Biomedical subjects

L Hong

Publications and source records attributed to L Hong.

At least 55 records · Page 3Linked to original sources

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↗

PubMed1999

Promoting effect of estrogen on the proliferation of hemangioma vascular endothelial cells in vitro.

PURPOSE: This study was designed to observe whether estrogen can enhance the proliferation of hemangioma vascular endothelial cells (VECs) and, if so, the possible inhibiting effect of tamoxifen against estrogen. METHODS: Two skin hemangiomas with positive estrogen receptor staining from 2 infants were used for VECs culture. Based on different culture conditions and treatment, the subcultured VECs of passage 3 derived from a hemangioma were divided into 5 groups: group 1, control without endothelial cell growth supplement (ECGS) in medium; group 2, estradiol (E2) without ECGS; group 3, control with ECGS in medium; group 4, E2 with ECGS; group 5, E2 and 4OH-tamoxifen with ECGS. Cell counts and 3H-TdR incorporations were determined on culture days 3, 6, and 9. VECs from the other hemangioma were divided into 2 groups: group 3, control with ECGS in medium; group 4, E2 with ECGS. RESULTS: At the end of the 9-day study, the cell counts (x10(4)/mL) of the 5 groups were 6.31+/-1.24, 6.52+/-1.08, 15.62+/-1.88, 36.77+/-3.96, and 6.88+/-1.20, respectively. 3H-TdR incorporations (cpm) were 511+/-127, 538+/-26, 1,350+/-67, 2,729+/-145, and 575+/-64, respectively. The results of the other hemangioma were similar to those of the first one. Our data showed that without ECGS in medium, E2 had no effect on the proliferation of VECs (group 1 v group 2, P>.05); with ECGS in medium, E2 yielded a 2-fold increase in the proliferation of VECs (group 3 v group 4, P<.01); when 4OH-tamoxifen was added, the proliferation of VECs was suppressed dramatically (group 4 vgroup 5, P<.01). CONCLUSIONS: Estrogen in vitro can promote the proliferation of hemangioma VECs. This promoting effect of estrogen may depend on certain growth factors, which can be inhibited by tamoxifen.

Cell Division↗

PubMed1999

A device for applying postsurgical pressure to the lateral face.

OBJECTIVE: The purpose of this study was to improve the effect of pressure applied on the lateral face after operations, particularly after parotid surgery for prevention of complications, especially the formation of salivary fistula. STUDY DESIGN: A pressure instrument (face pad) was designed to fit all types of facial morphology. The blood flow velocity of the superficial temporal artery was measured by means of a Doppler detector in 30 healthy volunteers under 2 different conditions, with and without the face pad. Values for 2 parameters, peak velocity and average peak velocity, were determined for the purpose of selecting an appropriate pressure. Each of 47 patients who had undergone regional parotidectomy received pressure with the face pad for 3 days; the results were compared with those in a control group of 44 patients who had undergone similar operations but received traditional packing dressings. RESULTS: The peak velocities of the superficial temporal artery with and without the face pad were not significantly different (t = 1.541, P = .132) when a pressure value of 4 to 5 N was applied. However, the average peak velocity of the superficial temporal artery increased significantly (t = 3.678, P = .001) with the face pad. The 47 patients with the face pad had no postoperative parotid fistula; in contrast, salivary fistula developed in 5 of the 44 control cases, for an overall fistula rate of 11.36%. A significant difference existed between the 2 groups (P = .023). CONCLUSIONS: The face pad worked quantitatively and was stable and comfortable. A pressure of 4 to 5 N on the lateral face did not influence the blood flow of the superficial temporal artery. The higher peak velocity was correlated with regional stenosis of the temporal vein caused by pressure. Evidently, the face pad can reduce postoperative complications after parotidectomy; moreover, it makes pressure dressing easy and shortens the in-hospital days of the patient as well.

Adult↗

PubMed1999

Myers Briggs Type Indicator and Tridimensional Personality Questionnaire differences between bipolar patients and unipolar depressed patients.

OBJECTIVES: The current study was designed to compare personality differences between bipolar patients and unipolar depressed patients, as evaluated on the Myers Briggs Type Indicator (MBTI) and the Tridimensional Personality Questionnaire (TPQ). METHODS: A group of bipolar and a group of unipolar depressed patients filled out the MBTI, the TPQ, the Beck Depression Inventory, and the CAGE questionnaire. The two groups were compared with each other as to responses on the above surveys, and subgroups of bipolar depressed and bipolar patients with manic symptoms were also compared. RESULTS: Bipolar patients were found to be significantly more extroverted (p = 0.004) and less judging (p = 0.007) on the MBTI. They were significantly more novelty seeking (p = 0.004) and less harm avoidant (p = 0.002) on the TPQ. Of the above differences, only the TPQ harm avoidance scale appeared strongly linked to the patients' level of depression. CONCLUSION: Significant differences in personality exist between bipolar disorder and unipolar depressed patients.

Adult↗

PubMed1999

An exploration of the sequence of a 2.9-Mb region of the genome of Drosophila melanogaster: the Adh region.

A contiguous sequence of nearly 3 Mb from the genome of Drosophila melanogaster has been sequenced from a series of overlapping P1 and BAC clones. This region covers 69 chromosome polytene bands on chromosome arm 2L, including the genetically well-characterized "Adh region." A computational analysis of the sequence predicts 218 protein-coding genes, 11 tRNAs, and 17 transposable element sequences. At least 38 of the protein-coding genes are arranged in clusters of from 2 to 6 closely related genes, suggesting extensive tandem duplication. The gene density is one protein-coding gene every 13 kb; the transposable element density is one element every 171 kb. Of 73 genes in this region identified by genetic analysis, 49 have been located on the sequence; P-element insertions have been mapped to 43 genes. Ninety-five (44%) of the known and predicted genes match a Drosophila EST, and 144 (66%) have clear similarities to proteins in other organisms. Genes known to have mutant phenotypes are more likely to be represented in cDNA libraries, and far more likely to have products similar to proteins of other organisms, than are genes with no known mutant phenotype. Over 650 chromosome aberration breakpoints map to this chromosome region, and their nonrandom distribution on the genetic map reflects variation in gene spacing on the DNA. This is the first large-scale analysis of the genome of D. melanogaster at the sequence level. In addition to the direct results obtained, this analysis has allowed us to develop and test methods that will be needed to interpret the complete sequence of the genome of this species. Before beginning a Hunt, it is wise to ask someone what you are looking for before you begin looking for it. Milne 1926

Alcohol Dehydrogenase↗

PubMed1999

Skull bone regeneration in primates in response to basic fibroblast growth factor.

OBJECT: The feasibility of using a biodegradable hydrogel incorporating basic fibroblast growth factor (bFGF) to induce bone regeneration at the site of a skull defect in monkeys was investigated. METHODS: Basic fibroblast growth factor was incorporated into a bioabsorbable hydrogel, which was prepared through glutaraldehyde crosslinking of gelatin. Following treatment of monkey skull defects measuring 6 mm in diameter (six defects/experimental group) with gelatin hydrogel incorporating bFGF, skull bone regeneration was evaluated using soft x-ray studies, dual x-ray absorptometry, and histological examinations. The water content of the hydrogels varied according to the glutaraldehyde concentration in the hydrogel preparation. Gelatin hydrogels incorporating 100 microg of bFGF significantly promoted bone regeneration and the skull defect was completely closed 21 weeks after implantation. This is in marked contrast with the effect of the same dose of bFGF in solution form. Bone mineral density (BMD) measured at the sites of skull defect was enhanced by the bFGF-incorporating hydrogels. The BMD enhancement was more prominent at lower water contents of hydrogel. Empty gelatin hydrogels neither induced nor interfered with skull bone regeneration. CONCLUSIONS: The findings of this study indicate that bFGF coupled with bioabsorbable hydrogel is a very promising tool to assist in the regrowth of bone at the site of a skull defect, which clinically has been recognized as almost impossible.

Absorptiometry, Photon↗

PubMed1999

Study on rt-PA production by recombinant CHO cells immobilized with a porous microcarrier.

Using the porous microcarrier Cytopore, immobilized cultivation of a recombinant CHO cell line 4B3 producing tissue type plasminogen activator (rt-PA) was performed in a 3L stirring tank bioreactor with the perfusion of serum-free medium DF5S. 4B3 cells could enter the inner space and grow both in the inner space and on the surface of the Cytopore. The highest viable cell density of 4B3 and the highest production level of rt-PA were 8.83 x 10(6) cells/mL and 12,473 IU/mL, respectively. Purified by MPG adsorption chromatography and lysine-Sepharose 4B affinity chromatography, the purified rt-PA with a purity exceeding 98% was obtained from the culture supernatant.

Animals↗

PubMed1999

[Prosthodontic treatment of secondary occlusal and maxillofacial deformities of postoperative cleft lip and palate].

OBJECTIVE: To investigate the kind and degree of deformtive and the charactertics and effects of prosthetic treatment in patients with secondary maxillofacial deformities after cleft lip and palate operation at early age. METHODS: Clinical examinations and cephalometric analysis were performed in 30 patients. RESULTS: The results showed that prosthetic treatment can improve facial form and oral functions a great deal but with limitations. CONCLUSION: Prosthetic treatment should be considered as an essential part in serial therapy of cleft lip and palate.

Adolescent↗

PubMed1999

[The study on the personality factors in patients' satisfaction with their complete dentures].

OBJECTIVE: To find out the relation between personality factors of edentulous patients and the degree of their satisfaction to the complete dentures. METHODS: Under the condition of controlling quality of complete dentures, 165 subjects were investigated by using the patient denture satisfaction questionnaire and the revised Cattell's 16 personality factors questionnaire after wearing the complete dentures for one and three months. RESULTS: The personality factors of edentulous patients such as conscientiousness (G factor), shrewdness (N factor) and so on do affect their denture satisfaction in every aspect of the dentures. CONCLUSION: The oral prosthodontists not only need improving technological quality of prostheses but also need paying attention to patients' psychological characteristics.

Adult↗