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Biomedical subjects

W H Lo

Publications and source records attributed to W H Lo.

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

A novel magnetite-immobilized cell process for heavy metal removal from industrial effluent.

The sorption and desorption of copper (II) (Cu[II]) ions from the wastewater by magnetite-immobilized cells of Pseudomonas putida 5-x with acidic pretreatment were studied. Pretreating cells with 0.6 N HCl was found to enhance greatly the adsorption capacity of biomass up to 85.6 mg/g and had no significant effect on the loss of P. putida 5-x cells during biosorbent pretreatment. The biosorption capacity to Cu2+ of magnetite-immobilized cells of P. putida 5-x harvested during various growth phases was also investigated. The experimental results illustrated that the adsorption capacity to Cu2+ of P. putida 5-x cultured in sulfate-limiting medium reached maximum during the late stationary growth phase or early death phase, and reached minimum during the log growth phase. The mechanism of copper sequestering by this type of biomass was studied via transmission electron microscopy. A degradation of the peptidoglycan layer of the cell wall was observed in the acidic pretreatment, but no further degradation appeared after the adsorption-desorption cycle. Cu(II) accumulated mostly on the surface of the cell walls and was effectively desorbed by the acidic treatment during the desorption process.

Adsorption↗
PubMed2000

Construction of recombinant Escherichia coli strains for polyhydroxybutyrate production using soy waste as nutrient.

Construction and comparison of recombinant Escherichia coli strains harboring the polyhydroxybutyrate (PHB) operon from Ralstonia eutropha using vectors possessing different promotors, as well as the production of PHB from soy waste by the recombinant strain, are reported. The lac promotor was the most efficient on expression of the phb operon among the three promotors studied: i.e., lac promotor, T7 promotor and the normal sigma 70 promotor. The pKS/PHB was the most efficient plasmid for phb operon expression among the three plasmids used: i.e., pKS-, pAED4, and pJM9131. It was observed that isopropyl-beta-D-thiogalactopyranoside was not required for the induction of the expression of phb operon. The cell dry wt and polyhydroxyalkanoate content by E. coli XL-1 Blue (pKS/PHB) were 3.025 g/L and 27.83%, respectively.

Cupriavidus necator↗
PubMed2000

Treatment of acetabular fractures: 10-year experience.

BACKGROUND: Acetabular fracture is a controversial and difficult fracture to manage. We retrospectively evaluated the outcome of the traditional management of acetabular fractures. METHODS: From 1987 to 1996, 112 cases of acetabular fracture presented at the Taipei Veterans General Hospital and were managed surgically in 73 cases and nonsurgically in 39 cases. The follow-up period was 90 (36-140) months. RESULTS: In the nonsurgically managed group, congruent reduction was achieved in 29 cases (74.3%) and good to excellent functional results were achieved in 25 cases (64.1%). In the surgically managed group, congruent reduction was achieved in 60 cases (82.2%) and good to excellent functional results were achieved in 57 cases (74.3%). In 51 (45.5%) cases, early or late complications developed after management, including one femoral artery perforation, one screw penetration, three wound infections, one iatrogenic sciatic nerve injury, one deep vein thrombosis, 21 heterotopic ossifications, two chondrolyses, three avascular necroses of the femoral head and 18 cases of symptomatic traumatic arthritis. CONCLUSIONS: The functional results correlated well with the final congruity of the joints and the severity of the complications.

Acetabulum↗
PubMed2000

Surgical treatment of full thickness rotator cuff tear in patients younger than 40 years.

BACKGROUND: Full thickness tear of the rotator cuff is a well-known entity in the middle-aged and elderly population and the results of surgical repair are well documented. Rotator cuff tear in patients under the age of 40 years is unusual and the cause and treatment are not well established. The present study reports 12 young patients with full thickness tear of the rotator cuff treated surgically. METHODS: Open anteroinferior acromioplasty and cuff repairs were performed on every patient after failure of nonsurgical treatment. The average follow-up was 59.5 months (range, 36-100 months). RESULTS: The average patient age at the time of surgery was 30.2 years (range, 17-39 years). Symptoms included pain and dysfunction in all patients and weakness in eight patients. The duration of symptoms before surgery ranged from 6 to 60 months (average, 22.8 months). Ten patients were able to return to their preinjury status within an average of 4.5 months (range, 3-9 months) after surgery. Three athletes were able to return to previous levels of competition. Nine patients had excellent functional results with regard to pain, motion, strength, function and satisfaction. Eleven patients were satisfied with the operation and had significant pain reduction compared with their preoperative status. CONCLUSIONS: An acute traumatic event was the etiology of the rotator cuff tears in this study. The results of surgical treatment in this younger group of patients were satisfactory and were comparable to the outcomes reported for surgical treatment of rotator cuff tears in older patients and athletes.

Adolescent↗
PubMed2000

Surgical treatment for peroneal nerve palsy.

BACKGROUND: Peroneal nerve palsy is the most frequently encountered mononeuropathy of the lower extremities. Although many studies advocated spontaneous resolution of peroneal nerve palsy, more recent studies confirmed obvious improvement with surgical treatment techniques. METHODS: This study reviewed the results obtained from surgically treated peroneal nerve palsy in 14 patients who were admitted to our hospital between 1990 and 1996. The patients consisted of 12 males and two females with an average age of 31 years (range, 12-68 years). Peroneal nerve palsy in these patients was caused by direct or indirect injury, as confirmed by clinical examination and electromyography. The status of the nerve was observed for at least 4 months and explored when the nerve failed to reveal evidence of recovery. The nerve was decompressed, repaired or reconstructed by nerve grafting, according to the status of the injury. Weber scales were used to assess the peripheral neuropathies preoperatively and postoperatively. RESULTS: At a mean of 23 months (range, 11-61 months), nerve palsy scores improved from an average of 5 points to 3.14 points. Despite the small number of patients, our results indicated that the time interval between onset of injury and date of surgical treatment (p < 0.05) was the most significant factor to influence the prognosis of surgery. Results obtained from surgery were not related to the method of treatment, length of nerve graft or mechanism of injury. CONCLUSIONS: Because peroneal nerve palsy does not always resolve spontaneously, this study favored early surgical exploration for peroneal nerve dysfunction, based on at least 4 months of follow-up.

Adolescent↗
PubMed1999

[Linkage studies of a familial spastic paraplegia pedigree from Tibet].

OBJECTIVE: To study the location of disease-related gene in a hereditary spastic paraplegia family with autosomal dominant inheritance in Tibet. METHODS: The AD-HSP family in Tibet was analyzed by linkage studies using 9 highly polymorphic microsatellite DNA markers at three chromosomal regions. RESULTS: The maxium Lod- Score of D14S264 was 0.5163(theta=0.05); of D14S75, 2. 1072 (theta=0);+D14S69, 0.2840 (theta=0.10); of D14S266, 0.9311 (theta=0);of D14S66, 0.7991(theta=0);OF GABRB3, 0(theta =0.40);of D15S128, 0(theta=0.40); of D2S2255, 0 (theta=0.40);and of D2S2347,0(theta=0.40). CONCLUSION: In this Tibetian family, the disease-related gene is linked to D14S75 locus of SPG3 region.

Female↗
PubMed1999

The influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing.

OBJECTIVE: To investigate the influence of contact alignment of the tibiofemoral joint of the prostheses in in vitro biomechanical testing. DESIGN: An experimental set-up was used to measure the total contact areas of the tibiofemoral joint of the prostheses subjected to a compressive load, and the malalignment situations were simulated. BACKGROUND: The contact alignment of the femoral component related to the tibial component in the literature was not described clearly and the effect of malalignment on the testing method has not been reported well. METHODS: Three commercial knee prostheses (Omnifit, Genesis, and AMK) were used for testing under a compression load (3000 N) at flexion 0 degrees and 10 degrees. After aligning the normal contact alignment, the simulated malalignment was done to evaluate the influence on the total contact areas in these conditions relative to the normal contact alignment. The simulated malalignment includes the medial-lateral translation (0.5 and 1 mm), anterior-posterior translation (2 and 4 mm) and internal-external rotation (1 degrees, 3 degrees and 5 degrees ) of the femoral component relative to the tibial component. RESULTS: The ratios of total contact areas of malalignment relative to normal contact alignment ranged from 1.06 to 0.93 in medial-lateral malalignment in these three prostheses. In anterior-posterior malalignment, the ratios ranged from 0.69 to 0.79 in Omnifit, 0.93-0. 96 in Genesis and 0.96-1.04 in AMK. In internal-external malrotation, the ratios ranged from 0.90 to 1.03 in these prostheses. CONCLUSIONS: This study proposes that contact alignment would affect the contact characteristics, especially in anterior-posterior alignment when high conformity knee prosthesis is tested. The contact alignment must be standardized in the procedure in in vitro biomechanical testing, which will be more objective to evaluate the contact characteristics of different knee prostheses. RELEVANCE: This study revealed the importance of contact alignment of the tibiofemoral joint of the prosthesis in in vitro biomechanical testing. Many published reports of the biomechanical evaluations on different designs of knee prostheses would show different results due to contact alignment. Furthermore, this study indicates that the ideal contact characteristics of the tibiofemoral joint in original design will be changed when the prosthesis under the malalignment condition which was caused by surgery technique or soft tissues imbalance.

Biomechanical Phenomena↗
PubMed1999

An in vitro comparison of the motion behavior of different bipolar endoprostheses.

The relative motion of 3 different bipolar endoprostheses was evaluated in vitro. A paired fresh acetabulum was frozen at 0 degrees C and defrosted 12 hours before the experiment. Three bipolar endoprostheses were evaluated: UNIQHIP system (United Orthopedics), UHR system (Osteonics), and AML system (Depuy). The surface roughness and spherical roundness of outer shells and inner heads of the bipolar prostheses were measured before the experiments. The acetabulum and outer shell of the bipolar prostheses were fixed on a Bionix 858 material testing system axially by separate fixation tools. The axial load of 1,400 N and 2,800 N was than applied on the specimen. The axis was rotated from 0 degrees to 90 degrees at the speed of 1 degree/s. All 3 outer shells were tested to this paired acetabulum randomly and separately. The frictional torque on the outer bearing surface of the different prostheses was recorded by the material testing system. The frictional torque on the inner bearing surface was also measured by the same procedure as was done for the outer bearing. The final results were statistically compared by the 1-way analysis of variance test method. Bipolar prostheses of the UHR system showed the largest frictional torque on outer bearing when it was loaded with 1,400 N and 2,800 N. The final results showed that all the bipolar prostheses had ideal motion behavior when functioning under the loading of 1,400 N. The frictional torque on the inner bearing was found to be larger than the frictional torque on the outer bearing in some prostheses when the loading was increased to 2,800 N. Thus, the bipolar endoprostheses functioned as unipolar prostheses. The only relative motion remained between the outer bearing surface and the acetabulum. This effect causes complications, such as implant protrusion in the acetabulum.

Hip Prosthesis↗
PubMed1999

Treatment of large skeletal defects in the lower extremities using double-strut, free vascularized fibular bone grafting.

This article reports on the use of double-strut, free vascularized fibular grafts to treat six patients with infected nonunion or traumatic bone loss in the femur or tibia after prolonged treatment and multiple operations. The defects were 6-13 cm long. Five patients achieved solid union within 6 months, and one patient required additional cancellous grafting to achieve union at the distal end of the fibula. One patient experienced a stress fracture due to strenuous exercise, and union was achieved 3 months after reapplying an external fixator. Although three patients had some restricted knee motion, all patients had a satisfactory outcome in regard to walking, and no limb-length discrepancies were noted in any patient.

Adult↗
PubMed1999

Percutaneous A1 pulley release for trigger digits.

BACKGROUND: Recently, percutaneous trigger digit release has been reported as a safe, effective office procedure. The purpose of this study was to further assess the safety and efficacy of this technique. METHODS: From November, 1996, to August, 1997, 69 consecutive patients with 71 primary trigger digits were treated with percutaneous A1 pulley release. The operations were performed using the tip of a 19-gauge needle, mounted on a 3-ml syringe. The mean age of the patients was 66 years. The mean duration of follow-up was 21 weeks. The patients were prospectively classified into two groups according to age, sex, digit involved, duration of symptoms and whether or not they had had previous local steroid injection. RESULTS: Sixty-three digits were completely free of triggering. Residual triggering or inadequate release was found in eight digits at final follow-up. The success rate was not associated with sex, age, digit involved, duration of symptoms or history of local steroid injection. No major complications were found in this study, but minor complications included persistent local tenderness in nine digits and subcutaneous hematoma in six digits. Risk factors related to persistent local tenderness were female gender and trigger thumb. CONCLUSIONS: Percutaneous A1 pulley release is an effective, safe and convenient procedure for the treatment of trigger digits.

Adult↗
PubMed1999

Vascularized iliac bone graft for displaced femoral neck fractures in young adults.

From November 1989 to September 1994, a total of 26 patients (18 men and 8 women) with acute displaced femoral neck fractures were treated with closed reduction and Knowles pinning combined with vascularized iliac bone grafting. Mean patient age was 37.5 years (range: 24-48 years). The mean time interval from injury to surgery was 3.6 days (range: 1-10 days). One patient experienced loss of the reduction at 6 weeks postoperatively and subsequently went on to hip replacement. Mean follow-up for the remaining 25 patients was 56.2 months (range: 20-78 months). All fractures united within 4 months. The average union time was 3.3 months. Plain radiographs confirmed the presence of avascular necrosis in 2 patients during the final follow-up; 1 of these patients developed systemic lupus erythematous 1 year after the fracture and had been treated with high doses of corticosteroid. Functional and radiographic results were satisfactory in the remaining patients.

Adult↗
PubMed1999

Salmonella infection in total hip replacement--report of successful reimplantation and review of the literature.

A case of Salmonella enteritidis group C infection following total hip replacement was treated by resectional arthroplasty and appropriate antibiotics. Total hip replacement with reimplantation of an antibiotic-impregnated cemented hip prosthesis was performed five months later. The postoperative course was smooth and hip function was good, without any sign of infection recurrence throughout 10 years of follow-up. The treatment protocol and clinical results are discussed along with a review of the literature.

Arthroplasty, Replacement, Hip↗
PubMed1999

AO fixateur interne in treating burst fractures of the thoracolumbar spine.

BACKGROUND: A burst fracture of the thoracolumbar junction is an unstable spinal fracture, which is caused by high-energy trauma. There are many methods of treatment, both surgical and nonsurgical, in dealing with spinal burst fractures. The Arbeitsgemeinschaft für Osteosynthesefragen (AO) Fixateur Interne (FI) system was introduced in 1985 for posterior spine surgery with a transpedicular screw system. METHODS: From April, 1989, through December, 1994, we encountered 42 patients with 42 acute burst fractures of the spine; 26 were male and 16 were female, with an average age of 41.2 years. One fracture occurred on T11, seven on T12, 16 on L1, 11 on L2, one on L3, four on L4 and two on L5. According to the Denis classification, there were eight type A, 23 type B, five type C, three type D and three type E fractures. All of these patients received posterior reduction without decompression, posterior short segmental fixation with AO FI instrumentation and posterior fusion. RESULTS: After follow-up for an average of 66.1 months, all fractures were found to have united with residual back pain in only six patients; five patients, including one with nonunion, had back pain without the necessity of medication, and the other one had occasional back pain that was well controlled by medication. The immediate postoperative Cobb's angle improved by an average of 14.2 degrees, and there was an average loss of 3.3 degrees at final follow-up. All patients were neurologically intact at final follow-up except two patients, who were Frankel D. Seven patients had complications during follow-up; one experienced nonunion; four experienced screw breakage, one had screw pullout, and the other experienced breakage of the connecting rod. CONCLUSIONS: From our retrospective study, the outcome of burst fracture of the spine treated with AO FI instrumentation system was satisfactory.

Adult↗
PubMed1998

Vascularized iliac bone graft for treating avascular necrosis of the femoral head.

BACKGROUND: Nontraumatic avascular necrosis of the femoral head (ANFH) is a common disorder causing disability of the hip joint. The means for optimally treating this disease are still controversial. In this study we evaluated the relatively new technique of vascularized iliac bone grafting for treating ANFH. METHODS: From March 1990 to March 1992, 17 hips (15 patients) with ANFH were treated using the vascularized iliac bone grafting technique in our hospital. The patients included 12 men and three women, with an average age of 38 years. Steinberg's classification was used to categorize the severity of hip disease. The clinical results were classified as excellent, good, fair and poor according to symptoms, hip function and roentgenographic changes after surgery. Life-table analysis was applied to assess graft survival and the log rank test was used to compare statistical differences between the steroid-related and nonsteroid-related groups. RESULTS: Cumulatively, 16 hips (14 patients), excluding one patient (one hip) lost to follow-up, were clinically evaluated for an average of 68 months. Among 12 hips at Steinberg stage II, eight progressed to stage IV, three to stage III and only one remained at stage II. Although most hips at stage II showed mild to moderate disease progression on plain radiography, 58% of the hips (7/12) that progressed to less than IVb showed good to excellent results. In the three hips at stage III, one progressed to stage IVa and two to stage V. In the two hips at stage IV, one remained at stage IV at final follow-up and the other was lost to follow-up. The steroid-related and nonsteroid-related groups did not differ with respect to clinical results. Both groups had 63% (5/8) good to excellent results (p > 0.05, log rank test). Only four hips were converted to prosthetic arthroplasties at final follow-up. Overall, 63% (10/16) of the hips had good to excellent results, 12% had fair results and 25% had poor results. Graft survival after seven years of follow-up was 63%. CONCLUSIONS: While treatment of ANFH still poses a challenge to orthopedic surgeons, the vascularized iliac bone grafting technique is a clinically acceptable option for treating the early stages of ANFH.

Adult↗
PubMed1998

Heterotopic ossification after cemented or uncemented bateman bipolar hemiarthroplasty.

BACKGROUND: This is a retrospective study to evaluate the incidence of heterotopic ossification (HO) in cemented and uncemented femoral neck fractures treated with Bateman bipolar hemiarthroplasty. METHODS: From October 1985 to July 1990, there were 451 cases of displaced intracapsular fractures of the femoral neck treated with Bateman bipolar hemiarthroplasty (261 uncemented vs 190 cemented) at the Veterans General Hospital-Taipei. RESULTS: After an average follow-up of 46 months, there was more HO in the cemented group than in the uncemented group (p = 0.014, chi-squared test). The average surgical time was approximately 20 minutes longer and the average blood loss was approximately 160 ml more in the cemented Bateman bipolar hemiarthroplasty group. CONCLUSIONS: HO formation is more common in cemented Bateman bipolar hemiarthroplasty than in the uncemented procedure. The incidence of HO is not related to age or sex.

Arthroplasty, Replacement, Hip↗
PubMed1998

Acute closed humeral shaft fractures treated with dynamic compression plate.

BACKGROUND: To define the efficacy of dynamic compression plates (DCPs) for the treatment of closed humeral shaft fractures. METHODS: A total of 165 patients with closed humeral shaft fractures were studied retrospectively. There were 120 patients who underwent open reduction and internal fixation with DCPs and no bone grafting (BG). Forty-five patients received the same procedures with BG. The mean follow-up period was 93 months. RESULTS: In the DCP without BG group, the average blood loss was 350 ml, operation time was 105 minutes, hospital stay was 8.5 days and fracture union time was 13.5 weeks. In the DCP with BG group, the average blood loss was 525 ml, operation time was 115 minutes, hospital stay was 7.9 days and fracture union time was 9.2 weeks. CONCLUSIONS: In our experience, DCPs are effective for surgical fixation of humeral shaft fractures. Prophylactic BG is recommended for cases with more comminution.

Adolescent↗