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Biomedical subjects

C Hong

Publications and source records attributed to C Hong.

At least 91 records · Page 5Linked to original sources
PubMed1993

Efficacy of doramectin in the prevention of gastrointestinal nematode infections in grazing cattle.

Two studies were performed to investigate the efficacy of doramectin in the prevention of infection with Ostertagia ostertagi and Cooperia oncophora in grazing calves. In each study, 24 parasite-naive calves were randomly allotted to two equal groups and treated with either doramectin at 200 micrograms kg-1 or saline prior to mid-season turnout (Day 0) onto contaminated pasture. Faecal egg counts were carried out twice weekly from 15 to 64 days after turnout and the cumulative faecal egg count was calculated for each group of calves. In the doramectin-treated animals, eggs first appeared in the faeces 19 days and 22 days later than in controls for Studies 1 and 2, respectively. Mean cumulative faecal egg counts over the 64 days were reduced in the doramectin-treated groups by 71% and 87% for Studies 1 and 2, respectively (P < 0.01). The potential utility of injectable doramectin in the seasonal control of gastrointestinal nematode infestations in relation to these findings is discussed.

Analysis of Variance↗
PubMed1993

Cognitive impairment and autoantibodies in systemic lupus erythematosus.

Nervous system involvement in systemic lupus erythematosus (SLE) includes a wide array of manifestations some of which have been associated with specific autoantibodies. These include reactivity to surface neuronal and lymphocyte antigens, ribosomal P and cardiolipin. The aim of the present study was to examine the association between cognitive abnormalities and these autoantibodies in an unselected female population of SLE patients. Using a battery of standardized neuropsychological tests, cognitive impairment was identified in 15/70 (21%) SLE patients compared to 1/25 (4%) patients with rheumatoid arthritis and 1/23 (4%) healthy subjects (P = 0.04). Circulating antineuronal antibodies were measured by indirect immunofluorescence using human neuroblastoma cell lines IMR-6 and SK-N-SH. Lymphocytotoxic antibodies were measured by microcytotoxicity. Antibodies to ribosomal P and cardiolipin were measured by ELISA. Antineuronal antibodies were detected in 34%, lymphocytotoxic antibodies in 47%, anti-P antibodies in 17% and anticardiolipin antibodies in 24% of patients. In the cognitively impaired and unimpaired SLE patients there was no significant difference in the prevalence of antineuronal antibodies (33 vs 35%), lymphocytotoxic antibodies (40 vs 50%), anti-P antibodies (20 vs 17%) or anticardiolipin antibodies (7 vs 29%). The titre and isotype of autoantibodies were also similar in both groups. These results suggest that autoantibodies which have previously been associated with nervous system manifestations of SLE are not likely to be directly involved in the pathogenesis of cognitive dysfunction.

Antibodies, Anticardiolipin↗
PubMed1993

Histomorphologic changes in expanded skeletal muscle in rats.

Tissue expansion is one of the powerful tools for various reconstructive procedures and has proven to provide more available local tissues. However, limited attention has been given to the characteristics of expanded skeletal muscle. Using a rat model (n = 41), we expanded the rat gracilis muscle and investigated the histomorphologic changes in the expanded skeletal muscle. By expansion, the gracilis muscle after 3 weeks increased 50.4 to 58.4 percent in length and 60.5 percent in width and decreased 39.0 to 42.0 percent in thickness. Histologically, the expanded muscle demonstrated a normal striation and no signs of inflammation or necrosis. The cross-sectional areas of muscle fibers indicated that expanded muscle consisted of predominantly smaller fibers. Vasculature in the expanded muscle demonstrated a longer network of arteries and a more obvious and developed arterial arcade. The average number of sarcomeres in a fiber estimated from the sarcomere length and fiber length was significantly greater (46.5 percent) in the expanded muscle. These findings suggest that the expansion of skeletal muscle is not a "stretching" process of muscle but rather a growth process of the muscle accompanied by an increase in the number of sarcomeres per fiber. Furthermore, the expanded skeletal muscle appears to preserve normal skeletal muscle architecture, vasculature, and function while undergoing the ischemic stress of expansion.

Animals↗
PubMed1993

Brain synaptosomal antibodies in systemic lupus erythematosus.

Nervous system involvement in systemic lupus erythematosus (SLE) has been linked to the production of autoantibodies that may bind to surface antigens on neuronal cells and cause cellular dysfunction. At present, little is known of the target antigens recognized by these antibodies. The aim of the present study was to examine reactivity to rat brain synaptosomes (RBS) in sera from patients with SLE. Sera from 73 unselected SLE patients and controls were studied. Crude RBS were prepared by differential centrifugation and enriched fractions of synaptosomes (SY-E), myelin (MY-E) and mitochondria (MI-E) were obtained by sucrose density centrifugation. Rat liver (RL) was used for control antigens. Wheat-germ lectin affinity chromatography yielded membrane-enriched fractions of RBS, RL and whole rat brain (WRB). Antibody binding was examined by Western blotting. IgM reactivity was detected in 12/73 sera (16%) and was directed to proteins of 62K, 48K 37K molecular weight. IgG reactivity was present in 5/73 sera (7%) to proteins of 52K, 48K, 37K and 29K molecular weight. Except for binding to the 52K and 37K proteins these autoantibodies were not detected in control sera. Reactivity was usually absent, or present in reduced amounts, in WRB and RL. Additional experiments revealed that binding of IgM to 62K was found predominantly in SY-E and MY-E fractions, 48K in SY-E and MI-E fractions and 37K in the SY-E fraction. Binding of IgG to 48K and 29K was detected in the SY-E and MI-E, but reactivity to 52K and 37K was restricted to the SY-E fraction. Thus, sera from SLE patients contain antibodies to synaptosomal antigens that may contribute to the neuropsychiatric manifestations of the disease.

Animals↗
PubMed1993

Effects of topical mitomycin C on glaucoma filtration surgery.

We studied the efficacy and safety of using topical mitomycin C (MMC) as an adjunct to glaucoma filtration surgery. Trabeculectomy was performed in 23 eyes of 19 patients with poor surgical prognosis. After the preparation of a scleral flap, 0.2 mg or 0.4 mg/ml MMC was applied to the exposed tissue for 5 minutes. The wound was then irrigated with 250ml of normal saline. The mean follow-up period was 7.8 months. Preoperative mean intraocular pressure (IOP) was 33.8mmHg, and the mean IOPs on 1, 3, 6, and 12 months after operation were 10.3, 12.5, 12.4 and 12.3mmHg, respectively. At postoperative 12 months, 74.7% achieved an IOP of less than or equal to 20mmHg without any antiglaucoma medication. There were early postoperative complications of aqueous leaking from conjunctival wounds in 3 eyes (13.0%), shallow anterior chamber in 2 eyes, and hyphema in one eye and one eye had long-term hypotony lasting more than 3 months. Although MMC is simple to use, it is a potent adjunct to glaucoma filtration surgery, more work should follow to determine the mechanism of action, indications, dosage and optimal exposure time of MMC.

Administration, Topical↗
PubMed1993

Effects of sodium hyaluronate on filtration bleb in rabbits.

Sodium hyaluronate can be used during a trabeculectomy to prevent early postoperative hypotony and shallow anterior chamber. To determine its long-term effect on the outcome of filtration surgery, fifteen rabbits underwent a posterior-lip sclerectomy in both eyes. Into their right eyes 0.2ml sodium hyaluronate, and into left eyes 0.2ml balanced salt solution were injected intracamerally. Gross and histopathological differences of bleb were observed. There was no statistically significant difference in longevity of the filtration bleb.

Animals↗
PubMed1993

Effect of apraclonidine hydrochloride on the attack of Posner-Schlossman syndrome.

The intraocular pressure (IOP) of glaucomatocyclitic crisis with the attack fell 50.3%, from 37.8 +/- 8.2 mmHg to 18.8 +/- 4.8 mmHg, 4 hours after instillation of 1% apraclonidine. Glaucomatocyclitic crisis showed a more significant hypotensive response to 1% apraclonidine than primary open-angle glaucoma (24.8%, from 43. 1 +/- 8.1 mmHg to 32.4 +/- 7.5 mmHg after 4 hours). The intraocular pressure decrease percentage was similar regardless of the initial level of intraocular pressure. Clinically significant changes in mean systolic and diastolic blood pressures, were not observed, however, a mild decrease in the pulse rate was noted. And the local mydriatic effect on the pupillary diameter was significant. Apraclonidine, 1% might be newly indicated to control the IOP rise of glaucomatocyclitic crisis. Further studies on the possible mechanism of the prostaglandin mediated hypotensive effect of 1% apraclonidine are suggested.

Adolescent↗
PubMed1993

Differential effect of HTLV infection and HTLV Tax on interleukin 3 expression.

To characterize the interactions between human T-cell leukemia virus (HTLV) infection and cellular gene expression, we examined the expression of the lymphokine interleukin 3 (IL-3) in the presence and absence of HTLV infection. IL-3, like granulocyte-macrophage colony-stimulating factor (GM-CSF), is produced by activated but not resting T cells, but although GM-CSF is constitutively expressed in HTLV-infected T cells IL-3 mRNA cannot be detected in either unstimulated or mitogen-stimulated HTLV-infected cells by polymerase chain reaction (PCR) analysis. In contrast, transient co-transfection studies with an IL-3 promoter-CAT reporter gene and an HTLV-II Tax expression construct demonstrate that Tax can transactivate the IL-3 promoter in HTLV-uninfected T cells. To determine whether differences in IL-3 promoter-binding proteins present in HTLV-infected and uninfected T cells account for this discrepancy, DNAase I footprinting of the IL-3 promoter was performed. Although crude nuclear extracts from both cell types protected the IL-3 sequences located between base pairs -168 and -125, the sequences between -125 and -103, which contain the lymphokine consensus sequences CK-1 and CK-2, were protected by extracts from HTLV-infected but not HTLV-uninfected T cells. Deletion of the region containing the CK-1 and CK-2 sequences from an IL-3 promoter CAT construct resulted in a sixfold rise in promoter activity in HTLV-infected but not uninfected T-cell lines, indicating that this region participates in the repression of IL-3 gene expression in HTLV-infected T cells.

Base Sequence↗
PubMed1992

Thyroid hormone effects on cardiac gene expression independent of cardiac growth and protein synthesis.

Prior studies have demonstrated the importance of hemodynamic loading in mediating thyroxine (T4)-induced cardiac hypertrophy. Direct cellular effects of thyroid hormone have been implicated in modulating the expression of the myosin heavy chain (MHC) genes and the slow sarcoplasmic reticulum calcium adenosine triphosphatase (SR Ca(2+)-ATPase) gene. In the present report, administration of T4 for 72 h did not stimulate growth of the hemodynamically unloaded heterotopic isograft. The synthetic rates of total cardiac proteins and MHC in the isograft remained significantly lower at 64 and 53% of the respective rates measured simultaneously in the in situ working heart. Although total left ventricle RNA content in the isograft was unchanged by T4, alpha-MHC and SR Ca(2+)-ATPase mRNA concentrations were increased 181 and 208%, respectively, and the previously observed beta-MHC expression was completely prevented. These data indicate that, although T4 requires an increased hemodynamic load to stimulate cardiac protein synthesis, it is capable of directly altering the expression of at least two myocyte-specific genes. Therefore some of the phenotypic alterations observed with thyroid hormone treatment are the result of direct effects of the hormones on specific cardiac genes and independent of changes in cardiac growth.

Animals↗
PubMed1992

Hemodynamic regulation of myosin heavy chain gene expression. Studies in the transplanted rat heart.

Cardiac work is a major determinant of heart size and growth. Heterotopic cardiac isografts are hemodynamically unloaded and undergo atrophy. To determine the molecular changes that occur as a result of hemodynamic unloading, we have studied the rate of synthesis of total cardiac proteins and myosin heavy chain (MHC) and the expression of the myosin heavy chain gene as reflected in the messenger RNA levels for alpha- and beta-MHC isoforms. 72 h after transplantation there is a significant decrease in left ventricular size accompanied by a 27% decrease in the rate of total cardiac protein synthesis and a 53% decrease in the rate of myosin heavy chain synthesis. In contrast to isografts 14 d after transplantation which have a decrease in protein synthetic capacity, simultaneous measurements of 18S ribosomal RNA and myosin messenger RNA suggest that after 3 d the decrease in synthesis is due to a change in the efficiency of protein translation. While the working in situ heart expresses primarily alpha-MHC mRNA (97%) hemodynamic unloading leads to a 43% decrease in alpha-MHC mRNA concentration and the de novo expression of the beta-MHC mRNA. Total MHC mRNA (alpha plus beta) concentration analyzed by a quantitative S1 nuclease protection assay was similar in the two groups of hearts. Thus, in association with hemodynamic unloading there are changes in cardiac myosin heavy chain content as a result of both gene transcription and protein translation mechanisms.

Animals↗
PubMed1992

Optic disc of the myopic eye: relationship between refractive errors and morphometric characteristics.

Because the optic disc in myopic eyes is different from a normal optic disc, there are many difficulties in examining the optic discs of myopic eyes. To study optic disc change due to myopia, we performed a morphometrical study of stereophotographs of 61 men, 109 eyes, who had no glaucoma history. The range of refractive error was from +0.75 diopter to -12.75 diopter, and all subjects had intraocular pressure below or equal to 21 mmHg. According to the increase in the myopic degree, the temporal slope of the disc cup was significantly decreased, but the ratio of the vertical disc diameter (VDD) to the horizontal disc diameter and the ratio of the width of peripapillary atrophy (PPA) to the VDD were significantly increased. The above results suggests that in high myopia the optic disc was tilted and the rim-cup border was indistinct and there are some problems in the estimation of the morphometric parameters. Also in evaluation of the PPA of myopic glaucoma patients, there may be some difficulty in deciding whether it is due to myopic change or glaucomatous damage.

Adolescent↗
PubMed1992

Effects of aqueous humor on filtering bleb in rabbits.

Preoperative aqueous humor, known to inhibit the growth of fibroblasts in tissue culture assay, was used as an adjunct to filtering surgery in rabbits to determine its effect in vivo on the outcome of filtering surgery. Fifteen rabbits underwent a posterior-lip sclerectomy in both eyes. In experimental eyes 1.4 ml preoperative aqueous humor and in fellow eyes 1.4 ml balanced salt solution were injected intracamerally. Gross and histopathological differences of bleb were observed. In this animal experiment, although there was no statistical significance or late postoperative effect, the rabbit eyes refilled with preoperative aqueous humor intracamerally just after filtering surgery, had a larger bleb and less fibroconnective tissue on the bleb than the control eyes in the early postoperative period.

Animals↗