Determination of the position and orientation of artificial knee implants using markers embedded in a bone: preliminary in vitro experiments

This study describes the method of determination of the position and orientation of artificial knee implants using a single-plane radiograph. To simplify the 3D/2D matching problem, we proposed to use small markers embedded in a bone. From the image coordinates of markers, it is possible to estimate the position and orientation of implants if the relationship between the markers and the implant is known. The results of the in vitro experiment showed that rms errors in in-plane/out-of-plane translations and rotations were 0.2/2.3 mm and 0.2/0.2 degrees, respectively.

Differential cytokine expression of human retinal pigment epithelial cells in response to stimulation by C5a

Human retinal pigment epithelial (RPE) cells form part of the blood-retina barrier where they potentially can regulate leucocyte function. RPE cells are known to secrete several cytokines in response to stimulation by other cytokines. Anaphylatoxin C5a, a potent inflammatory mediator produced during complement activation, binds to G-protein coupled C5a receptors (C5aR) on monocytes/macrophages and releases various cytokines from the cells. We previously reported that the human RPE cell line ARPE-19 possesses C5aR and expresses IL-8 mRNA in response to C5a stimulation. In this study, we used a primary human RPE cell line (RPE43) and found that C5a induces increased expression of IL-1beta, IL-6, MCP-1 and GM-CSF mRNAs as well as IL-8 mRNA. ARPE-19 cells showed similar increases in the same cytokines. Interestingly, the kinetics of expression of the various cytokines differed. These results provide further evidence that C5a stimulation of RPE cells may play a role in regulating leucocyte function during ocular inflammation in which there is complement activation.

Pose estimation of artificial hip joint using a single radiographic projection

Total hip joint arthroplasty is commonly used in cases of osteoarthritis and rheumatoid arthritis. A hip joint prosthesis consists of a cup and a stem. The relative pose (position and orientation) of the prosthesis, when the patient is standing naturally, is planned pre-operatively; however, there is no guarantee that the pre-operatively planned pose will be accurate. Prosthesis component malposition, which is inadequate positioning of the acetabular or femoral component, results in limited joint movement and a large prosthetic joint contact area, and this can cause dislocation of the femoral head from the cap. Because the range of motion after total hip joint arthroplasty is determined by the relative pose of the cup and the stem, it is important to know the relative pose after hip arthroplasty. Several pose estimation methods using single-plane fluoroscopy or conventional roentgenography have been proposed. Because a conventional radiograph system is commonly used at small cost, a method using conventional radiograms is desirable for use in a clinical setting. In this study, a pose estimation method using conventional radiography is proposed, and an in vitro experiment is performed to evaluate its accuracy. The rotational errors of the relative pose of the cup with respect to the stem were smaller than 2.3 degrees.

Kinetics and steady-state of VO2 responses to arm exercise in trained spinal cord injury humans

STUDY DESIGN

Cross-sectional study comparing trained spinal cord injured (SCI) subjects (lesion level: L1 - T6) with healthy young subjects (CONT).

OBJECTIVE

To investigate the kinetics of response in oxygen uptake (VO(2)) in human upper-body skeletal muscles, nine trained SCI subjects underwent submaximal supine arm exercises.

METHOD

The SCI subjects underwent an incremental arm exercise test until exhaustion. The days after this first round of testing, breath-by-breath VO(2) and beat-by-beat heart rate (HR) on- and off-kinetics were determined during three repetitions of constant exercise at 50% of VO(2peak). The overall time course of response was determined from the half time (t(1/2)). Increased capillary blood lactate production (delta[La]b) at the onset of exercise was defined as the difference between at rest and at the end of exercise. Cardiac output (Q) was measured using the acetylene rebreathing method during the steady state of exercise. In accordance with the Fick principle, the difference in arterial-venous O(2) content (Ca-vO(2)) was defined as VO(2)/Q.

RESULTS

During the steady state of the submaximal arm exercise, a more significant increase in the steady state of Q was obtained in the CONT subjects than in the trained SCI subjects: respectively, 14.9+/-1.4 l/min versus (12.7+/-0.8 l/min). There was no difference in the steady state of VO(2) between the two groups; as a result, SCI subjects had the greater Ca-v(2). Meanwhile, VO(2) on- and off-kinetics became much faster in the trained SCI subjects than in the CONT subjects. In addition, t(1/2) HR on-kinetics was not significantly different between the SCI and CONT groups. Increased Delta[La]b was closely related to larger t(1/2) VO(2) on-kinetics (r = 0.624, P < 0.05).

CONCLUSION

It is concluded that the acceleration of VO(2) on- and off-kinetics in the trained SCI subjects was observed even though there was no difference in HR on- and off-kinetics between the SCI and CONT groups and a lower steady state of Q in the trained SCI subjects. VO(2) kinetics would therefore be the limiting factor in oxidative phosphorylation in the upper skeletal muscles, thereby providing a lower lactic O(2)-deficit (ie delta[La]b).

Accurate in vivo measurement of polyethylene wear in total knee arthroplasty

This study describes a new technique to evaluate accurate linear polyethylene wear and reports the in vivo annual linear wear rate in total knee arthroplasty. Patients (n = 69) were assessed using a single standing anteroposterior radiograph with 8 reference markers around the knee, where 3-dimensional (3D) locations of markers and 3D geometry of the implant were known. By matching the 3D locations of the markers and their projected points on the radiograph, 3D/2D transformation parameters were estimated. Using these parameters, the 3D coordinates of the implant were estimated from the projected x-ray silhouette. After calculating the femorotibial shortest distance, wear and creep deformity of the polyethylene was defined with an accuracy of 0.1 mm or better. Measured linear wear in the 69 knees varied from 0 mm (1 month postoperatively) to 2.71 mm (7 years postoperatively). The correlation of linear wear (Y) and year (X) was Y = 0.23 X -0.11 (P<.001). This study revealed that annual wear rate was 0.23 mm and 2 times greater than the average annual wear rate in total hip arthroplasties.

Properties of exogenously added GPI-anchored proteins following their incorporation into cells

Isolated glycosylphosphatidylinositol (GPI)-anchored proteins, when added to cells in vitro, incorporate into their surface membranes and, once incorporated, exert their native functions. Virtually any protein of interest, if expressed as a GPI-reanchored derivative, can be modified to acquire this capacity. Such transfer of proteins directly to cells, termed "protein engineering" or "painting" constitutes an alternative to conventional gene transfer for manipulating cell surface composition that has many potential applications. Previous studies with incorporated GPI-anchored proteins have focused almost entirely on their extracellular functions. In this study, biotinylated human erythrocyte (E(hu)) decay accelerating factor, E(hu) acetylcholinesterase, and GPI-reanchored murine B7-1 and B7-2 were used as GPI-anchored reporters to characterize their plasma membrane organization and cell signalling properties following addition to Hela or Chinese hamster ovary cells. For each reporter, three types of cell-association were documented; (1) nonphysiological attachment and/or incomplete insertion, (2) uncomplexed membrane integration, and (3) organization into TX-100-resistant microdomains. Transit from the first two compartments into the third, i.e., microdomains, progressed slowly, continuing even after 24 to 36 h and was associated with the acquisition of cell signalling capacity. All four reporters, incorporated in two different detergents, behaved similarly. When organized in microdomains, caveolin and other GPI proteins co-isolated with the incorporated reporter. These results have implications for protein engineering of cells in general, and in particular, for cells such as modified tumor cell immunogens administered to patients for therapeutic purposes.

Kinematic analysis of mobile-bearing and fixed-bearing knee prostheses by simulation

The object of the study was to model fixed-bearing knee prostheses (FBKs) and mobile-bearing knee prostheses (MBKs) during weight-bearing deep knee bends and to analyse and compare the kinematics of the two prosthesis types. To obtain quantitative data, an overall model of a leg was constructed, and this included a three-dimensional model of the tibiofemoral joint and simplified two-dimensional models of the ankle and patellofemoral joint. The simulated movement pattern of the tibiofemoral contact point in the FBK was analysed to show the posterior contact position on the tibia at full extension and anterior translation as the knee was flexed from 30 degrees to 90 degrees. The simulated maximum displacements of the medial and lateral contact positions of the FBK were 5.6 and 6.2 mm, respectively. These results were almost in agreement with experimental studies. Compared with the FBK, the movement pattern of the tibiofemoral contact point in the MBK for the anterior contact position on the tibia at full extension and posterior translation, with respect to the tibia as the knee was flexed, gave results closer to those of the normal knee. The simulated displacements of the medial and lateral contact positions of the MBK with respect to the tibia were 9.0 and 13.0 mm from full extension to 90 degrees flexion, respectively. The difference in the kinematic results between the FBK and the MBK could be accounted for by movement of the insert and the larger force of the posterior cruciate ligament on the MBK.

Role of Visual Feedback in Upright Posture Control

We studied the role of visual feedback in upright posture control on the sagittal plane. In posture control, each sensory system has the following roles: initial detection of sway, suppression of short-term sway around the equilibrium point, and suppression of longterm sway induced by a slow shift in equilibrium. Experiments were conducted to examine features of each sensor and then visual contribution was studied. Based on measured sensory thresholds for the perception of sway during standing, it was suggested that visual input provided sensitive means of perceiving postural sway. Body sway of a subject was measured under several conditions in which the subject controlled upright posture utilizing the definite number of sensors. By analyzing and comparing measured sway waveforms under each condition, it was clear that the visual system suppressed short-term sway. Spectral analysis showed that the visual system suppressed body sway in a low frequency range around 0.2 Hz. Though visual feedback contains a large time delay, the influence of the delay is small in the low frequency range. It is rational that vision is efficient at suppressing body sway in the low frequency range.

[Collateral blood flow showing dissection-like filling defect on coronary arteriography: a case report]

A 51-year-old man presented under a diagnosis of angina pectoris manifesting as exertional chest pain. First coronary angiography showed severe stenosis with ulceration and spontaneous dissection at the proximal right coronary artery and linear dissection-like filling defects extending to the distal right coronary artery. After about 3 months, repeat coronary angiography showed the previously observed stenosis with unclear dissection, and better developed collaterals from the left coronary artery to the right coronary artery showing the linear dissection-like filling defects. The bilateral coronary angiography did not clearly show filling defects. This phenomenon suggested that the collateral flows were related to filling of the defects. Intravascular ultrasonic imaging demonstrated severe atherosclerotic lesions at the proximal right coronary artery, but no dissection in the distal right coronary artery. Percutaneous transluminal coronary angioplasty for the stenosis was performed successfully with a stent. Coronary angiography after the angioplasty showed no collaterals, and the right ventricular branch appeared, suggesting that the linear dissection-like filling defects extending to the distal right coronary artery were due to the collateral flows. Filling defects extending distal to a severe stenosis must be distinguished carefully from coronary dissection.

C5a receptor-mediated production of IL-8 by the human retinal pigment epithelial cell line, ARPE-19

PURPOSE

C5a anaphylatoxin is a potent inflammatory mediator that acts on polymorphonuclear cells (PMN) and monocytes via C5a receptors (C5aR). It mediates chemotaxis of both cell types and stimulates cytokine release from the latter. To investigate whether C5a can act on retinal pigment epithelial (RPE) cells, we examined ARPE-19 cells for the presence of C5aR and the effect of C5a stimulation.

METHODS

C5aR expression was measured by flow cytometry using specific anti-C5aR antibody and by RT-PCR analyses. Cells were stimulated with 50 nM C5a and the induction of IL-8 mRNA expression was measured by semi-quantitative RT-PCR.

RESULTS

Surface levels of C5aR on ARPE-19 cells were found to be comparable to those on human PMN. Stimulation with C5a induced a dose- and time-dependent increase of IL-8 mRNA expression.

CONCLUSION

The findings of C5aR on ARPE-19 cells and induction of IL-8 mRNA upon C5a stimulation suggests that C5a may participate in the defense of choroidal and retinal tissue during inflammation.

Long-term follow-up results of electrogustometry and subjective taste disorder after middle ear surgery

OBJECTIVES

The present study compares the long-term follow-up results of electrogustometry with patient reports of taste dysfunction after middle ear surgery.

STUDY DESIGN

Retrospective review of 371 patients who underwent middle ear surgery.

METHODS

Patients were divided into the following groups depending on the degree of manipulation or surgical damage to the chorda tympani nerves: the no-touch group (group 1 [n = 109]); the touch group (group 2 [n = 149]); and the severed nerve group (group 3 [n = 113]). Electrogustometry was periodically performed over the course of several years.

RESULTS

The incidences of postoperative subjective taste disorder in groups 1, 2, and 3 were 2.8%, 25.5%, and 38.9%, respectively. Although the subjective taste disorder usually recovered within 1 to 2 years after surgery in all groups, it persisted for more than 2 years in 2.7% of the touch group and 5.3% of the severed nerve group. Concerning postoperative electrogustometric results, in the no-touch group, 8.3% of patients showed threshold elevation on electrogustometry, but the elevated thresholds completely recovered in all cases. In the touch group, 45% of patients exhibited elevated electrogustometric thresholds on their first postoperative test, including 32.9% who subsequently had complete electrogustometric recovery, 10.1% who subsequently had incomplete recovery, and 2% who failed to recover during the follow-up period. In the severed nerve group, none of the patients was responsive to the electrical stimulus on the first postoperative test, including 8.8% of patients who subsequently exhibited complete electrogustometric recovery, 32.7% who later had incomplete electrogustometric recovery, and 58.4% who never recovered any electrogustometric responsiveness. Nerve repair in the severed nerve group produced better recovery, as measured electrically.

CONCLUSIONS

The incidence of postoperative subjective taste disorder was low, although inconsistent with the high incidence of threshold elevation on electrogustometry, especially in the severed nerve group. Preservation or repair of the chorda tympani nerve is recommended in order to maintain or recover gustatory function.

Tissue distribution of products of the mouse decay-accelerating factor (DAF) genes. Exploitation of a Daf1 knock-out mouse and site-specific monoclonal antibodies

Decay-accelerating factor (DAF) is a membrane regulator of C3 activation that protects self cells from autologous complement attack. In humans, DAF is uniformly expressed as a glycosylphosphatidylinositol (GPI)-anchored molecule. In mice, both GPI-anchored and transmembrane-anchored DAF proteins are produced, each of which can be derived from two different genes (Daf1 and Daf2). In this report, we describe a Daf1 gene knock-out mouse arising as the first product of a strategy for targeting one or both Daf genes. As part of the work, we characterize recently described monoclonal antibodies against murine DAF protein using deletion mutants synthesized in yeast, and then employ the monoclonal antibodies in conjunction with wild-type and the Daf1 knock-out mice to determine the tissue distribution of the mouse Daf1 and Daf2 gene products. To enhance the immunohistochemical detection of murine DAF protein, we utilized the sensitive tyramide fluorescence method. In wild-type mice, we found strong DAF labelling of glomeruli, airway and gut epithelium, the spleen, vascular endothelium throughout all tissues, and seminiferous tubules of the testis. In Daf1 knock-out mice, DAF labelling was ablated in most tissues, but strong labelling of the testis and splenic dendritic cells remained. In both sites, reverse transcription-polymerase chain reaction analyses identified both GPI and transmembrane forms of Daf2 gene-derived protein. The results have relevance for studies of in vivo murine DAF function and of murine DAF structure.

Decrease of neurons in the medullary arcuate nucleus in myotonic dystrophy

Respiratory insufficiency has been reported frequently in patients with myotonic dystrophy (MyD). Recent data support the hypothesis that this respiratory failure results from a primary dysfunction of the central nervous system. The medullary arcuate nucleus (ARC) has been shown to be involved in the regulation of respiration. We performed a quantitative study of neurons in the ARC in eight MyD patients, ten control subjects with other neurological diseases (control group A) and eight control subjects without neurological diseases (control group B). Alveolar hypoventilation of the central type occurred in three of the MyD patients but not in the remaining MyD patients or controls. The density of neurons in the ARC in MyD patients with hypoventilation was significantly lower than in MyD patients without hypoventilation and control groups A and B. There was no significant difference in the neuronal density of the ARC between MyD patients without hypoventilation and control groups A and B. These data suggest that the neuronal loss of the ARC is associated with the presence of hypoventilation in MyD.

Characteristics of somatosensory feedback in postural control during standing

In the present study, the function of the somatosensory feedback system in postural control was investigated. For the sake of simplicity, the present study considered only balancing in the anteroposterior direction using the ankle strategy, in which the ankle moment is mainly used to maintain balance. To suppress the vestibular and visual feedback paths, a subject stood on a force-measuring platform with a fixed back support. Because the subject's body was immovable under these conditions, the subject controlled a computer model that simulated the subject's load at the ankles. Information about the sway angle of the model was fed through the somatosensory feedback path. Frequency response functions of the ankle moment in response to the sway angle were calculated. The experimental results suggest that the human somatosensory feedback system has derivative characteristics and, consequently, can maintain an upright posture by itself. The results were compared with those of previous studies on vestibular and visual feedback systems. The comparison reveals that subject-to-subject variance in the somatosensory system is significantly smaller than that in the other systems. This may indicate that the somatosensory feedback is the most automatic of the systems and plays a dominant role when a subject maintains an upright posture using the ankle strategy.

Gastric versus duodenal feeding in patients with neurological disease: a pilot study

Both gastric and duodenal feeding tubes are used to provide enteral nutrition. Most studies comparing the two methods have focused primarily on rates of complications, rather than on nutritional outcomes, and show no difference in complications between the two methods. It is not clear which feeding route provides the best nutritional outcomes. The primary purpose of this randomized clinical pilot study was to compare the percentage of recommended calories and protein received by patients with neurological disease being fed enterally via gastric or duodenal feeding tubes. Secondary aims were to compare the following between groups: physiological effects of feeding, reasons for delay in feeding, volume of feeding residual, number of feeding tubes replaced, cost of feeding, and number and types of complications. A convenience sample of 25 neuro intensive care unit patients was randomly assigned to gastric or duodenal feeding. Enteral feeding was ordered by using a standardized prescription formula and provided by the nursing staff. Serum albumin and prealbumin levels were measured at baseline, day 3, and day 10. Nitrogen balance was measured on day 10. Enteral feeding data were collected daily. No significant differences were found between gastric and duodenal groups in nutritional outcomes, including percentage of recommended calories and protein received, physiological effects of feeding, reasons for delay in feeding, feeding residual, number of feeding tubes replaced, cost of feeding, and number and types of complications. Neither group achieved mean recommended caloric or protein intake during the 10 days of the study. Further research is needed to address how recommended nutrients can be provided enterally in a more timely and complete manner in critically ill NICU patients.

Dislocation of the incus into the external auditory canal after mountain-biking accident

We report a rare case of incus dislocation to the external auditory canal after a mountain-biking accident. Otoscopy showed ossicular protrusion in the upper part of the left external auditory canal. CT indicated the disappearance of the incus, and an incus-like bone was found in the left external auditory canal. There was another bony and board-like structure in the attic. During the surgery, a square-shaped bony plate (1 x 1 cm) was found in the attic. It was determined that the bony plate had fallen from the tegmen of the attic. The fracture line in the posterosuperior auditory canal extending to the fossa incudis was identified. According to these findings, it was considered that the incus was pushed into the external auditory canal by the impact of skull injury through the fractured posterosuperior auditory canal, which opened widely enough for incus dislocation.

Nucleotide sequence analysis of a human monoclonal antibody TONO-1 with cytotoxic potential for T-leukemia/lymphoma cells

A human monoclonal antibody (HuMab) TONO-1 (IgM, lambda) recognizes cell surface antigens associated primarily with human T-leukemia/lymphoma cells. In this study, we investigated the reactivity against T-leukemia/lymphoma cells in detail, cytotoxic potential and primary nucleotide and deduced amino acid sequences of the rearranged heavy and light chains of the HuMab TONO-1. Expression of the molecules (TONO-1 Ags) detected by a HuMab TONO-1 was significantly heterogeneous even in the same T-leukemia/lymphoma cell lines HPB-MLT and MOLT-4F. The flow cytometric curves showed an unusual broad-based spread of fluorescence intensity. HuMab TONO-1 was shown to have the ability to kill the T-leukernia/lymphoma cells efficiently in the presence of rabbit complements. However, HuMab TONO-1 did not demonstrate significant antibody-dependent cellular cytotoxic activity. Furthermore, HuMab TONO-1 heavy and light chain variable regions were cloned, sequenced and analyzed. HuMab TONO-1 uses a V(H) gene member of the V(H)IV gene family V(H)71-4, and is productively rearranged with the germ line D(H) gene D(XP')1, and the germ line J(H)5 gene with multiple somatic mutations. HuMab TONO-1 Vlambda belongs to the lambda light chain variable subgroup I family and is derived from the Vlambdalc germ line gene Humlv1042, and germ line gene Jlambda1 without somatic mutations. The results reveal that the production of HuMab TONO-1, with cytotoxic potential for human T-leukemia/lymphoma cells, is achieved by rearrangement of the V(H)71-4/Humlv1042 germ line variable region gene combination, that is associated with the autoimmune repertoire.

Refraction and Anterior Chamber Depth Change After Vitrectomy for Pseudophakia

Purpose: To evaluate the association between the vitreous and the refractive error in pseudophakia.Methods: Vitrectomy was performed in 67 eyes of 61 patients who underwent cataract surgery. Vitrectomy was needed for epiretinal membrane in 30 eyes, macular edema in 22 eyes, macular hole in 3 eyes, lamelar macular hole in 2 eyes, macular hole in 3 eyes, lamelar macular hole in 2 eyes, vitreous opacity in 6 eyes, and vitreous hemorrhage in 4 eyes. Refraction was measured before the operation, and 1 month, 3 months, 6 months, and 12 months after operation. Anterior chamber depth was measured in 10 eyes before the operation, and 1 month, 3 months, and 6 months after operation. We evaluated the refractive error after vitrectomy in 49 eyes that had predicted refraction.Results: The mean value of refractive change was -0.3 D 1 month postoperatively, and then gradually became positive. The variation of refraction (6-month postoperative refraction minus preoperative refraction) was negatively correlated with preoperative refraction (P =.0052, R(2) = 0.146). If preoperative refraction was more myopic than -1.5 D, then refraction became positive. If preoperative refraction was not more myopic than -1.5 D, then refraction became negative.Conclusion: About 15% of postoperative refractive error may be associated with the vitreous, but further investigation is required.

[Refraction and anterior chamber depth change after vitrectomy for pseudophakia]

PURPOSE

To evaluate the association between the vitreous and the refractive error in pseudophakia.

METHODS

Vitrectomy was performed in 67 eyes of 61 patients who underwent cataract surgery. Vitrectomy was needed for epiretinal membrane in 30 eyes, macular edema in 22 eyes, macular hole in 3 eyes, lamelar macular hole in 2 eyes, vitreous opacity in 6 eyes, and vitreous hemorrhage in 4 eyes. Refraction was measured before the operation, and 1 month, 3 months, 6 months, and 12 months after operation. Anterior chamber depth was measured in 10 eyes before the operation, and 1 month, 3 months, and 6 months after operation. We evaluated the refractive error after vitrectomy in 49 eyes that had predicted refraction.

RESULTS

The mean value of refractive change was -0.3 D 1 month postoperatively, and then gradually became positive. The variation of refraction (6-month postoperative refraction minus preoperative refraction) was negatively correlated with preoperative refraction (p = 0.0052, R2 = 0.146). If preoperative refraction was more myopic than -1.5 D, then refraction became positive. If preoperative refraction was not more myopic than -1.5 D, then refraction became negative.

CONCLUSION

About 15% of postoperative refractive error may be associated with the vitreous, but further investigation is required.

Experimental lupus nephritis in severe combined immunodeficient (SCID) mice: remodelling of the glomerular lesions by bystander IgM antibodies

MRL/Mp-lpr/lpr (MRL/lpr) mice develop glomerular lesions with regular variations in their histopathological manifestations, similar to those in lupus nephritis. These lesions are mainly either cell-proliferative or wire loop-like and are associated with glomerular deposits of immunoglobulins, most frequently IgG and IgM. We previously established a nephritogenic IgG3-producing hybridoma clone, B1, from an MRL/lpr mouse, which induces only a 'wire loop-like' type of glomerular lesion when injected into SCID mice. Injection of SCID mice with an anti-trinitrophenyl IgM antibody-producing hybridoma clone, Sp6, following injection of the B1 clone, however, resulted in the development of a 'cell-proliferative' type of glomerular lesion, associated with an accumulation of both antibodies in glomeruli. This accumulation occurred even though Sp6 IgM antibodies did not react with B1 IgG3 antibodies and vice versa. A mutant clone of Sp6, T/13microE/3.1, which produces antibodies deficient in C1q binding, produced a similar effect as that of the Sp6 clone, i.e. 'cell-proliferative' lesions. Again the B1 antibodies did not react with T/13microE/3. 1-IgM antibodies and vice versa. We therefore conclude that bystander IgM antibodies contribute to the remodelling of glomerular lesions in situ, following glomerular injury by the nephritogenic antibodies.

Accuracy of a single equivalent moving dipole model in a realistic anatomic geometry torso model

In this study, we investigated the accuracy of an algorithm to identify the spatial single equivalent moving dipole parameters in a realistic anatomic geometry torso model from potentials at the body surface. Specifically we investigated the effect of measurement noise, and dipole position and orientation in the accuracy of the algorithm. The boundary element method was used to calculate the forward potential distribution at 64 electrode positions on the body surface due to a point dipole. The mean and standard deviation of the distance of the true (obtained in the forward potential calculation) minus the estimated dipole location (obtained from the inverse algorithm) was estimated for each of the above three cases. Our results indicate that the dipole position has the most significant influence on the accuracy of our inverse algorithm.

Characterization of mouse DAF on transfectant cells using monoclonal antibodies which recognize different epitopes

Several membrane proteins prevent host cells from homologous complement attack. In humans, one such protein, decay-accelerating factor (DAF), exists as two isoforms, a GPI anchored form and a secreted form, which are generated by alternative splicing. DAF in mouse is also expressed as two isoforms, a GPI anchored form (GPI-DAF) and a transmembrane form (TM-DAF), which are produced from two separate genes. In this study, we transfected cDNA of mouse GPI-DAF or TM-DAF into Chinese hamster ovary (CHO) cells. Both isoforms of DAF on CHO cells were shown to regulate mouse complement C3 deposition mediated by the classical and alternative pathways and the inhibitory activity of both isoforms was species restricted. The two mouse DAF isoforms were effective against rat complement but not against human and guinea pig complement. Furthermore, we produced hamster mAbs to mouse DAF using GPI-DAF transfectant cells and established seven unique mAbs (RIKO-1-7). Western blotting analysis using RIKO-3, which reacts with both GPI-DAF and TM-DAF, and RIKO-4, which is an anti-GPI-DAF specific mAb, indicated that GPI-DAF was expressed on erythrocytes, spleen and testis, and that TM-DAF was expressed only in testis.