Activator protein-1 in epiretinal membranes of patients with proliferative diabetic retinopathy.
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Cell Membrane↗
Biomedical subjects
Y Mitamura
Publications and source records attributed to Y Mitamura.
Three-dimensional computer-aided design based design sensitivity analysis and shape optimization of the stem using adaptive p-method.
The number of stem designs for total hip arthroplasty is increasing, and occasionally design changes have yielded unexpected clinical results. At present, we are not able to clearly identify which parameter of the stem is most important, and the optimum value of many parameters. The goals of this study were to identify which parameter is most important, to understand the effect of design change, and to find the optimum stem shape. For this purpose, we used adaptive p-method together with three-dimensional computer-aided design software program for the design sensitivity analysis (DSA) and shape optimization of the stem. The results suggested that increasing the lateral and medial width of the distal cross-section together with decreasing the medial-lateral width and the medial radius of the distal cross-section from the default value would lead to a decrease in the largest maximum principal stress of the distal cement. The medial width of middle cross-section, however, was not so simple. The result of DSA suggested that decreasing this parameter from the default value decreased the stress in the distal cement, but the optimum shape was obtained by increasing this parameter. The method used in this study will assist our engineers and surgeons in the process of modifying and optimizing the stem design.
Arthroplasty, Replacement, Hip↗
Aqueous levels of macrophage migration inhibitory factor and monocyte chemotactic protein-1 in patients with diabetic retinopathy.
AIMS: To investigate the relationship of aqueous macrophage migration inhibitory factor (MIF) and monocyte chemotactic protein-1 (MCP-1) levels with the clinical stage of diabetic retinopathy. METHODS: We assayed MIF and MCP-1 levels in aqueous humour samples obtained from 40 diabetic patients (49 eyes) and 24 non-diabetic patients (31 eyes) using enzyme-linked immunosorbent assay. According to the clinical stage of diabetic retinopathy, the diabetic patients were classified into non-diabetic retinopathy (11 eyes), non-proliferative diabetic retinopathy (14 eyes) and proliferative diabetic retinopathy (24 eyes). RESULTS: The aqueous levels of MIF (mean +/- sd) were 6.34 +/- 4.53 ng/ml in proliferative diabetic retinopathy, 3.22 +/- 1.71 ng/ml in non proliferative diabetic retinopathy, 1.25 +/- 0.96 ng/ml in non-diabetic retinopathy and 1.07 +/- 0.94 ng/ml in non-diabetic patients. Significant differences were found among these four groups (P < 0.0001). Aqueous MCP-1 levels were 1668.6 +/- 1442.3 pg/ml in proliferative diabetic retinopathy, 1528.6 +/- 1994.6 pg/ml in non-proliferative diabetic retinopathy, 690.2 +/- 402.1 pg/ml in non-diabetic retinopathy and 622.7 +/- 245.3 pg/ml in non-diabetic patients. Significant differences were also found among these four groups (P < 0.0001). After correcting for total aqueous protein, the ratios of MIF and MCP-1 to total protein remained significantly correlated with the clinical stage of diabetic retinopathy (P < 0.0001, P = 0.0004, respectively). The ratios of MIF to total protein significantly correlated with the ratios of MCP-1 to total protein in diabetic patients (r = 0.680, P < 0.0001). CONCLUSIONS: Aqueous MIF levels significantly correlated with aqueous MCP-1 levels and the clinical stage of diabetic retinopathy. The results suggest that MIF has a co-operative role with MCP-1 in the progression of diabetic retinopathy.
Adult↗
Functional modulation of activated lymphocytes by time-varying magnetic fields.
Time-varying magnetic fields (TVMF), especially those of extremely low frequency (below 250 Hz), have been reported to have profound effects on biological systems due to the induced currents since the biological systems consist of electrolyte solution. We have been interested in utilizing TVMF for cellular immunomodulations, and have shown that the TVMF could augment macrophage activation. In this study, the effect of TVMF on lymphocyte activation was studied. Murine spleen lymphocytes were isolated from DDY mice and incubated in the presence of Concanavalin A (ConA) for 72 h. The lymphocytes were exposed to TVMF for various durations, from 20 min to 2 h. The proliferation activities of lymphocytes were assayed by ELISA by use of 5-bromo-2'-deoxy-uridine Labeling and Detection Kit III (Roche Diagnostic Corp. Indianapolis, IN, USA). The IL1beta and IL2 concentrations in the culture medium were measured by ELISA assay. The IL2 receptor expression on the lymphocytes was evaluated by FACS analysis by use of FITC-conjugated monoclonal antibody. The proliferation activities were significantly enhanced by the TVMF for up to 40 min exposure from the initiation of ConA stimulation. The degree of augmentation effects, defined by the ratio of activation index of with and without TVMF, was varied from 1.1 to 2.7, and related to the lymphocyte responsiveness to the ConA. The less responsive cells showed more TVMF augmentation effects. The TVMF exposure after 40 min from ConA addition showed no effect, suggesting that the TVMF effects are most likely related to the Ca ion influx. The prolonged exposure of TVMF depressed the augmentation effects, which was caused by the depressed IL-2 receptor expression although both IL1-beta and IL-2 productions were not affected.
Animals↗
NF-kappaB in epiretinal membranes after human diabetic retinopathy.
AIMS/HYPOTHESIS: Formation of epiretinal membranes (ERMs) in the posterior fundus results in progressive deterioration of vision. ERMs have been associated with numerous clinical conditions including proliferative diabetic retinopathy (PDR), but its pathogenic mechanisms are still unknown. This study was conducted to examine whether or not nuclear factor kappa B (NF-kappaB), a transcription factor that can be activated by various pathological conditions, is involved in the formation of ERMs after PDR. METHODS: ERM samples were obtained by vitrectomy from 22 cases with PDR aged 56+/-11 years with 18+/-10 years of diabetes and 15 cases with idiopathic ERM. They were processed for reverse transcription-polymerase chain reaction (RT-PCR) analysis. In addition, 5 ERM samples from PDR patients aged 51+/-16 years with 15+/-6 years of diabetes were processed for immunohistochemical analysis. RESULTS: NF-kappaB mRNA expression levels were higher (20 out of 22 cases vs. 9 out of 15 subjects in idiopathic ERM, p<0.05) in PDR subjects. Immunohistochemical analysis showed NF-kappaB protein expression in all the 5 ERMs derived from PDR patients, and that region was partially double-labelled with interleukin-8 (IL-8) and von Willebrand factor (vWF). CONCLUSIONS/INTERPRETATION: These results suggest a possibility that NF-kappaB is involved in the formation of ERMs after PDR, especially for the development of vascular endothelial cell component.
Adult↗
Development of an implantable high-energy and compact battery system for artificial heart.
The purpose of this study was to demonstrate the feasibility of the use of an implantable, high-energy, and compact battery system for an undulation pump total artificial heart (UPTAH). The implantable battery system tested consists of six lithium-ion batteries in series, a charge unit, and a charge/discharge control unit. A lithium-ion battery is currently the best energy-storage device because it has more energy density, a better life cycle, and a smaller temperature rise than those of other secondary batteries. The performance of the implantable battery system was evaluated in an in vitro experiment using an electric load that simulated the UPTAH. Also, sufficiently reliable operation of a system for supplying energy to a UPTAH consisting of a transcutaneous energy transmission system (TETS) and an implantable battery system was confirmed in three experiments using goats. The results of the in vitro and in vivo experiments showed that the implantable battery system supplied sufficient current to the UPTAH for maintenance of physiological conditions in the goat with maximum rise in temperature to less than 43 degrees C.
Animals↗
Ophthalmic artery occlusion following pars plana vitrectomy in a patient with Terson's syndrome.
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Adult↗
Spontaneous closure of traumatic macular hole.
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Adolescent↗
Cyclic fatigue-crack propagation in sapphire in air and simulated physiological environments.
Single-crystal aluminas are being considered for use in the manufacture of prosthetic heart valves. To characterize such materials for biomedical application, subcritical crack growth by stress corrosion (static fatigue) and by cyclic fatigue has been examined in sapphire along (1100) planes in 24 degrees C humid air and 37 degrees C Ringer's solution (the latter as a simulated physiological environment). The relationships between crack-propagation rates and the linear-elastic stress intensity have been determined for the first time in sapphire for both modes of subcritical cracking. It was found that growth rates were significantly faster at a given stress intensity in the Ringer's solution compared to the humid air environment. Mechanistically, a true cyclic fatigue effect was not found in sapphire as experimentally measured cyclic fatigue-crack growth rates could be closely predicted simply by integrating the static fatigue-crack growth data over the cyclic loading cycle.
Air↗
Hepatocyte growth factor levels in the vitreous of patients with proliferative vitreoretinopathy.
PURPOSE: To determine whether the hepatocyte growth factor is increased in the vitreous of patients with proliferative vitreoretinopathy. METHODS: We assayed hepatocyte growth factor levels by enzyme-linked immunosorbent assay (ELISA) in vitreous samples from 65 consecutive eyes (65 patients) with proliferative vitreoretinopathy (23 eyes), rhegmatogenous retinal detachment (22 eyes), and macular hole or idiopathic epiretinal membrane (control subjects, 20 eyes) having undergone pars plana vitrectomy. RESULTS: Vitreous levels of hepatocyte growth factor were 3.94 +/- 2.29 (mean +/- SD) ng/ml in proliferative vitreoretinopathy, 2.02 +/- 0.84 ng/ml in rhegmatogenous retinal detachment, and 2.16 +/- 1.39 ng/ml in the control subjects. The vitreous levels in proliferative vitreoretinopathy were much greater than levels in rhegmatogenous retinal detachment (P =.0002) and in the control subjects (P =.0007). In proliferative vitreoretinopathy, there was a tendency toward higher levels in eyes with grade D by the Retina Society terminology. CONCLUSION: The results suggest the possibility that hepatocyte growth factor may play a role in the pathogenesis of proliferative vitreoretinopathy.
Enzyme-Linked Immunosorbent Assay↗
Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.
Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.
Alloys↗
Corneal endothelial cell loss in eyes undergoing lensectomy with and without anterior lens capsule removal combined with pars plana vitrectomy and gas tamponade.
PURPOSE: To assess prospectively the comeal endothelial damage associated with pars plana vitrectomy combined with lensectomy and gas tamponade. METHODS: The corneal endothelium was examined with a specular microscope preoperatively and 6 months postoperatively in 42 eyes that underwent pars plana vitrectomy combined with total lensectomy and gas tamponade with SF6 (19 eyes) or C3F8 (23 eyes), and in 12 control eyes that underwent vitrectomy combined with anterior capsule-preserved lensectomy and gas tamponade. RESULTS: The mean +/- SD endothelial cell loss was 17.19+/-7.88% in the SF6 tamponade group, 27.54+/-10.57% in the C3F8 tamponade group, and 3.49+/-2.68% in the control group. Significant differences were found in the mean cell loss among these three groups. The degree of cell loss was significantly related to gas tamponade duration in the eyes with total lensectomy. CONCLUSION: These results suggest that ophthalmic surgeons must try to preserve the lens capsule as much as possible in vitrectomy combined with lensectomy and long-acting gas tamponade in order to prevent corneal endothelial damage.
Adolescent↗
Macular buckling combined with pars plana vitrectomy for complicated retinal detachment due to macular hole.
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Aged↗
Macrophage migration inhibitory factor levels in the vitreous of patients with proliferative diabetic retinopathy.
AIMS: To assess the potential role of macrophage migration inhibitory factor (MIF) in the pathogenesis of proliferative diabetic retinopathy (PDR). METHODS: MIF levels were assayed in the vitreous and paired serum samples of 73 consecutive patients with PDR (32 eyes) and macular hole or idiopathic epiretinal membrane (controls, 41 eyes). An enzyme linked immunosorbent assay technique was used to determine the concentrations of MIF. RESULTS: The median vitreous level of MIF was 11.93 ng/ml (range 4.16-103.85) in the patients with PDR, and 1.79 ng/ml (undetectable-8.93) in the controls. Vitreous levels in eyes with PDR were significantly greater than those in the controls (p<0.0001). Vitreous levels were significantly higher than serum levels in eyes with PDR (p=0.0026). MIF levels were significantly higher in the vitreous of PDR patients with severe fibrous proliferation than in those with slight proliferation (p<0.05). CONCLUSION: The results indicate increased levels of MIF in the vitreous of patients with PDR and a significant association between MIF levels and grades of fibrous proliferation, suggesting the possibility that MIF may play a part in the development of the proliferative phase of PDR.
Adult↗
Surface pitting of heart valve disks tested in an accelerated fatigue tester.
There are various reports on the fracture of mechanical heart valves implanted in humans or animals and it has been pointed out that fractures are induced by erosion of the disk surface due to cavitation bubbles. Cavitation erosion on mechanical heart valves was studied using our originally designed accelerated fatigue tester. Several valve housings with different compliance values were used. The number and position of pits on the valve disk were measured using an optical microscope. Disk-closing velocity was measured and cavitation bubbles were monitored by a high-speed video camera. It was found that disk-closing velocity increased and cavitation erosion was enhanced with an increase in compliance of the valve holder. Therefore, careful attention should be paid to the compliance of an accelerated fatigue tester.
Animals↗
Macrophage migration inhibitory factor levels in the vitreous of patients with proliferative vitreoretinopathy.
PURPOSE: To assess the potential role of macrophage migration inhibitory factor (MIF) in the pathogenesis of proliferative vitreoretinopathy. METHODS: We assayed MIF levels in vitreous and paired serum samples of 74 consecutive patients with proliferative vitreoretinopathy (26 eyes), rhegmatogenous retinal detachment (22 eyes), and macular hole or idiopathic epiretinal membrane (control, 26 eyes) by enzyme-linked immunosorbent assay. RESULTS: Vitreous levels of MIF were 51.33 +/- 49.21 ng/ml (mean +/- SD) in proliferative vitreoretinopathy, 19.11 +/- 16.13 ng/ml in rhegmatogenous retinal detachment, and 2.98 +/- 2.55 ng/ml in the controls. The vitreous levels in eyes with proliferative vitreoretinopathy were significantly higher than levels in eyes with rhegmatogenous retinal detachment (P = .0005) and in the control subjects (P < .0001). The vitreous levels were significantly higher than the serum levels in proliferative vitreoretinopathy (P < .0001) and rhegmatogenous retinal detachment (P = .0019), respectively. CONCLUSIONS: The results suggest that MIF may be involved in the pathogenesis of proliferative vitreoretinopathy.
Enzyme-Linked Immunosorbent Assay↗
Development of the Valvo pump: an axial flow pump implanted at the heart valve position.
Pulsatile artificial hearts having a relatively large volume are difficult to implant in a small patient, but rotary blood pumps can be easily implanted. The objective of this study was to show the feasibility of using the Valvo pump, an axial flow pump implanted at the heart valve position, in such cases. The Valvo pump consists of an impeller and a motor. The motor is waterproofed with a ferrofluidic seal. A blood flow of 5 L/min was obtained at a pressure difference of 13.3 kPa (100 mm Hg) at 7,000 rpm. The normalized index of hemolysis (NIH) was 0.030 +/- 0.003 (n = 3) for a blood flow of 5 L/min at a pressure difference of 13.3 kPa. The pressure resistance of the ferrofluidic seal was 37.5 kPa in a static condition and 26.3 kPa at 10,000 rpm. The seal exhibited no leaks for 41+ days against 20.0 kPa. The results showed that the Valvo pump can maintain systemic circulation with an acceptable level of hemolysis.
Animals↗
New technologies for the 21st century.
In the 21st century, medical science will move beyond the practice of transplantation and into fabrication of artificial organs using tissue and generative engineering. Artificial organs will be used not only to save lives at the end stage of diseases, but also to support daily life and to prevent disease. This article reviews some of the microelectromechanical systems that are being developed, which are key technologies for future artificial organs.
Artificial Organs↗