Biomedical subjects
Publications and source records attributed to M Oka.
Pilomatrixoma is a relatively rare benign skin neoplasm, which is generally present as a single, asymptomatic dermal or subcutaneous nodule, which occurs most often in the first 2 decades of life with a higher incidence in females. The usual sites are the face and upper extremities. This paper describes a case of such a tumour presenting in the right preauricular region of a 14-year-old Japanese girl.
We have attempted to develop an artificial articular cartilage on the basis of a new viewpoint of joint biomechanics in which lubrication and load-bearing mechanisms of natural and artificial joints are compared. We investigated poly(vinyl alcohol)-hydrogel (PVA-H) which has been recognized as a rubber-like gel and have improved the mechanical properties of this gel through a new synthetic process. In this article we report the biocompatibility and various mechanical properties of the new, improved PVA-H from the aspect of its usefulness as artificial articular cartilage. As regards the lubrication, we measured the change of thickness and fluid pressure of the gap formed between a glass plate and the specimen under loading and found that the PVA-H had a thicker fluid film under higher pressure than polyethylene (PE). The momentary stress transmitted through the specimen revealed that PVA-H had a lower peak stress and a longer duration of sustained stress than PE, suggesting a better damping effect. The wear factor of PVA-H was approximately five times as large as that of PE. Histological findings of the articular cartilage and synovial membranes around the PVA-H implanted for 8-52 weeks showed neither inflammatory nor degenerative changes. The PVA-H artificial articular cartilage could be attached to the underlying bone using an osteochondral composite material. Although there remain still some problems to solve, PVA-H seems to be a very interesting and promising material which meets the requirements of artificial articular cartilage.
This study evaluated the efficacy of using the periodic measurement of the serum level of squamous cell carcinoma antigen (SCC-antigen) for determining the local recurrence and/or metastasis of squamous cell and mucoepidermoid carcinomas after primary treatment. It was found that at the time of clinical recognition of recurrence, the SCC-antigen level was normal, but metastasis to regional lymph nodes or to remote organs generally was accompanied by an increase of SCC-antigen. Changes in the SCC-antigen level with mucoepidermoid carcinoma seemed to be less sensitive than with squamous cell carcinoma.
This article evaluates 16 cases of condylar fracture treated surgically, comparing them with the 20 cases treated nonsurgically, with a 2-year follow-up. Although severely displaced and luxated fractures were involved in the surgical group with rigid internal fixation, satisfactory postoperative function and occlusion were achieved at the same level as in the nonsurgical group, without severe complications.
While the mechanism of positive inotropic action of insulin is not yet fully known, glycose, insulin and potassium solution (GIK solution) has been used in cardiopulmonary resuscitation. Catecholamines continue to be the first line drug to increase blood pressure during cardiac arrest. This study was designed to determine the interaction of insulin and epinephrine on guinea pig papillary heart muscle. The mechanical response of papillary muscle isolated from guinea pig ventricle was observed. Epinephrine increased the twitch tension with a mean maximum contractile force of 766.4% of control. Insulin decreased the increased tension induced by epinephrine to 103.8% of control. This blocking phenomena was not influenced by preadministered insulin. Likewise, the effect of epinephrine was not affected by preadministered insulin.
A 34-year-old Japanese male had pain radiating from his right mandibular body to the temporal region. Computerized tomography was undertaken to examine his cerebral status. It eventually revealed the absence of the right submandibular gland, although the left submandibular gland was present. The corresponding space was occupied by a lymph node. Furthermore, sialography showed the existence of Wharton's duct only. The literature on this rare occurrence is reviewed and the significance to the patient discussed.
A case of traumatic carotid-cavernous sinus fistula, an abnormal communication at the base of the skull between the internal carotid artery and the cavernous sinus, complicating fractures of the zygoma and mandible is described. Typical signs and symptoms appeared immediately after the injury resulting from a traffic accident. Angiography revealed a definite CCSF and a balloon embolization was performed with a good result. The importance of a multidisciplinary examination of the ophthalmic function and periorbital condition following trauma is emphasized, and interdepartmental cooperation helped to establish a rational diagnosis and obtain a good result.
Protein kinase C (PKC) was detected in the yeast Saccharomyces cerevisiae with bovine myelin basic protein as the phosphate acceptor. The enzyme was purified at least 500-fold by a four-step column chromatographic procedure (phenyl-Sepharose CL-4B, Mono Q, Heparin-5PW, and hydroxyapatite). The molecular mass was approximately 90 kDa, as estimated by gel-filtration analysis. Yeast PKC was activated by the simultaneous addition of Ca2+, diacylglycerol, and phosphatidylserine. Free arachidonic acid alone could activate the enzyme to some extent. However, yeast PKC did not respond significantly to tumor-promoting phorbol esters. GTP did not serve as phosphate donor. The yeast enzyme showed substrate specificity distinctly different from that of mammalian PKCs. H1 histone and protamine were poor substrates. With myelin basic protein as a model substrate, yeast PKC phosphorylated threonyl residues preferentially, whereas rat brain PKCs phosphorylated seryl residues preferentially. Further studies should elucidate the role of yeast PKC in cellular regulation and cell cycle control.
Patients with an uncomplicated sliding hiatal hernia frequently experience dysphagia. The present study shows, using video barium contrast esophagograms, that the cause of dysphagia in 60% of these patients is an obstruction to the passage of the swallowed bolus by diaphragmatic impingement on the herniated stomach. Manometrically this was reflected by a double-hump high pressure zone (HPZ) at the gastroesophageal junction, and specifically to the length and amplitude of the distal HPZ and the length of the intervening segment between the two HPZs. The former represents the degree of the diaphragmatic impingement on the herniated stomach and the latter the size of the supradiaphragmatic herniated stomach. Surgical reduction of the hernia resulted in relief of dysphagia in 91% of the patients.
Linoleic acid has been shown to inhibit melanogenesis in cultured B16 mouse melanoma cells. We report here the possible involvement of protein kinase C (PKC) in linoleic acid-induced inhibition of melanogenesis in B16 cells. A single PKC subspecies (alpha-PKC) was detected in B16 cells. The enzyme was activated by linoleic acid in vitro. The effective concentrations at which PKC was activated (25 microM; maximum response) were consistent with those for the inhibition of melanogenesis in cell culture system. In addition, the permeable diacylglycerol 1-oleoyl-2-acetyl glycerol that activates PKC also inhibits melanogenesis at 100 microM. These results suggest that activation of PKC plays a pivotal role in the linoleic acid-induced inhibition of melanogenesis in B16 cells.
Decreased immunoglobulin production in pokeweed mitogen driven lymphocyte cultures has been reported in rheumatoid arthritis (RA). Here various activators and experimental designs have been used to determine the contribution of B cells, T cells, or monocytes to this low response. Sixty patients with RA and paired controls were studied at the onset of disease and again six months later. Concentrations of IgA, IgG, and IgM in cultures of RA peripheral blood mononuclear cells stimulated with thymus dependent activators were already decreased at the onset of the disease. Six months later RA mononuclear cells produced even lower concentrations of immunoglobulin. In contrast, stimulation with a T cell independent activator showed that RA B lymphocytes had retained normal potential to synthesise immunoglobulin. Poor helper function was indicated by costimulation experiments and cultures of mixed mononuclear cells from patients and controls. This notion was supported also by the fact that phytohaemagglutinin induced interleukin-2 production by RA mononuclear cells was less than half of the control values. Nonspecific suppressor activity was similar in RA and controls. Monocyte functions were normal when tested by addition of indomethacin or 2-mercaptoethanol to the mitogen activated cultures. The defect in mitogen stimulated immunoglobulin production in vitro of RA mononuclear cells thus was more pronounced with time and probably reflects impaired mediator associated help in the differentiation of B lymphocytes into immunoglobulin secreting cells.
The effect of Ba2+ on the catecholamine biosynthetic activity was studied by measuring the formation of [14C]catecholamines from L-[14C]tyrosine in cultured adrenal chromaffin cells. In the absence of Ca2+, [14C]catecholamine formation was markedly stimulated by Ba2+, and this stimulation was observed in a manner dependent on its concentration. The stimulation of [14C]catecholamine formation by relatively low concentrations of Ba2+ was suppressed by polymyxin B, a typical inhibitor of Ca2+/phospholipid-dependent protein kinase (protein kinase C); and this inhibitory action of polymyxin B was attenuated by increasing the Ba2+ concentration. On the other hand, a tendency toward the enhancement of Ba2+-stimulated [14C]catecholamine formation was observed by a protein kinase C activator, 12-O-tetradecanoylphorbol 13-acetate (TPA). In contrast to the acute effect of TPA, [14C]catecholamine formation stimulated by Ba2+ was reduced by long-term exposure of chromaffin cells to a high concentration of TPA, which has already been reported to cause the reduction of protein kinase C activity as a result of the down-regulation of this enzyme. These findings suggest that Ba2+ stimulates catecholamine biosynthesis, probably through its direct action on protein kinase C in adrenal chromaffin cells.
A radioimmunoassay method for endothelin was developed. Antisera raised against endothelin 1 showed significant crossreaction with endothelin 2 and 3 (45 and 13%, respectively). Considerable endothelin immunoreactivity was shown to be present in the cerebrospinal fluid of patients with a subarachnoid hemorrhage, ranging from 0.3 pmol/l cerebrospinal fluid to 4.5 pmol/l cerebrospinal fluid, though no endothelin immunoreactivity was observed in the cerebrospinal fluid of controls and patients with cerebral infarction, subdural haematoma or brain tumours. Endothelin immunoreactivity was also observed in two out of five cerebrospinal fluid samples from patients with cerebral bleeding. Reverse phase high performance liquid chromatography showed that the main immunoreactive component in cerebrospinal fluid appeared to elute at the same position. There was, however, an immunoreactive component which eluted at the same position as endothelin 3. These results may support the idea that endothelin immunoreactivity in the cerebrospinal fluid originate mainly from endothelial and neural tissues and that endothelin may contribute to the generation of the vasospasm often observed in subarachnoid hemorrhage, a conclusion based on the exceptionally high endothelin immunoreactivity in cerebrospinal fluid observed in patients with subarachnoid haemorrhage.
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The synthesis and antimicrobial activity of eight derivatives of 7-[(Z)-2-(2-aminothiazol-4-yl)- and 7-[(Z)-2-(5-amino-1,2,4-thiadiazol-3-yl)-2-methoxyiminoacetamido] cephalosporins having an (E) or (Z)-3-ammonio-1-propenyl group in the C-3 side chain are described. The (E)-propenyl derivatives were more active than their corresponding Z-isomers and showed well-balanced, broad antibacterial activity against both Gram-positive and Gram-negative bacteria including Pseudomonas aeruginosa.
A novel complex of isotetracenone (angucyclinone) group antibiotics was discovered from the cultured broth of Streptomyces griseorubiginosus No. Q144-2. The antibiotic consisted of six related factors, designated rubiginones A1, A2, B1, B2, C1 and C2. They significantly potentiated cytotoxicity of vincristine (VCR) against VCR-resistant P388 leukemia and Moser cells.
The gene coding for the ATCGAT specific BanIII DNA methyltransferase (M-BanIII) of Bacillus aneurinolyticus was cloned and its nucleotides sequenced. The coding region was assigned on the nucleotide sequence on the basis of the N-terminal amino acid sequence and molecular weight of the enzyme. The M-BanIII gene coded for a protein of 580 amino acid residues (MW 66,344). Comparison with other methylases indicated that the M-BanIII sequence contained a segment of tetra-amino acids, NPPY, characteristic of N6-adenine methylases. In addition, some homologous regions were found in the sequences of type II adenine methylases PaeR7I(CTCGAG), TaqI(TCGA) and PstI(CTGCAG), containing TCGA within the recognition sequences.
Unresectable hepatocellular carcinoma (HCC) has a poor prognosis and little sensitivity to anticancer agents. We planned a combination immunotherapy, associating with rIL-2 continuous injection. Combination immunotherapy consists of 5 different biological response modifiers (BRM), i.e., rIL-2, OK-432, adriamycin (ADR), cyclophosphamide (Cy), and famotidine (Fa). rIL-2, OK-432 and ADR were administered from implantable infuser port connecting to a catheter which was injected into the hepatic artery via the gastroduodenal artery under laparotomy. OK-432, Cy, and Fa were also administered systemically. From 1988 to 1990, seven patients with unresectable HCC and two patients who underwent curative resection were treated by this therapy. The objective responses were evaluated by CT and angiography. This combination immunotherapy produced 3 cases of complete response and 2 of minor response. Immunological monitoring of lymphocyte subsets and NK activity of peripheral blood mononuclear cells was also performed. NK activity was significantly augmented and the percentage of Leu 7(-) NCD 16(+) cells increased during this therapy. Serious toxicity, but transient high fever and hypotension, was not observed during this therapy. All of these patients left the hospital within two weeks and returned to their previous job or similar life activity. These results suggest that this combination immunotherapy is worth performing in further clinical trials for hepatocellular carcinoma.