Search PubMed⌕ Search

Biomedical subjects

E S Chang

Publications and source records attributed to E S Chang.

At least 37 records · Page 2Linked to original sources
PubMed1992

Distinct localization of collagenase and tissue inhibitor of metalloproteinases expression in wound healing associated with ulcerative pyogenic granuloma.

To examine the role of metalloproteinases in tissue remodeling associated with wound healing, we used in situ hybridization to localize the expression of collagenase and tissue inhibitor of metalloproteinases (TIMP) in samples of pyogenic granuloma. Strong hybridization for collagenase mRNA was detected in basal keratinocytes near the advancing edge of all ulcerative lesions, but no collagenase mRNA was seen in samples without ulceration. Distinct from the sites of collagenase expression, TIMP mRNA was detected in stromal cells and in cells surrounding proliferating vessels. No collagenase mRNA was found in the epidermis of healthy skin, although occasional stromal cells contained collagenase or TIMP mRNAs, and TIMP mRNA was detected in hair follicles and sebaceous glands. Our results suggest that basal keratinocytes adjacent to wounded epidermis are critically involved in matrix remodeling, much more so than adjacent or underlying dermal fibroblasts. Furthermore, as several reports have suggested, TIMP may play a role in angiogenesis. Finally, in contrast to findings from other models which indicate that collagenase and TIMP proteins are secreted by the same cells, our data also demonstrate that these proteins can be produced in vivo independently of each other.

Collagenases↗
PubMed1992

Acetylcholinesterase histochemistry of rectal suction biopsies in the diagnosis of Hirschsprung's disease.

Rectal suction biopsy with acetylcholinesterase (AChE) histochemistry has gained increased acceptance as the means of definitely diagnosing Hirschsprung's disease (HD) as well as of excluding this diagnosis when evaluating children with low intestinal obstruction or chronic constipation since the report of Meier-Ruge et al. in 1972. But this AChE histochemical study has not been reported yet in Korea. During the 14-month period from April, 1991 through June, 1992, 37 children, aged 3 days to 17 years had rectal suction biopsies for the diagnosis or exclusion of HD. In this study, AChE histochemistry (N = 37) was compared with hematoxylin & eosin (H&E) staining of same suction biopsy specimens (N = 35) for diagnostic accuracy. The histochemical criterion used for the diagnosis of Hirschsprung's disease was that of Chow et al. (1977), i.e., the presence of many coarse discrete cholinergic fibers in the muscularis mucosae and in the immediately subjacent submucosa regardless of an infiltration of cholinergic fibers in the lamina propria. Of 13 biopsies from the patients with Hirschsprung's disease (N = 13), there were 12 positive reactions, and one false negative reaction in a neonate with total colonic aganglionosis. All biopsies from 24 unaffected children demonstrated negative reactions with no false positive reaction. In comparison, of the 35 specimens examined by H&E staining, ganglion cells were present in the submucosal Meissner's plexus only in 15 of these 24 unaffected children. In conclusion, a 97% diagnostic accuracy was achieved with AChE histochemistry compared with a 74% accuracy with H&E staining (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1991

Ecdysteroids in the embryos and sera of the crabs, Cancer magister and C. anthonyi.

Ecdysteroids in the embryos and sera of ovigerous brachyuran crabs, Cancer magister and C. anthonyi, were measured and characterized by radioimmunoassay (RIA) and high-performance liquid chromatography (HPLC). C. magister embryos displayed a biphasic pattern of ecdysteroid fluctuation during development; titers decreased until mid embryogenesis and then increased and peaked prior to hatching. HPLC-RIA analysis indicated increasing ecdysone concentrations from mid embryogenesis to hatching. Endogenous biosynthesis of ecdysone by the embryos is suggested. In contrast, ecdysteroid titers in the embryos of C. anthonyi showed a steady decrease from very high initial concentrations. The decrease in titers of ecdysone and 20-hydroxyecdysone is suggestive of utilization of maternally derived ecdysteroids rather than endogenous biosynthesis during the shorter embryogenic period for C. anthonyi. Ecdysteroid concentrations did not differ with respect to location of the embryo within the egg mass. Serum ecdysteroids in C. magister females generally showed a monotonic pattern during brooding. However, for C. anthonyi females, increasing and decreasing titers were observed during the brood and interbrood periods, respectively. These fluctuations suggest mobilization of the ecdysteroids to the ovaries for subsequent storage and utilization during embryogenesis. The evolutionary significance of these differing patterns of ecdysteroid metabolism in these congeners is discussed.

Animals↗
PubMed1991

Ecdysteroids in relation to the molt cycle of the American lobster, Homarus americanus. II. excretion of metabolites.

Ecdysteroid (Ecd) excretion patterns were followed during the molt cycle of adult male and female lobsters. Homarus americanus. Urine was the major route of Ecd elimination, amounting to greater than or equal to 96% of the excreted radioimmunoassay activity for all molt stages. The other identified route of Ecd elimination from the hemolymph was the feces, which accounted for the remaining 4% of the total Ecd excretion. High polarity metabolites (HP), including 20,26-dihydroxyecdysone (2026E) and 20-hydroxyecdysonoic acid (20EA), were the major types of Ecds found in the urine. Other urinary Ecd components included 20-hydroxyecdysone (20E), ecdysone (E), and ponasterone A (P). The major portion of urinary HP was composed of conjugates of 2026E, 20E, E, P, and other unidentified metabolites. The fecal Ecds were predominately HP and apolar metabolites. Apolar fecal Ecds were hydrolyzable to release 20EA, 2026E, 20E, E, P, and other metabolites. By means of intubation, [3H]E was placed directly into the cardiac stomach of lobsters. The gut pathway formed an apolar conjugate of [3H]E which was found exclusively in the feces. Lobsters are therefore capable of excreting ingested Ecds without absorption.

Animals↗
PubMed1991

Ecdysteroids in relation to the molt cycle of the American lobster, Homarus americanus. I. Hemolymph titers and metabolites.

Hemolymph ecdysteroid (Ecd) titers were measured using radioimmunoassay (RIA) during the molt cycle of the American lobster, Homarus americanus. Individual animals showed small, transitory rises of Ecds which increased in magnitude with the onset of premolt and culminated in a large premolt peak at morphological stages D2(2)-D3(1). Male lobsters had significant postmolt peaks and late premolt titers that remained high until ecdysis. In females, postmolt peaks were absent and late premolt titers reached basal levels before ecdysis. At least seven different Ecd metabolites were identified by high-performance liquid chromatography-RIA analyses. High polarity products (HP) were the most abundant metabolites in virtually every molt stage. Titers of HP were significantly higher in males during late postmolt-early intermolt and in late premolt. Levels of 20-hydroxyecdysone (20E) were equivalent in both sexes and correlated with the morphological changes associated with premolt. Evidence was also obtained for the presence of ecdysone, ponasterone A, and other as yet unidentified metabolites. The pattern of Ecd metabolites in the hemolymph supports other data indicative of 20E as the major molting hormone. Metabolism of 20E is primarily toward more polar compounds, including conjugates.

Animals↗
PubMed1991

Binding proteins for a peptide hormone in the shrimp, Sicyonia ingentis: evidence from photoaffinity labeling with red pigment concentrating hormone analogs.

Two photoaffinity analogs of the crustacean erythrophore (red pigment) concentrating hormone (RPCH) have been synthesized and shown to cause pigment concentration in the shrimp Sicyonia ingentis. These two modified oligopeptides have azidosalicylamide groups which allow introduction of an 125I label and enable photochemically induced covalent attachment to a specific binding site. Incubation of [125I]-ASA-Glu1-CC-2 with the 100,000g membrane pellet and cytosol fraction from epidermis, eyestalks, muscle, and central nervous system (CNS), followed by irradiation, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and autoradiography results in covalent modification of certain protein bands in the membranes of selected tissues. Two such proteins were observed in neural tissues and showed competitive displacement by excess RPCH, indicative of specific high-affinity binding. This is the first report of peptide hormone-binding proteins in an invertebrate and provides further evidence of a role for RPCH as a neurotransmitter in the CNS.

Amino Acid Sequence↗
PubMed1991

Scanning electron microscopic study of capillary change in bleomycin-induced pulmonary fibrosis.

The architectural changes which occur in the capillaries are difficult to illustrate without a three-dimensional tool, such as scanning electron microscopy. Therefore, a scanning electron microscopic study was occasionally undertaken to show the capillary changes of lung fibrosis. Fibrosis was induced in twenty rats by an intratracheal injection of bleomycin. After 30 days the rats were sacrificed, and light microscopy and scanning electron microscopy were performed. The vascular trees of both lungs were cast with methacrylate. Light microscopically, the pulmonary fibrosis was patchy and inflammatory cell infiltration was rather sparse. Scanning electron microscopically, the intercapillary spaces became wider; and some capillaries revealed large irregular dilatation. The pleural and alveolar capillaries were variably dilated. The pleural capillary diameter was increased (P = 0.06), and the capillary plexus diameter was decreased (P = 0.00). Distance between the capillary branches of the pleural surface was increased (P = 0.06). The appearance of irregularly shaped capillaries, an increase in diameter with variable dilatation of alveolar capillary rings and a decrease in branching between the capillaries, resulting in a loss of surface area are the main scanning electron microscopic findings of the remodeling which occurs pulmonary capillaries in bleomycin-induced pulmonary fibrosis.

Animals↗
PubMed1990

Amino acid sequence of a peptide with both molt-inhibiting and hyperglycemic activities in the lobster, Homarus americanus.

A hydrophobic peptide of 71 residues was isolated from lobster sinus gland extracts that prolonged intermolt periods and lowered ecdysteroid titers in juvenile lobsters. Removal of the N-terminal pyroglutamyl residue allowed sequencing of 30 of the first 36 residues. Additional data were obtained from HPLC-purified fragments from endoproteinase cleavages (Lys-C, Glu-C, Arg-C, Asp-N), and carboxypeptidase Y digestion. This is the first reported amino acid sequence of a crustacean molt-inhibiting hormone. This peptide also has significant hyperglycemic activity.

Amino Acid Sequence↗
PubMed1990

Binding proteins for methyl farnesoate in lobster tissues: detection by photoaffinity labeling.

Methyl farnesoate (MF) is secreted by the mandibular organs of crustaceans, but its physiological role and biochemical distribution are only partially known. Characterization of specific MF binding proteins (MFBP) in homogenates of tissues of the American lobster, Homarus americanus, was achieved by photoaffinity labeling with tritium-labeled farnesyl diazomethyl ketone (3H-FDK). The tissues selected include epidermis, tail muscle, central nervous system, eyestalk, hemolymph, hepatopancreas, ovaries, testes, and Y-organ. Both high-speed pellets and supernatants were tested. Competing ligands employed to verify specificity of light-induced covalent modification included MF, methoprene, and unlabeled FDK. A 40-kDa band was labeled strongly in the hemolymph; the labeling was displaced in the presence of a 100-fold excess of unlabeled MF. Although many other tissues had proteins which labeled with 3H-FDK, none of these showed competition by MF. This MFBP is thus functionally analogous to the hemolymph JH-binding proteins of insects.

Affinity Labels↗
PubMed1988

Long-term studies of pancreas allotransplantation in experimental diabetes mellitus.

Pancreaticoduodenal (PD) allografts (Brown Norway-alloxan-diabetic rats, n = 190) were treated with cyclosporin A (Cy-A) 10 mg/kg/daily and compared with nondiabetics with Cy-A treatment (n = 55), diabetics (n = 50), and diabetics with Cy-A treatment (n = 45). Body weight, blood sugar, blood insulin, blood urea nitrogen (BUN), and creatinine were monitored periodically; there were marked elevations of BUN and creatinine levels, indicating probably nephrotoxicity of Cy-A at this dosage. Some islet cell atrophy in the PD allografts was noted at the conclusion of the study. With respect to the immunosuppressive effect of Cy-A in alloxan diabetic rats, Brown Norway PD transplants into Lewis rats were successful and free of rejection for as long as 15 months post-transplantation. The body weight of these PD transplanted rats, however, never approached values representative of the nondiabetic rats. In our experience, the PD allograft model is acceptable in the clinical situation, particularly in children if the microsurgical technique is mastered and if the Cy-A regimen is used in combination with other immunosuppressant(s).

Animals↗
PubMed1987

Allogeneic heart-lung transplantation in mice.

Using a simpler technique for mouse heart and lung transplantation, a histological comparison was made between groups of syngeneic and allogeneic transplants. The initial high postoperative mortality encountered was due to technical difficulty and as the operative technique improved, mortality lessened. While direct palpation of the abdomen is the key means in the detection of graft rejection, there is no practical determination of such graft rejection other than histological clarification. Doppler tracing also is not a sensitive method for detecting rejection. The transplantation technique in this study compares the time of rejection of heart and lung transplants more legitimately.

Animals↗
PubMed1987

Parameters altering the success of the one-anastomosis rat heart-lung transplant.

The single-anastomosis heart-lung transplantation method in the rat developed by Lee and associates has been examined and has proven to be simple and reproducible. Technical procedures are discussed emphasizing those procedures that require special caution to ensure successful graft function. The donor and recipient rat strain combination has been found to influence the success of the transplantation procedure. Rat strain combinations used in our laboratories resulted in different percentages of donor heart survival. Using Lewis rat (RT1 1/1) recipients, 68% of Brown Norway rat (RT1n/n) donor hearts and 97% of NBR rat (RT1 1/1) donor hearts survived. However, only 29% of Fischer rat (RT1 1/1) donor hearts survived longer than 2 days when transplanted into Lewis rat recipients. In our laboratories, the Lee method of single-anastomosis heart-lung transplantation has been used successfully to evaluate whether immunoregulatory compounds alter heart allograft rejection.

Animals↗
PubMed1987

Purification and amino acid composition of a peptide with molt-inhibiting activity from the lobster, Homarus americanus.

A peptide was isolated and purified from sinus glands of the lobster, Homarus americanus, that was able to decrease circulating titers of ecdysteroids and increase the molt interval of eyestalk-ablated juvenile lobsters. This molt-inhibiting activity was demonstrated to consist of two very closely related peptides by means of high-performance liquid chromatography and gel electrophoresis. By means of amino acid analyses, a molecular weight of approximately 8700 was obtained.

Amino Acids↗
PubMed1987

Ultrastructural morphogenesis of mitochondria in alcoholic liver.

Electron microscopic studies of 53 diagnostic liver biopsies from 23 patients were done. Ultrastructural study revealed most striking alteration to be in the mitochondria such as pleomorphism in shape and size, especially giant mitochondria with disorganization, crystalline inclusions and calcium-like electron dense bodies. These ultrastructural changes might have been induced by specific biochemical abnormality in alcohol bearing condition. Diagnostic use of electron microscopy will be useful in detecting alcoholic injury in alcoholic patient who fails to demonstrate any discernible laboratory and light microscopic abnormalities.

Adult↗
PubMed1982

Ecdysteroid induction of cell surface contacts in a Drosophila cell line.

Drosophila Kc cells are usually spherical in shape and are relatively free of cell-cell contacts. Soon after exposure to 20-hydroxyecdysone they develop extensions, assume a fibroblastic shape, and closely adhere to adjacent cells by means of cell-cell contacts to form large multicellular aggregates. This adhesive nature is enhanced with trypsin treatment without disruption of cell shape. Simultaneous addition of 20-hydroxyecdysone and juvenile hormone results in diminished aggregate formation without preventing the changes in cell shape. These factors point to the possibility that 20-hydroxyecdysone stimulates modifications in the cell surface that may be important during embryological differentiation. Key words Kc cells, aggregations, recognition, juvenile hormone.

Animals↗