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Biomedical subjects

K Ogata

Publications and source records attributed to K Ogata.

At least 703 records · Page 39Linked to original sources
PubMedDate not supplied

Phenotype and functional identity of GM-CSF-independent dendritic cells generated by long-term propagation of DC progenitor cells in bone marrow cells and skin Langerhans cells.

Evidence is provided that dendritic cells (DC) generated by either long-term bone marrow cell (BMC) culture with Flt3L and interleukin-6 (IL-6), or after short-term BMC culture with granulocyte macrophage-colony-stimulating factor (GM-CSF) and interleukin-4 (IL-4), contain heterogeneous cell populations of admixed DC and Mphi, regardless of the cytokine source. By employing GM-CSF-independent culture systems with the aid of Flt3/Flk-2 ligand and IL-6 and phenotypic characterization of BMC-derived DC and skin Langerhans cells (LC), revealed similar phenotypes. Furthermore, CD103 (OX62), which is widely used for rat DC separation, was found to be insufficient to enrich DC, due to downregulation of the marker. In this regard, the most efficient selection of rat DC, was obtained by CD161a (NKR-P1A), a member of the C-type lectin family. Despite the phenotypic similarity with BMC-derived DC, the nucleus of LC showed a distinct morphology. A large population of DC generated by Flt3L/IL-6 from GM-CSF receptor-deficient mice by do not express NK1.1 (NKR-P1B and NKR-P1C). The profiles for BMC-derived DC were the same as for skin Langerhans cells.

Animals↗
PubMedDate not supplied

Alpha2-plasmin-inhibitor deficiency (Miyasato disease).

A 25-year-old man, born in Okinawa, Japan, had a haemorrhagic diathesis characterised by prolonged bleeding and ecchymoses after minor trauma and spontaneous joint haemorrhage. The frequency and severity of these episodes were reduced by an antiplasminic drug. Routine coagulation studies revealed no abnormalities except for significantly sshortened euglobulin-lysis time and whole-blood clot lysis time. Activities of all known clotting and fibrinolytic factors were within normal ranges but no circulating alpha2-plasmin inhibitor was found in the plasma. alpha2-plasmin inhibitor is a potent and fast-acting protease inhibitor. Studies of family members indicated that this abnormality was inherited as an autosomal and recessive gene.

Adult↗
PubMedDate not supplied

Amino acid similarity matrix for homology modeling derived from structural alignment and optimized by the Monte Carlo method.

In this paper, we obtained a similarity matrix for homology modeling based on the structure of proteins in a structural alignment. The alignment procedure was executed within dynamic programming generally used in alignment methods. An initial matrix derived from the structural alignment was optimized by the Markov chain Monte Carlo method at low temperature to fit its sequence alignment to the structural alignment. Structural alignment was performed on the basis of the superposition of C alpha atoms for two protein structures. The objective function in the Monte Carlo procedure was defined by entropy in the information theory, allowing us to show that the amino acid similarity matrix aligned accurately. When compared with the structural alignment, the average number of incorrect amino acid residues in the sequence alignment was 22.6 for all residues and about 3.7 for residues in structurally conserved regions. The alignment with our matrix was more similar to structural alignment than to sequence alignments using other amino acid substitution matrices.

Algorithms↗
PubMedDate not supplied

The effect of varus stress on the moving rabbit knee joint.

Unicompartmental osteoarthritis was produced by applying varus stress to moving rabbit knee joints. Degenerative changes were confined to the medial tibial and the medial femoral articular surfaces. Within the range of varus stress used, duration appears to be more important than magnitude of varus stress in determining the severity of cartilage damage. The calcified zone remained histologically unchanged despite advanced changes in the noncalcified zone superficial to the tidemark. Intrachondral degenerative cysts were frequently found in the basilar layers of the noncalcified cartilage adjacent to the tidemark where shear stresses were likely to be highest and diffusible nutrients least available. Highly cellular cartilaginous tissue was noted in the subchondral marrow spaces in the specimens with advanced cartilage degeneration. These areas appeared to be continuous with the overlying degenerated cartilage through gaps in the calcified cartilage. Subchondral bone did not show remarkable trabecular thickening despite advanced degenerative changes in the articular cartilage.

Animals↗
PubMedDate not supplied

Pathomechanics of posterior sag of the tibia in posterior cruciate deficient knees. An experimental study.

This study was an investigation of the pathomechanics of posterior sag of the tibia in knees with posterior knee instability caused by PCL deficiency. By using fresh cadaver knees, the authors hoped to define the relationship of the posterior joint capsule and the medial and lateral collateral ligaments (MCL, LCL) with posterior knee instability in the PCL deficient knee. Thirty newtons of posterior stress were applied to the knees to simulate postoperative conditions. Roentgenographic methods were then used to evaluate posterior sag and change in the distance between the origin and insertion of the PCL. Strain gauges were used to measure the actual strain of the PCL and the collateral ligaments. The PCL, the posterior capsule, and the medial and lateral collateral ligaments were sequentially divided and the above measurements were then repeated in the same way, using 30 N of applied posterior stress. When only the PCL was cut, posterior sag and medial rotation of the tibia occurred with increasing severity as flexion increased. No sagging or rotation of the tibia was observed at full extension in the knees that had isolated PCL "injury". When the posterior capsule was sectioned, no significant changes were noted in the severity of the sag or the rotation. When the MCL or LCL was divided in a PCL deficient knee, greater sag occurred with flexion and a significant sag was observed even at full extension. The MCL "injury" was associated with increased medial rotation, whereas LCL "injuries" were associated with lateral rotation of the tibia.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMedDate not supplied

Quantification of the perfusion of the anterior cruciate ligament and the effects of stress and injury to supporting structures.

The perfusion of the normal ACL was quantitated using the hydrogen washout technique in a canine model. This was compared to the perfusion of the synovium in the suprapatellar pouch. Changes in the ACL perfusion were quantitated after the application of anterior stress, division of the infrapatellar fat pad, and dissection of the synovium enveloping the ACL. The ACL is relatively hypovascular, with one-half the blood flow of the synovium of the suprapatellar pouch. Application of an anterior stress diminishes the blood flow to the ACL to one-fifth of the baseline value, an effect which is reversible. Division of the infrapatellar fat pad causes a two-fold decrease in perfusion to the ACL, whereas dissection of the enveloping synovium results in a complete cessation of blood flow.

Animals↗
PubMedDate not supplied

Measurements of length and tension patterns during reconstruction of the posterior cruciate ligament.

The twofold purpose of this study was to develop an intraoperative technique to assess isometric positioning of posterior cruciate ligament grafts and to demonstrate the rationale for postoperative immobilization of the knee in full extension after a posterior cruciate ligament reconstruction. Multiple femoral fixation sites were selected on the medial intercondylar notch and the posterior cruciate ligament substitute was assessed for changes in length and tension at each of these sites during knee flexion from 0 degree to 120 degrees. The most isometric and isotonic femoral fixation site was localized over a small area slightly distal to the center of the medial intercondylar notch surface. This isometric point can be identified intraoperatively using recognizable surface markers within the knee. When a posterior stress was applied to the proximal tibia, the posterior cruciate ligament substitute showed the least increase in tension and length when the knee was locked in full extension for all of the potential femoral attachment sites assessed. This suggests that postoperative immobilization should be maintained in full extension to limit the stress placed on the posterior cruciate ligament reconstruction.

Aged↗
PubMedDate not supplied

A new three-dimensional osteotomy for cubitus varus deformity after supracondylar fracture of the humerus in children.

In the past, supracondylar osteotomy for the correction of cubitus varus deformity has been associated with a high failure rate and significant complications, even in simple lateral closing wedge osteotomy. This is because the supracondylar area is thin and fixation is difficult to maintain. In cubitus varus deformity, not only medial, but posterior, tilt and internal rotation of the distal fragment also frequently occurs. To correct all these deformities and to achieve a wide bony contact and more rigid fixation than simple lateral closing wedge osteotomy, we propose a new three-dimensional osteotomy. Among 12 patients who received this osteotomy, 11 had an excellent result and one had a good result.

Adolescent↗
PubMedDate not supplied

Congenital vertical talus and its familial occurrence: an analysis of 36 patients.

Thirty-six patients (57 feet) showing congenital vertical talus were treated at the St. Louis Unit of the Shriners Hospital between 1958 and 1978. A high incidence of congenital hip dislocatiom, arthrogryposis, congenital hypoplasia of tibia and CNA disorders was noted as associated abnormalities. These patients are classified in 3 groups: (I) primary isolated form (16 patients); (II) associated form without neurological deficit (12 patients); (III) associated form with neurological deficit (8 patients). Fifty per cent of the patients with primary isolated form had positive family history of foot deformities in their first degree relatives. Familial incidence of congenital vertical talus was observed in 2 families studied. Genetic factors may play an important role in the etiology of the primary isolated form of congenital vertical talus. The current treatment is a one-stage open reduction of the talonavicular dislocation, combined with a posterior release. A subtalar bone block is often imperative to maintain correction. Cast correction alone has never succeeded as the definitive treatment of this condition.

Female↗
PubMedDate not supplied

Barrier to material transfer at the bone-cartilage interface: measurement with hydrogen gas in vivo.

Hydrogen gas was used as a tracer to identify the barrier to material transfer at bone-cartilage interface in the rabbit knees in vivo. The transfer of hydrogen molecules from subchondral bone to articular cartilage was detected by means of platinum electrodes which were placed in varying depths in articular cartilage and subchondral bone. Hydrogen transfer was obstructed at the osteochondral junction in mature animals, while in immature animals there was no such barrier present in the bone-cartilage interface. The metabolism of articular cartilage in mature animals may be isolated from that of the underlying bone. All layers of the mature cartilage including those in the zone of calcified cartilage can receive nourishment and be maintained from the synovial fluid alone.

Animals↗
PubMedDate not supplied

The acute effects of periosteal stripping and medullary reaming on regional bone blood flow.

The immediate effects of surgical dissection on regional bone blood flow were studied using the hydrogen washout technique and the results were compared in mature and immature rabbits. Epiphyseal circulation in young animals was eliminated by stripping the epiphyseal periosteum, and even in mature rabbits epiphyseal blood flow was markedly reduced by periosteal stripping. This suggests that after skeletal maturity blood supply crossing from the metaphysis into the epiphysis is limited. The blood flow rate was not altered by wide reaming of the epiphyseal center in either young or old animals. The rates of bone blood flow in the metaphysis and diaphysis were not altered by separate periosteal stripping or medullary reaming in either age group. Combined reaming and stripping eliminated blood flow in the diaphyseal cortical bone, but in the metaphysis fairly rapid blood flow remained even after reaming and periosteal stripping were done. These findings suggest that arterial supply and venous drainage traverse both endosteal and periosteal surfaces, and either system is capable of sustaining adequate bone tissue circulation.

Animals↗
PubMedDate not supplied

1980 Volvo award winner in basic science. Nutritional pathways of the intervertebral disc. An experimental study using hydrogen washout technique.

The pathways of material transfer to the intervertebral disc were studied in adult dogs by measuring diffusion of hydrogen molecules in the nucleus pulposus before and after disruption of the route through the annulus fibrosus and before and after disruption of the end-plate route. The interfaces was only in the central two-thirds of one side, caused significantly greater decrease in the rate of hydrogen washout than the disruption of the annulus route. Histologically, the bone-cartilage interface was frequently perforated by marrow cavity and vascular buds. These findings suggest that the end-plate route is a major pathway for material transfer to the intervertebral disc.

Animals↗