Biomedical subjects

T K Liu

Publications and source records attributed to T K Liu.

At least 73 records · Page 4Linked to original sources

PubMed1992

Glycocalyx production and adherence of Staphylococcus to biomaterials.

Glycocalyx is suggested to play an important role in the pathogenesis of biomaterial-centered infection. Using an accurate and sensitive method to quantify glycocalyx and bacterial adherence, we have demonstrated that the producer of the most glycocalyx also exhibited the highest adherence index, whereas low producers exhibited the least (p less than 0.01). Additionally, at various concentrations the high producer had the greater tendency to adhere and grow on stainless steel wires and tubes (p less than 0.001). The adherence index, referred as the ratio of tritiated thymidine uptake on wires to colony forming units (CFU), was also the highest in high producers. The adherence index increased as the glycocalyx index increased. It was suggested that glycocalyx production enhanced the adherence of Staphylococcus epidermidis to biomaterials and caused persistent and intractable infections. In short, the glycocalyx index and the adherence index can be reliable indices of biomaterial-centered infection.

Bacterial Adhesion↗

PubMed1992

The effect of lasers on glycocalyx production by staphylococcus.

The present study was undertaken to evaluate the effects of lasers on glycocalyx production by Staphylococcus epidermidis. Three strains of S. epidermidis were irradiated (He-Ne, Ga-As, CO2, and argon laser) at different energy densities ranging from 0.24 to 100 J/cm2. The viability of the bacteria was measured by colony forming units (CFU) and glycocalyx production was quantitated by toluidine blue staining and spectrophotometer. The He-Ne, Ga-As, and Co2 laser (2W; 90 J/cm2) had no effect on glycocalyx production and CFU, when compared to the control group (p greater than 0.05). However, glycocalyx production by the high-producer strains of S. epidermidis was significantly suppressed by agron laser when compared to the control group (p less than 0.05). It was concluded that the agron laser is a potentially advantageous mean of inhibiting the glycocalyx production by S. epidermidis.

Glycoproteins↗

PubMed1992

[Meniscal repair with autogenous periosteum and fibrin adhesive system].

It is well recognized that meniscal tear in the avascular portion is difficult to heal. The purpose of this study is to evaluate the ability of periosteum and fibrin adhesive system (FAS) in promoting the meniscal repair in the avascular zone. Full-thickness defects of 1 x 3 mm were created in the avascular portion of lateral menisci in adult mongrels. The control menisci were left without any treatment. The experimental defects were either repaired with autogenous periosteum or the combination of periosteum and FAS. Histologic and ultrastructural evaluation of the reparative tissue were compared at 4, 8, and 16 weeks postoperatively. The reparative tissue in the control group remained fibrous even at week 16, whereas that in the grafted and graft/FAS groups resembled normal adjacent fibrocartilage. Moreover, the regenerated chondrocytes in the graft/FAS group appeared more mature than those in the grafted group. Our results suggest that periosteum is a potential source of primitive cells from which chondrocytes could be differentiated and developed during the reparative process of meniscal fibrocartilage. As to FAS, it not only acted as a hemostatic agent and a fixant, but also could indirectly accelerate the chondrogenesis of periosteum in the meniscal defects. It is sufficient to conclude that the combination of periosteum and FAS in promoting meniscal defects or severe tears in the avascular portion bears its potential in future clinical application.

Animals↗

PubMed1992

Bilateral severance of thumbs: report of two cases.

Management of hand injuries is a common practice but bilateral amputation of thumbs is very rare. We report on two cases of both thumbs amputated by a similar machine. In case 1, the man's left thumb was closed with a composite skin graft because the severance was through the middle of the nail. A wrap-around procedure was performed to reconstruct the right thumb which was infected after a primary V-Y advancement flap. The final results were acceptable. Replantation of detached thumbs, if possible, achieves the best functional recovery, which was well demonstrated in Case 2. Although the interphalangeal joints were arthrodesed, the patient was greatly satisfied with the results because of excellent appearance, adequate strength and nearly normal sensation. Prevention of bilateral thumb injuries is important. The paper-cutting machine on which these accidents occurred should be improved in order to prevent further similar catastrophes.

Adult↗

PubMed1992

Calcaneocuboid joint deformity in clubfoot.

In the management of congenital clubfoot, recent attention has been given to the deformity of the calcaneocuboid joint in addition to the changes in the talonavicular, talocalcaneal and ankle joints. Fifty-five patients with 86 clubfeet operated on in the past six years were retrospectively studied. Radiographically, the calcaneocuboid subluxations were graded from I to IV by the Thoemtz classification. The grading has some correlation with the gross deformity, although there is no statistical data to confirm it. Postoperatively, those with grade I feet seemed to have satisfactory results with a posterior release only or with a posteromedial release. Grade II-III feet generally required extensive posteromedial and lateral release. Those who had a calcaneocuboid release and reduction obtained better correction than those who did not. We conclude that calcaneocuboid subluxation should be appraised preoperatively and reduced during surgery in order to achieve good results.

Calcaneus↗

PubMed1992

Management of bony defects in open grade III fractures.

Early soft tissue reconstruction is recommended in treating open grade III fractures. Yet, there are still controversies regarding the way to handle bony defects when the soft tissue reconstruction is completed. This is a retrospective study to evaluate various methods of treating bony defects after soft tissue reconstruction in open fractures. From May 1985 to June 1988, we experienced 16 cases of open grade III fractures of the extremities with bony defects which received either local treatment with flap transfers (five cases) or free flap transfers (11 cases). The bony defects ranged from 3 cm to 10 cm in length. Cancellous bone grafting was performed in nine cases, and two of them received internal fixation at the same time. Seven cases received vascularized bone grafts (six fibulas and one iliac bone). Our results showed that bone grafting, with either a conventional cancellous bone graft or a vascularized bone graft, is useful in treating bony defects after soft tissue reconstruction. Internal fixation of the fractures after removing an extraskeletal fixator has the disadvantages of soft tissue breakdown and of possible infection. Early posterolateral bone grafting was beneficial if a cancellous bone graft was used on the tibia. Double free tissue transfers were quite useful, and we did not lose any free tissue transfers in our series. Vascularized bone grafts should be considered in cases where the osseous gap is greater than 6 cm, or where the recipient bed is bad.

Adolescent↗

PubMed1992

Surgical treatment for Perthes disease at risk.

The treatment of Perthes disease has remained controversial ever since the disorder was first described in 1910. It is generally accepted that surgical treatment is favorable if the patients are at risk clinically or radiologically. From March 1983 to March 1988, 13 patients suffering from severe Perthes disease were treated surgically at the National Taiwan University Hospital. There were 12 boys and one girl with an average age of eight years and eight months (ranging from five years and 10 months to 12 years and one month). They were all at risk either clinically or radiologically. All patients suffered from hip pain, limping and limited range of motion, except one who was pain-free. All femoral heads were classified as Catterall group III or IV, and had at least two radiologic risk signs. After nonsurgical treatment for an average duration of 13 months, including bed rest, traction and bracing as inpatients or outpatients, operations, including varus derotational osteotomy of the femur in three, Salter innominate osteotomy in one, combined surgery in three and triple innominate osteotomy in six patients, were performed. After following up for 36 months, we determined that surgical containment for Perthes disease can achieve satisfactory results. In our preliminary report, triple innominate osteotomy was one of the relatively simple and effective procedures.

Child↗

PubMed1992

A dynamic study of the ankle-foot complex.

A kinematic study of the ankle-foot complex in 19 healthy volunteers was performed using computerized radiocinematography. We found that the instant centers of rotation of the ankle joint fell closely within the talus in the sagittal plane. When the ankle joint moved, the talus, the calcaneus and the navicular bone performed different excursions. Except for the movement in the sagittal plane, the calcaneus assumed eversion in dorsiflexion and inversion in plantar flexion when the ankle moved in an open kinematic chain (under non-weight-bearing conditions). In a closed kinetic chain movement (under weight-bearing conditions), the lower leg exhibited internal rotation, and the talus moved plantarward when the ankle was dorsiflexed. The internal rotation of the lower leg did not cause a slippery rotation of the foot on the surface, but rather it was converted into eversion of the calcaneus in the frontal plane.

Adolescent↗

PubMed1992

Bizarre parosteal osteochondromatous proliferation of the phalanx: report of a case.

The bizarre parosteal osteochondromatous proliferation of the hand and foot is a benign lesion which occasionally may mimic osteochondromas, chondrosarcomas or osteosarcomas clinically, radiologically and histopathologically. This rare benign entity should be recognized in order to avoid unwarranted destructive therapy. The authors report a case of this disease and discuss the differential diagnosis and the relevant features of this disease entity. A 27-year-old female patient suffered from a painful swelling at the proximal middle phalanx of the right middle finger for five months. The lesion was excised but the residual lesion developed a distinct parosteal growth by radiologic studies one-and-a-half years later. The patient underwent reexcision of the lesion twice. No recurrence was noted 11 months following the last excision. Histopathologically, the first specimen contained bizarre chondrocytes. The recurrent nodular tumors, submitted in the second and third operations, were composed of cancellous bone with fatty marrow and a few marrow elements, and focally capped by cartilage. The adjacent soft tissue contained proliferating fibrous tissue. The osteochondral junctions in the latter two specimens were irregular. We believe that the documentation of this tumor at different stages of development has helped in the further understanding of this rare entity.

Adult↗

PubMed1992

[Preliminary study of cartilage repair with autologous periosteum and fibrin adhesive system].

The potential surgical transplantation with autogenous periosteal grafts and Fibrin Adhesive System (FAS) was attempted in a rabbit model. The grafts were taken from the tibia, transplanted and fixed with FAS to artificial full-thickness (0.4 x 0.3 cm) defect on the femoral condyle. Histologic and ultrastructural findings revealed chondrocyte regeneration in the control, grafted, and graft/FAS treated group at week 6; however, chondrogenesis of the reparative tissue was best demonstrated in the graft/FAS group. At week 12, the interface between the reparative tissue and the surrounding tissue was invisible in the FAS/graft group, as compared with the well-defined interface in the grafted group and the control. The results strongly suggest that FAS-treated periosteal transplant is a potential model for the repair of articular cartilage defects. Although the results are preliminary, all seem promising in the clinical aspects.

Animals↗

PubMed1992

Experimental structural scoliosis in rabbits.

Structural scoliosis was produced by purely posterolateral mechanical tethering of the spine with ligation of the scapula to the opposite pelvic bone in rabbits during the growing period. It is a simple and easy method without direct trauma to the spine. When the tethering force occurred discontinuously or only in the coronal plane by drawing of the scapula to the ipsilateral pelvic bone in 17 rabbits, spinal deformity could not be produced. The model provided evidence of biplanar deformity as one of the initial factors for the development of structural scoliosis.

Animals↗

PubMed1992

Preliminary studies of duration and intensity of ultrasonic treatments on fracture repair.

Bone formation of fractured fibulae stimulated by ultrasound was evaluated with roentgenography and fluorochromes labelling. The fibulae of male New Zealand rabbits were fractured to create a 3 mm-gap. Ultrasounds at 0.5 or 1.0 W/cm2 were applied for various durations, 5, 15, and 25 min/day for 4 weeks. Ultrasonic treatments at 0.5 W/cm2, 1.5 MHz significantly accelerated bone formation at the fracture site for all durations, whereas the higher intensity at 1.0 W/cm2 suppressed the bone formation of the treated fractured fibula. Ultrasounds at 0.5 W/cm2 were stimulatory to fracture repair, if given for 15 min/day, and were recommended for future clinical trials. However, ultrasounds at the intensity of 1.0 W/cm2 were deleterious to the treated fracture and not recommended for clinical trials.

Animals↗

PubMed1992

Ultrasonic effect on fracture repair and prostaglandin E2 production.

Ultrasound has been recently recognized of its potential in promoting fracture healing. However, its effects on bone healing remain unclarified. The present study was initiated to compare the effects of frequency on fracture healing and the possible role of endogenous prostaglandin E2 in fracture healing stimulated by ultrasound. Histologic evaluation of callus formation with labelled fluorochromes indicated that the use of ultrasound at 1.5 MHz was most effective in accelerating bone healing. In addition, at this frequency, the endogenous PGE2 level was significantly elevated, which paralleled the accelerated bone healing. It is suggested that bone healing stimulated by ultrasound may be mediated via the production of PGE2.

Animals↗

PubMed1992

Evidence for eicosanoids within the reparative front in avascular necrosis of human femoral head.

Eicosanoids, including prostaglandins and leukotrienes, are important mediators of inflammation. To observe inflammation after necrosis, the histology and the changes of eicosanoid levels were compared in the subchondral cortex and spongy bone of femoral head of sixteen patients with Ficat III or IV idiopathic avascular necrosis (AVN). Neither inflammatory cells nor elevation of eicosanoid levels were observed in the necrotic subchondral cortex or osteochondral junction, whereas infiltration of lymphocytes and plasma cells, fibrosis, and fat emboli were present in the reparative front of necrotic spongy bone. Biochemical analysis in this region revealed significant increases of prostaglandin E2 (PGE2), 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha), thromboxane B2 (TXB2), leukotriene B4 (LTB4), and LTC4. The increased eicosanoids due to initial necrosis become aggravating factors by increasing vascular permeability, which leads to marrow edema and intraosseous hypertension; it ultimately develops into a cycle of inflammation and AVN.

Femur Head Necrosis↗

PubMed1991

Absorption of lidocaine following topical application in microvascular procedures on rabbits.

Fifty rabbits were used to investigate the absorption of lidocaine following its topical application to blood vessels. The lidocaine level in the blood was determined by gas chromatography and the enzyme immunoassay. Animals were divided into five groups according to anatomic site (femoral vs iliac) and according to whether vessels were intact or anastomosed. In the last group (E), a water-tight sleeve was placed on the anastomosed femoral artery so that the lidocaine contacted only a small segment of the artery. In each group, 0.4 and 1 ml of 10% lidocaine were used. Our results revealed that absorption of lidocaine from topical usage was rapid. The absorption peak occurred within 5-15 min. The serum concentration of lidocaine was significantly higher in groups with intact vessels than in those with anastomosed ones. The peak level of lidocaine in the serum occurred sooner in the iliac area than in the femoral area. Absorption in group E was very low due to only a small segment of the artery being immersed with lidocaine. The main absorption site of lidocaine was not through the vessel but through the perivascular area. Toxicity may develop clinically if a high concentration of lidocaine is applied on a vessel during microsurgery.

Absorption↗

PubMed1991

Surgical management of resistant idiopathic congenital clubfoot.

For neglected clubfeet or clubfeet resistant to conservative treatment, there is an increasing tendency towards early and tailored release. From November 1983 to November 1987, we operated on 37 children with 53 neglected or resistant clubfeet which included 23 with limited release and 30 with radical release. Their ages ranged from 4 months to 8 years with an average age of 1 year 5 months. Operative treatment was indicated if the clubfeet had been neglected or had shown no corrective change after 12 weeks of intensive plaster treatment. We used the Cincinnati incision for one-stage release. The average follow-up was 3.5 years (range 2-5.5 years). Evaluation criteria included physical, functional and roentgenographic findings. The results were good or excellent in 96% of the feet based on the modified Magone rating scale. There was no significant difference in the operation results between different age groups. Both the limited and the radical release groups had a high rate of satisfaction. The limited procedure only effectively improved the tibio-calcaneal angle to a significant degree (p less than 0.01), while the radical operation changed every angle significantly (p less than 0.01). Complications included calf muscle atrophy in 4 feet, overcorrection in 3 feet, undercorrection in 3 feet, superficial skin necrosis in one foot, pin tract infection in one foot and residual metatarsal adductus in one foot. In conclusion, neglected or resistant clubfeet can be treated by early and adequate release with a high rate of success. Complications can be avoided by a thorough understanding of their pathoanatomy and by a meticulous surgical approach and release.

Child↗

PubMed1991

Additive effects of prostaglandin E2 and pulsed electromagnetic fields on fracture healing.

Bone formation of fractured fibulae stimulated by pulsed electromagnetic fields (PEMF), PGE2, and combination of both was assessed with roentgenography and fluorescent labelling compounds, tetracycline, xylenol orange, and calcein. A total of 72 male New Zealand rabbits was osteotomized by creating a 1 mm-gap at fibulae and randomly divided into 8 groups: one control, one treated with PEMF, three treated with PGE2 of various dosages, and three treated with combined treatments of PEMF and PGE2 of specified dosages. PEMF had positive effects on bone formation. Exogenous PGE2 mimicked the effect of PEMF on linear bone growth. The effect of PGE2 on bone formation or bone remodelling was dose-related (5, 15, 50 micrograms/kg), with 5 micrograms/kg body weight as the optimal dosage in this study. Combination of PEMF and PGE2 exhibited a trend of additive effect on bone formation, especially at 15 micrograms/kg of PGE2. It is hypothesized that PEMF may exert its action on bone healing by increasing the endogenous PGE2. We therefore concluded that external stimulation such as PEMF and PGE2 was beneficial and stimulatory towards bone formation and healing in our animal model. However, the effects were somehow specific in electrical waveforms and dosage. Similar to PEMF, PGE2, therefore, may be a potential agent in promoting bone formation in the clinical treatments of fractures or perhaps non-union.

Animals↗

PubMed1991

Ultrasound can affect bone healing both locally and systemically.

Bone formation of fractured fibulae stimulated by ultrasound was evaluated with roentgenography and fluorochromes labelling. The fibulae of male New Zealand rabbits were fractured to create a 3 mm-gap. A pilot study was performed to determine the treatment interval for fracture healing of the fibula. Ultrasonic treatment at 1.0 W/cm2, 1.5 MHz for 15 min/day significantly accelerated bone formation at the fracture site of the un-treated fibula, but suppressed the bone formation of the directly treated fractured fibula. Subsequent treatments with these specificities showed that ultrasonic treatment on the unoperated fibula also significantly accelerated the bone formation of the contralateral fractured fibula. It was suggested that locally applied ultrasound at the intensity of 1.0 W/cm2 was deleterious to the treated fracture or intact fibula, but simultaneously would stimulate bone formation of the contralateral fibula.

Animals↗