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Biomedical subjects

H Kawabata

Publications and source records attributed to H Kawabata.

At least 163 records · Page 9Linked to original sources
PubMed1989

Computer-aided analysis of Z-plasties.

Various Z-plasties were evaluated with a mathematical analytical method called the finite-element method. The lengthening and shortening effects on the skin proved to depend on the tip angle. Serial Z-plasties diminished the stress concentration after pairs of flaps had been transposed. Subdivided Z-plasties proved to be the most effective for lengthening. The finite-element method provided a good simulation of Z-plasties on a skin with complex properties. The lengthening and shortening effects on anisotropic skin were influenced not by the degree but by the direction of the anisotropy, whereas the total force required for transposing the two flaps was vice versa. The finite-element method was found to be useful for finding analytical solutions for biomechanical skin problems.

Animals↗
PubMed1989

Operations for forearm deformity caused by multiple osteochondromas.

We reviewed 36 cases of forearm deformity caused by multiple osteochondromas in 30 patients and classified them into three types: Type I showed a combination of ulnar shortening and bowing of the radius secondary to osteochondromas of the distal ulna (22 forearms). Type II showed dislocation of the radial head, either with osteochondromas of the proximal radius (Type IIa, two forearms) or secondary to more distal involvement (Type IIb, five forearms). Type III had relative radial shortening due to osteochrondromas at the distal radius (seven forearms). Operations were performed on 16 forearms in 13 patients, with 92% of satisfactory results. For Type I deformity, excision of osteochondromas, immediate ulnar lengthening and corrective osteotomy of the radius are recommended. For Type IIa, excision of the radial head is necessary, and for Type IIb, we advise gradual lengthening of the ulna using an external fixator. Excision of osteochondromas alone gave good results in Type III deformity. Our classification gives a reliable indication of the prognosis and is a guide to the choice of surgical treatment.

Adolescent↗
PubMed1989

Stretching of the brachial plexus in rabbits.

The brachial plexus of rabbits was stretched until mechanical failure. The level and site of rupture varied according to the direction of the stretching force. Upward and lateral traction of the forelimbs caused spinal nerve-root avulsions combined with nerve-trunk ruptures distal to the dorsal root ganglions. In such tractions the C5 nerves consistently exhibited postganglionic nerve-trunk rupture. The C6, C7, and C8 nerves had root avulsions. The T1 nerve was avulsed from the spinal cord in 7 cases out of 10; the other 3 cases had postganglionic nerve-trunk rupture. Downward traction of the forelimbs caused nerve avulsions from the scapulohumeral muscles innervated by the terminal branches of the brachial plexus and peripheral nerve ruptures in the course of the arm. The force producing trunk rupture of the C6 nerve was twice as great as that for root avulsion. The required stain was similar for nerve trunk rupture and root avulsion.

Animals↗
PubMed1989

DNA strand scission by antitumor antibiotics. Detection of C-4'-hydroxylated abasic sites in DNA.

Detection of C-4'-hydroxylated abasic site in calf thymus DNA was investigated. Upon heating with neutral hydrazine (90 degrees C, 5 min) C-4'-hydroxylated abasic site formed by photo-excited Co(III)bleomycin was converted to the fragments having 3'-phosphoro-3''-pyridazinylmethylate as illustrated on Scheme 1. Subsequent enzymatic digestion of the reaction mixture provided four kinds of pyridazine mononucleotides (1, 2, 3, and 4). The fact that the amount of free bases released from calf thymus DNA corresponded well to the amount of pyridazines indicates this reaction can be used for detection of C-4'-hydroxylated abasic site in DNA. By this assay, we first identified the formation of C-4'-hydroxy abasic sites in calf thymus DNA by neocarzinostatin.

Antibiotics, Antineoplastic↗
PubMed1988

Mr 85,000 membrane protein specifically expressed in adriamycin-resistant human tumor cells.

For the characterization of membrane changes related to Adriamycin resistance in tumor cells, we have developed monoclonal antibodies against Adriamycin-resistant human myelogenous leukemia K562 (K562/ADM). In addition to the monoclonal antibodies which recognize P-glycoprotein, we have obtained two monoclonal antibodies (designated MRK4 and MRK20) which recognize an Mr 85,000 membrane protein. Using MRK20 as a probe, we have studied the expression of the Mr 85,000 protein in various human multidrug-resistant and -sensitive cell lines. The Mr 85,000 protein was overexpressed in K562/ADM and in a human ovarian cancer cell line resistant to Adriamycin, 2780AD. The protein, if any, was not detected in other drug-resistant human cell lines such as colchicine-resistant KB cells (KB-C4), vinblastine-resistant CEM cells (CEM/VLB100), and vincristine-resistant K562 cells (K562/VCR). We have isolated subclones of K562/ADM cells which express different amounts of the Mr 85,000 protein. The expression of the Mr 85,000 protein diminished when the cells were not kept in Adriamycin, and increased when the clones were kept in the presence of Adriamycin. In contrast, the expression of P-glycoprotein remained constant whether in the presence or absence of Adriamycin during these experiments. These findings suggest that the Mr 85,000 membrane protein is closely related to the resistant mechanism specific to Adriamycin resistance, which is different from that of the pleiotropic drug resistance.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1988

Nerve repairs for traumatic brachial plexus palsy with root avulsion.

Thirty-six patients with traumatic brachial plexus lesions and root avulsions were treated surgically between 1972 and 1986 and were followed for more than 24 months (average, 42.6 months). Neurotization of the musculocutaneous nerve with intercostal nerves or the spinal accessory nerve resulted in satisfactory elbow flexion in 21 of the 33 cases (64%). Combined nerve repairs (i.e., intercostal and spinal accessory neurotization of the terminal branch of the brachial plexus in combination with nerve grafts from the upper spinal nerves of the brachial plexus) created a useful function in at least one functional level of the upper limb for 11 of the 15 cases so treated. Nerve repairs resulted in stability of the shoulder and elbow function controllable with a sensible hand for patients with root avulsion injury of the brachial plexus.

Adolescent↗
PubMed1988

Idiopathic scoliosis and growth--a biomechanical consideration.

Growth force proposed as an etiological factor in idiopathic scoliosis was analysed by a mathematical simulation; the results were compared with clinical roentgenograms of patients with idiopathic scoliosis. Growth force is a self-equilibrating internal stress derived from unbalanced growth between two adjacent structures with different growth rates. In the simulation, the localized growth force made the whole spinal column buckle. Two hundred anteroposterior roentgenograms were then compared with the buckling curves. The three most similar buckling curves for each roentgenogram were selected. Of the 600 selected curves, 406 were considered to have produced a high similarity. The curves produced by a growth force extending over a small area, especially at the mid-lower thoracic and lumbar regions, were qualified as curves with a high similarity. The growth force thus does not appear uniformly all over the spinal column but locally and at the mid-lower thoracic or lumbar region. This growth force may represent a factor in the etiology of idiopathic scoliosis.

Biomechanical Phenomena↗
PubMed1987

Pathologic rupture of flexor tendons due to longstanding Kienböck's disease.

A 62-year-old man was seen for rupture of the flexor digitorum superficialis and profundus to the index finger. X-ray films showed longstanding Kienböck's disease with a completely fragmented lunate bone with fragments lying in front of the anterior lip of the radius. Tendon transfer restored active flexion to the index finger.

Carpal Bones↗
PubMed1987

The effects of intra-arterially injected adriamycin on microvascular anastomosis.

Although free tissue transfer following limb-saving wide resection has become increasingly necessary in the treatment of sarcomas of the extremities, the side effects of adjuvant chemotherapy on the microvascular structure are not yet known. There may be significant effects, especially with intra-arterial administration. In order to study the time-dependent manifestations of possible effects, experimental microvascular anastomoses in the rat femoral artery were performed at various intervals, after intra-arterial injection of Adriamycin. This drug was used because of its popularity as an adjuvant chemotherapeutic agent. Vessels were examined at varying intervals for macroscopic changes affecting patency and for histologic changes. Anastomoses done at three weeks after Adriamycin injection resulted in the worst patency rate. Histologically, thrombotic occlusion was associated with widespread and profound disruption of the internal elastic lamina, thought to be thrombogenic trauma: the vessel was presumed to have been made fragile by preoperative Adriamycin treatment. Five weeks or longer after injection, this effect was reduced, according to patency rates and histologic findings. Endothelial damage was minimal and appeared insignificant.

Animals↗
PubMed1987

Treatment of preaxial polydactyly of the foot.

Fourteen patients with preaxial polydactyly are classified into four types according to their morphologic configuration: type 1--ray duplication; type 2--completely duplicated phalanges; type 3--incompletely duplicated metatarsals; and type 4--incompletely duplicated phalanges. The surgical treatment and timing thereof appropriate for each group are discussed. Three cases of congenital hallux varus deformity are analyzed, focusing on the pathomechanism of this disorder. Based on our experience, two main factors are noticed in the etiology of congenital hallux varus deformity: inadequacy of the adductor hallucis and tightening of the fibrous band pulling the big toe into the varus.

Abnormalities, Multiple↗
PubMed1987

Early microsurgical reconstruction in birth palsy.

Most patients with birth palsy can be expected to recover spontaneously. But in some patients the recovery is unsatisfactory and the functional results are disappointing. One possible way to improve the prognosis for such patients is early surgical nerve reconstruction. In six infants, exploration of the brachial plexus was carried out at about six months after delivery, when there were no signs of recovery in shoulder and elbow joint movements. Preoperative metrizamide myelography, computerized tomography with intrathecal metrizamide (CT myelography), and axon reflex test (histamine test) were followed by intraoperative electrophysiologic examinations of root sensory evoked potential (SEP), nerve action potential (NAP), and evoked muscle response (M-response). Microsurgical nerve repair was performed on the basis of intraoperative diagnosis. Metrizamide myelography showed 13% false-positive root avulsion. Reliability of the histamine test was 80%. The intraoperative electro-diagnosis is essential for understanding the actual condition of the brachial plexus lesion and obtaining better results from microsurgical reconstruction in birth palsy. The surgical results, with an average follow-up evaluation of two years and four months, have been encouraging enough to continue this diagnostic and therapeutic program, though its superiority to natural recovery has not yet been clarified.

Brachial Plexus↗
PubMed1986

Infantile digital fibromatosis after web construction in syndactyly.

A case of infantile digital fibromatosis with an unusual onset is reported. A Japanese girl, with a simple syndactyly of the right ring and little fingers, had an operation at the age of 2 1/2 years. Three months after the operation, multiple nodules appeared at the skin graft edge. The nodules were excised but soon recurred. When the patient was 8 years old, a large-scale excision of the tumors was performed. Intracytoplasmic inclusion bodies were shown by phosphotungstic acid-hematoxylin stain, and the case was diagnosed as infantile digital fibromatosis.

Female↗
PubMed1986

Characteristics of resistance to adriamycin in human myelogenous leukemia K562 resistant to adriamycin and in isolated clones.

An adriamycin (ADM)-resistant variant (K562/ADM) of human myelogenous leukemia K562 was established. K562/ADM was stable for 2 months in medium without ADM, and was 130-fold more resistant to ADM as compared to the parent K562. Twenty clones were isolated from K562/ADM by the limiting dilution technique. Five clones with different ADM sensitivity were selected and characterized further. The extent of clonal resistance to ADM was parallel to the extent of resistance to vincristine (VCR), except for one clone, KA-15. The majority of clones, including K562/ADM, accumulated far smaller amounts of daunomycin (DAU) or VCR as compared to the parent K562. However, a highly resistant clone did not necessarily accumulate less DAU in the cells, indicating that the mechanism of ADM resistance cannot be explained solely by a defect of ADM accumulation. All clones rapidly transported DAU and VCR from the cells. K562/ADM expressed on the cell surface three distinct glycoproteins with molecular weights of 180,000, 83,000 and 65,000 daltons. No change was detected in the actin and tubulin contents of K562 and clones. K562/ADM and its clones expressed double minute chromosomes and contained homogeneously staining regions in the chromosomes.

Actins↗
PubMed1986

[In vitro susceptibility, of bacterial isolates from patients with respiratory tract infections, to beta-lactam antibiotics II].

In vitro susceptibilities of bacterial pathogens to beta-lactam antibiotics were determined. Bacterial pathogens examined included various isolates from patients of respiratory tract infections at hospitals of Kyoto-Shiga area in 1984. Major organisms isolated from clinical specimens were Pseudomonas spp., Klebsiella spp., Haemophilus spp., Staphylococcus aureus and Streptococcus spp. An increase in the isolation frequency of Pseudomonas spp., a decrease in the isolation frequency of S. aureus, and no change in the isolation frequency of other organisms were observed between the years 1981, 1983 and 1984. Data from susceptibility tests of clinical isolates confirmed that cefazolin (CEZ), cefamandole and cefotiam (CTM) showed good antibacterial activity against S. aureus and cefmenoxime (CMX) was highly active against Streptococcus spp., but their susceptibilities to CEZ in 1984 were lower than in 1983. Susceptibilities of Klebsiella spp. to CMX, cefbuperazone, latamoxef, CTM, cefoperazone (CPZ) were better than those to other beta-lactam antibiotics tested, but there was a decline in the susceptibility to CEZ, cefmetazole and CTM. Further, CMX, CPZ and LMOX also showed good antibacterial activity against Haemophilus spp. Although gentamicin, cefsulodin, cefpiramide and piperacillin were highly active against Pseudomonas spp., resistant organisms were present for all the beta-lactam antibiotics tested.

Anti-Bacterial Agents↗
PubMed1985

Potentiation of antitumor agents by calcium channel blockers with special reference to cross-resistance patterns.

The calcium channel blockers verapamil, diltiazem, nicardipine, and niludipine potentiated the antitumor activities of mitotic poison antitumor agents, such as vincristine, vinblastine, vindesine, VP16-213, and taxol in P388 leukemia cells resistant to vincristine. The potentiating effect was generally dependent on the extent of cross-resistance seen in the cell line for these drugs. Calcium channel blockers also potentiate the antitumor activities of several DNA-interacting drugs, such as adriamycin, THP-adriamycin, daunomycin, aclacinomycin A, mitomycin C, actinomycin D, mitoxantrone, and nogalamycin derivatives in P388 leukemia resistant to adriamycin. Greater potentiation was observed for those antitumor agents to which the ADM-resistant cell line had become markedly cross-resistant, with the exception of the nogalamycin derivatives. Only a two-fold enhancement was observed for mitomycin C and aclacinomycin, as the cell line was only weakly cross-resistant to these agents. These results suggest the potential for therapeutic gain through the use of calcium channel blockers in combination with classic chemotherapeutic agents.

Animals↗
PubMed1985

Inhibition of spontaneous and experimental tumor metastasis by the calcium antagonist verapamil.

Verapamil, a calcium antagonist, inhibited both experimental (IV inoculation of tumor cells) and spontaneous metastasis (SC inoculation) of the highly metastatic B16 melanoma and colon adenocarcinoma 26 cell lines. Verapamil treatment resulted in a maximum 80% inhibition of metastases, the degree of inhibition varying among the different metastatic systems. Verapamil inhibited platelet aggregation induced by these tumor cell lines, the patterns of inhibition being different for B16 melanoma and colon adenocarcinoma. The inhibition of platelet aggregation induced by tumor cells is proposed as a mechanism by which the calcium antagonist exerts its antimetastatic effect. These results, together with our previous findings that calcium antagonists can increase the cytotoxicity of drugs in tumor cells with induced or inherent drug resistance by inhibiting outward transport of the drug, indicate that calcium antagonists have potential as a new class of adjuvant agents in the field of cancer chemotherapy.

Animals↗
PubMed1985

Congenital clasped thumb: a review of forty-three cases.

Over a 10-year period, 43 patients (75 hands) with congenital clasped thumb were seen in our institution. Three groups were identified: group I, 14 patients (24 hands) without contracture; group II, 14 patients (21 hands) with contractures of the palmar side; and group III, 15 patients (30 hands) with arthrogryposis multiplex congenita. Forty-two hands were treated with splinting alone and 16 hands with surgery. The remaining 17 hands were followed conservatively without splinting or surgery. The mean follow-up was 32 months. The results were evaluated by active abduction of the carpometacarpal joint and extension of metacarpophalangeal joint. All patients in group I showed good response to splinting, and the cause of the deformity appeared to be the predominance of the flexor muscles. In groups II and III, 10 patients (16 hands) who had severe deformity or no response to splinting were treated by release of the palmar soft tissues, skin grafts, and reconstruction of the extensors. Satisfactory results were obtained in 12 of 16 hands.

Adolescent↗