-phosphatidylinositol linkage.
Antigens, Surface↗
Studies on monoclonal anti-idiotypic and anti-isotypic antibodies against leukemia and myeloma: III. Analysis of monoclonal antibodies recognizing the antigenic epitopes by use of ELISA additivity test and microcomputer grouping programme.
ELISA double antibodies additivity test was employed to identify the epitopes which can be recognized by monoclonal antibodies (McAbs) against IgM of a patient with B chronic lymphocytic leukemia (B-CLL). The computer grouping programme analysis showed that 4 anti-isotype McAbs could be divided into two groups and 10 anti-idiotype McAbs could be divided into four groups. The result was consistent with that of the indirect ELISA, ELISA sandwich as well as ELISA inhibition test. The above findings suggested that there are at least 6 distinct IgM epitopes which can specifically react with 14 McAbs. Our study indicated that the combination of the ELISA additivity test and the computer grouping programme analysis provides a helpful tool for researchers into the relationship between the structure and function of antigens.
Animals↗