Biomechanical comparison of three fixation strategies for radial head fractures: a biomechanical study

Second-generation headless compression screws (HCSs) are commonly used for the fixation of small bones and articular fractures. However, there is a lack of biomechanical data regarding the application of such screws to radial head fractures. This study evaluated the mechanical properties of the fixation of radial head fractures using a single oblique HCS compared with those obtained using a standard locking radial head plate (LRHP) construct and a double cortical screw (DCS) construct. Radial synbone models were used for biomechanical tests of HCS, LRHP, and DCS constructs. All specimens were first cyclically loaded and then loaded to failure. The stiffness for the LRHP group was significantly higher than that for the other two groups, and that for the HCS group was significantly higher than that for the DCS group. The LRHP group had the greatest strength, followed by the HCS group and then the DCS group. The HCS construct demonstrated greater fixation strength than that of the commonly used cortical screws, although the plate group was the most stable. The present study revealed the feasibility of using a single oblique HCS, which has the advantages of being buried, requiring limited wound exposure, and having relatively easy operation, for treating simple radial head fractures.

Finite element analysis of coronoid prostheses with different fixation methods in the treatment of comminuted coronoid process fracture

BACKGROUND

Comminuted fractures of the coronoid process significantly compromise the stability and function of the elbow joint. Reconstruction of the coronoid process with a prosthesis has been suggested as an alternative to restore the architecture. The purpose of this study was to investigate the strength and stability of various methods for the fixation of a coronoid prosthesis by finite element analysis.

MATERIALS AND METHODS

A coronoid prosthesis was designed based on the morphological information from computed tomography images acquired from 64 subjects in whom the top 40% of the coronoid process height was replaced. Four methods for the fixation of the prosthesis were suggested: (1) a double 2.0-mm fixation bolt, anterior to posterior; (2) a double 2.5-mm fixation bolt, anterior to posterior; (3) a single 4.0-mm fixation bolt, posterior to anterior; (4) a single 4.5-mm fixation bolt, posterior to anterior. The integrated prosthesis-bone constructs were analyzed via the finite element analysis of 10 simulated proximal ulna models with loading applied along the axis of the humerus and with three different elbow flexion angles (30°, 90°, and 130°). The maximum principal stress and the total deformation were quantified and compared.

RESULTS

A coronoid prosthesis was developed. The maximum principal stress of the fixation bolts occurred around the neck of the fixation bolt. For a comparison of the strengths of the four fixation methods, the maximum principal stress was the lowest for fixation using a single 4.5-mm fixation bolt. The value of the maximum principal stress significantly decreased with increased elbow flexion angle for all fixation methods. The maximum deformation of the fixation bolts occurred at the head of the fixation bolt. For a comparison of the maximum deformations in the four fixation methods, the maximum deformation was the lowest for fixation using a single 4.5-mm fixation bolt. The value of the maximum deformation significantly decreased with increased elbow flexion angle for all fixation methods.

CONCLUSIONS

The present study suggested that fixation of a coronoid prosthesis with a single 4.5-mm fixation bolt from posterior to anterior is an excellent option in terms of the strength and stability. Level of Evidence Experimental study.

A novel low-profile external skeletal fixator for type IIIB open tibial fractures: A biomechanical and clinical pilot study

BACKGROUND

Although external fixator is standard for managing staged treatment of open tibial fracture, the main disadvantage of this device is too bulky to be tolerated by most patients for longtime use. The purposes of this pilot study were to compare the biomechanical properties of a novel low-profile external fixator (LP-ESF) with a traditional ESF and also to evaluate its performance in patients with Gustilo type IIIb tibial open fractures.

METHODS

A prospective clinical pilot study started from January 2015 to December 2017, and 18 patients with Gustilo type IIIb open tibial fractures underwent the fixation with a novel LP-ESF system. The biomechanical properties of the LP-ESF were compared with the Synthes External Fixation System according to the standard ASTM F1541-02. These patients were divided into two groups according to the size of bony defect. The postoperative clinical outcomes were subsequently collected.

RESULTS

The biomechanical properties of the LP-ESF were comparable with those of Synthes External Fixation System and had an improved the axial/torsional stiffness and ultimate strength. In the clinical study, all patients with LP-ESF had fracture union. The duration of application of LP-ESF was 3.5 to 18 months until fracture union. In 10 of 18 patients, their fractures were immobilized with the LP-ESF until bone union, and no pin tract infection and no chronic osteomyelitis were recorded. The 36-Item Short Form Health Survey life quality and health survey were good to excellent in these patients. Notably, the LP-ESF allowed a patient with severe bone and soft-tissue defects to preserve the leg and joints function.

CONCLUSION

In this study, we found that the novel LP-ESFs had improved clinical outcomes. The long-term LP-ESF application seems to be tolerable in our patients. This novel approach permits better controls in deep infection and faster healing of fractures, and thus may provide a viable alternative treatment for Gustilo type IIIb open tibial fractures.

Prediction of the Size of the Fragment in Comminuted Coronoid Fracture Using the Contralateral Side: An Analysis of Similarity of Bilateral Ulnar Coronoid Morphology

OBJECTIVE

To evaluate the morphological similarity of bilateral coronoid process.

METHODS

A total of 128 sets of computed tomography images of bilateral coronoid process from patients between January 2015 and December 2016 were acquired for three-dimensional reconstruction to generate a coronoid process model. The patients were aged between 31.4 ± 9.3 years. The upper 40% of the coronoid process was trimmed as targeted fragment for morphological analysis. The height, length, width as well as the radius of the medial and lateral facet of the targeted fragment were compared in terms of laterality, age, and gender. To evaluate the similarity of the articular surface of the coronoid process, a local coordinate was created and coordinate transformation algorithm was developed to realign the bilateral coronoid process for the following matching. Then Delaunay triangulation was introduced for calculation of the area of the articular surface. After matching of articular surface of the upper 40% of bilateral coronoid process, the overlapping area of the articular surface was quantified to assess the similarity in morphology and compared in regard to age and gender.

RESULTS

In this study, the height of the target fragment was 12.40 ± 2.74 mm, which was 12.62 ± 2.06 mm for male patients and 12.13 ± 3.76 mm for female patients (t = 0.94, P = 0.35). The height of the target fragment was 12.79 ± 1.76 mm for patients >40 years and 13.23 ± 3.16 mm for patients <40 years (t = 1.11, P = 0.27). The height of the target fragment of left and right coronoid process was 12.26 ± 3.40 mm and 12.74 ± 2.79 mm (t = 1.15, P = 0.25). The length of the target fragment was 23.81 ± 2.67 mm, which was 23.86 ± 2.11 mm for male patients and 23.76 ± 2.85 mm for female patients (t = 0.23, P = 0.82). The length of the target fragment was 22.92 ± 1.96 mm for patients >40 years and 23.23 ± 2.14 mm for patients <40 years (t = 0.76, P = 0.45). The length of the target fragment of left and right coronoid process was 22.52 ± 2.89 mm and 21.66 ± 3.01 mm, respectively (t = 1.00, P = 0.32). The width of the target fragment was 23.12 ± 1.92 mm on average, which was 23.06 ± 1.54 mm for male patients and 23.19 ± 2.82 mm for female patients (t = 0.33, P = 0.74). The width of the target fragment was 24.82 ± 2.23 mm for patients >40 years and 23.46 ± 3.38 mm for patients <40 years (t = 1.56, P = 0.12). The width of target fragment of left and right coronoid process was 24.42 ± 2.22 mm and 24.47 ± 2.69 mm, respectively (t = 1.31, P = 0.19). The radius of medial facet was 6.44 ± 1.01 mm, which was 6.41 ± 1.39 mm for male patients and 6.47 ± 0.95 mm for female patients (t = 0.28, P = 0.78). The radius of medial facet was 6.82 ± 1.28 mm for patients >40 years and 6.46 ± 0.94 mm for patients <40 years (t = 1.31, P = 0.19). The radius of medial facet of left and right coronoid process was 6.43 ± 1.24 mm and 6.64 ± 1.34 mm (t = 1.60, P = 0.11). The radius of lateral facet was 11.84 ± 3.71 mm, which was 11.61 ± 4.24 mm for male patients and 12.11 ± 3.09 mm for female patients (t = 0.74, P = 0.46). The radius of medial facet was 11.82 ± 3.28 mm for patients >40 years and 12.46 ± 3.94 mm for patients <40 years (t = 1.02, P = 0.31). The radius of lateral facet of left and right coronoid process was 11.97 ± 5.31 mm and 10.29 ± 3.29 mm, respectively (t = 1.70, P = 0.09). The covering percentage of the articular surface of the upper 40% of bilateral coronoid process was 87% ± 12% with the covering percentage as 85.3% ± 14.2% for male patients and 90.0% ± 11.2% for female patients (t = 0.75, P = 0.41). The covering percentage was 88.2% ± 11.7% for patients >40 years and it was 87.4% ± 13.2% for patients <40 years (t = 0.98, P = 0.33).

CONCLUSIONS

The present study suggested that bilateral coronoid process shares high similarity in terms of 3D structure and articular surface morphology, which suggested that the osseous architecture of the coronoid process with comminuted fracture could be predicted by the morphological information of the contralateral side.

Partially threaded headless screw may benefit adequate interfragmentary compression and reduced driving torque for small bone fixation

Headless compression screws (HCSs) are commonly used to fixate small bones and articular fractures. Understanding the biomechanical efficacy of different HCS designs can help surgeons make proper interfragmentary compression when a specific implant is chosen. HCSs with three different central shaft designs (unthreaded, fully threaded, and partially threaded) were studied: the Herbert-Whipple, Mini-Acutrak 2, and headless reduction (HLR). Polyurethane foam blocks were machined with a simulated fracture gap of 0.5 mm and set onto a custom-made jig to simultaneously measure compression force and driving torque during screw insertion. The maximal achievable compression forces and driving torques recorded were 47.4 ± 0.9 N and 145.11 ± 1.65 N mm for the HLR, 50.98 ± 1.29 N and 152.62 ± 2.83 N mm for the Mini-Acutrak 2, and 19.33 ± 1.0 N and 33.4 ± 2.2 N mm for the Herbert-Whipple. Overall, the compression force of the Mini-Acutrak 2 and HLR increased with the torque. Unlike the other screws, the Herbert-Whipple's driving torque increased while the compression force decreased after peak compression force was achieved. The partially threaded shaft design (HLR) demonstrated equivalent biomechanical advantage with the Mini-Acutrak 2 in interfragmentary compression. The HCSs with cone-shaped proximal ends (HLR and Mini-Acutrak 2) maintained their compression force during over-fastening, whereas the unthreaded central shaft of the Herbert-Whipple screw caused it to lose compression force.

Importance of a moderate plate-to-bone distance for the functioning of the far cortical locking system

The far cortical locking (FCL) system, a novel bridge-plating technique, aims to deliver controlled and symmetric interfragmentary motion for a potential uniform callus distribution. However, clinical data for the practical use of this system are limited. The current study investigated the biomechanical effect of a locking plate/far cortical locking construct on a simulated comminuted diaphyseal fracture of the synthetic bones at different distance between the plate and the bone. Biomechanical in vitro experiments were performed using composite sawbones as bone models. A 10-mm osteotomy gap was created and bridged with FCL constructs to determine the construct stiffness, strength, and interfragmentary movement under axial compression, which comprised one of three methods: locking plates applied flush to bone, at 2 mm, or at 4 mm from the bone. The plate applied flush to the bone exhibited higher stiffness than those at 2 mm and 4 mm plate elevation. A homogeneous interfragmentary motion at the near and far cortices was observed for the plate at 2 mm, whereas a relatively large movement was observed at the far cortex for the plate applied at 4 mm. A plate-to-bone distance of 2 mm had the advantages of reducing axial stiffness and providing nearly parallel interfragmentary motion. The plate flush to the bone prohibits the dynamic function of the far cortical locking mechanism, and the 4-mm offset was too unstable for fracture healing.

[The clinical analysis of corneal interface fluid syndrome after Laser lamellar corneal refractive surgery]

Objective: To analysis, the clinical characteristics, refractive changes, and clinical treatment of interface fluid syndrome after laser lamellar corneal refractive surgery. Methods: During Dec. 2010 to Apr. 2016. In total 6 cases(9 eyes), 3 cases were bilateral, 3 cases were unilateral. Five patients were male and 1 was female. The age of the patients ranged from 20 to 29 years was (24.83±4.02) years. Six cases(9 eyes)of IFS were diagnosed at our hospital. The history and complete ophthalmic examination that include Slit-lamp examination, Slit-lamp photography, refraction, corneal thickness measurement, corneal endothelial cell counting, IOP, anterior segment OCT(AS-OCT), exams were recorded. Results: Post-lasik Primary open angle glaucoma was 2 eyes in 1 patient. 1 patient(1 eye)was Posner-Schlossmann Syndrome and 1 patient(1 eye)was iritis after femtosecond laser. Post-small incision lenticule extraction by steroid drops induced elevated IOP were 5 eyes in 3 patients. Slit-lamp exam indicated edematous corneal flap or cap, lamellar haze, interface fluids accumulation. AS-OCT showed obvious interface dark area. The corneal flap or cap thickening and wrinkles, IOP change, diopter myopic shift, Corneal thickening. Conclusions: IFS is a rare but serious complication after Laser lamellar corneal refractive surgery. The main causes are high intraocular pressure and/or dysfunction of corneal endothelium. For patients with high IOP after laser lamellar corneal refractive surgery, follow up should be observed closely. accurate diagnosis by OCT and corneal endothelial cell counting. Early diagnosis, accurate treatment, its prognosis is good. (Chin J Ophthalmol, 2017, 53: 847-854).

Biomechanical effect of different femoral neck blade position on the fixation of intertrochanteric fracture: a finite element analysis

Medial migration or cutout of the neck helical blade has commonly occurred in the treatment of trochanteric fracture of the femur. The position of the helical blade within the femoral head is one of the influencing factors that cause the blade to perforate the intact joint surface; however, the ideal placement of the helical blade is not currently known. A finite element model of a femur/nail construct was utilized to analyze five possible blade positions in the femoral head. Normal strain at the fracture surface, the minimum principal strain in the cancellous bone, and the von Mises stress in the implant itself were calculated and compared between different blade positions. The results showed that a large area of normal compressive strain at the fracture surface was observed in the inferior and posterior blade positions. The volume of cancellous bone strained to yielding in the femoral head and neck was lower for the inferior and posterior positions, whereas it was the highest for the superior position. The inferior and posterior positions had lower von Mises stress in the implant itself. The inferior and posterior positions may be the ideal position for the intramedullary nail with a helical neck blade.

Larger screw diameter may not guarantee greater pullout strength for headless screws – a biomechanical study

Headless compression screws (HCSs) are commonly utilized devices for small bone fracture fixation. The Mini-Acutrak 2 and headless reduction (HLR) screws are the newer version types, in which both have fully threaded and variable pitch design. Specifically, the HLR is characterized by two thread runouts to facilitate implantation. With the thread runouts, the holding strength of the screw may be compromised. To the best of our knowledge, no study has examined the pullout force of the global sizes of a HCS. We sought to determine the pullout strength of the HLR and compare the strength of this screw with that of the Mini-Acutrak 2. Synthetic bone blocks with simulated transverse fractures were used to conduct the tests. Four commonly used sizes of the HLR were examined, and one Mini-Acutrak 2 was employed for comparison. Five screws of each size were tested. The pullout force of all screws that were tested in this study ranged from 45.23 to 233.22 N. The results revealed that the pullout force increased as the screw diameter increased. Interestingly, we found that one small screw outperformed the Mini-Acutrak 2, which has a larger diameter. This study provided extensive knowledge regarding the pullout strength of fully threaded HCSs of different sizes. An unexpected finding is that a small screw has higher holding power than a large one because of its increased number of threads. Therefore, we suggest that the thread number should be a critical consideration for the design of size distribution of HCSs.

Change in collateral ligament length and tibiofemoral movement following joint line variation in TKA

PURPOSE

The primary intent of total knee arthroplasty is the restoration of normal knee kinematics, with ligamentous constraint being a key influential factor. Displacement of the joint line may lead to alterations in ligament attachment sites relative to knee flexion axis and variance of ligamentous constraints on tibiofemoral movement. This study aimed to investigate collaterals strains and tibiofemoral kinematics with different joint line levels.

METHODS

A previously validated knee model was employed to analyse the change in length of the collateral ligaments and tibiofemoral motion during knee flexion. The models shifted the joint line by 3 and 5 mm both proximally and distally from the anatomical level. The data were captured from full extension to flexion 135°.

RESULTS

The elevated joint line revealed a relative increase in distance between ligament attachments for both collateral ligaments in comparison with the anatomical model. Also, tibiofemoral movement decreased with an elevation in the joint line. Conversely, lowering the joint line led to a significant decrease in distance between ligament attachments, but greater tibiofemoral motion.

CONCLUSION

Elevation of the joint line would strengthen the capacity of collateral ligaments for knee motion constraint, whereas a distally shifted joint line might have the advantage of improving tibiofemoral movement by slackening the collaterals. It implies that surgeons can appropriately change the joint line position in accordance with patient's requirement or collateral tensions. A lowered joint line level may improve knee kinematics, whereas joint line elevation could be useful to maintain knee stability.

LEVEL OF EVIDENCE

V.

Biomechanical effect of the configuration of screw hole style on locking plate fixation in proximal humerus fracture with a simulated gap: A finite element analysis

BACKGROUND

Locking plate fixation for proximal humeral fractures is a commonly used device. Recently, plate breakages were continuously reported that the implants all have a mixture of holes allowing placement of both locking and non-locking screws (so-called combi plates). In commercialized proximal humeral plates, there still are two screw hole styles included "locking and dynamic holes separated" and "locking hole only" configurations. It is important to understand the biomechanical effect of different screw hole style on the stress distribution in bone plate.

METHODS

Finite element method was employed to conduct a computational investigation. Three proximal humeral plate models with different screw hole configurations were reconstructed depended upon an identical commercialized implant. A three-dimensional model of a humerus was created using process of thresholding based on the grayscale values of the CT scanning of an intact humerus. A "virtual" subcapital osteotomy was performed. Simulations were performed under an increasing axial load. The von Mises stresses around the screw holes of the plate shaft, the construct stiffness and the directional displacement within the fracture gap were calculated for comparison.

RESULTS

The mean value of the peak von Mises stresses around the screw holes in the plate shaft was the highest for combi hole design while it was smallest for the locking and dynamic holes separated design. The stiffness of the plate-bone construct was 15% higher in the locking screw only design (132.6N/mm) compared with the combi design (115.0N/mm), and it was 4% higher than the combi design for the locking and dynamic holes separated design (119.5N/mm). The displacement within the fracture gap was greatest in the combi hole design, whereas it was smallest for the locking hole only design.

CONCLUSIONS

The computed results provide a possible explanation for the breakages of combi plates revealed in clinical reports. The locking and dynamic holes separated design may be a better configuration to reduce the risk of plate fracture.

Biomechanical comparison of conventional and anatomical calcaneal plates for the treatment of intraarticular calcaneal fractures - a finite element study

Initial stability is essential for open reduction internal fixation of intraarticular calcaneal fractures. Geometrical feature of a calcaneal plate is influential to its endurance under physiological load. It is unclear if conventional and pre-contoured anatomical calcaneal plates may exhibit differently in biomechanical perspective. A Sanders' Type II-B intraarticular calcaneal fracture model was reconstructed to evaluate the effectiveness of calcaneal plates using finite element methods. Incremental vertical joint loads up to 450 N were exerted on the subtalar joint to evaluate the stability and safety of the calcaneal plates and bony structure. Results revealed that the anatomical calcaneal plate model had greater average structural stiffness (585.7 N/mm) and lower von Mises stress on the plate (774.5 MPa) compared to those observed in the conventional calcaneal plate model (stiffness: 430.9 N/mm; stress on plate: 867.1 MPa). Although both maximal compressive and maximal tensile stress and strain were lower in the anatomical calcaneal plate group, greater loads on fixation screws were found (average 172.7 MPa compared to 82.18 MPa in the conventional calcaneal plate). It was noted that high magnitude stress concentrations would occur where the bone plate bridges the fracture line on the lateral side of the calcaneus bone. Sufficient fixation strength at the posterolateral calcaneus bone is important for maintaining subtalar joint load after reduction and fixation of a Sanders' Type II-B calcaneal fracture. In addition, geometrical design of a calcaneal plate should worth considering for the mechanical safety in practical usage.

The effects of implantation of tibio-femoral components in hyperextension on kinematics of TKA

PURPOSE

Implantation of prosthetic tibio-femoral components in hyperextension is a well-established and effective procedure, but whether prosthetic orientation in the sagittal plane has any effects on the postoperative kinematics remains unclear. The purpose of this study is to explore how the aforementioned hyperextension affects knee kinematics.

METHODS

Validated computational dynamic TKA models were established. Based on representative literatures and actual operation specifications, femoral and tibial components were assembled with 0° or 5° of hyperextension. Dynamic data, including the timing of cam-post engagement, anterioposterior femoral translation and tibial axial rotation coupling with knee flexion, were recorded for analysis.

RESULTS

5° of femoral component hyperextension delayed cam-post engagement by an angle of 2°. Nevertheless, a 5° posterior slope of the tibial component resulted in a 38° delay in engagement. Comparing this with the femoral component at the same angle of hyperextension, the tibial component could more evidently assist in the prevention of paradoxical femoral anterior translation and the promotion of tibial internal rotation through early flexion.

CONCLUSION

Tibio-femoral components in hyperextension did significantly alter postoperative kinematics, especially for the tibial component. These results suggest that the degree of tibial posterior slope cutting should be more highly scrutinized intraoperatively.

LEVEL OF EVIDENCE

II.

Mimicking anatomical condylar configuration into knee prosthesis could improve knee kinematics after TKA - a computational simulation

BACKGROUND

Restoration of femoral rollback and tibial internal rotation are two of the major objectives following total knee arthroplasty. Previously, we improved prosthetic knee kinematics by replicating the convexly lateral tibial plateau of intact knee. This study attempted to regain more normal knee kinematics through a posterior cruciate ligament retaining knee, which simultaneously incorporated convexly lateral tibial plateau and anatomical condylar configuration into the prosthesis design.

METHODS

Computational simulation was utilized to analyze motion of three-dimensional knee models. Three total knee systems with consistent convex insert design but with different condylar heights of 0, 2.7 and 4.7 mm were investigated in present study. Magnetic resonance images of the subject were utilized to construct the bone models and to distinguish the attachment sites of ligaments and tendons. The distal femurs were modeled to rotate about designated flexion axes of femoral components, and the motion of the proximal tibia was unconstrained except further activity of flexion/extension. Movements of the medial/lateral condyles and tibial rotation were recorded and analyzed.

FINDINGS

Significant improvements in posterior movement of the lateral condyle and in tibial internal rotation were observed for knee models with different condylar heights, as compared to the knee model with consistent condylar height, when flexion exceeded 100°. Results also revealed that excessive difference in condylar height over anatomical condylar configuration provided no contribution to the restoration of normal knee kinematics.

INTERPRETATION

Replicating the morphology of anatomical condylar configuration of the intact knee into knee prostheses could improve knee kinematics during higher knee flexion.

Clinical presentations of thyroid cancer patients with multiple primary cancers

BACKGROUND

In thyroid cancer patients with multiple primary cancers, primary cancers tend to be more aggressive.

AIMS

We analyzed multiple primary cancers in thyroid cancer patients and determined the differences between the incidence and the characteristics of primary cancers.

MATERIALS AND METHODS

A total of 3070 patients with thyroid cancer underwent a thyroidectomy and follow-up examination at a single medical center. The times of diagnosis of the primary cancers were categorized as antecedent, synchronous, or subsequent to the diagnosis of thyroid cancer.

RESULTS

After a mean follow-up period of 8.8 ± 0.5 yr, the presence of multiple primary cancers was histopathologically confirmed in 163 patients (5.3%). Patients with multiple primary cancers had a lower female-to-male ratio, an older mean age, advanced tumor-node-metastasis (TNM) stage, higher total mortality, and higher therapeutic radioactive iodide (131I) doses than patients without multiple primary cancers. Hematological malignancy and renal cell carcinoma, neither of which are among the 10 most common cancers observed in the general population of Taiwan, were the most common multiple cancers among women and men with thyroid cancer. Patient age, thyroid cancer tumor size, and thyroid cancer mortality in the antecedent, synchronous, and subsequent groups were not significantly different.

CONCLUSIONS

Patients with multiple primary cancers in advanced stages had shorter disease-free survival period after treatment. Thyroid cancer patients with multiple primary cancers should be closely followed up for the occurrence of other secondary cancers in order to improve total mortality.

Influence of post-cam design of posterior stabilized knee prosthesis on tibiofemoral motion during high knee flexion

BACKGROUNDS

The post-cam design of contemporary posterior stabilized knee prosthesis can be categorized into flat-on-flat or curve-on-curve contact surfaces. The curve-on-curve design has been demonstrated its advantage of reducing stress concentration when the knee sustained an anteroposterior force with tibial rotation. How the post-cam design affects knee kinematics is still unknown, particularly, to compare the difference between the two design features. Analyzing knee kinematics of posterior stabilized knee prosthesis with various post-cam designs should provide certain instructions to the modification of prosthesis design.

METHODS

A dynamic knee model was utilized to investigate tibiofemoral motion of various post-cam designs during high knee flexion. Two posterior stabilized knee models were constructed with flat-on-flat and curve-on-curve contact surfaces of post-cam. Dynamic data of axial tibial rotation and femoral translation were measured from full-extension to 135°.

FINDINGS

Internal tibial rotation increased with knee flexion in both designs. Before post-cam engagement, the magnitude of internal tibial rotation was close in the two designs. However, tibial rotation angle decreased beyond femoral cam engaged with tibial post. The rate of reduction of tibial rotation was relatively lower in the curve-on-curve design. From post-cam engagement to extreme flexion, the curve-on-curve design had greater internal tibial rotation.

INTERPRETATION

Motion constraint was generated by medial impingement of femoral cam on tibial post. It would interfere with the axial motion of the femur relative to the tibia, resulting in decrease of internal tibial rotation. Elimination of rotational constraint should be necessary for achieving better tibial rotation during high knee flexion.

Concave polyethylene component improves biomechanical performance in lumbar total disc replacement--modified compressive-shearing test by finite element analysis

Failure of ultra-high molecular weight polyethylene components after total disc replacements in the lumbar spine has been reported in several retrieval studies, but immediate biomechanical evidence for those mechanical failures remained unclear. Current study aimed to investigate the failure mechanisms of commercial lumbar disc prostheses and to enhance the biomechanical performances of polyethylene components by modifying the articulating surface into a convex geometry. Modified compressive-shearing tests were utilized in finite element analyses for comparing the contact, tensile, and shearing stresses on two commercial disc prostheses and on a concave polyethylene design. The influence of radial clearance on stress distributions and prosthetic stability were considered. The modified compressive-shearing test revealed the possible mechanisms for transverse and radial cracks of polyethylene components, and would be helpful in observing the mechanical risks in the early design stage. Additionally, the concave polyethylene component exhibited lower contact and shearing stresses and more acceptable implant stability when compared with the convex polyethylene design through all radial clearances. Use of a concave polyethylene component in lumbar disc replacements decreased the risk of transverse and radial cracks, and also helped to maintain adequate stability. This design concept should be considered in lumbar disc implant designs in the future.

Anatomic-like polyethylene insert could improve knee kinematics after total knee arthroplasty--a computational assessment

BACKGROUNDS

Deficiencies in contemporary posterior crucitate retaining knee included inadequate femoral rollback and insufficient tibial rotation. Current study attempted to restore normal femoral rollback and tibial rotation to facilitate in knee flexion/extension and to achieve appropriate posture at deep knee bending after total knee arthroplasy by mimicking the morphology of convexly lateral tibial plateau of intact knee.

METHODS

Computational simulation was utilized to analyze motion of three-dimensional knee models, including intact, traditionally symmetrical posterior crucitate retaining and newly anatomic-like posterior crucitate retaining knees. Solid bones, attachments of ligaments and tendons of simulation models were reconstructed by magnetic resonance images of the subject. According to the representative literature, the distal femur was modeled to rotate about the specific axes and the motion of the proximal tibial was unconstrained except for the flexion/extension. Movements of the medial/lateral condyles and tibial rotation were recorded and analyzed.

FINDINGS

The newly anatomic-like posterior crucitate retaining knee improved the posterior movement of lateral condyle and tibial internal rotation significantly during full range of flexion. Compared with traditionally symmetrical posterior crucitate retaining knee, the improvements displayed by newly developed posterior crucitate retaining knee in posterior movement of lateral condyle and tibial internal rotation were 11.2mm and 9.3° at full flexion, respectively.

INTERPRETATION

The newly anatomic-like posterior crucitate retaining knee demonstrated that mimicking the morphology of convexly lateral tibial plateau can be expected to restore normal knee kinematics.

Biodistribution study of [99mTc] TRODAT-1 alone or combined with other dopaminergic drugs in mice with macroautoradiography

A 99mTc labeled tropane derivative, [99mTc] TRODAT-1 (2beta-((N,N'-bis(2-mercaptoethyl) ethylene diamino)methyl), 3beta-(4-chlorophenyl) tropane), is a potential dopamine transporter (DAT) imaging agent for the central nervous system. To better understand the binding localization of [99mTc] TRODAT-1 both in the brain and the body, whole-body macroautoradiography (WBAR) was used in this study. The effect of DAT competing drugs, such as levadopa (L-DOPA), N-methyl-2beta-carbomethoxy-3beta-(4fluorophenyl)tropane (CFT, WIN 35,428) and methylphenidate, on the biodistribution of [99mTc] TRODAT-1 were also included in this study. Doses of 150 MBq [99mTc] TRODAT-1 were injected into normal male ICR mice through the caudal veins. For comparison, mice treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), L-DOPA, methylphenidate and CFT, respectively, were also investigated under the similar protocols. One and a half hours after [99mTc] TRODAT-1 injection, the mice were sacrificed. Whole-body autoradiography was performed immediately after sacrifice. Both frontal and sagittal sections showed that the liver and mucosa of stomach had the highest uptake of [99mTc] TRODAT-1. Other binding sites included the periphery of the spinal cord and the epithelium of the intestine. In the brain, autoradiographic imaging obtained from frontal sections showed symmetrical uptakes of [99mTc] TRODAT-1 in bilateral striata. Remaining binding sites include olfactory bulbs, thyroid gland, and salivary gland. The autoradiographic imaging obtained from sagittal sections showed a similar biodistribution. Mice treated with MPTP or L-DOPA showed no significant difference in the uptake of [99mTc] TRODAT-1 in bilateral striata, as compared to those of the control. In CFT or methylphenidate-treated mice, DAT binding sites were almost completely inhibited. These data showed that [99mTc] TRODAT-1 has potential clinical use for neurological investigation, such as Parkinson's and similar diseases.

Prophylactic effect of four prescriptions of traditional Chinese medicine on alpha-naphthylisothiocyanate and carbon tetrachloride induced toxicity in rats

AIM

To study the prophylactic effects of four Chinese traditional prescriptions against experimental liver injury.

METHODS

Liver toxins, alpha-naphthylisothiocyanate (ANIT), and carbon tetrachloride (CCl4) were used to induce acute liver injury. Simo Yin(SMY), Guizhi Fuling Wan (GFW), Xieqing Wan (XQW), and Sini San (SNS) were fed (500 mg/kg, in saline, po) to the rats before toxin administration. All the animals were killed 48 h after toxin insulted. Serum index of liver function and hepatic lipid peroxidation (LPO) were estimated. Histopathological observation was conducted simultaneously.

RESULTS

The rats treated with ANIT exhibited elevations of serum total bilirubin (TBI), alkaline phosphatase (ALP), glutamate-oxalate- transaminase (GOT), glutamate-pyruvate-transaminase (GPT), as well as cholestasis and parenchyma necrosis. In rats, challenged with ANIT, receiving the pre-treatment of prescriptions of SMY, XQW, and SNS, the biochemical and morphological parameters of liver injury were significantly reduced. The increased LPO level in liver tissue, associated with the provoked serum GOT and GPT levels were the salient features observed in CCl4-insulting rats. Pre-treatment of four prescriptions showed a remarkable protective effect, and also was effective in counteracting the free radical toxicity by bringing about a significant decrease in peroxidative level.

CONCLUSION

These recipes ameliorate liver damage induced by both ANIT and CCl4 despite the differences in their mechanisms of injury. Therefore they may be able to exert hepatoprotective effects through more than one mechanism of action because they contained a mixture of anti-hepatotoxic ingredients with mutual reinforcement and assistance.

Pathogenicity and drug susceptibility of the Pasteurella anatis isolated in chickens in Taiwan

A strain of Pasteurella anatis (PA) was isolated from the sinus of an adult leghorn laying chicken with sinusitis, nasal discharge, drop in egg production, and low mortality, symptoms initially thought to indicate infectious coryza. The tiny, smooth, whitish colonies were identified as PA. To compare its pathogenicity with that of commercial broilers, nine groups, 10 birds per group, of 10-day-old broilers were individually inoculated with the strain of PA, Pasteurella multocida (PM), or Escherichia coli (EC) by intravenous, intraperitoneal, intramuscular, or subcutaneous inoculation. The PA was determined to cause the signs, lesions, and septicemic death, which are similar to the symptoms of PM or EC infection. At 1 wk postinfection (PI), the mortality rate was between that of PM and EC infection at 1 wk PI. Twenty antimicrobial-containing discs were evaluated, and the isolate was highly sensitive to cetiofer, amoxicillin, lincopectin, and furazolidone. Furthermore, it was moderately sensitive to tetracycline and enrofloxacin and only slightly sensitive to cephalothin, chloramphenicol, flumequine, nalidixic acid, neomycin, oxolinic acid, streptomycin, and trimethoprim. The PA infection was treated successfully with amoxicillin.

Breast uptake of iodine-131 mimicking lung metastases in a thyroid cancer patient with a pituitary tumour

We report a case of a 44-year-old female thyroid cancer patient with a pituitary tumour. 131I whole body scanning showed a change of chest uptake from a unilateral crescent uptake to a bilateral full breast uptake pattern. Hyperprolactinaemia and a pituitary tumour were diagnosed as a result of observing the 131I breast uptake.

Sonographic features of breast abscesses with emphasis on "hypoechoic rim" sign

BACKGROUND

There are only limited reports on the ultrasound (US) features of breast abscess. The purpose of this paper is to review the US features of breast abscess with emphasis on "hypoechoic rim" sign which is more commonly seen in chronic abscess.

METHODS

In a period of 10 years, 20,998 patients were referred for breast US examinations. Medical records identified 204 patients in whom breast abscess was diagnosed. All patients were examined using high-resolution real-time US scanners. The initial ultrasound reports and hard copy images were all carefully reviewed. The grading of the echogenicity of the abscess was classified from grade 0 to grade 5. The contours of the lesions were described as smooth, macrolobulated, microlobulated, irregular, zigzag, spiculate or indistinct. The wall thickness was measured to document the presence of "hypoechoic rim" which denoted a wall thickness greater than 2 mm. The associated findings and other acoustic phenomena related to the lesion were recorded.

RESULTS

One hundred and thirty-six patients (136/204) having specific aspiration and/or biopsy/histopathological results were included in the study. All of the 136 patients showed abnormal US findings (100%). Most lesions showed grade 1 or grade 2 echogenicity (117, 86%). The contour of the abscess was usually smooth (42, 31%), macrolobulated (42, 31%), or irregular (22, 16%). A hypoechoic rim was noticed in 18 lesions (13%). Focal skin thickening was chiefly noticed in 91% of superficial abscesses (39/43) and 17% of intramammary abscesses (14/84). Diffuse skin thickening was exclusively evident in the breasts coexisting with mastitis. Hypoechoic interstitial streaks were not a common finding (7%), occurring in acute abscesses. The other findings included surrounding hypoechoic amorphous tissue (26%), posterior wall enhancement (71%), distal enhancement (60%) and lateral shadows (57%).

CONCLUSIONS

US plays an important role in confirmation of the clinical diagnosis of breast abscess and aids significantly in the management of inflammatory breast diseases. Presence of the hypoechoic rim surrounding a fluid space or a central area of low-level echoes (i.e., grade 1 to grade 3) is indicative of a chronic abscess.

Diagnostic value of 99mTc-labeled red blood cell SPET for a solitary solid liver mass in HBV carrier patients with different echogenicities

BACKGROUND/AIMS

The purpose of this study is to evaluate the efficacy of technetium-99m labeled red blood cell liver single photon emission computed tomography (RBC liver SPET) in evaluating the diagnostic ability for differentiating the nature of a solitary liver tumor detected with ultrasonography in hepatitis B carrier patients.

METHODOLOGY

One hundred and one hepatitis B carrier patients (56 males, 45 females, aged 13-70 years) with a solitary solid liver mass found on ultrasonography were included in this study. The final diagnosis was made after liver biopsy, aspiration with cytology and/or autopsy in 27 patients and after follow-up with both clinical and ultrasonography findings in 74 patients.

RESULTS

Hemangioma was found in 79 patients, hepatocellular carcinoma in 14, focal nodular hyperplasia in 5, fatty liver in 2, and metastasis in 1. The diagnostic sensitivity of RBC liver SPET for hemangioma, with a hyperechoic, hypoechoic, or isoechoic ultrasonography pattern, was between 75-80%, while the specificity for all patterns was 100%. For mixed-echoic lesions, the sensitivity was 100%, but the specificity was only 50%. Two false-positives were noted; both were mixed-echoic lesions.

CONCLUSIONS

RBC liver SPET is useful for differentiating hemangioma from other liver tumors in hepatitis B carrier patients with a various sonographic patterns, especially for those who had a mixed-echoic sonographic liver mass.

Interleukin-8 as a predictor of the severity of bacteremia and infectious disease

The relationship between cytokines and sepsis has been studied frequently in the intensive care unit (ICU). However, the determination of cytokines in patients as they enter the emergency department (ED) would be more meaningful in predicting the outcome of infection. This study investigated plasma interleukin-8 in the ED as the predictor of bacteremia and sepsis. One hundred patients admitted through the ED with signs of systemic inflammatory response syndrome were studied. Plasma IL-8, IL-6, and tumor necrosis factor (TNF) were assayed by enzyme-linked immunosorbent assay. Patient's data were evaluated using the APACHE II scoring system as predictive factors of morbidity and mortality. Plasma IL-8 (149 pg/mL) detected bacteremia with a positive predictive value of 90.9% and a specificity of 98.7%. Results indicated that the odds ratios (ORs) of bacteremia were 24.78 (P < 0.01, CI = 2.27-270.8), 5.42 (P < 0.05, CI = 1.37-21.4), and 6.05 (P < 0.05, CI = 1.36-26.8) for IL-8, IL-6, and APACHE II, respectively. Occurrence of bacteremia was highly correlated with increases in plasma IL-8 (P < 0.01). IL-8 (OR = 8.25, CI = 1.03-65.9) and APACHE II scores (OR = 12.6, CI = 2.24-70.4) were found to be significantly better predictive factors of mortality (P < 0.01) than IL-6 (OR = 3.60, CI = 0.57-22.7), TNF (OR = 0.24, CI = 0.01-11.0) and age (OR = 1.02, CI = 0.98-1.06). During bacteremia, IL-8 also correlated well with patient use of a ventilator (P < 0.01, OR = 2.43, CI = 2.41-311.19), use of vasopressors (P < 0.05, OR = 2.67, CI = 1.79-370.78), length of stay in the hospital (P < 0.01, OR = 3.14, CI = 1.87-988.31), and stay in the ICU (P < 0.01, OR = 2.51, CI = 2.98-449.80). Measuring IL-8 on patients in the ED with apparent bacterial infections appears to be a reliable predictor of bacteremia and the severity of disease.

The role of 67Ga in the early detection of spinal epidural abscesses

In this study, we evaluated the role of 67Ga whole-body and single photon emission tomographic (SPET) imaging in the early diagnosis and lesion localization of spinal epidural abscess before confirmation by gadolinium-enhanced magnetic resonance imaging (MRI). Six patients with fever of unknown origin had a 67Ga whole-body scan, four of whom also underwent SPET imaging. For further confirmation of a spinal epidural abscess, gadolinium-enhanced MRI was performed in all patients. All patients had increased 67Ga uptake in a spinal or paraspinal area on the whole-body scan. They were later confirmed to have a spinal epidural abscess after gadolinium-enhanced MRI. Of these six patients, five underwent surgical drainage plus parenterally administered antibiotics, and had complete or partial recovery. One died before operation due to sepsis. In conclusion, we suggest performing a 67Ga whole-body survey as early as possible in patients with fever of unknown origin, fever and back pain and/or the spinal syndrome, before MRI is performed. If a spinal epidural abscess is strongly suspected, SPET is needed for further confirmation of spinal versus non-spinal and contiguous versus non-contiguous lesion(s). If MRI is unavailable, then 67Ga scintigraphy is a satisfactory method for investigating spinal epidural abscesses.

Value of Ga-67 SPECT in monitoring the effects of therapy in invasive aspergillosis of the sphenoid sinus

PURPOSE

We report a case of invasive sphenoid sinus aspergillosis clinically presenting as a pituitary mass.

METHODS

After exploration via the trans-sphenoidal approach and subsequent treatment with amphotericin-B, Ga-67 brain SPECT was performed twice to monitor the therapeutic effect.

RESULTS

Three months after antifungal treatment, Ga-67 brain SPECT showed partial resolution of the lesion in the sella turcica region. The patient continued with fluconazole treatment for another 2 months and received another Ga-67 brain SPECT, which showed complete clearing of the previous lesion.

CONCLUSION

Ga-67 brain SPECT may play a potentially useful role in monitoring the therapeutic effect of treatment of invasive sphenoid sinus aspergillosis.

Complementary role of dual isotope in non-bacteriuric renal infection--a case report

To detect non-bacteriuric renal infection in a diabetic patient, though difficult but is very important because early diagnosis and early treatment can prevent later complications such as renal abscess, renal hypertension or even end stage renal disease. Herein, we presented a case of diabetic patient with septicemia whose urine culture and renal ultrasonography were negative initially. By using a combination of dual isotope images and single photon emission computed tomography technique, an infectious lesion in the upper pole of left kidney was revealed, which was identified as acute focal bacterial nephritis by computed tomography four days later. This case report showed that 67Ga plus 99mTc dimercaptosuccinic acid images are useful in patients under clinical suspicion of renal infection, especially for those with negative urine analysis and/or urine culture initially.

Multiple pyogenic granuloma demonstrated by SPECT using 99Tcm-labelled red blood cells

Pyogenic granuloma is a polypoid form of capillary haemangioma that occurs on the skin and mucosal surface. The eruption of multiple pyogenic granuloma is a rare phenomenon. We report the case of a 73-year-old male with a 2 year history of intermittent lower gastrointestinal bleeding. 99Tcm-labelled red blood cell scintigraphy was performed to rule out the possibility of capillary haemangioma on the mucosal surface of the gastrointestinal tract. The images showed disseminated haemangiomas involving the skull, abdominal wall, intestine, scrotum and right leg. The final diagnosis of multiple pyogenic granuloma was made by skin biopsy. To the best of our knowledge, this is the first case using 99Tcm-labelled red blood cell scintigraphy to demonstrate multiple pyogenic granuloma.

133Xenon ventilation scan as a functional assessment in bronchiectasis

BACKGROUND

Mucus impaction in the airways impairs ventilation and exercise tolerance in patients with bronchiectasis. Parameters for evaluating the ventilatory dynamic change have been limited by variable cofactors. We developed a tool to evaluate the changes directly on images of a ventilation scan.

MATERIALS AND METHODS

We used a 133Xenon ventilation washout scan to assess the time of half clearance (T1/2) of the regions of interest (ROIs) corrected by that of a control area (CA) as T1/2ROI/CA. We then compared the ventilation washout scan with high-resolution computer tomography (HRCT) scoring to assess the severity of bronchiectasis, as well as conducting 6-minute walking tests or spirometry for the evaluation of the clinical response to a 3-day course of chest physiotherapy. Nine patients with bronchiectasis and mucus hypersecretion were enrolled in this study.

RESULTS

The functional impairments by mucus impaction or air trapping were well documented in the ventilation washout scan, which not only provided an anatomical image but also dynamic profiles. The ratios of T1/2ROI/CA were significantly correlated to the corresponding scoring of HRCT (3.45 +/- 0.85 vs 7.50 +/- 1.51, r2 = 0.61, p = 0.023, n = 8). The improvement in T1/2ROI/CA (from 3.45 +/- 0.85 to 2.60 +/- 0.59, p = 0.022, n = 9) was paralleled by an increase in the 6-minute walking test (from 310.4 +/- 43.2 m to 352.4 +/- 45.1 m, p = 0.028, n = 7).

CONCLUSION

The 133Xenon scan may be used to evaluate the heterogeneity of ventilation abnormalities and the efficacy of clinical therapy directly in patients with bronchiectasis.

Fine needle aspiration cytodiagnosis of liver tumors. Results obtained with Riu's stain

OBJECTIVE

To present our experience with liver fine needle aspiration (FNA) diagnosis based on Riu's stain.

STUDY DESIGN

We reviewed a total of 322 liver fine needle aspirates from 286 patients seen in a seven-year period from April 1990 to April 1997 at Koo Foundation Sun Yat-Sen Cancer Center, Taipei. Surgical and/or clinical follow-up was available for confirmation in 292 aspirates.

RESULTS

The cytologic diagnosis was categorized into four groups: benign in 81 cases, suspicious in 13, malignant in 225, and inadequate specimen in 3 cases. There were 16 false negative and no false positive diagnoses. Two suspicious aspirates were negative. Our results showed a sensitivity of 93.3% and a specificity of 100% for the detection of malignancy. If suspicious cases were considered positive, the specificity decreased to 95.1%, while the sensitivity increased to 93.6%. Among 87 hepatocellular carcinomas (HCCs) in our series, correct FNA diagnosis was made in 84 cases with an accuracy of 96.6%. Out of 135 cases of non-HCCs, 1 was incorrectly diagnosed. The accuracy of identifying a liver malignancy as non-HCC was 99.3%.

CONCLUSION

Cytologic features of HCC are well demonstrated by Riu's stain, with high accuracy in identifying them. Liver FNAs using Riu's stain combined with cell block study and clinicopathologic correlation can achieve very high sensitivity and specificity in the detection of hepatic malignancies.

Rectus abdominis rhabdomyolysis after sit ups: unexpected detection by bone scan

Uptake of technetium-99m methylene diphosphonate by the rectus abdominis muscle was unexpectedly found in a 29 year old man who had started to perform 30 to 40 sit ups a day for five days before the bone scan. After a week of rest, serum creatine kinase activity was still abnormal but muscle uptake of technetium-99m methylene diphosphonate had ceased. This specific muscle injury after short term sit ups as well as the resolution of the phenomenon within a week are of interest.

Diagnostic thoracic-computed tomography in radiotherapy for loco-regional recurrent breast carcinoma

PURPOSE

This study was initiated to evaluate whether pretreatment diagnostic thoracic CT scan was useful for patients with loco-regional recurrent breast carcinoma, and to assess its impact on the design of radiotherapeutic treatment.

METHODS AND MATERIALS

Between March 1991 and January 1997, 44 patients underwent thoracic CT examination with contrast material before the consideration of radiotherapy for their isolated loco-regional recurrent breast carcinoma. The CT radiographs were prospectively reviewed for additional findings clinically undetected by prior physical examination and plain-chest radiograph. The changes made in treatment design and dosage of radiation as a result of CT findings were recorded for analysis. The correlation between prognostic indicators and the CT findings was also studied.

RESULTS

Twenty-two of 44 (50%) patients were found to have additional abnormalities detected only after thoracic CT examinations were performed. The strategy of radiation therapy was altered in 17 of 22 (77%) patients as a result. Patients with shorter disease-free interval (p = 0.08) and multiple sites of recurrence (p = 0.05) tended to have greater numbers of findings on CT scan previously unsuspected. Thus, CT scan is a valuable guide to treating loco-regional recurrent disease.

CONCLUSION

Pretreatment diagnostic thoracic CT scan offers essential information that can alter treatment planning and thus optimize treatment strategy for a large proportion of patients with clinically isolated loco-regional recurrent breast carcinoma. In this population of patients we recommend that thoracic CT examination be considered before the initiation of radiation therapy.

Comparison of acute physiology and chronic health evaluation III and II for prediction of mortality in multiple organ failure patients treated by plasma exchange

This study examined the efficacy of a different scoring system for multiple organ failure (MOF) patients treated by plasma exchange (PE). Twenty-five patients with MOF resulting from fulminant hepatitis who had been treated by PE for a total number of 91 PEs in a consecutive period of 22 months were included in our study. Data were collected from each patient to compute acute physiology and chronic health evaluation (APACHE) II and APACHE (AP) III scores. The sensitivity, specificity, and correct prediction of outcomes were measured. The correct prediction of outcomes was 86.5%in AP III and 77.5% in AP II. For the prediction of patient mortality, the AP III system seems to be more reliable than AP II.

Moebius syndrome: report of case

This is a review of diagnosis, etiology and abnormalities of Moebius syndrome. The Moebius syndrome is rare and the cause is still unclear. It presents a case of a premature newborn baby with Moebius syndrome, showing unilateral facial nerve palsy, asymmetry of facial expression, inability to tightly close the right eyelids, asymmetry of the angles of the mouth with frequent drooling, poor sucking ability, dysphagia, extremity abnormalities and other cranial nerve involvement (VIII, IX, X, XI). He also had hypoplasia of the pons, a heart defect, and bilateral cryptorchism. The baby died of apnea on the 41st day after birth.

Antimicrobial activities of iodinated polystyrene derivatives

The antimicrobial activities of insoluble halogenated acetamidomethy1-styrene polymers (prepared by covalent bonding of iodine to polystyrene) were assessed as were the factors determining antimicrobial efficacy. The most active materials were selected from chlorinated or iodinated polymers. Antimicrobial activities were assessed for Escherichia coli (ATCC 25922; American Type Culture Collection, Rockville, MD, U.S.A.), Saccharomyces cerevisiae, and Candida albicans by determining time-course changes in microbial counts in vitro. A 2-iodoacetamidomethylstyrene polymer (No.6-I:-CH2I) was found to have the greatest antimicrobial activity against both bacteria and fungi. No.6-I is the first antimicrobial material that did not make an inhibition hollow in the conventional diffusion test or for which conjugated iodine showed antibacterial activity. This material can be introduced into styrene units on the surface of devices by chemical modification. This material was most active at 37 degrees C. For coated dishes, antimicrobial activity depended on the depth or swollen character of the reactive layer. NO.6-I requires not only a minimum width of polymer layer, but also frequent contact with microbes to have an antimicrobial effect. No.6-I is valuable as a new material because it has strong antimicrobial activity by itself but does not release active iodine. This material is expected to have various applications in implantable clinical devices.

A specific 4977-bp deletion of mitochondrial DNA in human ageing skin

Mitochondrial DNA (mtDNA) mutations have recently been proposed as important contributors to ageing and degenerative diseases. In this study, we applied the polymerase chain reaction technique to detect 4.977 bp-deleted mtDNA, the most common and abundant deletion of mtDNA, in normal human skin. None of the skin specimens from patients less than 60 years of age were found to bear this type of mtDNA deletion. The incidence of the 4977-bp-deleted mtDNA increased with advancing age. The incidence of the deletion was 20%, 46.7% and 83.4% for patients of the age groups of 61-70, 71-80, and 81-90 years, respectively. Moreover, the incidence of 4977-bp-deleted mtDNA was significantly higher in exposed skin than that in non-exposed skin. We suggest that mtDNA mutations are molecular events associated with the human skin ageing process.

Treatment of septic shock with a protease inhibitor in a canine model: a prospective, randomized, controlled trial

OBJECTIVES

To evaluate the efficacy and mechanism of action of a protease inhibitor (ulinastatin) in septic shock.

DESIGN

Prospective, randomized, controlled trial.

SETTING

A university laboratory.

SUBJECTS

Twelve mongrel dogs.

INTERVENTIONS

One of the protease inhibitors, ulinastatin, a glycoprotein (molecular weight 67,000 daltons) detected in human urine was estimated. We used Escherichia coli to obtain a model of septic shock in dogs in vivo study. Human neutrophils were used as an activating target in vitro.

MEASUREMENTS AND MAIN RESULTS

The final concentration of E. coli was 1.9 x 10(6) colony-forming units/mL. There was no significant difference in E. coli concentration between ulinastatin-treated and control groups. Human neutrophils treated with 100 U/mL of ulinastatin showed 70.5% to 78.7% of the superoxide production or untreated neutrophils. Phagocytic activity was enhanced in a dose-dependently manner by ulinastatin. At a ulinastatin concentration of 100 U/mL, an approximate two-fold increase in activation was found. In the ulinastatin-treated group, cardiac index, blood pressure, lactic acid, blood glucose, and blood base values significantly improved 60 mins after ulinastatin administration, and the bacterial count was significantly decreased, while the endotoxin concentration in the control group showed a continuous increase of endotoxin concentration. The improvement in the monitored factors observed 60 mins after initiation of treatment persisted after the end of treatment. The survival rate after 1 wk in the ulinastatin-treated group was 84% (five of six dogs survived), while it was 16% (one of six dogs survived) in the control group (p = .04).

CONCLUSIONS

Ulinastatin does not have antimicrobial activity, and it does not sufficiently activate phagocytes. It is suggested that the efficacy of this agent in experimental septic shock is due to a mechanism that activates the reticuloendothelial system and septic reactions.

[Computed tomography for evaluation of hepatocellular carcinoma after treatment with transarterial chemoembolization]

Totally 135 series of computed tomography (CT) and angiographic examination were performed in 53 patients with proved hepatoma treated by TAE. CT examination was performed four to six weeks after TAE, and a comparative angiographic examination was performed within three weeks after CT examination. The pictures of CT scanning were read to determine 1). the grading of lipiodol retention inside the tumor, 2). the presence/absence of filling defect in the tumor margins coated by lipiodol, 3). the presence/absence of residual tumor tissue within or surrounding the main tumor, and 4). the presence/absence of developed satellite nodules. In comparison with angiographic findings, CT demonstrated 96.3% specificity and 58.2% sensitivity in the grading of lipiodol filling, and 96.3% specificity and 65.7% sensitivity in the tumor margins of lipiodol coating. However, it was difficult for CT to detect small nodules, especially those less than 1 cm in diameter. We find no statistically significant association between newly developed satellite nodules and grading of lipiodol retention inside the tumor or tumor margins of lipiodol coating. Therefore, when CT pictures reveal filling defect over the margins of the tumor coated by lipiodol or less-than-50% lipiodol filling inside the tumor, repeated angiography and further treatment with TAE are suggested.

Reflex bronchospasm-induced acute massive pulmonary collapse

Acute massive pulmonary collapse following reflex bronchospasm is described in a patient undergoing general anesthesia. The authors suggest that a chest radiograph should be taken as routine procedure after the onset of airway constriction during anesthesia.