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Biomedical subjects

T Toyoda

Publications and source records attributed to T Toyoda.

At least 55 records · Page 3Linked to original sources
PubMed1999

Anterior cruciate ligament reconstruction and physiological joint laxity: earliest changes in joint stability and stiffness after reconstruction.

Physiological joint laxity is an important element of normal knee joint function, providing smooth joint movement. However, the objective evaluation of post-operative results after knee ligament surgery is usually based primarily on stability and range of motion, and joint laxity has been ignored. In this study, we measured the joint stiffness of 82 knees undergoing anterior cruciate ligament (ACL) reconstruction with the Leeds-Keio artificial ligament, before the operation, immediately after the operation, and finally when the full range of motion was achieved postoperatively; changes in joint laxity after the ACL reconstruction were investigated. Before the operation, joint laxity was greater than that of the normal side (P < 0.01), but immediately after the operation it diminished compared not only with that observed preoperatively, but also with that of the normal side. When the full range of motion was achieved, joint laxity was lower than that observed immediately after the operation (P < 0.01), but still remained higher than that of the normal side (P < 0.01). In other words, stability was achieved, but joint laxity was diminished through the operation. In this series, a stiffer artificial ligament than the natural ACL was used, and maximum tension was applied during the operation, aiming at better stability, but this may cause diminution of joint laxity.

Adolescent↗
PubMed1999

Studies of bovine enterovirus structure by ultraviolet resonance Raman spectroscopy.

The structural comparison of bovine enterovirus MZ468 strain before and after the heat treatment was studied by ultraviolet resonance Raman (UVRR) spectra excited at both 235 and 251 nm. The difference between full, heated full and purified empty particles, which were expected as an in vitro model of uncoating, were demonstrated. At 235 nm excitation, the Raman bands of the capsid protein dominated in all the UVRR spectra. The UVRR spectra of the empty particles exhibited non-homogenious broadening for tryptophan W3 band and W7 Fermi doublet bands, which were characteristics of hydrophobic environment, when compared with those of the full particles. The results indicates that some Trp indole rings of the full particles were packaged inside the viral capsids and not strained by virion assembly. On the other hand, the Raman bands assigned to guanine residues of the single stranded-RNA genome were enhanced strongly in the 251-nm excited UVRR spectrum. The spectral differences between the packaged (full particles) and the unpackaged virions (heated full particles) indicates that some guanine residues had strong hydrogen bonds in the full particles.

Animals↗
PubMed1999

Prolonged circulation time of doxorubicin-loaded liposomes coated with a modified polyvinyl alcohol after intravenous injection in rats.

The purpose of this study was to evaluate the functions of a modified polyvinyl alcohol (PVA-R), which has a hydrophobic moiety, as a coating material for liposomes to be loaded with the anticancer drug, doxorubicin. The size controlled liposomes (egg phosphatidylcholine: cholesterol=1:1 molar ratio) were prepared by the hydration method followed by extrusion. Drug encapsulation and surface modification with polymers (PVA and PVA-R) were carried out simultaneously using a modified pH gradient method. The existence of a thick polymer layer on the surface of the liposomes was confirmed by an increase in particle size and the amount of polymer on the liposomal surface, especially for the PVA-R-coated liposomes. The effects of polymer coating on the behavior of the liposomes in vivo were evaluated by measuring the circulation time and biodistribution of the drug after i.v. administration of the liposomal drug in rats. The PVA-R-coated liposomes showed a more prolonged circulating time for the drug with less uptake by the reticuloendothelial system after i.v. administration in rats, compared with non-coated liposomes. These results confirm that polymer possessing a hydrophobic anchor at its end, like PVA-R, is a suitable material for modifying the surface of doxorubicin-loaded liposomes to improve their stability in the circulating blood.

Animals↗
PubMed1999

The effects of tensile load on the metabolism of cultured chondrocytes.

The effect of cyclic tensile load on articular cartilage metabolism was investigated experimentally using 12 Japanese White rabbits. Chondrocytes obtained from the knee joints were cultured on plates with flexible silicone rubber bases. They were subjected to a cyclic (3 seconds on and 3 seconds off) tensile load for 24 hours with a maximum increase in area of 17%. Proteoglycan synthesis, collagen synthesis, and tissue inhibitors of metalloproteinases production by the chondrocytes under the load were quantified and compared with those produced by the control cells in an unloaded condition. The cultured chondrocytes under the cyclic tensile load perpendicularly aligned to the direction of the tensile load. Collagen synthesis and tissue inhibitors of metalloproteinases production increased significantly under the cyclic tensile load, although no significant change in proteoglycan synthesis was observed. These results suggested that the cyclic tensile load on the chondrocytes contribute to the regulation of articular cartilage metabolism in part.

Animals↗
PubMed1999

Hypothermia-induced ischemic tolerance.

Delayed resistance to ischemic injury can be induced by a variety of conditioning stimuli. This phenomenon, known as delayed ischemic tolerance, is initiated over several hours or a day, and can persist for up to a week or more. The present paper describes recent experiments in which transient hypothermia was used as a conditioning stimulus to induce ischemic tolerance. A brief period of hypothermia administered 6 to 48 hours prior to focal ischemia reduces subsequent cerebral infarction. Hypothermia-induced ischemic tolerance is reversed by 7 days postconditioning, and is blocked by the protein synthesis inhibitor anisomycin. Electrophysiological studies utilizing in vitro brain slices demonstrate that hypoxic damage to synaptic responses is reduced in slices prepared from hypothermia-preconditioned animals. Taken together, these findings indicate that transient hypothermia induces tolerance in the brain parenchyma, and that increased expression of one or more gene products contributes to this phenomenon. Inasmuch as hypothermia is already an approved clinical procedure for intraischemic and postischemic therapy, it is possible that hypothermia could provide a clinically useful conditioning stimulus for limiting injury elicited by anticipated periods of ischemia.

Animals↗
PubMed1998

Crystallization and preliminary X-ray analysis of pig E3, lipoamide dehydrogenase.

Pig heart lipoamide dehydrogenase was crystallized by the hanging-drop vapor-diffusion method. X-ray diffraction patterns show that the hexagonal crystals have unit-cell dimensions of a = b = 359. 3, c = 140.5 A. The crystal structure has been preliminarily solved by the molecular-replacement method in the space group P6322. Three dimeric molecules have been found in the asymmetric unit, one of them located on the crystallographic twofold axis.

Animals↗
PubMed1998

Valence-difference contrast measurements utilizing X-ray anomalous scattering.

Anomalous scattering experiments with X-ray wavelengths close to an absorption edge have made it possible to determine independently the behaviour of ions in different valence states. The anomalous scattering factors of Fe(2+) and Fe(3+) obtained from both absorption and diffraction data have a large difference in f' between the two kinds of ions. Using a valence-difference contrast method, Bragg and diffuse scattering measurements were carried out for single crystals of Fe(3)O(4) at low temperatures. The results demonstrate the ability of the contrast method to resolve charge ordering and valence fluctuation details.

Journal Article↗
PubMed1998

Nucleotide sequence of the gene encoding the RNA polymerase and the 3' non-coding region of a bovine enterovirus Japanese isolate: rapid synonymous substitutions between European and Japanese strains.

The nucleotide sequences of the genome RNA encoding the RNA polymerase and the 3' non-coding region (NCR) of bovine enterovirus (BEV) serotype I Japanese isolate, MZ468, were determined. The genetic distance between the two BEV serotype I strains, MZ468 and VG-5-27, was calculated by pairwise comparison of nucleotide sequences. The synonymous substitution rate was high (1.40 x 10(-2)/site/year), and of the same order as those of influenza virus HA, HIV-1 gag and env, and enterovirus 70 VP1 genes.

Amino Acid Sequence↗
PubMed1998

A comparison between magnetic resonance imaging and pathologic findings in patients with disc displacement.

PURPOSE: This study compared the magnetic resonance imaging (MRI) and pathologic findings in patients with disc displacement without perforation. PATIENTS AND METHODS: Eleven patients and 30 asymptomatic volunteers underwent MRI using the three-dimensional (3D) fast imaging with a steady precession sequence (FISP) acquisition technique. The 11 patients (11 joints) then underwent discectomy, and the pathologic and MRI findings were compared. RESULTS: MRI (FISP-3D) examination of the temporomandibular joint in 11 patients (11 joints) showed low signal intensity in the anterior band and the intermediate zone of the disc, and high signal intensity in the posterior band of the disc and retrodiscal tissue. On microscopic examination, the anterior band and intermediate zone of the disc were found to consist of dense collagenous bundles showing mild hyaline degeneration. Myxomatous degeneration was seen in the posterior band of the disc (11 joints), and edematous change was seen in the retrodiscal tissues (seven joints). CONCLUSIONS: Pathologic changes in the disc and the retrodiscal tissues are accurately depicted by FISP-3D.

Adult↗
PubMed1998

Crystal structure of eucaryotic E3, lipoamide dehydrogenase from yeast.

The crystal structure of eucaryotic lipoamide dehydrogenase from yeast has been determined by an X-ray analysis at 2.7 (partially at 2.4) A resolution. The enzyme has two identical subunits related by a pseudo twofold symmetry. The tertiary structure is similar to those of other procaryotic enzymes. The active site, consisting of FAD, Cys44, and Cys49 from one subunit and His457' from the other subunit, is highly conserved. This enzyme is directly bound to the core protein E2 of the 2-oxoglutarate dehydrogenase complex, whereas it is bound to the pyruvate dehydrogenase complex through a protein X. The calculated electrostatic potential suggests two characteristic regions for binding with these two proteins.

Amino Acid Sequence↗
PubMed1998

Tensile load and the metabolism of anterior cruciate ligament cells.

It generally is recognized that tensile load plays a major role in maintaining the homeostasis of the anterior cruciate ligament fibers, but its detailed mechanism remains a matter of controversy. The effect of cyclic tensile load on the metabolism of the anterior cruciate ligament were investigated experimentally using cultured cells from the anterior cruciate ligament of rabbits. Using culture plates with flexible rubber bases, a cyclic tensile load was applied to the cultured cells for 24 hours, and the changes in shape, alignment, and metabolism of the cells were analyzed. Under the cyclic tensile load, the shape of the cells from the anterior cruciate ligament changed to spindle and aligned perpendicularly to the direction of the tensile load. The cyclic tensile load also caused an increase in collagen synthesis by the cells from the anterior cruciate ligament, which was predominant in Type I. The cells from the synovium showed similar changes in shape and alignment under the cyclic tensile load, but no significant change was observed in cell metabolism. These observations suggest that the application of cyclic tensile load on the anterior cruciate ligament cells is an important factor in the regulation of collagen synthesis in the anterior cruciate ligament.

Animals↗
PubMed1998

Attenuation of experimental subarachnoid hemorrhage-induced cerebral vasospasm by CGS 26303, an endothelin-converting enzyme inhibitor.

The effect of CGS 26303, an endothelin-converting enzyme inhibitor, on the prevention and reversal of cerebral vasospasm was investigated in a rabbit model of subarachnoid hemorrhage (SAH). In the prevention study, rabbits were injected with 3 ml of autologous blood in the cisterna magna and treatment with CGS 26303 i.v. was initiated 1 h later. The compound was subsequently administered at 12, 24, and 36 h post SAH and animals were sacrificed at 48 h post SAH. Treatment with CGS 26303 at 3, 10, and 30 mg/kg resulted in dose-dependent increases in the concentrations of the compound in cerebrospinal fluid samples, and the arterial narrowing after SAH was significantly attenuated in all three groups. Morphologically, corrugation of the internal elastic lamina of vessels was often observed in the vehicle-treated group, but it was not prominent in the CGS 26303-treated groups and the healthy controls. In the reversal study, treatment with CGS 26303 was initiated 24 h post SAH and a second injection was given 12 h later. Arterial narrowing was significantly attenuated in rabbits treated with CGS 26303 at 30 mg/kg. These results demonstrate that CGS 26303 may be an effective agent in prevention and reversal of cerebral vasospasm after aneurysmal SAH.

Animals↗
PubMed1998

Enhanced endogenous antioxidant activity and inhibition of cerebral vasospasm in rabbits by pretreatment with a nontoxic endotoxin analog, monophosphoryl lipid A.

OBJECT: Monophosphoryl lipid A (MPL) and diphosphoryl lipid (DPL) are derivatives of the lipopolysaccharide (endotoxin) of Salmonella minnesota strain R595. Monophosphoryl lipid A is relatively nontoxic and can stimulate the natural defense or immune system. Diphosphoryl lipid is relatively toxic; however, at higher concentrations, it can also stimulate an immune response. The purpose of the present study was to determine the effects of these endotoxin analogs on cerebral vasospasm after the onset of subarachnoid hemorrhage (SAH) in rabbits. METHODS: Intrathecal administration of MPL or DPL (5 microg/kg) was performed immediately before and 24 hours after induction of SAH in New Zealand White rabbits. Forty-eight hours after induction of SAH, the animals were killed by perfusion fixation for morphometric analyses of vessels or perfused with saline and assayed for superoxide dismutase (SOD) activity. Additional rabbits were administered MPL or DPL and killed 24 hours later for assessment of SOD activity; no SAH was induced in these animals. Experimental SAH elicited spasm of the basilar arteries in each group. Vasospasm was markedly attenuated in animals treated with MPL (p < 0.01 compared with vehicle-treated animals), but not in animals treated with DPL. A substantial reduction in SOD activity in the basilar artery accompanied the vasospasm; this loss of activity was significantly blocked by treatment with MPL, but not DPL. In animals that were not subjected to experimental SAH, MPL elicited a significant increase in SOD activity over basal levels, whereas DPL was ineffective. CONCLUSIONS: These data provide evidence of a marked protective effect of the endotoxin analog MPL against vasospasm. Although the mechanism(s) responsible for the protective effect of MPL remains to be verified, an enhancement of basal antioxidant activity and an inhibition of SAH-induced loss of this activity are attractive candidates. An MPL-based therapy could represent a useful addition to current therapies for SAH-induced cerebral injury.

Adjuvants, Immunologic↗
PubMed1998

[Management and delivery of radiation dose distribution images using the Internet].

Dose distribution images play important roles in the management of cancer patients. To date hard copies of these images have been stored and referred to by radiation oncologists as needed. In most cases, these images were not available to medical personnel outside the radiation oncology department. We have developed a mechanism in the hospital to access these dose distribution images via WWW (World Wide Web). A screen snapshot of a dose distribution image on the CRT of a treatment planning machine is copied to the WWW server and converted to a GIF image. Similarly, we can register dose volume histograms and digitally reconstructed radiographs on the WWW. Medical personnel throughout the hospital can access the images through the WWW browser. As a result, radiation oncologists are given detailed information on target definition in treatment planning by expert physicians. The system also helps co-medical staff in understanding dose distributions and predicting radiation injuries. At the same time, it actualizes an electronic archive of dose distribution images, which is a database for quick and reliable review, evaluation and comparison of treatment plans. This technique also furthers a close relationship among radiation oncologists, physicians, and co-medical personnel.

Computer Communication Networks↗
PubMed1998

[Percutaneous drainage of a bulla with tuberculous infection in a patient].

A 63-year-old man complaining of low grade fever and dry cough was admitted to our hospital. Chest X-ray showed infiltrative shadows and a bulla with a fluid level in the left upper lung field. Bacteriological examination of sputum and bronchoalveolar lavage fluid did not yield any diagnostic results. Percutaneous aspiration of the bulla under fluoroscopy was performed. Bulla with tuberculous infection was considered because a high ADA level was detected in the fluid of the bulla. A culture of the bulla fluid was positive for mycobacterium tuberculosis (TB), which was sensitive to all anti-mycobacterial drugs. The fluid in the bulla gradually increased, and occupied the entire space of the bulla three months later. Percutaneous aspiration of the bulla was performed again and a fluid smear was positive for TB. It was thought that systemic administration of anti-mycobacterial drugs had been ineffective, so percutaneous drainage and subsequent injection of anti-mycobacterial drugs into the bulla was performed. The fluid in the bulla subsequently disappeared and the bulla shrank gradually. Percutaneous drainage of a bulla with tuberculous infection should be considered in those who do not respond to medical management.

Antitubercular Agents↗
PubMed1998

[Sealing effect of fibrin adhesive by various method on protection of air leakage in lung surgery].

We used fibrin adhesive for the treatment of pulmonary air leak after pneumonectomy to sealing effect of fibrin adhesive which was classified by application and obtained the following results. 98 patients with pulmonary air leak were randomly allocated to the double layer group and spray group. The following were investigated between the double layer group and spray group. 1) size and dose of fibrin adhesive, 2) airway pressure where pulmonary air leak was observed before and after application, 3) duration of postoperative pulmonary air leak, 4) degree of postoperative pulmonary air leak, and 5) postoperative complication. The dose of fibrin adhesives was significantly smaller, the mean duration of postoperative pulmonary air leak was significantly shorter and the degree of postoperative pulmonary air leak was significantly more slight in the spray group than in the double layer group. In addition, the sutured part was examined before and after application of fibrin adhesives with a scanning electron microscope. Fibrin nets were formed more uniformly by the spray method than by the double layer method. From these investigations it is concluded that since the appliance for the spray method is improved and easily used and fibrin nets are formed uniformly by this method, the spray method is useful for the prophylaxis of pulmonary air leak.

Aerosols↗
PubMed1998

Dysregulation of trace element composition in ovariectomized cynomolgus monkey bones.

One of the challenging issues in modern biomedical science is the increasing number of osteoporosis patients due to the expansion of elderly populations. Among aging-related pathogenic changes, alterations in bone function and skeletal pathogenesis is a particularly important issue of concern. Osteoporosis is one of the most serious bone-related pathogenic states, as it causes serious loss of quality of life. Alterations in estrogen levels in accordance with aging are one of the key risk factors for osteoporosis. Complexed estrogen actions on bones can be traced by analyzing bone mineral components, as those elements accumulate as mineral complexes, reflecting the context of multiple cellular reactions such as bone resorption/osteogenesis. We have analyzed bone trace element composition in ovariectomized (OVX-treated) Cynomolgus monkey models in this study. In order to gain insights into the effects of such defects on bone trace element composition, inductively coupled plasma atomic emissions spectrometry (ICP-AES) analysis was performed. Marked changes in bone trace element levels were found in vertebral bones of OVX-treated Cynomolgus monkeys. An assessment of these trace element spectra in OVX model animals is discussed. These results could provide useful markers for understanding the physiological states of bones in postmenopausal women.

Animals↗