Biomedical subjects

T K Liu

Publications and source records attributed to T K Liu.

At least 55 records · Page 3Linked to original sources

PubMed1993

One-stage correction of neglected congenital dislocation of the hip without preoperative traction.

The value of preoperative traction of a neglected congenital dislocation of the hip (CDH) is a controversial issue. A retrospective study was performed to evaluate the effects of one-stage, total correction without traction used in neglected CDH. From April 1984 to November 1988, 64 patients (74 untreated dislocated hips) were operated upon with one-stage total correction without preoperative traction. Their ages ranged from 1 year 2 months to 8 years 6 months. Forty-five patients (53 hips) underwent open reduction and a Salter's osteotomy. Ten patients (11 hips) had additional femoral shortening. Nine patients (10 hips) underwent open reduction and a triple osteotomy with femoral shortening. With a minimum of two years of follow-up, all of the hips were well contained, except for two hips with subluxation and one hip with redislocation (reduced after a secondary operation). Avascular necrosis of the femoral head was evident in three hips (one in each group). All of the patients without complications functioned well without significant leg length discrepancy. The other patients also performed well after their complications were treated. In conclusion, neglected CDH in patients up to nine years of age can be safely and effectively treated by one-stage, total correction without preoperative traction.

Child↗

PubMed1993

Reappraisal of skeletal tuberculosis: role of radiological imaging.

Skeletal tuberculosis (TB) can present with a broad spectrum of variable clinical manifestations which may cause diagnostic difficulties. To further elucidate these possible diagnostic pitfalls, 14 cases of bacteriologically or histologically proven skeletal TB, which were initially diagnosed otherwise, are reviewed. In five cases with lumbar or midthoracic spinal involvement, concomitant traumatic history and degenerative radiological changes were the main reasons for not suspecting the possibility of skeletal TB. A differential diagnosis between TB and metastatic lesions can be difficult in the very early stage when X-ray images usually have a low contrast and are not sharp. In nine cases with bone and joint involvement, a long-lasting discharging sinus led the clinician to an initial impression of septic arthritis; sometimes concomitant gouty arthritis can mask the clinical manifestations of skeletal TB. In five cases, minor erosive lesions over the peripheral margin of the involved bone were the earliest findings on the plain X-ray films and were overlooked. To facilitate the early diagnosis of skeletal TB and to avoid the possibility of complications in the management of patients, medical practitioners should be familiar with the usual forms of the condition and the wide variety of clinical manifestations.

Adult↗

PubMed1993

Factors affecting knee motion after total knee arthroplasty: a cadaveric study of the collateral ligament.

Many of the factors affecting postoperative knee motion are related to collateral ligament imbalance. In a cadaveric knee model, the center of origin of either the medial or lateral collateral ligament was found to be located at the center of the quarter circle of the posterior femoral condyle. Two distances were identified: OD (from the center of origin of the collateral ligament to the distal tibiofemoral articulation) and OP (from the center of origin of the collateral ligament to the posterior tibiofemoral articulation). The effect of the collateral ligaments on knee motion was demonstrated by stimulating joint line elevation and ligamentous stretching in a cadaveric knee model. In the knee with an elevated joint line without concomitant anterior displacement (OD reduced, OP unchanged), the flexion limit was reduced. When the collateral ligaments were stretched in a knee with constant OD and OP, both the flexion and extension limits were reduced. A correct joint level can be achieved by measuring the OD, OP and the tension of the collateral ligaments during total knee arthroplasty.

Arthroplasty↗

PubMed1993

Effect of patellar thickness on kinematics of the knee joint.

Patellofemoral problems are common complications after total knee replacement. In order to investigate the effect of an increase in the patellar thickness on the kinematics of the knee joint, four intact embalmed cadaveric knee specimens were prepared to control the thickness of the patella and to measure: 1) the excursion lengths of the quadriceps muscles during knee flexion using a linear voltage displacement transducer; 2) patellar tracking and patellofemoral contact pressure using pressure sensitive Fuji prescale film; and 3) patellar movement during knee flexion using an image processing system. As the patellar thickness increased from the original dimension to a 7-mm increment, the excursion lengths of the quadriceps muscle during knee flexion did not vary significantly, but lateral patellar subluxation was clearly demonstrated by an increase in the patellofemoral contact pressure on the lateral femoral condyle and by lateral displacement of the patella. Increased patellar thickness in a total knee replacement is considered to be one of the causes of lateral subluxation. The importance of monitoring the patellar thickness using a patellar cutting jig is stressed.

Biomechanical Phenomena↗

PubMed1993

Long-term results of the Steindler flexorplasty.

Seventy-one consecutive patients were treated with a modified Steindler flexorplasty from 1970 to 1987. The mechanisms of injury and etiologies included 45 motor vehicle accidents, 13 birth injuries, and 13 cases of poliomyelitis. Additional operative procedures included shoulder fusion (45 patients), tendon transfer (20 patients), and wrist tenodesis (3). Follow-up averaged 8.2 years. The outcome was excellent in 32%, good in 47%, fair in 13%, and poor in 8%. Postoperatively, the mean arc of active elbow flexion was 114 degrees; the average elbow extension loss, 28 degrees; the mean active pronation, 74 degrees; and supination, 30 degrees. Wire breakage was found in two cases. Additional tendon transfer of flexor carpi ulnaris to extensor carpi radialis brevis improved the outcomes in the patients without active supination. The modified Steindler flexorplasty provided predictable functional improvement in carefully selected patients with paralyzed upper extremities.

Adolescent↗

PubMed1993

Ununited femoral neck fractures by open reduction and vascularized iliac bone graft.

Neglected femoral neck fractures are frequently complicated with nonunion and avascular necrosis of the femoral head. The treatment is especially difficult in young adults because arthroplasty is not indicated. Five cases of neglected femoral neck fractures in young patients were treated by open reduction and internal fixation with pins. The defect of the femoral neck was filled with a block of vascularized iliac bone graft. After at least two years, the fractures were healed without avascular necrosis of the femoral head. The leg-length discrepancy was corrected in all but one case. The pedicled iliac graft provided a viable bone graft, which maintained the viability of the head and hastened fracture healing.

Adolescent↗

PubMed1993

Estradiol-induced knee osteoarthrosis in ovariectomized rabbits.

Experiments in animals have shown that estrogen is chondrodestructive. The existence of 17 beta-estradiol receptor in rabbit chondrocyte and canine cartilage suggests that estrogen is associated with the development of osteoarthrosis (OA). The increased frequency of knee OA in obese postmenopausal women, who are often associated with hyperestrogenism, suggests a link between estradiol and OA. The pathologic changes induced by nine and 12 weeks of intraarticular injection of high doses of estradiol (0.3 mg/kg body weight/day) and low doses of estradiol (0.06 mg/kg body weight/day) into knee joints of ovariectomized rabbits have been examined. In the high-dose group, loss of condyle surface congruity, thinning, fissuring, and fibrillation of the remaining cartilage surface were observed at Week 9. At Week 12, cartilage erosion extended to the calcified layer, exposing the subchondral bone. Scanning electron microscopy (SEM) further revealed numerous pits, which indicated formation of cysts on the cartilage surface. Injection of low dose estradiol, conversely, did not induce significant pathologic changes. The results demonstrated that the direct interaction of estradiol and rabbit cartilage was dose- and duration-dependent. Pathologic changes from the current animal model of knee OA closely resembled those of knee OA in humans. Thus, this model constitutes a potential tool for further studies of the early pathologic changes of OA and the possible prevention of cartilage degeneration by estrogen receptor inhibitors.

Animals↗

PubMed1992

Estrogen and osteoarthritis: a study of synovial estradiol and estradiol receptor binding in human osteoarthritic knees.

Estrogen appears to be a risk factor in knee osteoarthritis (OA). Results from 21 patients revealed that synovial estradiol level was highly related to the severity of OA. Increased estradiol receptor bindings in the medial compartment of the femoral condylar and tibia plateau cartilages were observed; the increase was significantly higher in the medial than in the lateral compartment (p less than 0.05). Although the synovial estradiol level was significantly lower in women with OA than in men with OA (p less than 0.01), postmenopausal women were hypothesized to be more susceptible to OA, since the possible existence of synovial testosterone might counteract the high estradiol synovial level in men, which results in a lower incidence of knee OA in men than in postmenopausal women. We suggest that excessive synovial estradiol and higher estradiol receptor bindings may be involved in the development of knee OA, particularly in postmenopausal women.

Aged↗

PubMed1992

Osteoarthritis in women: its relationship to estrogen and current trends.

With our expanding knowledge of osteoarthritis (OA) over the years, our concept of this "aging" disease has been re-evaluated to that which is the opposite of traditional views. To clinicians and scientists, OA is no longer the inevitable disease of aging, as one conceptualizes gray hair. Epidemiological studies show a higher incidence of OA affecting polyarticular joints in women than age-matched men, particularly those over the age of 55. This discrepancy in sex difference in the OA incidence highlights the significance of sex hormones and their alterations in menopause. Evidence indicates that this alteration possibly occurs early in adult life and may well persist into menopause. As well, this hormonal perturbation is thought to be consequent to obesity in these women. Both in vivo and in vitro studies suggest that estrogen is chondrodestructive via the receptor-mediated mechanism. The finding of estrogen receptor in canine, rabbit, and human articular cartilage further confirms this hypothesis. Recent findings of elevated synovial estradiol level and higher estrogen receptor bindings in human osteoarthritic cartilage strongly suggest the importance of local uptake of estradiol (E2) and the possible up-regulation of estrogen receptors. Estrogen, like other hypothesized etiologies, is important in the development of OA in women.

Aging↗

PubMed1992

Up-regulation of estrogen receptors in rabbit osteoarthritic cartilage.

The purpose of this study was to investigate the alteration of estrogen receptors in an early stage of estradiol-induced osteoarthritic knees. After 3 weeks of intraarticular injections of estradiol benzoate to both knees in ovariectomized rabbits, the articular cartilages of femoral condyle and tibial plateau were harvested and pooled separately in each rabbit. The cytosolic estradiol receptor was determined by hydroxylapatite-column assay. The receptor levels (fmol/mg protein) were determined by the analysis of specific 3H-labelled estradiol binding data. In the present study, the specific binding to 3H-estradiol in the femoral condyle cartilage of estradiol-treated rabbits was 1.7 fold of that in vehicle-treated rabbits. The difference between them was highly significant (p less than 0.01). On the other hand, estrogen receptors were nondetectable in the tibial plateau of either vehicle- or estradiol-treated rabbits. It appeared that the cytosolic estradiol receptor existed preferentially in the cartilage of the femoral condyle, rather than in that of the tibial plateau. Since a direct link of estrogen to the development of osteoarthritis in rabbit knees was demonstrated as early as 3 weeks, it is suggested that up-regulation of estrogen receptors in cartilage might initiate the osteoarthritic changes.

Animals↗

PubMed1992

Inhibition of estradiol-induced early osteoarthritic changes by tamoxifen.

Previous studies on osteoarthritic changes induced by intraarticular injections of estradiol benzoate (EB) suggest estrogen as a risk factor in the development of knee osteoarthritis (OA). The present study observed the anti-arthritic effects of tamoxifen (TMX). Oophorectomized rabbits were subjected to intraarticular injections of vehicle control, EB, TMX, or EB/TMX for 3 weeks. The cartilage changes were assessed by light and scanning electron microscopic examination, enzyme histochemical analysis, and the amount of alcian blue stain binding to glycosaminoglycans. EB injections resulted in cell necrosis, chondrocyte clonings, and pittings, whereas the vehicle control, TMX, and EB/TMX-injected groups showed no histologic abnormalities. Histochemical analysis showed that the numbers of lactate dehydrogenase (LDH)-reactive chondrocytes in the EB-injected group were significantly reduced when compared to other groups (p less than 0.001). The injections of EB/TMX significantly reduced the chondrocyte numbers in the lateral superficial layer (p less than 0.05), compared with the vehicle injection. TMX-injected group revealed slight although insignificant decreases in chondrocyte numbers. The amount of alcian blue stains, representing the relative amount of proteoglycans, significantly decreased only in the superficial layer of the EB- and EB/TMX-injected groups (p less than 0.05). TMX, when concurrently injected with EB, antagonized the chondrodestructive effects of estradiol at the early stage of knee OA in rabbits. The results suggest the potential therapeutic use of TMX at the early stage of OA.

Alcian Blue↗

PubMed1992

Concentration of plasma calcium in response to human calcitonin in female rats during aging.

The effects of aging and estradiol on the concentration of plasma calcium in response to human calcitonin (hCT) were investigated in rats. Old (20 months) and young (2 months) female rats were catheterized via the right jugular vein and the left femoral vein before an infusion of 1 nM hCT (0.1 ml/min) into the left femoral vein. Young ovariectomized (Ovx) rats were injected subcutaneously with estradiol benzoate (EB, 25 micrograms/kg) or oil once daily for 3 days before hCT challenge. Blood samples were collected from the jugular catheter before and after the hCT infusion. The basal level of plasma calcium was not affected by age. The infusion of 1 nM hCT decreased the plasma calcium concentration by 18% in old and by 29% in young female rats. The post-infusion levels of plasma calcium were comparatively higher in old rats than in young rats (p less than .05 at 30 min and p less than .02 at 90 min). In young rats, the responses of plasma calcium to hCT infusion were reduced after ovariectomy. Short-term estrogen injection, however, did not restore the sensitivity of young Ovx rats to the CT infusion. These findings suggest that the plasma calcium level in response to calcitonin is decreased in rats during aging. The reduction of the hypocalcemic effect of calcitonin in old female rats at least was estradiol-independent.

Aging↗

PubMed1992

Reconstruction of skeletal defects in the femur with 'two-strut' free vascularized fibular grafts.

Large skeletal defects of the femur caused by infected nonunions remain a challenge to orthopedic surgeons. Conventional bone grafting may not succeed when the recipient bed is not ideal. Single fibular grafts were proven very useful in bridging this type of defect, yet were complicated by the high incidence of refracture and the need for protection of long duration. By dividing the fibula into two struts connected by the nutrient vessels, we doubled the effective cross-sectional area of bone grafting with only one set of vascular anastomoses. Five cases of infected nonunion of the femur after a high-energy trauma were successfully managed with this technique. All the fractures healed in an average of 7 months. By 1 year the grafts hypertrophied to the size of the femur. A follow-up of at least 2 years recommends this technique in the management of certain chronic osseous defects of the femur.

Adult↗

PubMed1992

Age-related differences in basal and calcium-stimulated plasma calcitonin levels in female rats.

The effects of aging on calcitonin (CT) secretion in female rats were investigated. Old (24 mo) at constant diestrus status and young (2 mo) at diestrus status rats were either ovariectomized (Ovx) or left intact as controls. Ovx rats were injected subcutaneously with estradiol benzoate (25 micrograms/kg body wt) or sesame oil one time per day for 3 days. All rats were infused with CaCl2 (10 mg/ml) at a rate of 2 ml/h for 30 min via a jugular catheter connected to a peristaltic pump. Blood samples (0.5 ml each) were collected at 0, 30, 60, and 120 min. The basal and post-CaCl2 levels of plasma Ca measured with radioimmunoassay were significantly higher (P less than 0.05-0.01) in old than in young female rats. The pre- and post-CaCl2 levels of plasma Ca and CT in young rats were not altered by Ovx or estradiol replacement. In old rats, Ovx caused a higher (P less than 0.01) level in plasma CT at 0 and 30 min after CaCl2 infusion. Both basal and stimulated levels of plasma CT were higher (P less than 0.01) in old Ovx than in young Ovx rats. These results demonstrated that 1) the increase of plasma CT in response to Ca challenge was greater in old than in young female rats, 2) the influence of estradiol and ovarian function on plasma CT concentration increases as a function of age, and 3) estradiol reduced the plasma CT in response to hypercalcemia in old Ovx rats. The sensitivity of the target tissue of young rats may be lower in response to the modulation of estrogen during hypercalcemia without compromising the secretion and hypocalcemic effect of CT in young rats. All suggested an age-related relationship between estrogen and CT secretion in minute-to-minute regulation during Ca infusion in rats.

Aging↗

PubMed1992

Lymphocyte subsets and mitogen induced proliferation in adjuvant arthritis. Part I. Migration and function of the peripheral T lymphocytes.

Adjuvant arthritis (AA) was used as an animal model of rheumatoid arthritis in this study. Seventy 10-week-old inbred female rats of both Long-Evans rats (LE, high responder of adjuvant arthritis) and Sprague-Dawley rats (SD, low responder of adjuvant arthritis) were inoculated with adjuvant. Using monoclonal antibodies, we demonstrated that redistribution, migration, or an imbalance of T lymphocytes rather than the change of total T cells are involved in the pathogenesis of AA. After the adjuvant injection, the lymphocytic proliferative responses of LE and SD rats to phytohemagglutin (PHA) had no significant difference, whereas the response of LE rats to concanavalin A (ConA) was significantly lower than that of SD rats. In addition, a highly significant positive correlation was found between the absolute numbers of helper T cells and the lymphocytic proliferative response to PHA, and between absolute numbers of suppressor T cells and the lymphocytic proliferative response to Con A. We postulated high responder strain LE would have a defect in suppressor T lymphocytes leading to severe arthritis, while in low responder strain SD, adjuvant-activated suppressor T lymphocytes might reduce the severity of arthritis.

Animals↗

PubMed1992

Lymphocyte subsets and mitogen induced proliferation in adjuvant arthritis. Part II. Changes in function and numbers of lymph nodes T lymphocytes.

To evaluate the effects of lymphocytes on the pathogenesis of adjuvant arthritis (AA), the lymphocytic responses to phytohemagglutinin (PHA) and concanavalin A (Con A) and the percentages of T cell subpopulations were investigated in the inguinal lymph nodes of Long-Evans (LE) rats and Sprague-Dawley (SD) rats after a single injection of complete Freund's adjuvant. The response of LE to PHA increased to its maximum on the 14th day and correlated with the severity of AA. The responses of LE and SD rats to Con A were decreased on the 7th, 11th, and 14th days. Additionally, percentage of suppressor T cells of LE rats was lower than that of SD rats. Significant increases of percentage of helper T cells and of helper/suppressor T cell ratio were observed in LE rats, indicating a decrease or defect in the suppressor T cells in LE rats. In LE, we postulated that helper T cells are involved in the induction of AA, and a defect in the suppressor T cell function or numbers would subject LE to the development of AA. SD rats, on the other hand, with higher suppressor T cell numbers, were less susceptible to AA.

Animals↗

PubMed1992

Lymphocyte subsets and mitogen induced proliferation in adjuvant arthritis. Part III. Numbers and functions of T lymphocytes in spleen.

The changes and the possible roles of splenic T lymphocyte subpopulations in high-responder Long-Evans (LE) rats and low-responder Sprague-Dawley (SD) rats with induced adjuvant arthritis (AA) were investigated. Total splenic T lymphocytes of both strains did not change significantly after the adjuvant injection. However, LE rats exhibited an increase in percentage of helper T cells and helper/suppressor T cell ratio, whereas SD rats expressed a decrease in the ratio with concomitant increase of suppressor T cells. This observation suggested that an imbalance of T lymphocyte ratio not only existed in the peripheral blood as reported by other investigators, but also existed in the spleen of rats with AA. In vitro measurement of phytohemagglutinin (PHA) responses of splenic T lymphocytes revealed an increased PHA response in LE but a markedly decreased PHA response in SD. Both LE and SD rats showed decreased response to concanavalin A (Con A) stimulation. We concluded that PHA response, as an index of helper T cell function, coincided with the development of AA and may be responsible for the immunoregulation of the disease. The increased proliferation of suppressor T cell in SD rats may also be significant in regulating the immune response to AA.

Animals↗

PubMed1992

Morphological and immunocytochemical characterization of osteoblast cultures from long bones of neonatal rats.

The present study reports a successful culture system of rat bone cells obtained from the bare long bone fragments of neonatal Wistar rats. The morphology, histochemical and immunocytochemical properties of the cultured cells were characterized by phase contrast microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), histochemical staining with alkaline phosphatase (ALP), and immunocytochemical staining with the anti-osteocalcin antibodies. Under phase contrast microscopy, the cultured rat bone cells changed their morphology from being slender with relatively-short cytoplasmic processes to becoming polygonal with longer processes, and subsequently flattened. These cultured bone cells formed bone nodules after 3 weeks. Under SEM, the cultured bone cell appeared polygonal with some microvilli. The TEM showed that their cytoplasm contained abundant endoplasmic reticulum and well-developed Golgi apparatus. Positive histochemical staining of ALP was also detected as a blue coloration and granular appearance in the cultured bone cells. Immunocytochemistry with the polyclonal and monoclonal anti-osteocalcin antibodies showed the localization of osteocalcin in both the cytoplasm and nucleus. All these data lead us to consider that the cultured bone cells in our system were probably osteoblasts from growing bone tissue in vitro. This provides a convenient test system for further studies on the regulation of the growth and metabolism of rat bone cells.

Alkaline Phosphatase↗