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Biomedical subjects

Y Hong

Publications and source records attributed to Y Hong.

At least 145 records · Page 8Linked to original sources

Structures and chromosomal localizations of the glycosylphosphatidylinositol synthesis gene PIGC and its pseudogene PIGCP1.

More than 10 genes are involved in the biosynthesis of glycosylphosphatidylinositol (GPI), which anchors many mammalian cell surface proteins to the membrane. Paroxysmal nocturnal hemoglobinuria (PNH) is caused by a somatic mutation in a GPI biosynthesis gene within the hematopoietic stem cell. The X-linked gene PIGA has been found to be mutated in all patients with PNH. This is probably because all other GPI synthesis genes are autosomal; hence two somatic mutations must occur to cause PNH, whereas one somatic mutation is sufficient to inactivate PIGA. Consistent with this notion, three other genes, PIGB, PIGF, and PIGH, are autosomal. Here we isolated a genomic clone of another GPI-synthesis gene, PIGC, and mapped it to chromosome 1q23-q25, further supporting this notion. PIGC is an intronless gene. We found an intronless pseudogene of PIGC, PIGCP1, and mapped it to chromosome 11p12-p13. The presence of a processed pseudogene is a common feature of PIGA, PIGF, and PIGC.

Amino Acid Sequence↗

Mutational analysis of transcriptional activation by the bovine papillomavirus type 1 E6.

While the bovine papillomavirus type 1 (BPV-1) E6 induces tumorigenic transformation of murine C127 cells, it does not bind or promote the degradation of p53. We recently showed the cellular protein ERC-55/E6BP binds BPV-1 E6 as well as the cancer-related human papillomavirus (HPV) E6 proteins. BPV-1 E6 also binds E6-AP, a ubiquitin ligase necessary for HPV E6-induced p53 degradation. We previously reported that the transforming activity of a set of BPV-1 E6 mutants correlated with their E6BP-binding ability. Another function of BPV-1 E6 is stimulation of transcription when targeted to a promoter, although cellular promoters responsive to BPV-1 E6 have not been identified. To examine whether its transcriptional function is required for oncogenic activity, or is related to its interactions with E6-AP or E6BP, a series of BPV-1 E6 mutants were analyzed as fusions to a sequence-specific DNA binding domain for activity in yeast and in mammalian cells. We show that some transformation defective mutants retained substantial levels of transcriptional activation activity. These mutants also distinguish transcriptional activation from E6-AP and E6BP binding. These results suggest the transcriptional activation function of BPV-1 E6 is not sufficient for cell transformation.

3T3 Cells↗

Substituted hexahydrobenzo[f]thieno[c]quinolines as dopamine D1-selective agonists: synthesis and biological evaluation in vitro and in vivo.

A series of substituted 9,10-dihydroxyhexahydrobenzo[f]thieno[c]quinolines (TB[f]Q), varying with respect to the position of the thiophene relative to the benzo[f]quinoline core and the nature and position of the substituent on the thiophene, were prepared and evaluated for their affinity and selectivity for the dopamine D1-like receptor. The thieno[3,2-c]B[f]Q regioisomers bearing a small alky1 (C1-C3) substituent at the 2 position were potent (Ki < 20 nM) and selective (D2/D1 > 50) D1 agonists with close to full agonist activity (IA > 85%). The compounds were resolved and found to exhibit a high level of enantiospecificity in their interaction with the D1 receptor. Selected compounds were tested in vivo in the 6-OHDA rodent model of Parkinson's disease and for their liability to produce seizure-like activities in mice. (5aR)-trans-2-Propyl-4,5,5a,6,7, 11b-hexahydro-3-thia-5-azacyclopent-1-ena[c]phenanthrene-9,10-diol (5) emerged as the compound with the best overall in vivo profile in terms of potency (ED50 = 0.04 mumol/kg) and safety.

Adenylyl Cyclases↗

Actin depolymerizing factor (ADF/cofilin) enhances the rate of filament turnover: implication in actin-based motility.

Actin-binding proteins of the actin depolymerizing factor (ADF)/cofilin family are thought to control actin-based motile processes. ADF1 from Arabidopsis thaliana appears to be a good model that is functionally similar to other members of the family. The function of ADF in actin dynamics has been examined using a combination of physical-chemical methods and actin-based motility assays, under physiological ionic conditions and at pH 7.8. ADF binds the ADP-bound forms of G- or F-actin with an affinity two orders of magnitude higher than the ATP- or ADP-Pi-bound forms. A major property of ADF is its ability to enhance the in vitro turnover rate (treadmilling) of actin filaments to a value comparable to that observed in vivo in motile lamellipodia. ADF increases the rate of propulsion of Listeria monocytogenes in highly diluted, ADF-limited platelet extracts and shortens the actin tails. These effects are mediated by the participation of ADF in actin filament assembly, which results in a change in the kinetic parameters at the two ends of the actin filament. The kinetic effects of ADF are end specific and cannot be accounted for by filament severing. The main functionally relevant effect is a 25-fold increase in the rate of actin dissociation from the pointed ends, while the rate of dissociation from the barbed ends is unchanged. This large increase in the rate-limiting step of the monomer-polymer cycle at steady state is responsible for the increase in the rate of actin-based motile processes. In conclusion, the function of ADF is not to sequester G-actin. ADF uses ATP hydrolysis in actin assembly to enhance filament dynamics.

Actin Cytoskeleton↗

The bZip dimerization domain of the Epstein-Barr virus BZLF1 (Z) protein mediates lymphoid-specific negative regulation.

The Epstein-Barr virus (EBV) immediate-early (IE) protein, BZLF1 (Z), initiates the switch from latent to lytic infection, Z transactivation of an early viral promoter, BMRF1, is relatively inefficient in lymphoid cells (compared with epithelial cells), unless the other EBV IE protein, BRLF1, is also present. Cellular proteins, including the p65 component of NF-kappa B, have been shown to interact directly with Z in vitro through the bZip dimerization domain and inhibit Z-induced transactivation. Here we precisely define a residue within the bZip dimerization domain of Z (amino acid 200) which is required for interaction in vitro with the p65 component of NF-kappa B, but is not essential for Z homodimerization. In lymphoid cells, a Z mutant which has been altered at amino acid 200 (tyrosine to glutamic acid) transactivates both the early BMRF1 promoter and the immediate-early BZLF1 promoter (Zp) four- to fivefold better than wild-type Z. In contrast, mutation of amino acid 200 does not affect Z transactivator function in epithelial cells. The results suggest that Z function is specifically inhibited by a lymphoid-specific protein(s) through amino acid 200 in the bZip dimerization domain. Modulation of Z's activator function may help to regulate the stringency of viral latency in lymphocytes.

Cell Line↗

Transactivation of dianthin transgene expression by African cassava mosaic virus AC2.

We have recently described a novel strategy for engineering resistance to African cassava mosaic virus (ACMV) in transgenic Nicotiana benthamiana plants using a virus-inducible promoter to control the expression of a plant ribosome-inactivating protein (RIP) transgene (Y. Hong et al., Virology 220, 119-127, 1996). Here, we have used a potato virus X (PVX) vector to express the ACMV transactivator protein, AC2, in planta. We confirm that amplification of RIP activity in transgenic plants is mediated by AC2; disruption of AC2 expression by either the introduction of an in-frame stop codon or the deletion of 5'-terminal or 3'-terminal coding sequences reduced RIP expression to the basal level associated with PVX-infected plants. AC2 expression from the PVX vector induced necrosis in nontransformed plants as well as in plants containing the RIP transgene, suggesting that the protein can functionally interact with PVX and/or host factors. The potential of this system to provide a direct and sensitive assay to investigate AC2 function in planta is discussed.

Antiviral Agents↗

Persisting sensitization of the behavioural response to formalin-induced injury in the rat through activation of serotonin2A receptors.

Serotonin potentiates pain induced by intraplantar injection of other inflammatory mediators through the 5-hydroxytryptamine2A receptor, and 5-hydroxytryptamine2A antagonists dose-dependently block pain induced by formalin. The present study examined the temporal characteristics of 5-hydroxytryptamine-mediated potentiation of pain in the rat. Simultaneous injection of the 5-hydroxytryptamine2 receptor agonist alpha-methyl-5-hydroxytryptamine (10 micrograms) plus prostaglandin E2 (0.1 microgram) produced 10 min of lifting and licking of the injected paw. When alpha-methyl-5-hydroxytryptamine was injected before prostaglandin E2, the response decreased as the interval increased, and by 1 h, it was not different from injection of prostaglandin E2 alone. When prostaglandin E2 was injected prior to alpha-methyl-5-hydroxytryptamine, sensitization to the latter persisted for more than 3 h. It was blocked by the 5-hydroxytryptamine2 antagonist ketanserin (5 micrograms), injected locally 5 min before alpha-methyl-5-hydroxytryptamine. Ketanserin (5 micrograms) or the 5-hydroxytryptamine1A/2A antagonist spiperone (0.3 microgram), injected locally 5 min before alpha-methyl-5-hydroxytryptamine and prostaglandin E2, reduced pain by 80-90%, but only by 40-50% when injected 2 min after. Formalin produced a biphasic pain response. The 5-hydroxytryptamine2 antagonists, ketanserin (50 micrograms), spiperone (3 micrograms) and ritanserin (50 micrograms) injected 5 min before formalin reduced the pain response by 70, 90 and 74%, respectively, but only by 40, 30 and 24% when injected at the beginning of the second phase. Pretreatment of the paw with 2 micrograms indomethacin did not alter the response to alpha-methyl-5-hydroxytryptamine plus prostagladin E2, indicating that the sensitization was not due to prostaglandin synthesis. These data show that 5-hydroxytryptamine sensitizes tissue to the pain-producing actions of other inflammatory mediators, and that the sensitization produces a persisting change in tissue that can be blocked by pretreatment with an antagonist, but not reversed after it has occurred. The data imply that 5-hydroxytryptamine2A antagonists may act prophylactically to prevent the evolution of pain in injured tissue, but do not reduce already-present pain.

Animals↗

Acupressure treatment for prevention of postoperative nausea and vomiting.

Postoperative nausea and vomiting are still common problems after general anesthesia, especially in ambulatory surgery. Drug therapy is often complicated with central nervous system symptoms. We studied a nonpharmacological method of therapy--acupressure--at the Pericardium 6 (P.6) (Nei-Guan) meridian point. Two hundred consecutive healthy patients undergoing a variety of short surgical procedures were included in a randomized, double-blind study: 108 patients were in the acupressure group (Group 1) and 92 patients were in the control group (Group 2). Spherical beads of acupressure bands were placed at the P.6 points in the anterior surface of both forearms in Group 1 patients, while in Group 2 they were placed inappropriately on the posterior surface. The acupressure bands were placed before induction of anesthesia and were removed 6 h postoperatively. They were covered with a soft cotton wrapping to conceal them from the blinded observer who evaluated the patients for presence of nausea and vomiting and checked the order sheet for any antiemetics prescribed. In both groups, the age, gender, height, weight, and type and duration of surgical procedures were all comparable without significant statistical difference. In Group 1, only 25 of 108 patients (23%) had nausea and vomiting as compared to Group 2, in which 38 of 92 patients (41%) had nausea and vomiting (P = 0.0058). We concluded that acupressure at the P.6 (Nei-Guan) point is an effective prophylaxis for postsurgical nausea and vomiting and therefore a good alternative to conventional antiemetic treatment.

Acupressure↗

Moderate genetic influences on plasma levels of plasminogen activator inhibitor-1 and evidence of genetic and environmental influences shared by plasminogen activator inhibitor-1, triglycerides, and body mass index.

Both genes and environmental factors have been reported to influence plasma levels of plasminogen activator inhibitor-1 (PAI-1). However, the relative importance of genetic influences (i.e., heritability) on plasma PAI-1 levels has not yet been investigated. Furthermore, PAI-1 levels are correlated with body mass index (BMI) and triglycerides. These correlations could reflect genetic and/or environmental factors in common to PAI-1, triglycerides, and BMI. We applied multivariate genetic analysis methods to assess the relative importance of genetic and environmental influences on plasma PAI-1 levels and to test the significance of genetic and/or environmental influences shared by PAI-1, triglycerides, and BMI in 217 pairs of middle-aged and elderly twins, of whom 113 pairs were reared apart and 121 pairs were women. The heritability estimate for PAI-1 levels was 42%. Individual-specific environmental factors explained 36% of the variance for PAI-1 levels. The remaining variance of PAI-1 was explained by rearing and residual-familial environmental factors. Furthermore, a genetic correlation of 1.00 between PAI-1 and triglycerides, a rearing environmental correlation of 1.00 between PAI-1 and BMI, a residual-familial environmental correlation of 1.00 between PAI-1 and triglycerides, and a genetic correlation of 0.63 between PAI-1 and BMI, were found. In conclusion, the present results suggest that genetic influences on plasma PAI-1 are moderate. Genetic and shared rearing or residual-familial environmental factors shared by PAI-1, BMI, and triglycerides explain the phenotypic association between these measures. It appears that all the genetic influences for PAI-1 are more or less shared with those for triglycerides and BMI.

Adoption↗

Megakaryocyte ploidy and platelet changes in human diabetes and atherosclerosis.

Altered platelet morphology and function have been reported in patients with diabetes. They are likely to be associated with the pathological processes and increased risk of vascular disease seen in these patients. Mean platelet volume (MPV), platelet count, and megakaryocyte (MK) ploidy (DNA content) were measured in (1) nondiabetics with normal coronary arteries, (2) nondiabetics with coronary artery atherosclerosis, (3) diabetics without evidence of vascular complications, and (4) diabetics with vascular disease. The platelet count (+/- SD) was increased in all groups but only significantly in the diabetics with vascular disease (236 +/- 65 versus 250 +/- 54 versus 257 +/- 64 versus 295 +/- 90 [P < or = .05] x 10(9)/L, for groups, I, II, II, and IV, respectively). The MPV was significantly increased in patients with atherosclerosis (7.0 +/- 0.4 versus 8.0 +/- 1.2 [P < or = .05] versus 7.2 +/- 0.9 versus 8.1 +/- 0.9 [P < or = .05] IL). Geometric mean MK ploidy was significantly increased in all groups compared with controls (16 +/- 1.5 versus 18.7 +/- 1.8 [P < or = .05] versus 19.8 +/- 1.6 [P < or = .05] versus 20.1 +/- 2.7 [P < or = .05]). Furthermore, some patients with vascular disease and/or diabetes had a modal ploidy shift from 16 (the normal mammalian modal ploidy) to 32, with a concomitant reduction of MKs in the 8 and 16 ploidy classes. This shift was seen particularly in the diabetics with vascular disease (P = .007). Interleukin-6 (IL-6) levels were measured and were elevated in patients with atherosclerosis; the highest levels were found in the diabetic patients (0.7 +/- 0.9 versus 5.3 +/- 5.5 [P < or = .05] versus 2.5 +/- 2.8 versus 6.7 +/- 5.5 [P < or = .05] ng/L). In the diabetic patients with atherosclerosis, fibrinogen levels were also increased (2.85 +/- 0.76 versus 3.34 +/- 1.32 versus 2.43 +/- 1.50 versus 5.59 +/- 1.72 [P < or = .05] g/L). Furthermore, IL-6 levels correlated with MK ploidy (r = .45, P = .009) and fibrinogen levels (r = .5, P = .0001). This study demonstrates that patients with vascular disease, particularly diabetics, have an altered MK ploidy distribution, showing a shift toward higher ploidy in association with an increased platelet mass (count x volume). Changes in platelets in diabetes probably reflect MK changes, which themselves are a response to systemic change.

Aged↗

In vitro assessment of the biological activity of basic fibroblast growth factor released from various polymers and biomatrices.

The kinetics of controlled release of basic fibroblast growth factor (bFGF) from polymers (sutures, polycarbonate, Hydron, and Elvax), biopolymers (alginate), and biomatrices (lens capsules), and conditions for storage of bFGF (temperature, plastic type, heparin) were evaluated in vitro. Tissue culture proliferation bioassays with 3T3 fibroblasts, showed that only lens capsules with bFGF had a sustained release of bFGF for up to three weeks. The other materials released all of the 'bound' bFGF with two hours or produced an inflammatory response in vivo. Therefore, the lens tissue had the most potential for controlled long-term delivery of bFGF in vivo. These studies emphasise the importance of in vitro analysis of release kinetics of growth factors from a range of materials as a basis for potential in vivo applications.

3T3 Cells↗

Associations between insulin-like growth factor-I (IGF-I), IGF-binding protein-1, insulin and other metabolic measures after controlling for genetic influences: results from middle-aged and elderly monozygotic twins.

It has previously been shown that the serum levels of insulin-like growth factor-I (IGF-I), IGF-binding protein-1 (IGFBP-1), and insulin are influenced by genetic effects to various degrees. From a clinical and preventive point of view, however, it is important to identify potentially modifiable non-genetic factors influencing the levels of these measures. Because monozygotic twin pairs share the same genetic background, differences in phenotypic levels within monozygotic twin paris are believed to be due to non-genetic influences. Accordingly, the associations between intrapair differences in one phenotype and intrapair differences in another phenotype are also due to non-genetic influences. The present sample of 97 pairs of monozygotic twins from the population-based Swedish Adoption/Twin Study of Aging (SATSA) provided the opportunity to assess non-genetic influences on the levels of IGF-I, IGFBP-1, and insulin. Several metabolic measures were found to account for the variation of IGF-I, IGFBP-1, and insulin after controlling for the genetic influences. IGFBP-1 and glucose were significant predictors for the levels of IGF-I. IGFBP-1 and glucose together explained about one quarter of the non-genetic variation of IGF-I. However, when IGFBP-1 was dropped from the regression model, insulin was the only independent predictor of IGF-I, and explained about 19% of the non-genetic variation for IGF-I. For IGFBP-1, insulin and IGF-I, were the significant non-genetic predictors. Insulin and IGF-I explained about 28 and 8% respectively of the non-genetic variation for IGFBP-1, while for insulin, IGF-I, triglycerides, body height, glucose, and body mass index (BMI) explained approximately 20, 12, 6, 5 and 5% respectively of the non-genetic variation.

Aged↗

Immunosurgical studies on cytological and cytogenetic toxicity analysis of rat blastocysts after in vivo exposure to cyclophosphamide.

AIM: To establish immunosurgery and indices of cytogenetic assessment for blastocyst and its inner cell mass (ICM), and to evaluate the toxic effects after in vivo exposure to cyclophosphamide. METHODS: Modified immunosurgery was established by preparation of rabbit-anti-rat spleen antiserum and induction of diluted rat mixed serum as complement. Pregnant rats on d 3 of gestation were injected i.p. cyclophosphamide (10, 20, and 40 mg.kg-1). On d 4, immunosurgery was performed on rat blastocysts. The cell number and the micronuclei of blastocyst and ICM were evaluated respectively. RESULTS: In the cyclophosphamide-treated rats, decreases of cell number (35 +/- 3, 32 +/- 1, 30 +/- 1, and 14 +/- 2, 11 +/- 1, 9 +/- 2) and increases of frequency of micronuclei (1.81%, 2.27%, 3.14%, and 2.53%, 2.98%, 4.75%) in blastocysts and ICM were observed in a dose-related manner. The changes of blastocyst were, however, not parallel to those of ICM which were more serious. CONCLUSION: Modified immunosurgery, an objective and elegant technique, was used on rat blastocysts. In vivo could cyclophosphamide injured ICM more than blastocysts.

Animals↗

[Reconstruction of the hypopharyngeal and cervical esophagus using flap of epiglottis].

Reconstruction of the hypopharyngeal and cervical esophagus was performed for eight patients after the resection of hypopharyngeal carcinoma. The flap of the epiglottis and the facial flap of the sternohyoid muscle or the uninvolved mucous membrane of the hypopharynx were used for the reconstruction of the hypopharyngeal and cervical esophagus. A good swallowing function was obtained. No pharyngeal-cervical fistula occurred. Although stomach transposition or colon interpolation and pectoralis major myocutaneous flap could be used to reconstruct the hypopharynx and the cervical esophagus, however, the operative time became longer, more complex and the patient suffered more. The procedure of the flap of epiglottis had the following advantages: (1) a rich vascularized flap; (2) simple operative technique; (3) higher success rate; and (4) few complications.

Adult↗

Genetic and environmental architecture of the features of the insulin-resistance syndrome.

The contribution of genetic and environmental effects to the clustering of metabolic factors contained in insulin-resistance syndrome (IRS) is still unclear. To explore the genetic architecture of IRS, we examined a population of elderly twins from the Swedish Adoption/Twin Study of Aging. A sample of 289 pairs of twins (mean age 65.5 years; range 52-86 years), of whom 140 pairs had been reared apart, was studied. The features contained in the IRS consisted of body-mass index (BMI), insulin resistance, triglycerides, HDL cholesterol, and systolic blood pressure. Intraclass correlations, cross-twin correlations, and model-fitting analyses were used to evaluate the relative importance of genetic and environmental influences for variation in and covariation among the components of the syndrome. All of the five principal metabolic components contained in IRS are more or less influenced by a single latent genetic factor, whereas only three of the components (triglycerides, insulin resistance, and HDL cholesterol) are influenced by a latent individual-specific environmental factor. The genetic factor reflected influences of importance to BMI and insulin resistance and to a lesser degree to triglycerides, HDL cholesterol, and systolic blood pressure, whereas the individual-specific environmental factor reflected influences in common to triglycerides and HDL cholesterol and to a lesser degree to insulin resistance. Systolic blood pressure was related to IRS, albeit weakly, only through genetic effects. In conclusion, IRS appears to be influenced by different sets of genetic and environmental mechanisms. The set of genetic influences in common to all the components may initiate the abnormalities underlying IRS.

Aged↗

Effect of crosslinked poly(1-vinyl-2-pyrrolidinone) gels on cell growth in static cell cultures.

Poly(1-vinyl-2-pyrrolidinone) (PVP) and copolymers of 1-vinyl-2-pyrrolidinone are insoluble in water when crosslinked but they can absorb very large amounts of water to become syringe-injectable hydrogels. Such gels have been investigated recently as potential substitutes for the vitreous humour in the eye. In this study, during the cytotoxic evaluation by sulforhodamine B colorimetric assay of variously crosslinked PVP gels, it was found that many of them showed protective/growth promoting effects on 3T3 mouse fibroblasts in static cultures, a phenomenon encountered previously only with aqueous solutions of a limited number of natural or synthetic polymers. Particularly, the gels crosslinked with diethylene glycol dimethacrylate (DEGDMA) induced a significant enhancement of cell proliferation, especially in serum-free cultures. No correlation between this effect and the essential gel properties (chemical composition, viscoelasticity and equilibrium water content) could be established. The study demonstrated that crosslinked PVP hydrogels showed a serum-like growth promoting effect on an anchorage-dependent cell line, which may be due to physical protection, inability of the insoluble gels to penetrate cell membranes, and their ability to mimic the extracellular matrix.

3T3 Cells↗

Effects of basic fibroblast growth factor on the differentiation, growth, and viability of a new human medulloblastoma cell line (UM-MB1).

We presently report the effects of human recombinant basic fibroblast growth factor (bFGF) on a newly established medulloblastoma cell line, UM-MB1. This predominantly adherent cell line has a mean doubling time of 39.3 hours and was found, by karyotypic analysis, to be near triploid. UM-MB1 consists of undifferentiated cells expressing markers of neuronal lineage such as the three neurofilament subunits as well as neuron-specific enolase, synaptophysin, and microtubule-associated proteins 1 and 5. In contrast, no immunoreactivity for glial fibrillary acidic protein was evident. When exposed to nanomolar amounts of bFGF, UM-MB1 cells began to extend neurite-like processes with arborizations and growth-cone-like structures. In addition, UM-MB1 cells treated with bFGF exhibited ultrastructural alterations that reflect their enhanced differentiation as well as the increased expression of at least one of the neurofilament subunits as evidenced both immunocytochemically and on Western blots. Furthermore, bFGF significantly decreased UM-MB1 cell growth as well as induced their death. UM-MB1 cells treated with bFGF for several days displayed DNA cleavage, nuclear shrinkage, and chromatin condensation while retaining their cytoplasmic and mitochondrial membrane integrity, all early indices of apoptosis. After this, cell death was evident with the concomitant appearance of the classical apoptotic bodies. By flow cytometry, bFGF was found to increase the proportion of cells in G1 before inducing their death by apoptosis. In conclusion, UM-MB1 cells can, when appropriately stimulated, be induced to differentiate along their neuronal lineage pathway. Their differentiation induced by bFGF, although incomplete, appears to promote or inhibit the expression of apoptotic effectors or suppressors in these cells, respectively, so to induce their death by an apoptotic-like mechanism.

Antigens, Differentiation↗