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H M Wang

Publications and source records attributed to H M Wang.

At least 91 records · Page 5Linked to original sources
PubMed1991

Low salt mimics effects of dark pulses on circadian pacemaker in cultured chick pineal cells.

Chick pineal cells in static culture display a persistent photosensitive circadian rhythm of melatonin production and release. Pulses of white light or darkness, in otherwise constant red light, induce phase shifts in subsequent cycles whose magnitude and direction depend on the phase at which the pulse is given. Such "phase-dependent phase shifts" are mediated by effects on the underlying pacemaker. We reported previously that inhibiting the Na-K-ATPase with ouabain or salt solutions lacking potassium evokes phase shifts with the same phase dependence as those induced by pulses of darkness. One of the consequences of inhibiting the sodium pump is cell swelling. To test the relevance of this effect, we exposed chick pineal cells to pulses of medium containing reduced concentrations of NaCl, which should cause cell swelling. These hypotonic solutions induced phase shifts in the melatonin rhythm with the same phase dependence as those caused by pulses of ouabain or darkness. The size of the phase shifts varied with degree of dilution, and phase shifting was prevented by replacement of NaCl. In view of previous results showing that hypertonic media mimicked the phase-shifting effects of light, these results suggest that cell swelling may mediate the darklike effects of ouabain on the circadian pacemaker in chick pineal cells.

Animals↗
PubMed1990

Structural variation in the antithrombin III binding site region and its occurrence in heparin from different sources.

A tetrasaccharide possessing a biosynthetically permissible structural variability in and adjacent to the antithrombin III (ATIII) binding site has been isolated from heparin lyase depolymerized bovine lung heparin by using strong anion-exchange high-pressure liquid chromatography (SAX-HPLC). On the basis of two-dimensional 500-MHz 1H NMR experiments, including phase-sensitive correlated spectroscopy (COSY) and rotating frame nuclear Overhauser enhancement spectroscopy (ROESY), and fast-atom bombardment mass spectrometry (FAB-MS), the primary structure of this tetrasaccharide was unambiguously established as delta UAp2S (1----4)-alpha-D-GlcNp2S6S(1----4)-beta-D-GlcAp(1----4)-alph a-D-GlcNp2S3S6S (where delta UA represents 4-deoxy-alpha-L-threo-hex-4-enopyranosyluronic acid). The 1H NMR ROESY experiment proved to be particularly valuable in offering sequence information. Heparins from a variety of species and tissue sources were examined by oligosaccharide mapping using SAX-HPLC and gradient polyacrylamide gel electrophoresis. Two of these heparins are used as anticoagulants; they are porcine intestinal mucosal heparin and bovine lung heparin. The predominant ATIII-binding site in porcine heparin contained an N-acetylated glucosamine residue. We now report the structure of the predominant ATIII-binding site in bovine heparin as----4)-alpha-D-GlcNp2S6S(1----4)-beta-D-GlcAp(1----4)-alph a-D- GlcNp2S3S6S(1----4)-alpha-L-IdoAp2S(1----4)-alpha-D-GlcNp 2S6S(1----. This study shows the presence of one or both types of ATIII-binding-site variants in all of the heparins that were examined.

Animals↗
PubMed1990

Examination of the substrate specificity of heparin and heparan sulfate lyases.

We have examined the activities of different preparations of heparin and heparan sulfate lyases from Flavobacterium heparinum. The enzymes were incubated with oligosaccharides of known size and sequence and with complex polysaccharide substrates, and the resulting degradation products were analyzed by strong-anion-exchange high-performance liquid chromatography and by oligosaccharide mapping using gradient polyacrylamide gel electrophoresis. Heparinase (EC 4.2.2.7) purified in our laboratory and a so-called Heparinase I (Hep I) from a commercial source yielded similar oligosaccharide maps with heparin substrates and displayed specificity for di- or trisulfated disaccharides of the structure----4)-alpha-D-GlcNp2S(6R)(1----4)-alpha-L-IdoAp2S( 1----(where R = O-sulfo or OH). Oligosaccharide mapping with two different commercial preparations of heparan sulfate lyase [heparitinase (EC 4.2.2.8)] indicated close similarities in their depolymerization of heparan sulfate. Furthermore, these enzymes only degraded defined oligosaccharides at hexosaminidic linkages with glucuronic acid:----4)-alpha-D-GlcNpR(1----4)-beta-D-GlcAp(1----(where R = N-acetamido or N-sulfo). The enzymes showed activity against solitary glucuronate-containing disaccharides in otherwise highly sulfated domains including the saccharide sequence that contains the antithrombin binding region in heparin. A different commercial enzyme, Heparinase II (Hep II), displayed a broad spectrum of activity against polysaccharide and oligosaccharide substrates, but mapping data indicated that it was a separate enzyme rather than a mixture of heparinase and heparitinase/Hep III. When used in conjunction with the described separation procedures, these enzymes are powerful reagents for the structural/sequence analysis of heparin and heparan sulfate.

Carbohydrate Conformation↗
PubMed1990

Oligosaccharide mapping of low molecular weight heparins: structure and activity differences.

Low molecular weight heparins from a variety of commercial sources were examined. These had been prepared by several methods including peroxidative cleavage, nitrous acid cleavage, chemical beta-elimination, enzymatic beta-elimination, and chromatographic fractionation. The molecular weight and polydispersity of these low molecular weight heparins showed greater differences than were observed for typical commercial heparin preparations. Considerable differences were also observed in the antithrombin III mediated anti factor Xa activity, the heparin cofactor II mediated antifactor IIa activity, and the USP activity of these low molecular weight heparins. An oligosaccharide-mapping technique (comparable to the peptide mapping of proteins) was applied to these low molecular weight heparins in an effort to understand the structural features responsible for their activity differences. Heparin lyase from Flavobacterium heparinum was first used to depolymerize the low molecular weight heparin into its constituent oligosaccharides. The oligosaccharides present in the resultant mixture were identified and quantitated by using standard oligosaccharides of defined structure on gradient polyacrylamide gel electrophoresis and strong anion exchange high pressure liquid chromatography. Six of the oligosaccharide products have been identified and represent nearly 90 wt % of heparin's mass. Even though all the low molecular weight heparins showed these six oligosaccharide components, their content in each varied greatly, accounting for 20 to over 90% of their mass. The antithrombin III mediated anti factor Xa activities of the low molecular weight heparins correlated only poorly to the concentration of a hexasaccharide containing a portion of heparin's antithrombin III binding site. The heparin cofactor II mediated antifactor IIa activity, however, could not be correlated to these six oligosaccharides of known structure nor to the molecular weight or charge density of these low molecular weight heparins. The low molecular weight heparins prepared by different methods each showed a new distinctive oligosaccharide in their maps. Their isolation and structural characterization, which included two-dimensional NMR and fast atom bombardment mass spectrometry, indicated that these unusual oligosaccharides result from end-sugar modification during chemical depolymerization. Both gel electrophoresis and high-pressure liquid chromatography mapping techniques showed a greater structural diversity between low molecular weight heparins than had previously been observed between similarly analyzed commercial heparins.

Factor Xa Inhibitors↗
PubMed1990

The protective effect of ascorbic acid in retinal light damage of rats exposed to intermittent light.

Retinal light damage in dark-reared rats supplemented with ascorbic acid and exposed to multiple doses of intermittent light was studied and compared with damage in unsupplemented dark-reared and cyclic-light-reared rats. The extent of photoreceptor cell loss from intense light exposure was determined by whole-eye rhodopsin levels and retinal DNA measurements two weeks after light treatment. Two weeks after 3 or 8 hr of intermittent light, ascorbate-supplemented animals had rhodopsin and retinal DNA levels that were two to three times higher than in unsupplemented dark-reared rats. In both types of rats rhodopsin levels were influenced by the number of light doses, the duration of light exposure, and to a lesser extent, by the length of the dark period between exposures. Rhodopsin levels in the dark-reared ascorbate-supplemented rats were significantly higher than in unsupplemented dark-reared rats, and were similar to the levels in unsupplemented cyclic-light-reared animals. Ascorbate treatment had no effect on the rate of rhodopsin bleaching. However, regeneration was greater in supplemented rats after multiple 1-hr light exposures. Intermittent light also resulted in lower ascorbate levels in the retinas of supplemented and unsupplemented rats, with dramatic losses from the retinal pigment epithelium (RPE)-choroid in both types of animals. We conclude that ascorbic acid protects the eye by reducing the irreversible Type I form of light damage in dark-reared rats. Ascorbate appears to shift light damage to the Type II form typical of cyclic-light-reared animals.

Animals↗
PubMed1990

[Complications of colostomies and colostomy closure].

Three hundred and sixty patients underwent 369 colostomies over 7 years, 66 for benign and 303 for malignant disease, and were followed up for an average of 20 months. Stomas were made electively in 246 cases and urgently in 123. Thirty-seven stomas were brought out through incision and 332 from separate sites. End colostomy was made in 179 cases, loop colostomy in 136 and double barrel colostomy in 54. There were 102 complications in 85 patients (27.6%). The most common complication was wound infection (10.8%). The total number of complications was not related to the urgency of the procedure, the disease process, or the stoma site. Wound infection, however, increased in incisional stomas. Extraperitoneal tunneling of end colostomy did not decrease the complication rate of parastomal hernia or intestinal obstruction. Sixteen cases (4.3%) received another operation for complications. Eighty-five patients the colostomy closed on an average of 3.4 months after its creation. Four patients had 5 complications (5.9%). Two patients required another operation. Complications increased with Hartmann closures and may be related to the timing of the colostomy closure.

Adolescent↗
PubMed1989

EGF induces differentiation of an IL-3-dependent cell line expressing the EGF receptor.

Interleukin 3 (IL-3) is a T cell-derived lymphokine that supports the growth and development of hematopoietic cells. Tyrosine phosphorylation has been suggested to play an important role in IL-3-dependent cell proliferation. To test whether a growth factor receptor carrying a tyrosine kinase can be functional in IL-3 dependent cells, we used a retroviral vector to introduce the human EGF receptor into a murine IL-3-dependent pre-mast cell line, IC2. The EGF receptors expressed on the infected clones bind EGF with both high and low affinities. EGF stimulates the infected cells for a short term growth response. In the presence of IL-3 and EGF, infected clones differentiate into more mature mast cells characterized by increases in intracellular granulation and histamine content. This differentiation is reversible when EGF is removed. EGF induces tyrosine phosphorylation of several cellular proteins and the expression of oncogenes c-fos and c-myc, in a manner analogous to IL-3 stimulation. These results indicate that the EGF receptor is functional in the pre-mast IC2 cells; EGF can support short-term proliferation and activates the signals that induce cell differentiation. Thus, EGF receptor-expressing IC2 cells provide a unique cellular system for in vitro study of mast cell differentiation.

Animals↗
PubMed1989

Sequence analysis of highly sulfated, heparin-derived oligosaccharides using fast atom bombardment mass spectrometry.

Heparin, a polydisperse, sulfated copolymer of 1----4 linked glucosamine and uronic acid residues, has been used clinically as an anticoagulant for half a century. Despite a yearly use of over 50 million doses in the U.S. alone, heparin's exact chemical structure remains unclear. The negative ion fast atom bombardment mass spectrometry (FAB-MS) analysis is presented for a series of enzymatically prepared, homogeneous, structurally characterized, highly sulfated, heparin-derived oligosaccharides using triethanolamine as the FAB matrix. In addition to the clear presence of monoanionic sodiated molecular ions, structurally significant (sequence) fragment ions are observed and characterized with respect to the known structure for five of the heparin-derived oligosaccharides. The structure of a sixth oligosaccharide is predicted by using negative ion FAB-MS and subsequently confirmed by chemical, enzymatic, and NMR spectroscopic methods.

Heparin↗
PubMed1989

Turnover of platelets adhered to fibrinogen-coated surfaces.

The dynamic interactions between platelets and fibrinogen-coated surfaces were investigated by using a tube-flow device and a rotating rod device. The net platelet accumulation to the fibrinogen-coated surfaces in both devices reached maximal values of 30-40 platelets/1000 um2. This adhesion phenomenon was completely inhibited by EDTA. In the tube-flow device, the density of platelets adhered to the tube surface increased with flow time and decreased with distance from the tube inlet. These adhered platelets were difficult to be washed off the tube surface and showed little turnover. The platelet accumulation kinetics in a rotating rod device increased with rotation speed from 300 rpm to 1200 rpm. At 1200 rpm, about half of these platelets adhered to the rod were exchangeable with platelets in the suspension whereas the rest of them were permanent. The detachment of platelets from the rod surface depended on the presence of erythrocytes and platelets in the suspension and it was facilitated by the presence of EDTA in the suspension. These observations suggest that the turnover of platelets adhered to fibrinogen-coated surfaces depends on experimental conditions.

Blood Platelets↗
PubMed1989

Fc receptors in corneal epithelium.

The corneal epithelia of the mouse, rabbit and human were shown to contain Fc receptors by an indirect method with immunoglobulins, labelled second antibody and the avidin-biotin peroxidase complex (ABC); and a direct method with the peroxidase conjugated Fc fragment. The cornea epithelia of all three species exhibited a high concentration of the Fc gamma R with either homologous or heterologous immunoglobulins. The binding specificity of Fc receptors was further supported by competitive inhibition of binding of labeled antibody by homologous, unlabeled antibody. Although Fc alpha R was also present it was at a much lower concentration. The Fc receptor for IgM (Fc microR) was difficult to demonstrate. However, it appeared to be present in very low concentration on only the mouse and rabbit corneal epithelium.

Animals↗
PubMed1989

Immunohistochemical evaluation of murine HSV-1 keratouveitis.

The intraocular inflammatory reaction in a murine model of herpes simplex keratouveitis was studied using immunohistochemical techniques. 5 x 10(5) PFU of HSV-1 (Stewart strain) was applied to the abraded cornea of BALB/c mice. The subsequent development of keratouveitis was documented by sequential examination, conventional histology and immunohistochemical staining of frozen sections with the following monoclonal antibodies: Thy-1, Lyt-1, Lyt-2, Ia, Mac-1 and Lyb-8.2. At one week (in the early stage) there was moderate central corneal edema with inflammatory cell infiltration, consisting of a predominance of polymorphonuclear leukocytes, with the appearance of helper/inducer T-cells(Th/i). At two weeks (in the middle stage), a geographic corneal ulcer developed and the majority of inflammatory cells were still polymorphonuclear leukocytes. However, there was a further increase in the Th/i cell population, with the first appearance of B-cells. At three weeks (in the late stage), a dense stromal corneal scar was observed and there was a decrease in the inflammatory cell population, with the predominant cell being the B-cell. Throughout the evolution of HSV-1 keratouveitis, a mild inflammatory reaction was observed in the uvea. However, the number of inflammatory cells present was too small to allow more definitive characterization. Patchy Ia staining which is noted in the normal choroid increased markedly throughout the keratouveitis.

Animals↗
PubMed1989

[Determination of the contents of mineral elements in the soil where the jinin big-wild ginseng grows].

The element contents in the soil where the Jilin Big-Wild Ginseng grows were determined with plasma emission spectrometry. 23 elements in the soil were found, of which 12 are macro and trace elements indispensable to Ginseng growth. This study provides a scientific basis for selecting suitable soil for planting wild ginseng, or for creating optimum soil conditions for the bumper harvest and high quality of Ginseng.

Calcium↗
PubMed1989

Retinal light damage in rats exposed to intermittent light. Comparison with continuous light exposure.

Visible light-induced photoreceptor cell damage resulting from exposure to multiple intermittent light-dark periods was compared with damage resulting from continuous light in albino rats maintained in a weak cyclic-light environment or in darkness before light treatment. The time course of retinal damage was determined by correlative measurements of rhodopsin and visual cell DNA at various times after light exposure, and by histopathological evaluation. The effect of intense light exposures on rhodopsin regeneration and on the level of rod outer segment docosahexaenoic acid was also determined. For rats previously maintained in weak cyclic light, 50% visual cell loss was measured 2 weeks after 12 1 hr light/2 hr dark periods, or following 24 hr of continuous light. A comparable 50% loss of visual cells was found in dark-reared rats after only 5 hr of continuous illumination or 2-3 hr of intermittent light. As judged by histology, cyclic-light-reared rats incurred less retinal pigment epithelial cell damage than dark-reared animals. In both experimental rat models intermittent light exposure resulted in greater visual cell damage than continuous exposure. Visual cell damage from intermittent light was found to depend on the duration of light exposure and on the number of light doses administered. Measurements of rhodopsin and DNA 2 hr and 2 weeks after light exposure of up to 8 hr duration revealed that visual cell loss occurs largely during the 2 week dark period following light treatment. The loss of docosahexaenoic acid from rod outer segments was also greater in rats exposed to intermittent light than in animals treated with continuous light. It is concluded that intermittent light exposure exacerbates Type I light damage in rats (involving the retina and retinal pigment epithelium) and the schedule of intense light exposure is a determinant of visual cell death.

Animals↗
PubMed1989

[Postoperative leakage of rectal cancer after EEA stapled anastomoses--analysis of 196 cases].

A retrospective analysis was conducted in 196 consecutive patients who received restorative resection for rectal cancer with EEA stapled anastomoses between 1983 and 1987, and with no proximal protective colostomy or any previous surgical treatment. The data of each case, including age, sex, body weight, tumor location, operative time and blood loss, were analyzed statistically between postoperative leakage group and the non-leakage group. The details of EEA instrumentation included the completeness of donut tissue, presentation of intraoperative leakage and hand-sewn anastomotic repairment. There were three (1.5%) cases of operative mortality. The anastomosis-related complications were 13 cases of imperfect EEA donut, eleven cases of intraoperative leakage and seven cases of post-operative leakage. Significant differences were found between the two groups, as shown by the Mean-Whitney U test and Chi-square test, in blood loss, tumor location, operative method and instrumentation of EEA stapler.

Adult↗
PubMed1989

[Evaluation of rapid colon preparation by oral intake of dulcolax for colorectal surgery].

The optimal result of colorectal surgery is best achieved by adequate preoperative colon preparation, which should be simple, safe, rapid, and thoroughly clean with little or no discomfort at all for patients. Conventional mechanical preparation, though effective, is time-consuming and unpleasant for patients, therefore new methods have been frequently presented in recent literature to meet the above ideal. A prospective and randomized study was conducted to evaluate preoperative colon preparation in elective, nonobstructive colorectal surgery. Group I included 32 patients who received three-day diet control and enema, while group II included 42 patients who received one-day diet control and oral dulcolax. Both groups were given systemic antibiotics. The result favored group II because of its significantly less abdominal fullness, but the electrolyte change and bacteriologic study revealed no significant difference between two groups. Neither did they exhibit variance in the adequacy of bowel cleansing (81.3% in group I vs 81% in group II). It is therefore suggested that, without enema and with less abdominal fullness, oral dulcolax should be encouraged for colon preparation in colorectal surgery.

Administration, Oral↗
PubMed1988

Mapping and quantification of the major oligosaccharide components of heparin.

A new method of determining the oligosaccharide composition of commercial glycosaminoglycan heparin is described in which heparin was first depolymerized using heparin lyase (EC 4.2.2.7), and then analysed by a single h.p.l.c. step. All 20 of the porcine and bovine heparins examined were found to contain a small number of major oligosaccharide components, which on average comprised 86% of their mass. The five most abundant oligosaccharides have defined chemical structures. Although the relative abundance of oligosaccharides varied, the heparins examined were surprisingly similar. Porcine, bovine, low-Mr, and high and low antithrombin III (ATIII)-affinity heparins, however, each had distinctly different proportions of these major oligosaccharide components. The concentrations of one of these five oligosaccharides, containing a portion of the ATIII binding site, correlated with the anticoagulant activity of the ATIII-affinity-fractionated porcine-mucosal heparins from which it was derived. An additional oligosaccharide of undetermined structure was found in significant quantities in both bovine heparin and high ATIII-affinity porcine-mucosal heparin. The correlation between oligosaccharide concentration and anticoagulant activity suggests that the oligosaccharide is derived from a structural variant of the ATIII-binding site. Finally, for the heparins examined chondroitin/dermatan sulphate formed 0.6-7.4% of their mass.

Animals↗
PubMed1988

Characterization of pigment epithelial cell plasma membranes from normal and dystrophic rats.

Retinal pigment epithelial cell plasma membranes were isolated from the eyes of normal and RCS-dystrophic rats by binding glass microbeads to the intact pigment epithelial cell layer, removal of the bead-bound cells from the eyes and subsequent sucrose density gradient centrifugation. Plasma membranes were recovered from the gradients in identical yields and characterized by membrane marker enzymes, lipid analysis and SDS-polyacrylamide gel electrophoresis. Membrane purification by alkaline phosphodiesterase I and 5'nucleotidase activities averaged 8-fold for normal rats and 5.5 for the dystrophic rats. The ratio of cholesterol per microgram protein indicated 6 to 7-fold purification for both types of plasma membranes. Na+K+-ATPase in the normal and mutant rat plasma membranes was purified 5- and 3.5-fold, respectively, but the specific activities of both Na+K+-ATPase and 5'nucleotidase were higher in the dystrophic rat membranes than in normal. Subcellular organelle contamination was low and relatively uniform in both types of membranes, while opsin contamination was less than 1%. By electrophoretic analysis the plasma membrane proteins were similar, with 30-40 identifiable bands present in each membrane type. The plasma membranes both contain high levels of cholesterol, sphingomyelin and phosphatidylcholine and low levels of polyunsaturated fatty acids. However, the dystrophic rat membranes had significantly higher levels of docosahexaenoic acid than normal, and significantly lower levels of arachidonic acid. The differences in these plasma membrane fatty acids and in the membrane-bound enzymes may affect the ionic balance of the interphotoreceptor matrix or otherwise contribute to degenerative changes in dystrophic rat photoreceptors.

Animals↗