Biomedical subjects

K Fujiwara

Publications and source records attributed to K Fujiwara.

At least 577 records · Page 32Linked to original sources

PubMed1989

Evidence for the association between two myosin heads in rigor acto-smooth muscle heavy meromyosin.

The rigor complexes that formed between rabbit skeletal muscle F-actin and chicken gizzard heavy meromyosin (HMM), in which the heavy chains had been cleaved with trypsin into 24K, 50K, and 68K fragments, were examined by using the zero-length chemical cross-linker 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC). Two cross-linked products of approximate Mr 115K and 60K were generated. These products were not obtained by EDC treatment of HMM in the absence of F-actin. The HMM fragments that participated in cross-linking were identified by fluorescent labeling and amino acid composition studies. The 115K peptide was determined to be a covalently cross-linked complex that formed between actin and the COOH-terminal 68K fragment of the HMM heavy chain. Our results are in agreement with a previous study which proposed that the site of cross-linking between HMM and F-actin resides within the COOH-terminal 22K fragment of the myosin subfragment 1 heavy chain [Marianne-Pépin, T., Mornet, D., Bertrand, R., Labbé, J.-P., & Kassab, R. (1985) Biochemistry 24, 3024-3029]. The 60K peptide, however, was not a product of cross-linking between HMM and F-actin. On the basis of its amino acid composition, we concluded that this 60K peptide was a cross-linked dimer of the NH2-terminal 24K fragments of the HMM heavy chain. The cross-linking of acto-gizzard HMM significantly increased the Mg-ATPase activity of gizzard HMM without any observable phosphorylation of the regulatory (20K) light chains.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗

PubMed1989

Carbodiimide-catalyzed cross-linking sites in the heads of gizzard heavy meromyosin attached to F-actin.

In the rigor complex between rabbit skeletal muscle F-actin and chicken gizzard heavy meromyosin (HMM), the direct contact between two HMM heads was demonstrated by using a zero-length cross-linker 1-ethyl-3-[3-(dimethylamino)propyl]maleimide (EDC) [Onishi, H., Maita, T., Matsuda, G., & Fujiwara, K. (1989) Biochemistry (preceding paper in this issue)]. Here, the 60K peptide which was a product of the EDC cross-linking between two 24K heavy chain (tryptic) fragments of HMM was further fragmented with cyanogen bromide, and the location of the cross-linking sites on the amino acid sequence of the HMM heavy chain was investigated. The result showed that one site resided within the 77-residue peptide region (residues 1-77) on one head of HMM, whereas the other site belonged to the 40-residue peptide region (residues 164-203) on the other head. This finding suggests that the two HMM heads are in contact with each other at different sites. Ultracentrifugal fractionation revealed that the head-to-head cross-linked gizzard HMM could be reversibly released from F-actin in the presence of Mg-ATP. The yield of the head-to-head cross-linking was not significantly changed with the acto-HMM complex between actin/HMM head molar ratios of 1 and 4, and it was very slightly decreased even at a molar ratio of 8, where HMM molecules were attached sparsely to actin filaments.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗

PubMed1989

Plasma alpha 2-plasmin inhibitor-plasmin complex and FDP-D-Dimer in fulminant hepatic failure.

Plasma levels of alpha 2-plasmin inhibitor-plasmin complex (PI-Pm) and FDP-D-Dimer (FDP-D), one of cross-linked fibrin degradation products, were determined at 42 points in time in 8 patients with fulminant hepatic failure. PI-Pm was abnormally increased at all 25 points when intractable bleeding was present, whereas FDP-D was increased only at 5 of these points. Of 17 points unassociated with such bleeding, both PI-Pm and FDP-D were increased at 3 points; increased PI-Pm alone was found at 1 point measured next day after the bleeding ceased; and increased FDP-D alone were at 5 points when ascites, one of common complications of fulminant hepatic failure, developed. When PI-Pm was increased, plasma levels of fibrin/fibrinogen degradation products (FDP) changed together with FDP-D.

Adult↗

PubMed1989

Incidence of adult T-cell leukemia/lymphoma among human T-lymphotropic virus type I carriers in Saga, Japan.

Using a population-based cancer registry, we tabulated 69 definite adult T-cell leukemia/lymphoma cases (36 males and 33 females) and 2.20 expected cases (0.95 for males and 1.25 for females) diagnosed from 1981 to 1983 in Saga, Japan. The number of human T-lymphotropic virus type I carriers was computed by applying sex- and age-specific anti-human T-lymphotropic virus type I antibody positive rates among blood donors at the blood center in 1986 to the whole population of Saga Prefecture in 1982. The age-specific incidence rates among male human T-lymphotropic virus type I carriers from 40 to 79 yr of age per 100,000 were significantly higher than those of female carriers (P less than 0.05), and the rates from 60 to 69 yr of age were the highest in both sexes. The annual crude incidence rates among carriers were 115.9 for males and 66.4 for females. The summary incidence rates with 95% confidence intervals were 115.9 (58.4 to 193.0) for males and 65.9 (30.0 to 115.9) for females. The cumulative risks were 4.5% (0.8 to 11.0) for males and 2.6% (0.3 to 7.0) for females. These morbidity figures were assumed to be underestimated partly due to the newly proposed clinical entity of adult T-cell leukemia/lymphoma.

Adolescent↗

PubMed1989

In situ evaluation of the stimulatory state of hepatic macrophages based on their ability to produce superoxide anions in rats.

When a liver perfusion with nitro blue tetrazolium (NBT) and phorbol myristate acetate (PMA) was performed in carbon tetrachloride (CCl4)-intoxicated rats, formazan deposition was remarkable in macrophages in the necrotic areas of the liver, its intensity varying with the extent of injury. The deposits almost disappeared after addition of Cu(Lys)2, a scavenger of intra- and extracellular superoxide, but were not affected by superoxide dismutase (SOD), which acts extracellularly. The formazan content after incubation with NBT and PMA was higher in macrophages isolated from CCl4-intoxicated liver than in those from normal liver, though their PMA-induced chemiluminescence did not differ. In Corynebacterium parvum-treated liver, both Cu(Lys)2 and SOD reduced the deposits. This method can estimate in situ the ability of hepatic macrophages to produce superoxide and the cellular sites of its production.

Animals↗

PubMed1989

Hepatic sinusoidal cell destruction in the development of intravascular coagulation in acute liver failure of rats.

Rats received a dose of dimethylnitrosamine (DMN) or carbon tetrachloride (CCl4). In the liver of rats given DMN, apoptosis of fat-storing cells occurred at 7.5 h, and sinusoidal endothelial cell degeneration followed, with parenchymal cell necrosis after 9 h. Fibrin thrombi appeared in the sinusoids as well as in these necrotic areas after 12 h. In contrast, in the liver of rats given CCl4, parenchymal cell degeneration was seen after 6 h and necrosis with fibrin thrombi developed after 9 h. Fat-storing cells and endothelial cells were almost intact, and fibrin thrombi were not present in the sinusoids. SGPT values increased with decreased plasma levels of fibrinogen and antithrombin III and prolonged prothrombin time after 3 and 6 h, in the CCl4 and DMN models, respectively. An extensive reduction in plasma factor VIIIC levels and peripheral platelets was seen after 18 and 24 h, respectively, only in the DMN model. These results suggest that endothelial cells destruction can cause fibrin formation in the hepatic sinusoids in acute liver injury. Fat-storing cell injury may contribute to the destruction.

Animals↗

PubMed1989

Further confirmation of serotonin reduction in the neostriatum during hyperthermia-induced convulsions: a quantitative immunohistochemical study.

Changes occurring in serotonin neurons during hyperthermia and hyperthermia-induced convulsions were examined by quantitative immunohistochemistry. A marked increase in serotonin immunoreactivity was observed at the rostral and intermediate levels of the neostriatum of mice kept at high temperatures with no convulsions, and a significant reduction in serotonin immunoreactivity was verified throughout the neostriatum of mice which had hyperthermia-induced seizures. These results suggest that serotonin neurons change significantly during thermal stress and seizures, and that regional analysis is essential for an understanding of the role of serotonin neurons.

Animals↗

PubMed1989

Reciprocal changes in serum albumin and alpha-fetoprotein levels in the recovery course of acute viral hepatitis stimulated by glucagon and insulin therapy: analysis of a double blind controlled trial.

The records of 57 patients with acute viral hepatitis (28 given hormones and 29 placebo) in a double blind controlled trial of one week of glucagon and insulin therapy were analyzed. In the placebo group, SGPT values dropped after treatment with improved prothrombin time and serum levels of total bilirubin and albumin. In the hormone group, they changed similarly, except serum albumin levels which were reversed during treatment (P less than 0.05). There was a bottom line of serum albumin levels which preceded a peak of serum alpha-fetoprotein levels within one week in the placebo group, but was around the peak in the hormone group. There were 12 patients in the hormone group in whom serum alpha-fetoprotein levels rose with treatment and decreased after its discontinuation, and 5 in the placebo group (P less than 0.05). Such a change in serum alpha-fetoprotein levels was accompanied by decreased serum albumin levels in 6 of 10 patients given hormones and none of the 5 given placebo (P less than 0.05). These results indicate reciprocal changes in serum albumin and alpha-fetoprotein levels appearing during the recovery course of acute viral hepatitis, and suggest that this therapy may stimulate its development. Stimulation of liver regeneration by this therapy merits consideration.

Adult↗

PubMed1989

A multi-centre double-blind controlled trial of glucagon and insulin therapy for severe acute hepatitis.

A cooperative study was conducted to determine the efficacy of one week of treatment with infusion of 1 mg glucagon and 10 units insulin twice daily in severe acute hepatitis. Ninty-eight patients with either prothrombin time less than 60% or thrombotest or hepaplastin test less than 50% of normal were randomly assigned to hormone or placebo treatment. SGOT and SGPT values dropped after treatment with a gradual decrease or increase in total serum bilirubin or cholesterol levels similarly in both groups receiving hormone or placebo. Deranged prothrombin time improved more rapidly in the hormone group than in the placebo group. Glucagon and insulin infusion may stimulate recovery of the liver from injury.

Acute Disease↗

PubMed1989

Additive stimulation of hepatic putrescine production by glucagon and insulin after partial hepatectomy in rats.

When rats received glucagon or insulin every 2 h after partial hepatectomy (Hx), hepatic putrescine content was increased above control levels at 6 and 12 h, respectively. When the two hormones were combined, the increased levels were additive. Hepatic ornithine decarboxylase activity was above control levels at 12 h after insulin treatment. Hepatic spermidine N1-acetyltransferase activity was enhanced at 6 h only when glucagon was dosed. Putrescine administration from 0 to 4 h or from 6 to 10 h increased hepatic DNA synthesis to similar levels 22 h after Hx. These results suggest that glucagon and insulin additively stimulate hepatic putrescine production after Hx. This may explain the cooperative stimulation of liver regeneration by both hormones.

Acetyltransferases↗

PubMed1989

Effects of idebenone on neurological deficits following cerebrovascular lesions in stroke-prone spontaneously hypertensive rats.

The effects of 6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone (idebenone) on neurological deficits following cerebrovascular lesions were examined in stroke-prone spontaneously hypertensive rats (SHRSP). The SHRSP were maintained on a 1% NaCl solution as drinking water to shorten the onset time of cerebrovascular lesions (stroke). After the onset of stroke, the salt solution was exchanged for tap water, and idebenone (30 and 100 mg/kg) was administered orally once daily for 3 weeks. The neurological deficits were evaluated by a specially designed scoring system or by an open-field test. Idebenone decreased the severity of the neurological deficits in a dose-dependent manner and this was statistically significant in the high-dose group. The severity of neurological changes was inversely related to the motor activity in the open-field test performed when the experiment was terminated, indicating the appropriateness of the scoring system. Moreover, the compound (100 mg/kg) significantly ameliorated a decrease in food intake (anorexia) that followed the onset of stroke. These results suggest that idebenone may be useful to treat patients with cerebrovascular lesions.

Animals↗

PubMed1989

Growth characteristics of Tyzzer's organism in cultured mouse hepatocytes.

The growth characteristics of Tyzzer's organisms in cultured mouse hepatocytes were examined by direct bacterial counting and plaque assay. The viability of propagated bacteria and time required for the maximum titers depended on incubation time and inoculum dose, respectively. Both infectious titers and bacterial counts at optimum harvests were much higher than those obtained from infected mouse livers. Immunofluorescence revealed, after a lag phase of about 2 h, a linear multiplication during a 6 h period.

Animals↗

PubMed1989

Treatment of chronic liver injury in mice by oral administration of xiao-chai-hu-tang.

Oral administration of Xiao-Chai-Hu-Tang, the extract of a mixture of seven herbs, attenuated the hepatic fibrosis developed in mice after repeated doses of carbon tetrachloride. Its pre-administration reduced the derangement of liver function tests seen after a single dose of carbon tetrachloride as well as that seen after d-galactosamine intoxication. Xiao-Chai-Hu-Tang may be effective in the treatment of chronic liver injury through hepatocytoprotection.

Alanine Transaminase↗

PubMed1989

Factors affecting infectivity of Tyzzer's organism in cultured mouse hepatocytes.

Factors affecting the infectivity of Tyzzer's organism, an obligate intracellular bacterium, were examined in cultured mouse hepatocytes. The organisms were subjected to physical and chemical impairments and the infectivity was estimated by immunofluorescence that discriminated adhesion and entry of the organisms to host cells and by the plaque assay. Pretreatment of the organisms with either mild heat or formalin abolished adhesion. UV irradiation completely removed the plaque forming ability, while adhering and entering capacity were more resistant in this order. Entry of the organism into host cells was suppressed in the presence of erythromycin, gentamicin or oxytetracycline, while it was relatively little susceptible to ampicillin, kanamycin or rifampicin. Plaquing efficiencies were increased by centrifugation during the infection. These results suggest that not only a structural but also a functional integrity of the organisms was requisite for establishment of the infection at the initial stage.

Animals↗

PubMed1989

Initial phase of infection with Tyzzer's organism in cultured mouse hepatocytes.

The initial phase of infection with Tyzzer's organisms in cultured mouse hepatocytes was observed using indirect immunofluorescence (IF) and a plaque assay. The organisms adhered poorly to aldehyde- or acetone-fixed cells, but once adhered to host cells, whether methanol-fixed or unfixed, they were not removed by methanol or acetone. By the IF as well as the plaque assay, both of which discriminated intra- and extracellularly located organisms, the number of cell-associated organisms increased linearly up to 3 h post-inoculation. The number of intra-cellular organisms increased rapidly in the first 1 h, followed by linear increase at a much lower rate. Similar results were obtained by the plaque assay.

Animals↗

PubMed1989

Electron microscopic studies of viruses labeled with magnetite.

We were able to develop a method with which to successfully and specifically detect virus particles under the electron microscope by using magnetite. This method was devised on the principle that magnetite-labeled antibody or magnetite coupled with protein A selectively bind virus or antibody-treated virus particles on the electron microscope grid by the action of an electromagnet. Another advantage characterizing the technique is the possibility of detection of a small number of virus particles. This is done through a process of concentration and purification of the reaction complexes trapped rigidly by magnetic force.

Antibodies, Viral↗

PubMed1989

Immunopathology of chronic progressive hepatitis in nude mice infected with low-virulent mouse hepatitis virus.

Progressive hepatitis in athymic nude (nu/nu) mice due to a low-virulent mouse hepatitis virus, MHV-2 cc, was examined for involvement of immunocytes and serum antibodies. At 3 to 6 weeks postinoculation (p.i.) a considerable number of Mac 1- and asialo GM1-positive cells were accumulated in the affected liver and spleen. There were also some Thy-1-positive cells. Later than 2 weeks p.i., serum IgG and IgM antibodies were detected in parallel with virus-neutralizing activity, while the IgG levels were lower than those of infected euthymic (nu/+) littermates. By transfer of the infected nu/nu mouse serum, the recipient euthymic mice acquired resistance to lethal challenge infection with a virulent virus, MHV-2.

Animals↗

PubMed1989

Effect of deglycosylation of N-linked sugar chains on glucose oxidase from Aspergillus niger.

Endo-beta-N-acetylglucosaminidase from Flavobacterium sp. released about 30% of the N-linked sugar chains from the glucose oxidase of Aspergillus niger. To elucidate the role of the carbohydrate moiety, the enzymatic properties of native and carbohydrate-depleted glucose oxidases were compared. It was found that their catalytic activities and thermal and pH stabilities were identical. However, the carbohydrate-depleted glucose oxidase was more rapidly precipitated by the addition of trichloroacetic acid and ammonium sulfate than the native enzyme. These results show that the N-linked sugar chains of the glucose oxidase contributed to the high solubility of the enzyme in water.

Acetylglucosaminidase↗