[Mathematical model analysis of human ligament incorporating non-uniformity of fascicle property and mechanical interaction between fascicles].
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Biomechanical Phenomena↗
Biomedical subjects
S Hirokawa
Publications and source records attributed to S Hirokawa.
A case of body stalk anomaly arising in the second baby of a triplet pregnancy after in-vitro fertilization and embryo transfer.
We report a case of body stalk anomaly arising in the second baby of a triplet pregnancy after in-vitro fertilization and embryo transfer (IVF-ET). Body stalk anomaly or limb-body wall complex is a rare congenital anomaly with a series of similar clinical manifestations and poor prognosis. IVF-ET is an effective treatment for various types of infertility. We summarize and discuss herein the relation with the sequence of genesis for such malformations and multiple pregnancies after IVF-ET.
Abdominal Wall↗
Non-Hodgkin's lymphoma of the ascending colon in a patient with becker muscular dystrophy: report of a case.
We herein present the findings of a 10-year-old boy with non-Hodgkin's lymphoma of the ascending colon which caused intussusception and intestinal bleeding. He had a history of Becker muscular dystrophy. However, he had neither hypertrophic calves nor cardiomyopathy, and his serum creatine kinase (CK) level always exceeded 2000 IU/l. Preoperatively, a laboratory examination revealed high serum levels of CK (2038IU/l), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH), and the blood hemoglobin level was 7.0g/dl. A barium enema examination revealed an intussusception in his ascending colon, which was found to be a highly vascular tumor on Doppler ultrasound scans. A right hemicolectomy was performed. Macroscopically, the 5 x 6 x 8-cm solid tumor of the ascending colon resembled a submucosal tumor and had two ulcerous lesions at the tip. The tumor was histologically diagnosed to be a diffuse large B-cell lymphoma of the ascending colon. General examinations revealed no involvement of lymphoma postoperatively. At 13 months after surgery, the CK (37861U/l), AST (110lU/l), ALT (1381U/ l), and LDH (420lU/l) levels are still high, and the patient is doing well without any signs of recurrence.
Child↗
Ileoileal intussusception and ileal stricture associated with necrotizing enterocolitis in a premature infant: report of a case.
A 630-g male infant developed presumed necrotizing enterocolitis (NEC) after fungal enteritis that resulted in subsequent fungal septicemia associated with pneumoperitoneum on the 9th day of life. Urgent percutaneous Penrose drainage was required. During the operation on the 14th day, an ileoileal intussusception and an ileal stricture were found with perforations on each oral side of the lesions. The distinction between NEC and intussusception in premature infants when they coexist can be difficult, as these conditions share common symptoms. The relation between ischemic injury and dysmotility of the intestine is also discussed. The similarity of intrauterine fetal distress and NEC in premature infants, as seen in the present case of the intussusception associated with focal NEC, suggests that mesenteric and enteric vascular ischemia could be one trigger of intussusception in neonates.
Diagnosis, Differential↗
Circumferential measurement and analysis of strain distribution in the human ACL using a photoelastic coating method.
Large variable deformations of the ligament cannot be adequately quantified by one-dimensional and/or localized measurements. To obtain accurate measurement of non-uniform strains over the entire surface of anterior cruciate ligament (ACL), we used a photoelastic coating technique and a method that allowed us to photograph an ACL around its longitudinal axis. A cadaver knee was modified to expose its ACL for observation, and the ligament was then coated with a photoelastic material. The knee was locked in a jig that allowed simulation of natural knee motion. The jig containing the knee was then mounted on a stand, which allowed the exposed ACL to be photographed from any angle around its longitudinal axis while set at a chosen degree of knee flexion. The jig itself was rotated on its stand so as to obtain a panoramic view of the ACL at a given knee angle. The obtained images of the photoelastic fringe patterns yielded significant information for understanding how the strain distributions along the fiber bundles change in association with knee motion. From the results we obtained using the photoelastic measuring method, we reached the following conclusions. Reciprocal functioning between the anterior and the posterior bundles from extension to flexion of the knee does occur. Strain distribution is not uniform even along the same bundle. The strain behavior of the ACL under uniaxial tensile test does not duplicate the conditions in which the ACL is damaged during knee motion. The differences in strains on the ACL under active and passive knee motions may not be as large as those reported previously in the literature.
Aged↗
Three-dimensional deformation and stress distribution in an analytical/computational model of the anterior cruciate ligament.
In this study, a constitutive equation for the ACL composite was formulated, and 3-D finite deformations and stress distributions of the ACL were calculated using a finite element method to simulate knee flexion. The mathematical model of the ACL was created by a structurally motivated phenomenological approach. It was assumed that the ACL can be ideally represented as a homogeneous hyperelastic matrix (Mooney-Rivin material) in which two families of densely distributed extensible fibers are embedded; the fibers in one family have a parallel orientation, the other fibers extend radially in eight equally spaced directions. The non-linear stress-strain characteristic exhibited by collagen fibers was represented by a tri-linear curve. Simulation was performed and the results provided some original data; the stress distribution within the ACL body as well as that over the surface, the 3-D deformations and stress distributions of the ACL viewed from other sides in addition to those from the medial side, and the variations of the stress distribution pattern in the ACL which occurred when the tibia was displaced anteriorly or posteriorly.
Anterior Cruciate Ligament↗
Analysis of strain distribution in the medial collateral ligament using a photoelastic coating method.
The strain distribution over the entire medial collateral ligament (MCL) was measured using a photoelastic coating method. This new approach utilized a polyurethane monomer as a photoelastic coating film. The initial experiments investigating MCL strain measurement showed that this film had a high sensitivity for strain and good adhesion to the ligament. It was confirmed that strain distribution could be obtained qualitatively over the entire ligament using this method. The mechanism of MCL injury was studied by applying this polyurethane coating film to the entire MCL in a femur-MCL-tibia complex. When simple tension was applied to the complex, strain concentrations were centred at the tibial insertion site, and all the specimens ruptured at the MCL tibial insertion site. With application of a valgus bending moment, increased strain was seen in the MCL from the medial femoral condyle to the medial epicondyle. Histological analysis demonstrated midsubstance ligament ruptures in this same region. For both tests, rupture sites and increased strain concentration sites correlated. In addition, an impingement phenomenon of the MCL on the medial femoral condyle can be seen during application of valgus force, and this phenomenon may explain the higher incidence of MCL injuries on the femoral side seen in the clinical setting. This polyurethane coating method allows for direct and visual measurements, and can qualitatively measure the strain behaviour over the entire MCL surface. This new technique represents a significant improvement over previous point-by-point strain measurement methods.
Animals↗
Acupuncture: neurophysiological perspectives.
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Acupuncture Therapy↗
Neuroblastoma in an adult with a high serum level of carbohydrate antigen, CA125: report of a case.
We report herein the case of a 56-year-old woman with a neuroblastoma associated with a high serum level of carbohydrate antigen, CA125. The patient presented with massive ascites and a firm mass in her upper abdomen for which a laparotomy was performed. However, a recurrent tumor was found 6 months later and she died of the disease within 1 year of surgery despite several courses of adjuvant chemotherapy. Neuroblastoma rarely occurs in adults, and the features of 58 adult cases described in the world literature is summarized following the presentation of the clinical data on this case. The distribution of primary sites in adults is dispersed compared to that seen in pediatric cases, while the natural history of the disease in adults may be longer and less sensitive to chemotherapy than in children. The survival rate of adults with this disease is poor. We conclude that aggressive surgical intervention combined with appropriate chemotherapy protocols as applied in children should be performed in an attempt to achieve complete remission and improve the survival rate of adults with neuroblastoma.
Abdominal Neoplasms↗
Strain distribution in the ligament using photoelasticity. A direct application to the human ACL.
Large and highly variable deformations of the anterior cruciate ligament (ACL) in the human knee cannot be adequately quantified by one-dimensional and/or localized measurements. In order to measure strains in the entire area of the ACL, we employed the photoelastic coating method to analyze stress on the basis of the strains. A specific kind of polyurethane possessing optically high fringe-sensitivity was found to be most suitable for the measurement purposes. Although the photoelastic method has been successfully applied in various fields for stress analyses, its use in studying large deformations of biological tissues has not been reported. Therefore, before proceeding with our main study, we first examined the effects of polyurethane film on the mechanical properties of the ligament. We found that the film had a negligible effect on the tissues' properties, and closely reflected the strain behavior of the tissues. We then applied the method to measure strains on an actual ACL during free flexion-extension of the knee. A specially designed apparatus was used to allow a natural motion of the knee. A portion of the femoral bone was removed to expose the ACL to view. Measurement and analysis gave continuous information about strain distribution, including the variations of strain along the principal strain directions in the ACL.
Animals↗
A photoelastic study of ligament strain.
The anterior cruciate ligament (ACL) in the human knee is known to exhibit as large as 10-20% of strain in association with knee flexion, while usual Hookean elastic materials exhibit at most 0.3%. Furthermore the complex ACL in shape deforms in highly variable manners due to the complicated three-dimensional (3-D) movements of the insertions in association with knee flexion. Such large and highly variable deformations of the ACL cannot be adequately quantified by one-dimensional (1-D) and/or localized measurements. In order to measure strains over the entire area of the ACL, we employed the photoelastic coating method to analyze stress on the basis of the strains. A specific kind of polyurethane possessing optically high fringe-sensitivity was found to be most suitable for measurement purposes. From the preliminary experiments, it was found that a linear relation with 99% of correlation coefficient between the birefringence order and the strain on the polyurethane film continued up to 45% of strain. This study was done in two steps. In the first step, a study was done using a unique model of a knee joint fabricated in a way which allowed deformation and strain distribution in the model ACL to be directly observed and measured by means of the photoelastic coating method. It was confirmed that the film, having negligible effect on the mechanical properties of some biological soft tissues, closely reflected the strain behavior of the tissue. Thus in the second step, the photoelastic method was employed to measure the strains on an actual ACL during free flexion-extension of the knee. A specially designed apparatus was used to allow a natural motion of the knee. The photoelastic measurements demonstrated the potential utility of the application to measuring strain distributions not only on a model ligament but also on an actual ligament. The measurement of an actual ACL led the following results; The principal strain lines well depicted its fiber directions. A reciprocal function between the anterior and posterior bundles was observed. And there was a zero-strain area on the central and posterior sides near the tibial insertion.
Anterior Cruciate Ligament↗
Hyper-elastic model analysis of anterior cruciate ligament.
The objectives of this study were to theoretically analyze changes in shape and stress distribution which occur over the entire surface of the anterior cruciate ligament (ACL). While many studies on the cruciate ligaments' tensile characteristics have been conducted, the length patterns and the differential function of the ACL are still controversial issues for two reasons. Highly variable deformations of the ligaments (which are not uniaxial structures such as a bundle of separate fibres) cannot be adequately quantified by one-dimensional and/or localized measurements. Furthermore, it is impossible to directly measure in situ, non-uniform distribution of biaxial strain over the entire surface of the intra-articular ligaments. We employed an alternative approach which may have the potential to solve some of these difficulties. Using the finite element method, in which the ligament was treated as an incompressive hyper-elastic membrane, the finite deformation of the ligament was theoretically analyzed. Boundary conditions were applied by prescribing the displacements at the boundary nodes corresponding to the insertions. Special attention was paid to the distribution of longitudinal strain. The following values were obtained as a function of knee flexion: three-dimensional change in shape and strain distribution, length change of each fibre, length changes in positions along a fibre, resultant pull force on the tibial insertion, and change of strain pattern by anterior-posterior displacement of the tibia. The results demonstrated that strain distribution varied, even along the fibre run, and large strain gradients were observed in the regions near the insertions. It was found that distance between insertions introduced noticeable discrepancies from the length along a curved fibre. The net resultant force at the tibial insertion of the ligament was maximum at 0 degree of flexion, decreased until 50 degrees of flexion, then slightly increased up to 120 degrees of flexion. Predominantly, the anterior and the posterior displacements of the tibia, respectively, increased and decreased strain in the ligament, however, some portions were even more stretched by the posterior displacement.
Anterior Cruciate Ligament↗
Effect of Hachimi-jio-gan on scopolamine-induced memory impairment and on acetylcholine content in rat brain.
The effect of Hachimi-jio-gan (HJ) on scopolamine induced memory impairment was studied using a radial maze performance, the effect of HJ on the central cholinergic system as measured by acetylcholine (ACh) content, choline acetyltransferase (CAT) and acetylcholinesterase (AChE) activities was also examined. HJ (0.01-1.0 g/kg, p.o.) showed no influence on the radial maze performance. However, with the administration of scopolamine (0.5 mg/kg, i.p.), the number of the correct choices decreased and the number of the error choices increased. HJ (0.1 and 0.5 g/kg, p.o.) reduced this scopolamine-induced cognitive disturbance. The effect of HJ on ACh content and enzyme activities in the brain, frontal cortex, hippocampus and striatum was also investigated. In normal rats, HJ (0.1 and 0.5 g/kg, p.o. x 7 days) significantly increased ACh content in the frontal cortex, although it did not increased ACh content in the hippocampus. In scopolamine-treated rats, ACh content decreased in the brain regions examined. HJ (0.5 g/kg, p.o.) inhibited a decrease in ACh content in the frontal cortex, and with the same dosage of HJ increased CAT activity in the frontal cortex and AChE activity in the hippocampus. These results suggest that the behavioral effects of HJ may be related to its effect on the central cholinergic system.
Acetylcholine↗
Energy expenditure and fatiguability in paraplegic ambulation using reciprocating gait orthosis and electric stimulation.
To clarify the relationship between metabolic energy expenditure and fatiguability in paraplegic persons fitted with orthoses, we measured energy consumption in six thoracic paraplegic patients ambulating by means of reciprocating gait orthosis (RGO) used with and without functional electrical stimulation (FES). The data obtained from persons using both RGO and FES were adjusted to allow for the effects of fatiguability so as to obtain an approximate value for upper-body consumption. The data obtained from persons using RGO only were not adjusted, because no energy consumption occurred in the lower portion of the body. The data, expressed in kcal/kg-min and kcal/kg-m, were plotted against walking speed attained using RGO, and RGO with FES. The results were compared with those from persons fitted with long leg braces (LLB), hip guidance orthoses (HGO) and an FES walking aid (data obtained from available literature). We found that the lowest energy expenditure in kcal/kg-m across the full range of walking speeds occurred when both RGO and FES were used together, followed by RGO only, HGO, LLB, and FES only, respectively. The lowest energy expenditure in kcal/kg-min, for walking speeds, below 0-28 m/s, also occurred when both RGO and FES were used together, followed by RGO only, HGO, LLB, and FES only. The results suggest that, although the use of FES with RGO may increase oxygen uptake, it decreases energy expenditure in the upper extremities, thereby reducing patient fatigue. They also suggest that mechanical orthosis giving passive support to the hip, knee and ankle in combination with FES may provide the most efficient walking aid for paraplegic persons.
Adult↗
Anabolic-androgenic steroid abuse in weight lifters: evidence for activation of the hemostatic system.
Anabolic-androgenic steroid abuse has recently been linked with acute vascular events in athletes. To date, the relationship between steroid abuse and the potential for cardiovascular disease has been considered almost exclusively in terms of lipid metabolism. However, recent reports of thrombosis in androgen abusing athletes with no evidence of atherosclerosis suggests the hypothesis that thrombosis risk in such athletes could be mediated through androgen induced abnormalities of coagulation. To determine if anabolic-androgenic steroid abuse in weight lifters is associated with an activation of the hemostatic system we studied forty-nine weight lifters recruited through advertisements. History of androgen use or abstinence was confirmed via urine assays. Plasma was assayed for clotting and fibrinolytic activity by measuring thrombin/antithrombin complexes (TAT), prothrombin fragment 1 + 1 (F1 + 2), and D-dimers (D-di); markers of the endothelial based fibrinolytic components were assayed by measuring tissue plasminogen activator antigen (t-PA Ag) and its inhibitor (PAI-1); finally, the activity of antithrombin III, protein C, and protein S were measured. Abnormally high concentrations of TAT complexes were noted in 16% of our confirmed steroid using weight lifters compared to 6% of our confirmed nonusers (P = .01). Steroid users also demonstrated abnormally high concentrations of F1 + 2 and D-dimers when compared to nonusers (44 vs. 24%, P < .001, and 9 vs. 0%, respectively). Non-steroid users were more likely to have elevated levels of t-PA Ag and PAI-1 than our steroid using weight lifters (both P < .001). The activities of antithrombin III and protein S were more likely to be higher in users compared to nonusers (22 vs. 6%, P = .005; 19 vs. 0%, respectively). Some anabolic-androgenic steroid using weight lifters have an accelerated activation of their hemostatic system as evidence by increased generation of both thrombin and plasmin. These changes could reflect a thrombotic diatheses that may contribute to vascular occlusion reported in young athletes using these drugs. The predictive value of these coagulation abnormalities in terms of risk of thrombosis to individual steroid using weight lifters or the population as a whole remains to be studied.
Adult↗
Effect of hachimijiogan, an oriental herbal medicinal mixture, on experimental amnesia in mice.
The effect of Hachimijiogan on cognitive disturbance was investigated using step-through passive avoidance failure techniques: scopolamine-, cycloheximide- and cerebral ischemia-induced amnesia. Pre-acquisition trial administration of Hachimijiogan (0.5 g/kg, p.o.) prolonged the step-through latency reduced by scopolamine and cycloheximide. Hachimijiogan (0.5 and 1.0 g/kg, p.o.) also ameliorated the cerebral ischemia-induced amnesia. Physostigmine (0.1 mg/kg, i.p.) ameliorated all three amnesia models. The ameliorating effects of Hachimijiogan and physostigmine on cycloheximide-induced amnesia were diminished by the combination with scopolamine. These results suggest that Hachimijiogan possesses a wide-ranging pharmacological profile in anti-amnesic actions and that its anti-amnesic activities may be related to the cholinergic neuronal system.
Amnesia↗
Thrombosis and hormone replacement therapy in postmenopausal women.
OBJECTIVE: The effects of postmenopausal hormone replacement therapy on thrombosis remain controversial. We tested the hypothesis that estrogen or progesterone has no significant effect on thrombosis by means of newly developed markers of blood clotting, specifically prothrombin fragment 1 + 2, a marker of factor Xa generation, and thrombin-antithrombin III complex, a marker of thrombin generation. STUDY DESIGN: A prospective study that included 106 women, 68 postmenopausal women on hormone replacement therapy and 38 postmenopausal controls, was performed. Plasma levels of prothrombin fragment 1 + 2 and thrombin-antithrombin III complex were measured by enzyme-linked immunosorbent assay. Multivariate analysis of the covariance was used for statistical analysis, controlling for patient's age because the hormone replacement therapy group was older. RESULTS: There were no statistically significant differences between the hormone replacement therapy and control groups in either of the clotting parameters measured. A comparison of the levels of prothrombin fragment 1 + 2 and thrombin-antithrombin III complex in patients receiving estrogen alone or estrogen plus progestin also revealed no differences. CONCLUSIONS: Current doses of postmenopausal hormone replacement therapy do not appear to enhance in vivo clotting. Thromboembolic complications among postmenopausal women receiving hormone replacement therapy may therefore be secondary to congenital or other acquired coagulation defects.
Adult↗
Protective effect of hachimi-jio-gan, an oriental herbal medicinal mixture, against cerebral anoxia.
The protective effect of Hachimi-jio-gan (HJ) against cerebral anoxia was investigated with various experimental models in mice. Minimal effective dose of HJ which significantly prolonged the survival time was 0.5 g/kg, p.o. for normobaric hypoxia and 0.5 g/kg, p.o. for KCN- (4 mg/kg, i.v.) induced anoxia. HJ reduced the duration of coma induced by a sublethal dose of KCN (1.8 mg/kg, i.v.) in a dose-dependent manner. Furthermore HJ potentiated the anti-anoxic effect of physostigmine and the effect of HJ was diminished by the treatment with atropine.
Animals↗