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Biomedical subjects

Y M Cheng

Publications and source records attributed to Y M Cheng.

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

Dynamics of dental implants and orthodontics in today's periodontal prosthesis.

Periodontal prosthesis refers to multidisciplinary efforts to stop disease progression, correct deformities created by dental diseases, and establish a therapeutic occlusion to restore the form and function of the masticatory system. These efforts are critical for the long-term prognosis and maintenance of the guarded teeth and the overall prosthesis. This article presents a functionally and esthetically challenging case, which illustrates a multidisciplinary approach--specifically implantology and orthodontics--and how they impact on each other during treatment. The role and importance of dental implants and orthodontics in setting up a case is illustrated in this article.

Alveolar Bone Loss↗
PubMed1999

Hypermethylation of the p16 gene in sporadic T3N0M0 stage colorectal cancers: association with DNA replication error and shorter survival.

Hypermethylation in the promoter region of the p16 gene was suspected to be involved in the tumorigenesis of colorectal cancers, although its clinical and biological significance remains obscure. In this study, we collected 84 T3N0M0 stage primary colorectal cancers that were curatively resected. The clinicopathologic data were reviewed. p16 hypermethylation was determined by a methylation-specific polymerase chain reaction (PCR). p53 overexpression was detected by immunocytochemistry (ICC). The point mutations in the 12 and 13 codons of the K-ras gene were screened by restriction enzyme analysis. Loss of heterozygosity (LOH) of the DCC (Deleted in Colorectal cancer) gene was examined by PCR using primers of the DCC (18q21) microsatellite marker. The DNA replication error (RER) was examined using 7 microsatellite markers at distinct chromosomal loci. p16 hypermethylation, regarded as an indication of p16 inactivation, was evident in 24 (28.6%) of the tumors. No correlation was found between p16 hypermethylation and various clinicopathologic factors, includinig age, sex, tumor location, tumor size, growth pattern, tumor differentiation, mucin production, vascular and/or lymphatic invasion, lymphocyte infiltration of the tumor, and serum level of carcinoembryonic antigen. There was no association between p16 hypermethylation of K-ras gene mutation, p53 overexpression and LOH of the DCC gene. However, p16 hypermethylation was significantly associated with DNA RER (p = 0.01). Survival analysis revealed a significant survival disadvantage of p16-hypermethylated versus non-p16-hypermethylated tumors (p = 0.0001). These findings indicate that p16 hypermethylation plays a role in the carcinogenesis of a subset of colorectal cancers; and the presence of p16 hypermethylation predicts shorter survival in T3N0M0 stage colorectal cancers.

Aged↗
PubMed1999

Subtalar arthrodesis for late sequelae of calcaneal fractures: fusion in situ versus fusion with sliding corrective osteotomy.

Primary subtalar arthritis is not common. In most cases, it is the late sequela of intra-articular calcaneal fracture. Subtalar arthrodesis is mostly used for the treatment of traumatic subtalar arthritis in our clinics. We have compared our early cases of in-situ subtalar fusion with our recent cases of fusion with sliding corrective osteotomy in this clinical report. From 1989 to 1992, 15 feet of 13 patients were treated with subtalar arthrodeses for subtalar arthritis caused by malunion of calcaneal fractures. Fusion in situ was done by Ollier's approach, and resection of bony protrusion was done if there was lateral entrapment syndrome. From 1992 to 1995, 13 feet of 12 patients also received subtalar arthrodeses to salvage their calcaneal fractures, but the subtalar fusion was done by wide lateral approach, calcaneal sliding corrective osteotomy, and sometimes (11 of 13 feet) with Achilles tendon lengthening to restore the calcaneal height and width. Patients of both groups experienced obvious clinical improvement in subtalar pain relief, but there was no difference with walking distance, running, or jumping. The group undergoing fusion with sliding corrective osteotomy was more satisfied with regard to cosmetic results and shoe wear. The overall satisfactory rate in the group who underwent fusion with sliding corrective osteotomy (92%) was superior to the group who underwent fusion in situ (77%). Though our method of sliding corrective osteotomy does not provide much improvement to the talus declination angle, it is suitable for those patients with a "banana"-shaped calcaneus malunion. If the patient has prominent anterior ankle pain caused by tibiotalar impingement, we believe that a distraction subtalar arthrodesis would be more appropriate.

Adult↗
PubMed1999

Ankle arthrodesis: internal non-compression arthrodesis versus internal compression arthrodesis.

Ankle arthrodesis is still considered to be the standard treatment for most disabling types of ankle arthritis, but fusion methods are varied. We report our experience of ankle arthrodesis and compare a group of 34 cases treated by Blair's non-compression arthrodesis to another group of 32 cases treated by internal compression arthrodesis using two crossed screws. The same surgeon performed all the operations. The Blair's non-compression arthrodesis group included 21 males and 13 females with an average age of 42 y/o (range 18-70 y/o) and an average follow up period of 38.6 months (range 26-62 months). The union rate was 91.2% and the average union time was 5.6 months (range 2-10 months). There were three cases of non-union. The cross-screw compression arthrodesis group included 20 males and 12 females with an average age of 45 y/o (range 20-86 y/o) and an average follow up period of 38.3 months (range 15-81 months). The union rate was 96.9% and the average union time was 2.7 months (range 1.5-4.4 months). There was one case of non-union. We conclude that our cross-screws compression arthrodesis with its shorter fusion time was found to be superior to the Blair's non-compression arthrodesis.

Adult↗
PubMed1999

The influence of the gap size on the interfacial union between the bone and the tendon.

An in-vivo model of New Zealand white rabbit was used to study the influence of gap size on the interfacial union between bone and tendon through histological observation and mechanical testing. In the model, the anterior cruciate ligament (ACL) was cut and reconstructed by autografted semitendinosus tendon (with average diameter of 1.48 mm +/- 0.12 mm). Mechanical testing of the interfacial healing tissue was done on the 15th post-operative day. At that time the mean maximal tensile strength was 2.511 +/- 0.293 kg to a bone tunnel size of 1.5 mm. The maximal tensile strength lowered to 1.853 +/- 0.563 kg to a bone tunnel size of 1.8 mm. The maximal tensile strength lowered to 1.302 +/- 0.657 kg to a bone tunnel size of 2.0 mm. Using a paired-t test, the gap size was found to have great influence on the tensile strength of the interfacial healing tissue (p < 0.05). The histological study showed that the interfacial gap was connected by the new growing collagen fibers. The healing tissue appeared much denser and much more maturated and organized in the smaller interfacial gap in comparison with specimens with a larger gap so that it can tolerate higher tensile strength. From this study, we concluded that the gap size really plays an important role in the process of maturation and organization of interfacial healing tissue. Furthermore, we recommend that in order to achieve greater anchoring strength of the grafted tendons, the bone tunnel should be made with approximately the same diameter of grafted tendon.

Animals↗
PubMed1998

Identification and characterization of the Escherichia coli-expressed RNA-dependent RNA polymerase of bamboo mosaic virus.

Bamboo mosaic virus (BaMV), a member of the potexvirus group, infects primarily members of the Bambusoideae. The open reading frame 1 (ORF1) of BaMV encodes a 155-kDa polypeptide that was postulated to be involved in the replication and the formation of cap structure at the 5' end of the viral genome. To characterize the activities associated with the 155-kDa viral protein, it was expressed in Escherichia coli BL21(DE3) cells with thioredoxin, hexahistidine, and S. Tag fused consecutively at its amino terminus, and the fusion protein was purified by metal affinity chromatography. Several RNA fragments, prepared by in vitro transcription, were tested as substrates for the RNA-dependent RNA polymerase (RdRp) activity. Among them, the expressed fusion enzyme was able to generate a 32P-labeled RNA product when 3'-end RNA fragments of the positive strand or negative strand of BaMV were included in the assay mixture. Dot hybridization assay revealed that the reaction products are complementary to their RNA substrates. Taken together, the evidence suggests that the 155-kDa protein encoded by ORF1 of BaMV has an RdRp activity and should be involved in the replication of BaMV. Mutational analyses demonstrate the importance of the GDD motif in the polymerase activity, and deletion studies suggest that the polymerase activity resides in the carboxyl terminus of the 155-kDa viral protein.

Base Sequence↗
PubMed1998

Modified Mitchell osteotomy for hallux valgus.

From 1988 to 1995, 96 patients (161 feet) underwent a modified Mitchell distal metatarsal osteotomy performed for mild-to-moderate hallux valgus. On AP x-rays of the standing foot, the average intermetatarsal angle was corrected from 15 degrees to 9 degrees, and the first metatarsophalangeal angles were corrected from an average of 41 degrees to 15 degrees. Criteria for evaluation of clinical results included relief of pain, appearance of foot, and shoe wear. After an average follow-up of 38 months, the overall satisfaction rate was 92.5%. Complications included 13 pin tract infections, two delayed unions, and two correction losses. The most common late sequela was transfer metatarsalgia of the lesser toes, which occurred in 20 feet (12.4%), leading to some dissatisfaction. The Mitchell osteotomy can be used on cases with less than 20 degrees of intermetatarsal angle, offering a stable construct with easy postoperative care.

Adolescent↗
PubMed1998

Surgical treatment for pilon fracture of the ankle-open reduction and internal fixation.

From 1991 to 1994, 39 ankles of 38 patients underwent surgical open reduction and internal fixation for pilon fractures. These patients included 29 males and 9 females with an average age of 38.6 y/o (range 28 y/o-58 y/o). The follow up and evaluation period averaged 31.7 months (range 22Ms-44Ms), during which time a standing x-ray for arthrosis grading and functional scale was used for clinical evaluation. Complications included 1 case of infection, 1 case of loss reduction, 2 cases of partial skin necrosis and 2 cases of delayed union. Post-traumatic arthritis occurred in 23 ankles (59%) but only 4 ankles of grade 4 arthrosis resulted in poor functional scale and the overall satisfactory rate was 82%. It was found that anatomic reduction, rigid fixation and early motion exercise are important to successful treatment of ankle fractures. Regarding pilon fracture, specifically the severity of fracture pattern and delay of reduction are important problems to overcome to ensure successful results. Therefore, adequate surgical approach for entire view of ankle joint, reduction and fixation of fibula, sufficient bone graft for articular support, intraoperative x-ray check and postoperative immobilization are essential for the achievement of better clinical results.

Adult↗
PubMed1998

Ankle arthrography and chronic lateral ankle instability.

Sixty-five ankle arthrograms of the patients who underwent surgical reconstruction for their chronic ankle instability from 1987 to 1995 were studied retrospectively by comparing their operative findings. There were 15 cases (23.1%) with definite positive arthrographic findings. In the remaining 50 cases (76.9%), the arthrograms showed a "tear-drop" extravasation of dye beneath the fibular tip which we called "suspectable positive". Of these all but one, which had normal ligament, proved to correspond to the operative finding. As there was only one false positive finding among our surgical cases with both the "definite" and "suspectable" positive arthrograms, we concluded that ankle arthrography is relatively reliable and may be worth doing even in chronic cases if only for reference. Even when other diagnostic methods are negative, arthrography might help surgeons make surgical decisions in clinical symptomatic cases.

Adolescent↗
PubMed1998

Modified Blair method for ankle arthrodesis.

In this study, the ordinary Blair's ankle arthrodesis was modified by longitudinal oblique cutting to get the sliding bone graft, up side down grafting, and additional screw fixation at talar site with or without staples fixation of tibia-talar junction. The method of ankle arthrodesis was used on 34 cases from 1987 to 1990 with a 91.2% fusion rate and an average 5.6 months fusion time. The oblique cut bone graft provided larger contact surface to enhance bony fusion and the upside-down bone graft provided stronger tibia-talar bone bridge with thicker cortex for distal screw fixation and the distal screw fixation of bone graft to talus had the advantage of securing union and maintaining position. With such modifications, solid ankle arthrodesis could be obtained even without interarticular compression.

Adolescent↗
PubMed1997

Surgical treatment of complete acromioclavicular separations.

A retrospective study of fifty-two patients (48 cases followed up), with Allman-Tossy grade III acromioclavicular separations, who were treated with coracoclavicular reconstruction by Mersilene prosthetic substitute (Mersilene tape with polyester suture, 5 mm wide, 30 cm, Ethicon), was carried out. The average follow up was 38 months, with the longest being 10 years, and the shortest being 8 months. The average age of the patients was 32 years, with a range from 20 to 62 years. Two groups were divided by age. Although the younger age group showed better results than the elder one in pain, range of motion and return to previous occupation or sports, the overall outcome was satisfactory in 41 of 48 (86%) followed patients. For the grade III acromioclavicular separation patients, surgical reconstruction with Mersilene looping provides a reliable result including use of the arm for sports or repetitive work.

Acromioclavicular Joint↗
PubMed1997

Liposomes-coated hydroxyapatite and tricalcium phosphate implanted in the mandibular bony defect of miniature swine.

Hydroxyapatite and tricalcium phosphate have been used as bone implants for some period of time. Now unfortunately, these materials have failed to become the nucleation sites for bone regeneration. We hypothesized that coating hydroxyapatite and tricalcium phosphate with negatively charged liposomes may improve the nucleation process for new bone formation. The present study was designed to test this hypothesis. Experiments were carried out in 15 miniature swines' mandibular angle with artificial bony defects. In each of the swine, the bony defects on one side were implanted with either liposomes coated with hydroxyapatite or liposomes coated with tricalcium phosphate, while the other side served as control. At the end of the third and sixth weeks following the operation, we observed result, took histology and radiographs of the operated area. The results showed that liposomes-coated materials were biocompatible and their clinical endpoint was enhanced. At the end of the third week, the implant material was surrounded by dense connective tissues. At the end of the sixth week, there were new bone formations near the implanted material. In addition, liposomes which were immobilized in agarose gel and implanted in the defects showed new bony bridge formation. These observations suggest that liposomes have the ability in promoting repair of osseous deficiencies.

Alveolar Process↗
PubMed1997

Surgical treatment of pathologic fracture of the femur.

A retrospective study of the surgical treatment of 32 metastatic lesions of the femur in 30 patients at the Kaohsiung Medical College Hospital was performed from 1987 to 1994. There were 16 women and 14 men with an average age of 61 years. A surgical technique combining internal fixation or prosthesis and methylmethacrylate cement was used in all cases. Adequate pain relief was achieved in thirty-one cases (97 %). Of the entire group, 20 cases (62%) remained ambulatory, 10 cases (31%) were confined to a wheelchair, only two cases had implant failure and one suffered from infection.

Adult↗
PubMed1997

Salvage operation for neglected ankle fractures.

From 1986 to 1993, 49 cases of untreated or poorly treated ankle fractures who received salvage surgery were followed up for an average of 36.4 months. The patients included 31 males & 18 females with an average age of 41.6y/o and the time interval from initial injury to reconstructive surgery average due 17.6 months. They were classified and treated according to their grade of reduction and degree of arthrosis. The surgical methods included arthrotomy & joint debridement, revised open reduction, lower tibial osteotomy and ankle arthrodesis, depending on different individual conditions. After surgery, all cases had symptomatic relief and functional improvement with an average score increased from 26.3 preoperatively to 86.8 at follow up. The goals of ankle fractures is as articular fractures, they are treated by surgical anatomic reduction with rigid fixation as early as possible in order to provide good functional results. Nevertheless they are varied in neglected ankle fractures according to their individual conditions: open reductions were performed on cases with no or little arthritic change even though arthrosis might occur later because, if necessary, future conversion to osteotomy or arthrodesis would be easier. As for late cases with advanced arthritis, ankle arthrodesis were done by compressive arthrodesis with necessary bone graft to secure fusion in an optimal position.

Adolescent↗
PubMed1997

Subtalar arthrodesis for subtalar arthritis.

Primary subtalar arthritis is not common except in cases of generalized arthritis such as rheumatoid arthritis. The majority of subtalar arthritis results from intraarticular calcaneal fractures. Arthrodesis seems to be the only way to solve this problem. Thirteen patients (15 feet) were treated with subtalar arthrodesis at KMCH. Preoperative diagnosis included 13 feet with traumatic arthritis secondary to a calcaneal fracture, one foot with rheumatoid arthritis and one foot with primary osteoarthritis. The mean follow up period was 24.9 months. Lateral approach without fibular osteotomy was done with decompression if there was entrapment syndrome and the arthrodesis were accomplished with use of staples for internal fixation. Eleven (85%) of the patients were satisfied with the results. Objectively, the results were excellent after 11 arthrodesis (73%), good or fair after three (20%), and poor after one (7%). There was no nonunion. Complications occurred in 1 patient who developed superficial wound infection, and in 1 patient with staple loosening. Though there was no case of nonunion, the fusion time was rather long. This might have been due to the fixation method because staples can not provide compression force which accelerates union. We believe subtalar arthrodesis is appropriate for isolated subtalar arthritis unless there are associated talonavicular or calcaneocuboid arthritis in which case triple arthrodesis will be more appropriate.

Adult↗
PubMed1994

Lower tibial osteotomy for osteoarthritis of the ankle.

Ankle arthrodesis is still the treatment of choice for most disabling arthritic ankles. But in spite of its popularity, ankle arthrodesis has many disadvantages, including long immobilization, a high pseudoarthrosis rate, and load shift with increased stress on neighboring joints of ankle. Lower tibial osteotomy is one of the methods which attempts to halt ankle arthritis in the intermediate stage and trying to prevent ankle arthroadesis. From Aug. 1989, we performed 8 operations of lower tibial osteotomy in our hospital on intermediate arthritic ankle which included 4 post-traumatic ankle arthritis and 4 ankle osteoarthritis. The patient's ages ranged from 21y/o to 72y/o with an average of 41.6y/o. The mean time of followed up was 31.7 months. The patients were evaluated by the ankle functional scale preoperatively and during their followed up. The average preoperative functional score was 49.6 and the last follow up score was 88.5 which is increasing year by year. Significant improvement occurred in function and pain relief and there was improvement of ankle motion in most patients except one. Complications included late infection in 1 patient and implant failure with subsequent revision surgery due to overcorrection in 1 patient. No nonunion was noted. Although our series was small, we had encouraging short-term results. We believe lower tibial osteotomy, by pressure redistribution on the joint surface, is an alternative for the treatment of ankle osteoarthritis and may save or delay arthritic ankle from the fate of fusion.

Adult↗
PubMed1994

Hallux valgus: soft tissue procedure versus bony procedure.

Hallux valgus is one of the most common fore-foot problem in civilized populations. 49 feet of 33 cases, 8 males and 25 females with an average age of 50 years old, were treated surgically from 1987 to 1992 for hallux valgus and followed up for an average of 47.8 months, comprising 20 feet with McBride's soft tissue procedure and 29 feet of Mitchell metatarsal osteotomy. The clinical criteria for follow up included pain relief, cosmetic out look, shoe wearing comfort, metatarsophalangeal motion etc. 87.5% of the cases in the McBride's group and 95% of the cases in the Mitchell group were satisfied with the clinical results. The immediate post-operative metatarsophalangeal (MP) angle and intermetatarsal (IM) angle were both well corrected, but there was a significantly higher recurrence rate of hallux valgus in the group with the McBride's procedure (P < 0.05). One case in the McBride's group had the complication of hallux varus and one case from the Mitchell group had delayed union. The Mitchell bony procedure has a more stable result compared to the McBride's soft tissue procedure for the correction of moderate hallux valgus, and the modified Mitchell osteotomy is less invasive, easier to perform, easier to care for, and has more satisfactory long-term results.

Adolescent↗