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N Akamatsu

Publications and source records attributed to N Akamatsu.

At least 19 recordsLinked to original sources
PubMed1992

Intracellular EGTA alters phasic firing of neurons in the rat supraoptic nucleus in vitro.

To determine the function of intracellular free Ca2+ which is important in generating the phasic firing pattern characteristic of vasopressin neurons in the supraoptic nucleus (SON), we injected the highly specific Ca(2+)-chelating agent ethyleneglycol-bis-(beta-aminoethyl ether) N,N-tetraacetic acid (EGTA) into SON cells in the rat hypothalamic slice preparation. Intracellular recordings from 29 SON neurons which showed phasic firing were analyzed. Of the 29 SON neurons, 21 were recorded with microelectrodes filled with 3 M potassium acetate and 20 of the 21 neurons retained the phasic pattern more than 1 h after penetration by the electrode. Only one neuron lost phasic firing and fired randomly. By contrast, in all 8 neurons which were recorded with microelectrodes filled with 100 mM EGTA/2 M potassium acetate, phasic firing disappeared 10-80 min after penetration of the recording electrode although the neurons still showed spontaneous activity. These neurons also lost the after hyperpolarization and plateau potentials which followed bursting discharges. Our results suggest that intracellular free Ca2+ may play an important role in generating phasic firing.

Action Potentials↗
PubMed1992

Alteration of rat liver proteoglycans during regeneration.

Sepharose CL-6B column chromatography of crude extracts from the slices of regenerating rat livers after partial hepatectomy and sham-operated controls labeled with [35S]sulfuric acid revealed an enhancement of [35S]sulfate incorporation into proteoglycan fractions during regeneration. The 35S-labeled proteoglycans contained heparan sulfate (more than 80% of the total) and chondroitin/dermatan sulfate. The 35S-incorporation into both glycosaminoglycans increased to maxima 3-5 days after partial hepatectomy and decreased thereafter toward the respective control levels. When [35S]sulfuric acid was replaced by [3H]glucosamine, similar results were obtained. These results suggest that the maximal stimulation of proteoglycan synthesis in regenerating rat liver follows the maximal mitosis of hepatic cells 1-2 days after partial hepatectomy. The 35S-labeled proteoglycans from regenerating liver 3 days after partial hepatectomy and control were analyzed further. They were similar in chromatographic behavior on a gel filtration or an anion-exchange column and in glycosaminoglycan composition. Their glycosaminoglycans were indistinguishable in electrophoretic mobility. However, these proteoglycans were slightly but significantly different in their affinity to octyl-Sepharose and in the molecular-weight distribution of their glycosaminoglycans.

Animals↗
PubMed1992

Osteofibrous dysplasia of the tibia treated by bracing.

Osteofibrous dysplasia of the tibia in children will commonly recur after surgical resection. The use of a leg brace until puberty offers a useful method of conservative management. Seven female patients, age three months to nine years at the time of brace treatment, have been followed for 3.5 to 18 years, an average of nine years, with evidence of satisfactory healing of the lesions in all. Three of the cases had recurred after surgery, two with fibular grafts and one required leg lengthening. The use of a brace to control bowing of the tibia while awaiting spontaneous regression is advised until epiphyseal closure.

Braces↗
PubMed1992

Concurrent changes in sinusoidal expression of laminin and affinity of hepatocytes to laminin during rat liver regeneration.

Distribution of fibronectin, laminin, and collagens type I, III, IV, and V in the lobular regions of regenerating rat liver was studied by indirect immunofluorescence. Little or no laminin was detected in sham-operated controls throughout the experimental period, while it was detected in sinusoids of regenerating liver as early as 6 h after partial hepatectomy (PH). After reaching a maximum at 24 h, it decreased and was barely detectable 6 days after PH. Changes in the other extracellular matrix (ECM) proteins were evident 3 days after PH, but not earlier than 24 h. Hepatocytes isolated from regenerating rat livers were tested in a short term assay for attachment to the substrates coated with the ECM proteins. The attachment of hepatocytes to laminin substrates increased 12 h after PH, reached a maximum at 24 h, and decreased to the control level 6 days after PH, while that of the control remained constant. The attachment to fibronectin substrates was not different between regenerating livers and controls at any time point. The attachment to collagen did not change earlier than 24 h after PH, but increased slightly 3 days after PH. Primary rat hepatocytes cultured on the substrates coated with the ECM proteins were determined for replicative DNA synthesis in response to epidermal growth factor. Both in normal liver and in regenerating liver 24 h after PH, laminin was one of the most effective substrates in supporting the responsiveness of hepatocytes to the growth stimulus. Taken together, these results suggest the importance of hepatocyte-laminin interaction during the early stage of liver regeneration possibly in growth stimulation of hepatocytes and/or maintenance of hepatocyte-specific functions.

Animals↗
PubMed1992

Normal aggregations of glycoprotein IV (CD36)-deficient platelets from seven healthy Japanese donors.

Since glycoprotein IV (GPIV) has been shown to play an important role in the interaction of platelets with collagen and thrombospondin, the aggregation and secretion of GPIV-deficient platelets were examined. Using a binding assay with monoclonal 125I-OKM5 antibody against CD36 antigen and crossed immunoelectrophoresis of the solubilized platelets against anti-GPIV antibody, the platelets from seven (4.1%) out of 170 healthy Japanese donors were found to be deficient in GPIV. The GPIV-deficient platelets showed normal aggregations in response to collagen as well as ADP, epinephrine, arachidonic acid and thrombin in comparison with GPIV-positive platelets. Polyclonal anti-GPIV antibody aggregated GPIV-positive platelets but not the GPIV-negative ones. The F(ab')2 fragments of the anti-GPIV antibody competitively inhibited the anti-GPIV-induced aggregation, but did not affect the collagen-induced aggregation of GPIV-positive platelets. These results suggest that the deficiency of GPIV does not affect platelet aggregability.

Adenosine Diphosphate↗
PubMed1992

Interaction of platelets and blood vessels--vascular injuries induced by platelet activation in vivo.

We have found that vascular injuries are induced by intravascular aggregation of platelets activated by arachidonic acid (AA) or ADP. The characteristic findings are the appearance of vacuoles in endothelial cells and eventual deendothelialization. In deendothelialized regions, formation of platelet thrombi was observed. The platelets in the thrombi were stained with 2T60, a monoclonal antibody that recognizes activated platelets. The change was more remarkable in the AA-injected animals because AA has a stronger platelet activating effect and a detergent effect on the endothelium. The ADP-injection experiments clarified the role of platelets in vascular injury. These findings suggest that activated platelets play a role in the genesis of vascular injuries, and that their role is related to thrombus formation.

Adenosine Diphosphate↗
PubMed1992

Adrenergic receptors and adenylate cyclase activity in hepatocytes of the streptozotocin-diabetic rat.

Effects of short and long exposure to the diabetic state induced by an injection of streptozotocin to young female rats on glucagon- and catecholamine-sensitive adenylate cyclase activity and adrenergic receptors of hepatic membranes have been studied. The short period of exposure to the diabetic state exhibited an increase in the sensitivity of the enzyme to isoproterenol without changes in the affinity and the number of beta-adrenergic receptors. The increased response of adenylate cyclase activity to isoproterenol was accompanied with a greater GTP-induced lowering of the affinity to the beta-adrenergic agonist in diabetic membranes than in the controls. The chronic diabetic state produced a decrease in the adenylate cyclase activity to hormonal or non-hormonal stimuli with a fall in the number of alpha- and beta-adrenergic receptors. These results suggest that the observed effects of the diabetic state on hormonally sensitive adenylate cyclase activities and their receptor binding sites of the hepatic membranes would vary depending on the duration and/or severity of the diabetic state experimentally induced.

Adenylyl Cyclases↗
PubMed1992

Quantitative ultrasound diagnosis of endometrial cysts.

We measured the ultrasonic frequency dependent attenuation of ovarian cysts using the spectral difference method to find the difference in the characteristics of attenuation of the endometrial cyst and other ovarian cysts. We investigated an analytical method to measure the ultrasonic frequency dependent attenuation of ovarian cysts and we called this method the boundary echo spectrum method. The endometrial cyst had an attenuation slope of 0.67 +/- 0.27 dB/cm/MHz, and attenuation value was 1.85 +/- 1.27 dB/cm, and it had significantly higher attenuation slope and attenuation value compared with those of serous cystadenoma and mucinous cystadenoma, but no significant difference compared with those of dermoid cyst (fat component). Compared with attenuation slope and attenuation value, attenuation slope is superior because of smaller standard deviation and better linearity between water immersion and transabdominal method.

Adenoma↗
PubMed1992

[Detection of circulating activated platelets by anti-GMP-140 monoclonal antibodies].

The clinical significance and detection methods for circulating activated platelets are reviewed. It has been recently demonstrated that three kinds of platelet granules, dense granule, alpha-granule and lysosome, have specific membrane proteins; granulophysin, GMP-140 (PADGEM) and CD63 antigen, respectively, and that these specific granule-membrane proteins become exposed on the surface of the activated platelets. It is believed that detection of circulating activated platelets, using monoclonal antibodies specific to these granule-membrane, may be reliable and diagnostic value in thrombotic and prethrombotic diseases. Preliminary clinical studies using 2T60, a newly developed anti-GMP-140 monoclonal antibody, was presented.

Antibodies, Monoclonal↗
PubMed1992

[Methicillin-resistant Staphylococcus aureus infection in the orthopaedic field].

A retrospective report regarding MRSA infections, related to wards and physicians in the hospital, was carried out. The number of the patients infected by MRSA in every wards was compared. Less patients with MRSA infection ware observed in the orthopaedic ward. An epidemiologic study using culture sampling of MRSA was performed at the isolated room for the patient with MRSA infection. Positive cultures were also detected in several areas in the ward, in addition to that room. Then the infection risk of every places in the hospital was suspected. Four cases of orthopaedic patients with MRSA were described.

Adult↗
PubMed1991

Postnatal changes in sialylation of glycoproteins in rat liver.

Glycoproteins containing N-linked oligosaccharides were prepared from plasma and liver microsomes of rats aged 0-5 weeks, and galactose and sialic acid content were determined. The sialic acid/galactose ratios in plasma membrane N-glycans remained at about 1 throughout the postnatal period, suggesting that most of the galactose residues are sialylated. In the same way, it was suggested that most of the galactose residues of microsomal N-glycans were sialylated at 0, 4 and 5 weeks of age, but that the degree of sialylation was lower at the other ages, with a minimum at 2 weeks. When the activities of sialyltransferase and galactosyltransferase in liver Golgi membranes were determined, age-dependent changes were found, not only in the specific activities of the enzymes, but also in the Golgi membrane content per g of liver. The activity of galactosyltransferase per g of liver increased immediately after birth, whereas that of sialyltransferase remained at a low level for 2 weeks and then increased to a constant level at 4 weeks. It is probable that this delayed increase in the activity of sialyltransferase results in the decreased sialylation of microsomal N-glycans at 1, 2 and 3 weeks. Sialyltransferase was solubilized from the liver microsomes of rats aged 2, 3 and 4 weeks and characterized. Phosphocellulose column chromatography separated the activity into two subfractions, designated transferase I and transferase II in the order of elution. The increase in total sialyltransferase activity during this period was caused mainly by an increase in transferase I. Rechromatography of each transferase from 3-week-old rats after neuraminidase treatment showed that transferase I but not transferase II contained sialic acid residue(s) and that desialylated transferase I was eluted in a similar way as transferase II. Although the apparent Km value for CMP-N-acetylneuraminic acid and the heat stability of transferase I were different from those of transferase II, the difference was abolished by treating transferase I with neuraminidase, suggesting that transferase II may be a desialylated form of transferase I. These changes in the sialylation of membrane glycoproteins, including sialyltransferase, may be related to the control of liver growth during postnatal development.

Aging↗
PubMed1991

Serum IgG from CBA/K1Jms-lprcg/lprcg mice induces interleukin 3 in an interleukin-3-dependent cell line--possible correlation with lymphadenopathy.

Serum IgG of CBA-K1Jms-lprcg/lprcg (lprcg/lprcg) mice with spontaneous systemic lymphadenopathy supported the proliferation of an IL-3-dependent cell line, FDC-P2/185-4. The lprcg/lprcg IgG induced IL-3 synthesis in FDC-P2/185-4 cells, and cells grew by an autocrine mechanism. There was virtually no time lag between the appearance of lymphadenopathy and an increase of IL-3-inducing activity in the sera. We have previously shown that serum IgG from other autoimmune mice with lymphadenopathy, MRL/Mp-lpr/lpr(MRL/lpr) and C3H/HeJ-gld/gld(C3H/gld), also induces IL-3 synthesis and cell growth in FDC-P2/185-4 cells. Furthermore, neither F1 (lprcg/+) mice between lprcg/lprcg and CBA(-)+/+ nor those (lpr-gld) between C3H-lpr/lpr and C3H/gld showed such IL-3-inducing activity, while those (lprcg-gld) between lprcg/lprcg and C3H/gld showed activity much lower than that of their parental strains but significantly higher than that of normal CBA(-)+/+ mice. This result is consistent with the incidence and degree of lymphadenopathy in these F1 mice. Our results suggest that expression of IgG(s) with cytokine-inducing activity might be controlled by these mutant genes, lpr, gld, and lprcg, and might be related to lymphadenopathy in these mice.

Animals↗
PubMed1991

Arthroscopic surgery of the hip joint.

Hip arthroscopic examination of 196 joints was performed in 104 patients treated during the past 4 years. Of these, 11 joints were treated by arthroscopic surgery. We have developed a technique using a two-directional approach that facilitates a global view of joint areas and allows simpler performance of surgical procedures. Removal of loose bodies, joint debridement in osteoarthritis, and synovectomy in rheumatoid arthritis are good indications for arthroscopic surgery of the hip joint. Short-term follow-up was satisfactory, and a reduction of pain was obtained in all patients. Although the joint space of the hip is narrower and the operative technique is more difficult to perform than in the knee, we believe that arthroscopic surgery of the hip is a suitable method in selected cases.

Arthroscopy↗
PubMed1990

Magnetic resonance imaging of the ovarian cyst: its diagnostic value of endometrial cyst.

The role of magnetic resonance imaging (MRI) in diagnosing the ovarian cyst was reviewed with emphasis on its diagnostic value of endometrial cyst. 94 cystic ovarian masses in 77 patients were evaluated using 0.15 Tesla MRI just before laparotomy at Okayama University Hospital from 1984 to 1987 and these images were followed up by histopathological data. From these obtained images, 6 parameters; that is (1) laterality and (2) delineation of the cyst, (3) presence or absence of septal image, and (4) homogeneity, (5) signal intensity and (6) T1 value of the cyst contents, were extracted and analyzed respectively. In 95.5% of endometrial cysts, homogenous internal pattern was observed in all 3 images (short spin echo (SE), inversion recovery (IR) and long SE) and its signal intensity was at the same level or higher than that of myometrium. On the other hand, in all cases of follicular cyst, para-ovarian cyst, corpus luteum cyst and in 95.0% of serous cystadenoma and in 90.9% of mucinous cystadenoma, cyst contents showed either lower signal intensity than the myometrium or similar to it in T1 contrast images (short SE and IR). 93.1% of dermoid cyst showed heterogenous signal intensity in all 3 images and their signal intensity levels were widely ranging. High signal intensity of cyst contents in all 3 images could be observed in 72.7% of endometrial cyst, 5.0% of serous cystadenoma with internal hemorrhage, 9.1% of mucinous cystadenoma with internal hemorrhage and 3.4% of dermoid cyst consisted of fatty tissue only. Endometrial cyst showed markedly shortened T1 value (209.6 +/- 102.7 ms) and the other hemorrhagic cyst showed comparatively short value (360-970 ms). On the other hand, T1 value of non hemorrhagic cyst was as high as the level of urine. All of endometrial cysts were clearly defined from the other pelvic structures. In result, endometrial cysts were found to exhibit the characteristic findings in MRI images such as homogenous high signal intensity of internal fluid and clear delineation of cyst contour. The diagnostic accuracy of MRI in endometrial cyst were considered 96.8% in our cases.

Cystadenoma↗
PubMed1979

Mutagenicity of metal cations in cultured cells from Chinese hamster.

The mutations at the hypoxanthine-guanine phosphoribosyl transferase (HGPRTase) locus in Chinese hamster V79 cells induced by metal cations were examined by the development of resistance to 8-azaguanine (8AG). The spontaneous frequency of 8AG resistance was 5.8 per 10(6) cells, and the frequency was enhanced to 2-6 times that of the control by treatment of cells with the chlorides of beryllium and manganese. About 75% of 8AG-resistant colonies were sensitive to amethopterin, and 86% of the resistant colonies showed less than 3% of the HGPRTase activity of the wild-type cells. The mutant frequency in cultures treated with cobalt and nickel chlorides were slightly increased, and mutation induction was only detectable at very low rates of cell survival.

Animals↗
PubMed1979

Hexokinase of Angiostrongylus cantonensis: presence of a glucokinase.

1. Angiostrongylus cantonensis contains a glucokinase which was isolated by DEAE-cellulose column chromatography. 2. This enzyme has a much higher affinity toward glucose (apparent Km, 0.2 mM) than fructose (apparent Km, 85 mM). Glucose-6-phosphate (10 mM) does not inhibit glucose phosphorylation. 3. Molecular weight obtained by a molecular sieve chromatography (60,000) is also close to the value of mammalian glucokinase. 4. While Vmax value for mannose is one-third smaller than that for glucose, Km for mannose is rather lower than that for glucose. 5. In addition to the cytosol enzyme, a particle bound hexokinase is found in the worm.

Angiostrongylus↗