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Biomedical subjects

K Yamano

Publications and source records attributed to K Yamano.

At least 37 records · Page 2Linked to original sources
PubMed1996

Revascularization in nontraumatic osteonecrosis of the femoral head.

To study the revascularization pattern of nontraumatic osteonecrosis, superselective angiography of the femoral medical circumflex artery was done twice on 13 hips for which no treatment had been given. Angiographic evaluation of the hips with early-stage osteonecrosis not visible on radiographs showed the absence of superior retinacular arteries from the stump in all hips. Penetration of small vessels was seen on 6 hips. Bony scintigraphy of 13 hips and magnetic resonance imaging of 9 hips were taken at about the same time. Bony scintigraphy and magnetic resonance imaging results were positive in 11 of 13 hips and in all 9 hips, respectively. The patients were observed until evidence of necrosis appeared on radiographs. When this sign became evident, a second angiography was conducted, which indicated the penetration of erratically formed vessels with increase in size in 12 hips. It was assumed that the blood supply from the superior retinacular arteries was interfered with in large areas of the femoral head and that revascularization started with the formation of small vessels, followed by further penetration of large vessels.

Adolescent↗
PubMed1996

Agents for the treatment of overactive detrusor. IX. Synthesis and pharmacological properties of metabolites of N-tert-Butyl-4,4-diphenyl-2-cyclopentenylamine (FK584) in human urine.

We synthesized the racemates of the five presumed metabolites (1b-f) of (S)-(--)-N-tert-butyl-4,4-diphenyl-2-cyclopentenylamine hydrochloride (FK584, S(--)-1a), a novel agent for the treatment of overactive detrusor syndrome, in order to confirm the structures of the metabolites and also to evaluate their inhibitory activity against detrusor contraction. (+/-)-N-tert-Butyl-4-(4-hydroxyphenyl)- and 4-(4-hydroxyphenyl)- and 4-phenyl-2-cyclopentenylamines (1b--e) were synthesized via 5-(4-methoxyphenyl)- and 5-(4-benzyloxy-3-methoxyphenyl)-5-phenyl-2-cyclopenten-1-one (9g, h), respectively. Compounds 1b-f prepared in this study were identical with the metabolites in human urine in gas chromatography-mass spectrometry and analytical HPLC. The inhibitory activity of compounds 1b-f against detrusor contraction in vitro induced by electrical field stimulation in guinea-pigs was less potent than that of FK584.

Amines↗
PubMed1995

cDNA cloning of thyroid hormone receptor beta for the Japanese flounder.

cDNA encoding the beta type of thyroid hormone receptor (THR) was cloned from a lambda gt10 library prepared from the whole bodies of metamorphosing flounder (Paralichthys olivaceus). The deduced amino acid sequence of the flounder THR beta (fTHR beta 1) showed higher homologies to the known THR beta s of other vertebrate animals than to THR alpha s, including flounder THR alpha s. Unlike any other THR, fTHR beta 1 possessed an insertion sequence composed of nine amino acids in the region prior to the hormone-binding domain. PCR analyses suggested the presence of transcripts for another THR beta (fTHR beta 2) that had a longer insertion sequence than fTHR beta 1. The analyses further suggested that the cDNA sequences of the two flounder THR beta s most likely shared a constant sequence except for a 60-base additional sequence found only in fTHR beta 2. The flounder genome possessed a single gene for both fTHR beta 1 and beta 2, suggesting that the two THR beta variants are produced from the same gene through an alternative splicing system.

Amino Acid Sequence↗
PubMed1994

Cloning of thyroid hormone receptor genes expressed in metamorphosing flounder.

Two distinct cDNAs encoding thyroid hormone receptors (THRs) were cloned from a lambda gt10 library prepared from the whole bodies of metamorphosing flounder larvae (Paralichthys olivaceus). Deduced amino acid sequences of the two isolated cDNAs shared 96% and 92% homologies in their DNA- and hormone-binding domains, respectively. These were highly conserved when compared to THRs for other vertebrates: 88-96% in the DNA-binding domain and 84-94% in the hormone-binding domain. Other receptors in the nuclear receptor family showed lower homologies than those of THRs. Both THRs for the flounder had higher homologies with the alpha-type THRs of other vertebrates than with the beta-type. Thus, the two THRs for flounder were designated as fTHR alpha A and fTHR alpha B.

Amino Acid Sequence↗
PubMed1994

Effect of thyroid hormone on developmental transition of myosin light chains during flounder metamorphosis.

Thyroidal control of the transition of myosin isoforms during flounder metamorphosis was examined by the administration of either only thiourea (TU), a potent inhibitor of thyroid hormone synthesis, or thyroxine (T4) together with TU into premetamorphic larvae. Immersion of premetamorphic larvae in 400 microM of TU inhibited the appearance of the adult-type DTNB (5,5'-dithio-bis-nitrobenzoic acid) light chain, LC2, whereas administration of T4 with TU induced a precocious appearance of LC2 and decreased the relative amount of the larval-type DTNB light chain, LC2*. TU was administered into juveniles just after completion of metamorphosis. The treatment did not affect the composition of the myosin light chains. These results suggest that thyroid hormone irreversibly turns on the switch for transition of the DTNB light chains from larval to adult type during metamorphosis of the flounder.

Animals↗
PubMed1992

Intra-operative screw trimming in direct screw fixation of the odontoid process fracture--technical note.

For a satisfactory direct screw fixation of fractures of the odontoid process it is necessary to use a screw of the proper total length and thread length, but such an optimal ready-made screw is not always available. The authors describe a technique of intra-operative screw trimming using a high-speed diamond drill. This adjustment is easily and quickly performed. It enables the screw to act as a compression screw, which facilitates fusion of the fractured surfaces.

Bone Screws↗
PubMed1992

Direct skull marking for a pre-operative localization in regional cerebral surgery. Technical note.

A method is described in which an open neurosurgical target is pre-operatively marked on the skull of a patient. A target point of the scalp surface localized from neuroimaging studies is transferred onto the skull by an injection of pyoktanin blue. Its accuracy and reliability is far superior than that of the usual scalp marking. The method is simple, practical, and allows a smaller, regional craniotomy with the advantage of minimum operative invasiveness.

Adult↗
PubMed1992

[Fresh fracture of the odontoid process treated with direct screw fixation; a case report].

A case of a fresh type II fracture (Anderson & D'Alonzo) of the odontoid process treated with direct screw fixation is reported. A 52-year-old man complained of severe neck pain following a hit on his forehead incurred in a falling accident. Neurological examination was normal. Cervical spine x-ray films and axial CT scans revealed a fracture at the base of the dens. It was slightly oblique leftup and rightdown, and the dens fragment was displaced 3mm lateral to the right. One week after the injury, this odontoid fracture was directly fixed with a compression screw by an anterior cervical approach. Immediately after the operation, his neck pain disappeared. He had only 4 days of bed rest and 2 months of external immobilization with a simple neck collar. He returned to his previous job 2 months after surgery without any limitation of his neck movement. At follow-up examination 16.5 months after the operation, x-ray films demonstrated complete fusion of the fracture and no problem about the screw such as displacement or breakage. Direct screw fixation of an odontoid fracture via a transcervical approach was thought to be a reasonable method of treatment. For proper assembly of this method, the following two points are particularly recommended: a screw insertion perpendicular to the fracture plane and the use of an optimal screw with both the desired total and thread lengths.

Bone Screws↗
PubMed1991

Thyroid hormone regulates developmental changes in muscle during flounder metamorphosis.

Morphological and biochemical changes in the muscular tissue of metamorphosing flounder were studied in relation to the regulatory role of thyroid hormone. Premetamorphic larvae were reared in seawater alone or seawater containing either thyroxine (T4) or an antithyroid drug (thiourea, TU). Histological changes in the muscle were examined and biochemical changes in the muscle proteins were evaluated by SDS-PAGE and immunoblotting for troponin T (TNT). The muscle tissue of premetamorphic larvae was characterized by abundant vacuoles and basophilic sarcoplasm. In control fish, the larval muscle transformed into the adult type during metamorphic climax; the fibers were filled with abundant myofibrils and the vacuoles disappeared. Analysis by SDS-PAGE showed that the bands at 41.5, 35.5, 34.0, 33.5, 25.5, 23.0, 20.0, and 19.0 kDa clearly increased in density from the climax stage. Premetamorphic larvae possessed two immunoreactive TNT isoforms of 41.5 and 34.0 kDa, the former being predominant. At the climax stage an additional isoform appeared at 33.5 kDa, and the 34.0- and 33.5-kDa TNT became predominant. The administration of T4 precociously induced these histological and biochemical changes in the muscle tissue of flounder larvae. In contrast, TU treatment inhibited these developmental changes in the larval muscle. Our results suggest that the developmental changes in the muscular tissue of metamorphosing flounder are regulated by thyroid hormone.

Animals↗
PubMed1991

A micromanipulator for precise control of a brain retractor. Technical note.

A new microsurgical device for delicate brain retraction is described. The device, a micromanipulator with a holder for a brain spatula fixed at the end of a self-retaining retractor arm, allows smooth, steady, fine displacement of the retractor tip ("minimal sliding retraction"), operated by the surgeon's two fingers. This has proved to be a useful and safe method of retraction for critical brain structures such as blood vessels, cranial nerves and aneurysm domes in deep microsurgical fields.

Equipment Design↗
PubMed1990

Brachycephalic, serrated curettes for anterior cervical spinal microsurgery. Technical note.

Modified spinal fusion curettes with two unusual features on the tip are described for anterior cervical procedures. The features are: 1) an elliptical, long sidewise ("brachycephalic") scoop at the tip and 2) a serration equipped on the distal scoop edge. These designs allow reliable manipulation and significant removal of the intervertebral space contents in the deep operative field under the microscope.

Cervical Vertebrae↗
PubMed1990

Intracranial chondrosarcoma--case report.

The authors report the case of a 54-year-old male who was found to have a large intracranial chondrosarcoma at the site from which chondromas had been partially removed twice, 6 and 10 years previously. On the third admission, the second through tenth and the twelfth cranial nerves on the right side were involved. Computed tomographic scans showed a large mass in the right middle and posterior fossae and the right ethmoid sinus. Angiography demonstrated an extradural mass in the right middle fossa. The tumor in the middle and posterior fossae was subtotally removed, and second, third, and eighth cranial nerve function improved postoperatively. Histological examination of tumor specimens showed active proliferation of poorly differentiated cartilagenous cells, suggestive of sarcomatous transformation of the pre-existing chondroma. It is emphasized that chondromas should be removed as completely as possible and that patients must be followed carefully after surgery.

Brain Neoplasms↗
PubMed1990

[A study of vascular changes on disintegration and repair of the femoral head with advanced osteoarthritis of the hip].

Microangiography was performed on 65 femoral heads with advanced osteoarthritis to investigate the vascular changes on disintegration and repair of the femoral head. Affected femoral heads were removed during prosthetic replacement. A needle was inserted into the nutrient vessel of the extraosseous area and the contrast medium was injected by manual pressure through the needle. After slicing the femoral head, decalcification was performed and Spalteholz's preparations were prepared. Anastomosis between the superior and inferior retinacular arteries was found in all cases. Hypertrophy and hypervascularity of the retinacular arteries were observed on the weight bearing region. On the cystic lesion corresponding to the weight bearing region, numerous arteries were extended around the cyst. On the surface of the eburnated femoral head, the peripheral arteries coursing to the joint was not tapered and dilatation of these arteries was demonstrated. On some areas of the head, however, repairing arteries reaching to the joint surface lay horizontally. From this result, it was assumed that numerous arteries proliferated to the eburnated area and to around the cyst for repairing reaction, but that these were damaged by mechanical stress.

Adult↗
PubMed1989

Kinetic studies of the pyridoxal kinase from pig liver: slow-binding inhibition by adenosine tetraphosphopyridoxal.

Pyridoxal kinase from pig liver has been purified 10,000-fold to apparent homogeneity. The enzyme is a dimer of subunits of Mr 32,000. The enzyme is strongly inhibited by the product pyridoxal 5'-phosphate. Liver pyridoxamine phosphate oxidase, another enzyme involved in the biosynthesis of pyridoxal 5'-phosphate, is also strongly inhibited by this compound [Wada, H., & Snell, E. E. (1961) J. Biol. Chem. 236, 2089-2095]. Thus, the biosynthesis of pyridoxal 5'-phosphate in the liver might be regulated by the product inhibition of both pyridoxamine phosphate oxidase and pyridoxal kinase. Kinetic studies revealed that the catalytic reaction of liver pyridoxal kinase follows an ordered mechanism in which pyridoxal and ATP bind to the enzyme and ADP and pyridoxal 5'-phosphate are released from the enzyme, in this order. Adenosine tetraphosphopyridoxal was found to be a slow-binding inhibitor of pyridoxal kinase. Pre-steady-state kinetics of the inhibition revealed that the inhibitor and the enzyme form an initial weak complex prior to the formation of a tighter and slowly reversing complex. The overall inhibition constant was 2.4 microM. ATP markedly protects the enzyme against time-dependent inhibition by the inhibitor, whereas another substrate pyridoxal affords no protection. By contrast, adenosine triphosphopyridoxal is not a slow-binding inhibitor of this enzyme.

Adenine Nucleotides↗
PubMed1989

A microangiographic study of idiopathic osteonecrosis of the femoral head.

Microangiography was performed on 31 femoral heads with idiopathic osteonecrosis to investigate the pathogenesis of this disease from the aspect of circulation disturbance. Microangiography showed the following: (1) the interruption of the superior retinacular arteries in the extraosseous area; (2) the presence of numerous newly formed vessels of varying diameter arising from the stumps of the interrupted superior retinacular arteries; (3) compensatory hypertrophy and large-area invasion of the inferior retinacular arteries and the ligamentum teres arteries, both of which medially enter the affected head; and (4) the blockage of revascularization, which occurred along the area of subchondral fracture and collapse at the weight-bearing region. These findings strongly suggest that revascularization is aborted by the subchondral fracture and collapse caused by weight bearing. It was assumed that interference with revascularization occurred repeatedly in the repair process of affected heads due to the influence of subchondral fracture and collapse caused by weight bearing.

Angiography↗
PubMed1988

Arteriovenous malformation with crossed total hemiatrophy: a case report.

A case of crossed total hemiatrophy (right side of the face, and left side of the trunk and left extremities) with a right precentral to central arteriovenous malformation is reported. The atrophy of trunk and extremities was well accounted for by the contralateral arteriovenous malformation, but a pathological early auditory response was the only brainstem sign possibly related to the facial atrophy.

Adult↗