PubMed Health⌕ Search

Biomedical subjects

L Hong

Publications and source records attributed to L Hong.

At least 37 records · Page 2Linked to original sources
PubMed2000

IL-11 selectively inhibits aeroallergen-induced pulmonary eosinophilia and Th2 cytokine production.

IL-11 is a pleiotropic cytokine that induces tissue remodeling with subepithelial fibrosis when expressed in the airway. Its effects on the Th2-dominated airway inflammation that is characteristic of asthma, however, are poorly understood. To characterize the effects of IL-11 on Th2 tissue inflammation, we compared the inflammatory responses elicited by OVA in sensitized mice in which IL-11 is overexpressed in a lung-specific fashion (CC10-IL-11) with that in transgene- wild-type littermate controls. Transgene- and CC10-IL-11 transgene+ mice had comparable levels of circulating Ag-specific IgE after sensitization. OVA challenge of sensitized transgene- mice caused airway and parenchymal eosinophilic inflammation, Th2 cell accumulation, and mucus hypersecretion with mucus metaplasia. Exaggerated levels of immunoreactive endothelial cell VCAM-1, mucin (Muc) 5ac gene expression and bronchoalveolar lavage and lung IL-4, IL-5, and IL-13 protein and mRNA were also noted. In contrast, OVA challenge in CC10-IL-11 animals elicited impressively lower levels of tissue and bronchoalveolar lavage inflammation, eosinophilia, and Th2 cell accumulation, and significantly lower levels of VCAM-1 and IL-4, IL-5, and IL-13 mRNA and protein. IL-11 did not cause a comparable decrease in mucus hypersecretion, Muc 5ac gene expression, or the level of expression of RANTES, monocyte chemoattractant protein-2, or monocyte chemoattractant protein-3. In addition, IL-11 did not augment IFN-gamma production demonstrating that the inhibitory effects of IL-11 were not due to a shift toward Th1 inflammation. These studies demonstrate that IL-11 selectively inhibits Ag-induced eosinophilia, Th2 inflammation, and VCAM-1 gene expression in pulmonary tissues.

Administration, Inhalation↗
PubMed2000

Global distribution of the CCR2-64I/CCR5-59653T HIV-1 disease-protective haplotype.

OBJECTIVES: Several natural polymorphisms in the genes for the human CC-chemokine receptors CCR5 and CCR2 are associated with HIV-1 disease. The CCR2-64I genetic variant [a G to A substitution resulting in a valine (V) to isoleucine (I) change at position 64] is in strong linkage disequilibrium with a mutation within the CCR5 regulatory region (CCR5-59653T). Individuals with two CCR2-64I alleles are not resistant to sexual transmission of HIV-1, but progress significantly more slowly to HIV-1 disease. It is therefore important to determine the global distributions of CCR2-64I and CCR5-59653T genetic variants and define the degree of linkage between them. DESIGN AND METHODS: We have developed molecular beacon-based, real-time PCR allele discrimination assays for all three chemokine receptor mutations, and used these spectral genotyping assays to genotype 3923 individuals from a globally distributed set of 53 populations. RESULTS: CCR2-64I and CCR5-59653T genetic variants are found in almost all populations studied: their allele frequencies are greatest (approximately 35%) in Africa and Asia but decrease in Northern Europe. We confirm that CCR2-64I is in strong linkage disequilibrium with CCR5-59653T (96.92% of individuals had the same genotype for both CCR2-64I and CCR5-59653T polymorphisms). CONCLUSIONS: The greater geographical distribution of the CCR2-64I/CCR5-59653T haplotype compared with that of CCR5-delta32 suggests that it is a much older mutation whose origin predates the dispersal of modern humans.

Alleles↗
PubMed2000

A Drosophila complementary DNA resource.

Collections of nonredundant, full-length complementary DNA (cDNA) clones for each of the model organisms and humans will be important resources for studies of gene structure and function. We describe a general strategy for producing such collections and its implementation, which so far has generated a set of cDNAs corresponding to over 40% of the genes in the fruit fly Drosophila melanogaster.

3' Untranslated Regions↗
PubMed2000

Bone regeneration by transforming growth factor beta1 released from a biodegradable hydrogel.

This paper describes the sustained release of transforming growth factor beta1 (TGF-beta1) from a biodegradable hydrogel based on polyion complexation for the enhancement of bone regeneration activity. Basic TGF-beta1 was adsorbed onto the biodegradable hydrogel of acidic gelatin with an isoelectric point of 5.0 by an electrostatic interaction. The TGF-beta1 could not be adsorbed onto basic gelatin. When acidic gelatin hydrogels incorporating 125I-labeled TGF-beta1 were implanted into the back subcutis of mice, the radioactivity decreased with time and the in vivo retention of TGF-beta1 was prolonged with a decrease in the water content of hydrogels. The higher the water content of hydrogels, the faster their biodegradation. The in vivo retention of TGF-beta1 correlated well with that of gelatin hydrogels, indicating that TGF-beta1 was released from the gelatin hydrogel as a result of hydrogel biodegradation. The ability of TGF-beta1-incorporated into acidic gelatin hydrogels to induce bone regeneration was evaluated in a rabbit calvarial defect model. Eight weeks after treatment, the gelatin hydrogels with water contents of 90 and 95 wt% induced significantly high bone regeneration compared with those with lower and higher water contents and free TGF-beta1. This indicates that the sustained release of TGF-beta1 from the hydrogel with suitable in vivo degradability is necessary to effectively enhance its osteoinductive function. Rapid hydrogel degradation will result in a retention time of TGF-beta1 which is too short to induce bone regeneration. It is possible that the slow degradation of the hydrogel physically blocked TGF-beta1-induced bone regeneration at the skull defect. It can be concluded that the gelatin hydrogel is a promising matrix of TGF-beta1 release to induce skull bone regeneration.

Absorbable Implants↗
PubMed2000

Toward a transformed approach to prevention: breaking the link between masculinity and violence.

Men are disproportionately overrepresented among both perpetrators and victims of violent crime. Scholars from the men's studies movement have documented a clear link between socialization into stereotypical norms of hegemonic masculinity and an increased risk for experiencing violence. Despite this evidence, most campus prevention programs fail to recognize the link between men and violence and use only traditional approaches to violence prevention. The most that on-campus prevention programs provide are self-defense seminars for potential female victims of rape and general campus safety measures. In this article, the author describes a comprehensive, transformed approach to violence prevention. Data from a year-long case study of Men Against Violence, a peer education organization at a large university in the South, demonstrate the feasibility of meaningfully expanding male students' conceptions of manhood and appropriate gender roles and, thus, reducing the likelihood of men's engaging in sexually or physically violent behavior.

Adult↗
PubMed2000

Promoted bone healing at a rabbit skull gap between autologous bone fragment and the surrounding intact bone with biodegradable microspheres containing transforming growth factor-beta1.

This study is a trial to promote repairing of the rabbit skull bone gap between an autologous bone flap and the intact bone with biodegradable gelatin microspheres containing transforming growth factor-beta1 (TGF-beta1). A 10-mm diameter bone defect was prepared in rabbit skulls by drilling out a bone flap of 6 mm in diameter. After a surrounding gap defect of 2 mm was created and treated with 0.5 microg of free TGF-beta1 and gelatin microspheres containing 0.5 microg of free TGF-beta1, the circular autologous bone flap was placed in the center. Significant bone healing at the gap defect was observed 3 weeks after implantation of the TGF-beta1-containing gelatin microspheres. The bone mineral density (BMD) was significantly higher than that of other experimental groups. On the contrary, when applied with free TGF-beta1, a fibrous tissue initially infiltrated into the gap defect, resulting in impairing bone healing. The tissue response was similar to that at the defect implanted with empty gelatin microspheres and TGF-beta1-free phosphate-buffered saline solution alone. There was more space in the gap-filling bone in the 16-week view than the 3-week view. It is possible that this was an intermediate step along the way toward normal healing and formation of cancellous bone. We conclude that gelatin microspheres containing TGF-beta1 show promise as an agent to promote bone regeneration of subcritical size defects between surgically positioned autologous bone flaps and surrounding host bone.

Animals↗
PubMed2000

Crystal structure of an in vivo HIV-1 protease mutant in complex with saquinavir: insights into the mechanisms of drug resistance.

Saquinavir is a widely used HIV-1 protease inhibitor drug for AIDS therapy. Its effectiveness, however, has been hindered by the emergence of resistant mutations, a common problem for inhibitor drugs that target HIV-1 viral enzymes. Three HIV-1 protease mutant species, G48V, L90M, and G48V/L90M double mutant, are associated in vivo with saquinavir resistance by the enzyme (Jacobsen et al., 1996). Kinetic studies on these mutants demonstrate a 13.5-, 3-, and 419-fold increase in Ki values, respectively, compared to the wild-type enzyme (Ermolieff J, Lin X, Tang J, 1997, Biochemistry 36:12364-12370). To gain an understanding of how these mutations modulate inhibitor binding, we have solved the HIV-1 protease crystal structure of the G48V/L90M double mutant in complex with saquinavir at 2.6 A resolution. This mutant complex is compared with that of the wild-type enzyme bound to the same inhibitor (Krohn A, Redshaw S, Richie JC, Graves BJ, Hatada MH, 1991, J Med Chem 34:3340-3342). Our analysis shows that to accommodate a valine side chain at position 48, the inhibitor moves away from the protease, resulting in the formation of larger gaps between the inhibitor P3 subsite and the flap region of the enzyme. Other subsites also demonstrate reduced inhibitor interaction due to an overall change of inhibitor conformation. The new methionine side chain at position 90 has van der Waals interactions with main-chain atoms of the active site residues resulting in a decrease in the volume and the structural flexibility of S1/S1' substrate binding pockets. Indirect interactions between the mutant methionine side chain and the substrate scissile bond or the isostere part of the inhibitor may differ from those of the wild-type enzyme and therefore may facilitate catalysis by the resistant mutant.

Amino Acid Substitution↗
PubMed2000

Bone formation at a rabbit skull defect by autologous bone marrow cells combined with gelatin microspheres containing TGF-beta1.

The objective of the present study is to investigate the addition effect of transforming growth factor (TGF)-beta1 on the bone formation at a rabbit skull defect induced by autologous bone marrow (BM). Following application of gelatin microspheres containing TGF-beta1, with or without BM cells to skull bone defects, bone formation at the defect was assessed by soft X-ray, dual energy X-ray absorptometry (DEXA), and histological examinations. After implantation for 6 weeks, gelatin microspheres containing 0.05 microg of TGF-beta1 plus 10(6) of BM cells induced bone formation at the 6 mm diameter bone defect. The defect was histologically closed by newly formed bone tissue, whilst both gelatin microspheres containing 0.05 microg of TGF-beta1, and 10(6) and 10(7) of BM cells were ineffective. A DEXA experiment revealed that combination of gelatin microspheres containing TGF-beta1 with BM cells enhanced the bone mineral density at the skull defect to a significantly greater extent than other agents. These findings indicate that a combination of gelatin microspheres containing TGF-beta1 enabled BM cells to enhance the osteoinductive ability, resulting in bone formation even at the cell number at which BM cells alone were ineffective.

Animals↗
PubMed2000

Synergistic effect of gelatin microspheres incorporating TGF-beta1 and a physical barrier for fibrous tissue infiltration on skull bone formation.

The objective of this study is to examine whether or not bone formation at a skull bone defect induced by gelatin microspheres incorporating transforming growth factor (TGF)-beta1 is promoted by prevention of fibrous tissues into the defect. The 6-mm diameter bone defect of rabbit skulls was applied with gelatin microspheres incorporating TGF-beta1 or free TGF-beta1 and physically covered by a barrier membrane. When the bone formation at the defect was assessed 6 weeks postoperatively, combinational application of gelatin microspheres incorporating 0.1 microg of TGF-beta1 with the barrier membrane induced bone formation at the skull defect, in marked contrast to that of 0.1 microg of free TGF-beta1 and empty gelatin microspheres. Complete defect closure was histologically observed by the newly formed bone tissue. Without the barrier membrane, gelatin microspheres incorporating TGF-beta1 were less effective in inducing bone formation, whereas free TGF-beta1 and empty gelatin microspheres were ineffective. The skull defect was occupied by fibrous tissue infiltrated in place of bone tissue. The bone mineral density at the skull defect applied with gelatin microspheres incorporating TGF-beta1 plus the membrane was significantly higher than that of gelatin microspheres incorporating TGF-beta1 alone. The present data indicated that physical protection from the soft tissue infiltration enabled gelatin microspheres incorporating TGF-beta1 to synergistically enhance the osteoinductive ability at the skull defect.

Animals↗
PubMed2000

Bone regeneration at rabbit skull defects treated with transforming growth factor-beta1 incorporated into hydrogels with different levels of biodegradability.

OBJECT: Skull bone regeneration induced by transforming growth factor-beta1 (TGFbeta1)-containing gelatin hydrogels (TGFbeta1-hydrogels) was investigated using a rabbit skull defect model. Different strengths of TGFbeta1 were examined and compared: different TGFbeta1 doses in gelatin hydrogels with a fixed water content, different water contents in gelatin hydrogels with a fixed TGFbeta1 dose, and TGFbeta1 in solution form. In addition, regenerated skull bone was observed over long time periods after treatment. METHODS: Soft x-ray, dual energy x-ray absorptometry, and histological studies were performed to assess the time course of bone regeneration at a 6-mm-diameter skull defect in rabbits after treatment with TGFbeta1-hydrogels or other agents. The influence of TGFbeta1 dose and hydrogel water content on skull bone regeneration by TGFbeta1-hydrogels was evaluated. Gelatin hydrogels with a water content of 95 wt% that incorporated at least 0.1 microg of TGFbeta1 induced significant bone regeneration at the rabbit skull defect site 6 weeks after treatment, whereas TGFbeta1 in solution form was ineffective, regardless of dose. The in vivo degradability of the hydrogels, which varied according to water content, played an important role in skull bone regeneration induced by TGFbeta1 -hydrogels. In our hydrogel system, TGFbeta1 is released from hydrogels as a result of hydrogel degradation. When the hydrogel degrades too quickly, it does not retain TGFbeta1 or prevent ingrowth of soft tissues at the skull defect site and does not induce bone regeneration at the skull defect. It is likely that hydrogel that degrades too slowly physically impedes formation of new bone at the skull defect. Following treatment with 0.1-microg TGFbeta1-hydrogel (95 wt%), newly formed bone remained at the defect site without being resorbed 6 and 12 months later. The histological structure of the newly formed bone was similar to that of normal skull bone. Overgrowth of regenerated bone and tissue reaction were not observed after treatment with TGFbeta1 -hydrogels. CONCLUSIONS: A TGFbeta1-hydrogel with appropriate biodegradability will function not only as a release matrix for the TGFbeta1, but also as a space provider for bone regeneration. The TGFbeta1-hydrogel is a promising surgical tool for skull defect repair and skull base reconstruction.

Absorptiometry, Photon↗
PubMed2000

[Does simple posterior dislocation of the elbow necessitate strict immobilization?].

OBJECTIVE: To research for the ideal treatment of isolated posterior dislocation with the elbow after reduction. METHODS: 36 patients of isolated posterior dislocation of the elbow after closed reduction (male 26, female 10; left 14, right 22; dominant extremity 21, undominant extremity 15; average age 22) were examined by varus and valgus stress test and push-draw test. Satisfactory stability from 30 degrees to 130 degrees flexion of the elbow was found in all patients. For the 30 patients below 35 years old, long-arm posterior splint was applied to immobilize the elbow joint at 90 degrees flexion and pronation for one week. For 6 patients over 35 years old, we only immobilized the elbow joint for 3 to 5 days with a neck-wrist sling. Prompt active motion begin after the swelling and pain reduced slightly, but the last 30 extension was not allowed for the first 1 to 2 weeks. Forceful passive motion and stretching of the elbow joint were avoided in all patients. RESULTS: The average follow-up time was 9 months (3 - 15 months). Range of motion and muscle power were regained within 3 - 4 months. 32 patients rehabilitated completely and 4 of the 6 patients decreased extension for 5 degrees - 10 degrees. No unstable symptoms and signs or recurrent dislocation were found. No ectopic calcification or post-traumatic arthritic changes were found on X-ray follow-up. CONCLUSIONS: The ulna-humeral joint is one of the most highly constrained joints in the body with intrinsic stability. Bony structure is stable enough to allow for capsular and ligamental structure healing, even during active motion. For isolated posterior dislocation of the elbow joint, short-term immobilization and early functional exercise are desirable. Elbow instability and recurrent dislocation are rare and do not necessitate long-term strict immobilization.

Adolescent↗
PubMed2000

[The disinfection efficiency comparison of different treatments on dental impression and gypsum casts].

OBJECTIVE: In this study, the disinfecting efficiency of five disinfecting methods to three bacterial: Staphylococcus epidermidis, Streptococcus sanguis and Bacillus subtilis were evaluated. METHODS: Germ free impressions and gypsum casts were divided into three teams contained 16 impressions and 5 gypsum casts for each one. Each team was smeared with each one of the three bacterial solutions. Then four disinfecting methods were administrated on these impressions separately, 2% glutaraldehyde immersion, 2% glutaraldehyde spray, 5% Eric immersion, 5% Eric spray. And ozone treatment was administrated on gypsum casts. Control teams were set up. After the treatment the impressions and gypsum casts were sampled at standard sites. The colonies were counted after culture and were used to deduce the germicidal ratio as the standard of disinfecting efficiency. RESULTS: There was no difference between the efficiencies of five disinfecting methods for Streptococcus sanguis and Staphylococcus epidermidis. But for B. subtilis, the immersion methods have the highest efficiency among the methods and the ozone treatment has the least efficiency. CONCLUSION: 2% glutaraldehyde immersion, spray, 5% Eric immersion, spray are all effective disinfecting methods for impressions and ozone treatment is an effective method in disinfecting the gypsum casts.

Bacillus subtilis↗
PubMed2000

[Clinical study of direct digital radiography in caries detection].

OBJECTIVE: Direct digital radiography is a computer-based image technique, the purpose of this paper is to investigate possible usage of direct digital radiography-radio visiography (RVG) in caries detection in clinic. METHODS: A human head model with teeth was used to establish the operative exposure time for RVG in vitro, then RVG images for normal and carious tooth were obtained in vivo and were compared with conventional E-speed film in image quality and diagnostic accuracy. RESULTS: The optimal exposure time for RVG image was obtained, and the exposure time was different in each tooth quarter. The acceptable rate of image quality and diagnostic accuracy of RVG was statistically equivalent to that of E-speed film (P > 0.05), however, the excellent rate of RVG was statistically superior to that of E-speed film (P < 0.05). CONCLUSION: The conventional X-ray will be substituted by RVG in caries detection in clinic.

Adolescent↗
PubMed2000

Preparation of anti-idiotypic antibodies specific for anti-HEL and analysis of their functional mimicry.

OBJECTIVE: This study is to investigate the functional mimicry by using anti-idiotypic antibodies of enzymes. METHODS: Monoclonal anti-idiotypic antibodies against anti-HEL (hen egg-white lysozyme, HEL) antibodies were obtained by fusion of Sp2/0 myeloma cells with spleen cells of syngeneic mice immunized with monoclonal anti-HEL antibodies against HEL's different antigenic epitopes. Then bacteriolysis of the anti-idiotypic antibodies were observed. RESULTS: Eight hybridomas strains secreting anti-idiotypic antibodies were selected and characterized. It was shown that two of eight anti-idiotypic antibodies secreted by two hybridomas (1A10C9 and 2A11C1B3) could mimic HEL catalytic activity to lyse Micrococcus lysodeikticus and that the catalytic effect of mixed anti-idiotypic antibodies of 1A10C9 and 2A11C1B3 was stronger than that of one of them, but less than HEL. CONCLUSION: The results demonstrated that the anti-idiotypic antibodies that could mimic enzyme activity existed in the idiotype network during anti-enzymatic immune response.

Animals↗
PubMed1999

Association of Nafion with Polypyrrole Nanoparticles in a Hydrophilic Polymer Network: Effects on Proton Transport.

Proton-conducting polymer composites containing perfluorosulfonic polymer (Nafion) and polypyrrole (PPy) nanoparticles in a polyacrylamide network, P(AAM-MBAM), were synthesized as proton-conducting electrolytes. An investigation into the assembling of Nafion polymer molecules as well as the colloidal PPy-Nafion complexes in the P(AAM-MBAM) network was carried out on the basis of DSC and XRD analysis. It was found that the proton conductivity of the composites was largely affected by the occurrence of the free volume between the P(AAM-MBAM) network and Nafion polymer as well as the concentration of the PPy-Nafion complexes in the composites according to the measurements of the electrical resistance and the frequency-dependent impedance. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Intensity-modulated tangential beam irradiation of the intact breast.

PURPOSE: To evaluate the potential benefits of intensity modulated tangential beams in the irradiation of the intact breast. METHODS AND MATERIALS: Three-dimensional treatment planning was performed on five left and five right breasts using standard wedged and intensity modulated (IM) tangential beams. Optimal beam parameters were chosen using beams-eye-view display. For the standard plans, the optimal wedge angles were chosen based on dose distributions in the central plane calculated without inhomogeneity corrections, according to our standard protocol. Intensity-modulated plans were generated using an inverse planning algorithm and a standard set of target and critical structure optimization criteria. Plans were compared using multiple dose distributions and dose volume histograms for the planning target volume (PTV), ipsilateral lung, coronary arteries, and contralateral breast. RESULTS: Significant improvements in the doses to critical structures were achieved using intensity modulation. Compared with a standard-wedged plan prescribed to 46 Gy, the dose from the IM plan encompassing 20% of the coronary artery region decreased by 25% (from 36 to 27 Gy) for patients treated to the left breast; the mean dose to the contralateral breast decreased by 42% (from 1.2 to 0.7 Gy); the ipsilateral lung volume receiving more than 46 Gy decreased by 30% (from 10% to 7%); the volume of surrounding soft tissue receiving more than 46 Gy decreased by 31% (from 48% to 33%). Dose homogeneity within the target volume improved greatest in the superior and inferior regions of the breast (approximately 8%), although some decrease in the medial and lateral high-dose regions (approximately 4%) was also observed. CONCLUSION: Intensity modulation with a standard tangential beam arrangement significantly reduces the dose to the coronary arteries, ipsilateral lung, contralateral breast, and surrounding soft tissues. Improvements in dose homogeneity throughout the target volume can also be achieved, particularly in the superior and inferior regions of the breast. It remains to be seen whether the dosimetric improvements achievable with IMRT will lead to significant clinical outcome improvements.

Breast↗
PubMed1999

Possible causes of socioeconomic and ethnic differences in seat belt use among high school students.

This study has assessed seat belt use and factors which may influence seat belt use among high school students from three types of schools. The inner city schools had high proportions of African American and Hispanic American students from low income families, whereas the middle class school and private schools had high proportions of non-Hispanic white students from middle class families with college educated parents. Students from the inner city schools reported less seat belt use than students from the middle class school or private schools. Our analyses evaluated several hypotheses concerning possible reasons why inner city youth had lower rates of seat belt use. In accord with the social influences hypothesis, inner city youth reported lower rates of parental seat belt use and less often being told by parents to use their seat belts, and our regression results indicate that less parental modeling and encouragement of seat belt use was an important cause of inner city youth's lower rates of seat belt use. Our other hypotheses received weaker support, but we did find evidence for two hypothesized differences in attitudes which influence seat belt use. Specifically, inner city youth were more likely to agree with the statement, 'there is no point in wearing seat belts since you have no control over your fate or destiny', and inner city youth attributed less importance to safety concerns as a motivation for seat belt use. These attitudes appeared to contribute to lower rates of seat belt use by inner city youth.

Adolescent↗