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Biomedical subjects

M Hashimoto

Publications and source records attributed to M Hashimoto.

At least 667 records · Page 37Linked to original sources
PubMed1993

Site-directed mutagenesis in hemoglobin: functional and structural study of the intersubunit hydrogen bond of threonine-38(C3)alpha at the alpha 1-beta 2 interface in human hemoglobin.

To clarify the functional and structural roles of Thr-38 alpha at the alpha 1-beta 2 interface, two artificial alpha-chain mutants, in which Thr-38 alpha is replaced by Ser (Hb T38 alpha S) or Val (Hb T38 alpha V), were prepared. Thr-38 alpha is one of the highly conserved amino acid residues in hemoglobins and forms a hydrogen bond to Asp-99 beta, which is a crucial residue to stabilize the T state, via a water molecule in the deoxygenated form. We investigated their oxygen binding properties together with structural consequences of the mutations by using various spectroscopic probes. Their oxygen equilibrium curves showed small changes in the oxygen binding properties. Structural probes such as ultraviolet-region derivative and oxy-minus-deoxy difference spectra, resonance Raman scattering, and 1H-NMR spectra also indicated that the oxy and deoxy forms of these mutants show spectra characteristic of the R and T states, respectively, and the R-T transition is not very disturbed. The present structural and functional data of the mutants imply that the hydrogen bond between Thr-38 alpha and Asp-99 beta does not play a key role in stabilizing the deoxy T structure, which is in sharp contrast to the role of the hydrogen bond between Tyr-42 alpha and Asp-99 beta, and suggest that the interactions via the intersubunit hydrogen bonds are highly site-specific, depending on the amino acid residue which participates in them.

Globins↗
PubMed1993

1-Oleoyl-2-docosahexaenoyl phosphatidylcholine increased paradoxical sleep in F344 rats.

The effects of administration of 1-oleoyl-2-docosahexaenoyl-sn-glycero-3-phosphorylcholine (O-DH-PC), a kind of lecithin, and of glycerophosphorylcholine (GPC) on sleep were investigated in male F344 rats. Intracerebroventricular administration of O-DH-PC at a dose of 10 micrograms/rat induced significant increase in paradoxical sleep time and total sleep time in the following 24 h, while administration of GPC did not. Results suggest that O-DH-PC affects on neuronal mechanism relating to paradoxical sleep, and that the effect of O-DH-PC might be caused by fatty acid residues, rather than choline residue.

Animals↗
PubMed1993

[Experimental study with radiofrequency-induced thermal arterial occlusion].

A preliminary experiment on arterial occlusion using radiofrequency energy was performed. A surgitron FFPF was used as a radiofrequency power generator, and a Tracker 18 catheter was used as a probe insulator. A 10 mm length of the guide wire protruding from the tip of catheter was used as the radiofrequency probe. To examine the safety of this procedure within the vessels, the following experiments were performed. A 2.5 mm diameter dimple at the surface of a sausage was filled with human blood. We inserted various lengths of non-insulated guide wire into the dimple and supplied radiofrequency power. We then measured the time until air bubbles appeared in the dimple. With a 10 mm length of non-insulated guide wire, this took over 30 sec. Animal experiments were carried out in 17 canine arteries. The diameter of these arteries ranged from 1.3 to 3.7 mm. Before the procedure, angiograms were taken using a 5 F catheter from the right femoral artery. A tracker 18 catheter and guide wire were inserted to the target position co-axially. The guide wire was attached to the radiofrequency generator. The tip of the guide wire functioned as the convergence point of an electrically conducting induced current. Treatment was performed by supplying radiofrequency power of various durations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[A study of transsplenic CO2 gas enhanced portal angioechography].

Transsplenic CO2 gas enhanced portal angioechography was examined. The spleen of three dogs was punctured by 23 gauge needle with two side holes. From 5 ml to 20 ml of CO2 gas was injected into the splenic vein via the splenic parenchyma, and elevation of echo level of the liver was observed. Hematoma was not seen at the site of puncture. Good image was obtained in the case of 5 ml CO2 injection. In one dog with pseudotumor in the liver, the hyperechoic tumor changed into negative enhanced nodule after CO2 gas enhancement. Transsplenic CO2 gas enhanced portal angioechography is thought to be useful to evaluate hepatic tumors.

Animals↗
PubMed1993

The effects of transforming growth factor alpha and somatostatin on regenerating hepatocytes in the rat.

Transforming growth factor alpha (TGF alpha) stimulates DNA synthesis in adult rat hepatocytes, and plays a physiological role after partial hepatectomy by an autocrine mechanism. Somatostatin (SS-14) is a potent inhibitor of gastrointestinal function and inhibits proliferation in various cell types. We examined the proliferative effect of TGF alpha and the inhibitory effect of SS-14 on hepatocytes isolated at various times after partial hepatectomy. To study the mechanism of SS-14 further, we treated rats with the long acting SS-14 analog, octreotide, before or after 70% hepatectomy to determine whether or not a differential effect could be seen. We confirmed the proliferative effects of TGF alpha, and the inhibitory action of SS-14 in the early phase of liver regeneration in vitro. Regenerating hepatocytes isolated from hepatectomized livers respond to TGF alpha only at early time points (2 h) but do not respond to SS-14. In addition, the long acting SS-14 analog, octreotide, inhibited hepatic regeneration only when administered prior to hepatectomy. We conclude that exogenous peptide stimulation is effective only in the early phase of the hepatic proliferative response. After the initial changes brought about by hepatectomy, subsequent steps of the regenerative process appear refractory to external stimuli.

Animals↗
PubMed1993

Measurement of beta 2-glycoprotein I (apolipoprotein H)-independent anticardiolipin antibody in human immunodeficiency virus-1-positive and -negative hemophiliacs.

The authors studied whether or not anticardiolipin antibody (aCL), which is frequently detected in hemophiliacs with human immunodeficiency virus-1 (HIV-1) infection, is dependent on beta 2-glycoprotein I (GPI), a cofactor of cardiolipin (CL). GPI-independent aCL was positive in 27 of 36 hemophiliacs with HIV-1 antibody (75%) and in 23 of 29 patients without HIV-1 antibody (79%). However, only six HIV-1-positive and four HIV-1-negative patients were positive for GPI-dependent aCL. Thus the aCL in these hemophiliacs was GPI independent and therefore different from the aCL found in autoimmune diseases, such as systemic lupus erythematosus.

Antibodies, Anticardiolipin↗
PubMed1993

Anticoagulant activity of an anti-beta 2-glycoprotein I antibody is dependent on the presence of beta 2-glycoprotein I.

We studied whether or not an anti-beta 2-glycoprotein I antibody (aGPI) had lupus anticoagulant-like activity, employing the diluted Russel viper venom time (dRVVT) and kaolin clotting time (KCT) as indices. aGPI prolonged the dRVVT and KCT of beta 2-glycoprotein I (GPI)-depleted normal plasma in the presence of extrinsic GPI. This prolongation of the dRVVT and KCT occurred immediately after the addition of aGPI and GPI, and was subsequently enhanced further in a time-dependent manner. The GPI/aGPI combination was judged to have lupus anticoagulant-like activity by the dRVVT-platelet neutralization test, but this was not confirmed by a lupus anticoagulant-specific test, i.e., the activated partial prothrombin time (APTT) using hexagonal phospholipid. From these findings, it can be concluded that aGPI has lupus anticoagulant-like activity in the presence of GPI, but may be a partially or considerably different antiphospholipid antibody from lupus anticoagulant. Further investigations may be needed to clarify this point.

Antibodies↗
PubMed1993

Calcium pretreatment induces the decrease in epidermal growth factor binding through the activation of transglutaminase in isolated liver membrane.

Pretreatment of hepatocytes with Ca2+ and A23187 resulted in the decrease in epidermal growth factor (EGF) binding to the receptor. This decrease could be induced by only the pretreatment of the isolated liver membrane with Ca2+. By the pretreatment with 1 mM Ca2+ for 30 min, EGF binding was decreased to 40% of control. Scatchard plot analyses indicated that high affinity binding sites of EGF receptor disappeared after Ca2+ pretreatment. No effect of Ca2+ pretreatment on the degradation of receptor occurred. The Ca2+ effect was prevented by monodansylcadaverine or iodoacetamide, transglutaminase (TGase) inhibitors. After membrane-bound TGase was inactivated, the Ca2+ effect did not occur, except in the presence of purified TGase. Labeled putrescine was incorporated into some proteins of membrane with Ca2+ treatment. These results suggest that Ca(2+)-activated TGase induces the decrease in EGF binding to the receptor via modification of some membrane protein.

Animals↗
PubMed1993

Management of gallstones in cirrhotic patients.

34 cirrhotic patients who underwent either cholecystectomy alone or in conjunction with common duct exploration were retrospectively reviewed. In Child A and B patients morbidity was low and there were no postoperative deaths. However, all patients who underwent additional cholecystectomy during the non-shunting operation for esophageal varices required blood transfusion. Cholecystectomy in Child C patients is frequently associated with considerable intraoperative bleeding and subsequent postoperative complications. In the 23 patients who were not operated upon for gallstones, no patients developed symptomatic biliary disease. Ultrasonographically, most of these gallstones were strongly suspected to be black stones. Elective surgical intervention for symptomatic Child A and B patients would normally be warranted, but hemorrhage and resulting complications due to additional cholecystectomy for asymptomatic gallstones during the non-shunting operation should be minimized. An additional cholecystectomy should be considered, provided such a cholecystectomy is thought to be easily performed judging from the degree of development of collateral circulation around the hepatoduodenal ligament and unless black stones are suspected ultrasonographically. For symptomatic gallstones in Child C patients every type of medical treatment should be attempted. After considering the bleeding tendency or ascites, percutaneous transhepatic gallbladder drainage is considered to be one of the safest treatments.

Adult↗
PubMed1993

The intrapleural administration of recombinant interleukin-2 (rIL-2) to patients with malignant pleural effusion: clinical trials.

Recombinant IL-2 (rIL-2) was administered intrapleurally according to an original protocol to 11 patients with malignant pleural effusion, 7 of whom suffered from breast cancer and 4 from esophageal cancer. The pleural effusions either disappeared or decreased roentgenographically, and malignant cells disappeared from all 13 pleural cavities in the 11 patients, confirming the validity of this therapy to be 100%. The mean survival time from the initial administration of rIL-2 was 15.9 months. We ensured that the concentration of IL-2 in the effusion was maintained at a high level for a sufficient period of time, and that the lymphokine-activated killer (LAK) activity of lymphocytes in the effusion was augmented. Fever, eosinophilia, and a transient increase in the pleural effusion were the main side effects, but the symptoms were temporary and not serious. The results of this study therefore suggest the efficacy of intrapleural rIL-2 for patients with malignant pleural effusion.

Adult↗
PubMed1993

Magnetic resonance imaging of ganglion cell tumours.

The MRI and CT studies of four patients with ganglion cell tumours, one with a cerebellar gangliocytoma (Lhermitte-Duclos disease), and three with gangliogliomas are reported. MRI in Lhermitte-Duclos disease clearly demonstrated a mass of low signal intensity in the left cerebellum on T1-weighted spin-echo (SE) images and an area of high signal intensity with a blurred margin on T2-weighted SE images. These MRI studies were useful for delineating the lesion, which was verified at surgery. In the ganglioglioma, MRI demonstrated two isointense solid masses on T1-weighted SE images, which enhanced clearly with Gd-DTPA. The enhancement study was advantageous in planning surgery.

Adolescent↗
PubMed1993

Abnormal systolic blood pressure response during exercise recovery in patients with angina pectoris.

OBJECTIVES: This study was conducted to clarify the mechanisms of the abnormal systolic blood pressure response after exercise in patients with angina pectoris. BACKGROUND: An abnormal systolic blood pressure response in patients with angina pectoris has been observed not only during exercise but also during the recovery period after exercise. However, the mechanisms of this abnormal response during recovery have not been elucidated. METHODS: Thirty-five patients with angina pectoris and 17 control subjects underwent bicycle ergometric studies after insertion of a Swan-Ganz catheter. RESULTS: In control subjects, all hemodynamic variables decreased rapidly after exercise. In 7 of the 35 patients, systolic blood pressure increased after exercise. The patients with angina were classified into two groups. In group I (17 patients), changes in systolic blood pressure during recovery were smaller than those in control subjects. In group II (18 patients) recovery of systolic blood pressure was normal. Changes in stroke index from rest to peak exercise were smaller in group I than in group II. Stroke index in both patient groups increased paradoxically during recovery. The increase in systemic vascular resistance index during recovery and the ratio of plasma norepinephrine concentration to cumulative work load were greater in group I than in group II. CONCLUSIONS: An abnormal systolic blood pressure response after physical exercise in patients with angina pectoris is indicative of severe myocardial ischemia during exercise and may be caused by an increase in stroke volume due to recovery from myocardial ischemia and increased systemic vascular resistance secondary to exaggerated sympathetic nervous activity.

Adult↗
PubMed1993

The significant effect of HLA-DRB1 matching on long-term kidney graft outcome.

Serotyping and genotyping (polymerase chain reaction with sequence-specific oligonucleotide probes method) were conducted on 520 unrelated individuals to determine the linkage disequilibrium of HLA-B and HLA-DRB1. Analyses of 511 kidney transplants (300 related and 211 cadaver recipients) were carried out at 4 transplant centers using the linkage disequilibrium of HLA-B and HLA-DRB1 established previously. All transplant recipients received CsA immunosuppression and were transplanted from June 1983 to December 1991. There were 51 significant linkages formed between HLA-B and HLA-DRB1 alleles (P < 0.05). DRB1-compatible transplants experienced a comparable 5-year graft success rate of 94% as did the HLA-identical recipients with a 100% 5-year success rate. However DRB1-incompatible recipients displayed a significantly reduced 5-year graft survival rate of 73% (73% vs. 94% P < 0.01). The 5-year graft survival rate of HLA-DR-incompatible recipients of 71% was compatible to the 73% for HLA-DRB1-incompatible recipients. No variation of rejection rate for DRB1-compatible grafts was seen in any of the 4 transplant centers. The results also indicated that HLA-DRB1 compatibility was essential for optimal success rate, regardless of HLA class I mismatches. The overall conclusion was that matching for HLA-DR was important to achieve optimal kidney graft survival on the molecular level but not on the serotyping level.

Alleles↗
PubMed1993

A partial physical map for the chromosome of alkalophilic Bacillus sp. strain C-125.

Bacillus sp. strain C-125 has been chosen as a model alkalophilic bacterium to understand how adaptation to growth at high pH is achieved. To aid genetic analysis, we have started characterization of its genome. By using the two infrequently-cutting restriction endonucleases, AscI and Sse8387I, in conjunction with pulsed-field electrophoretic techniques, the size of the genome was found to be 3.7 Mb. Southern blot analysis of single, double and partial digests of Bacillus sp. strain C-125 DNA, using AscI-linking clones, gene probes and purified Bacillus sp. strain C-125 restriction fragments, allowed a putative chromosome map to be constructed.

Adaptation, Physiological↗
PubMed1993

Immediate inhibitory effect of methylprednisolone suleptanate (U-67590A) on antigen-induced cutaneous and airway anaphylactic responses in guinea-pigs.

1. Inhibitory effects of water-soluble glucocorticoids administered intravenously were examined on skin and airway reactions caused by antigen challenge or chemical mediators in guinea-pigs. 2. Methylprednisolone suleptanate (U-67590A) which is an analogue of methylprednisolone, produced immediate inhibition of 3-h and 7-day homologous passive cutaneous anaphylaxis (PCA) reactions, but not of histamine- or bradykinin-induced cutaneous vascular permeability, when administered 10 min before antigen challenge. In contrast, methylprednisolone succinate (MP) or dexamethasone (DXM) administered 10 min before antigen challenge failed to show an immediate inhibitory effect on the PCA or mediator-induced reactions. When administered 1 to 5 h before antigen challenge, all the steroids used in this study reduced both PCA and mediator-induced reactions. 3. Pretreatment with cycloheximide almost completely abolished the late inhibition of 3-h PCA and histamine reactions produced by U-67590A or MP, but it did not affect the immediate inhibition of 3-h PCA produced by U-67590A. 4. U-67590A also demonstrated immediate inhibitory effects on antigen-induced bronchoconstriction in guinea-pigs actively sensitized with ovalbumin even when administered 10 min before antigen challenge, whereas MP and DXM failed to show the immediate inhibitory effect. When administered 3 h before antigen challenge, all the steroids used in this study reduced the response to antigen. 5. The late inhibitory effect of U-67590A administered 3 h before antigen challenge was almost completely abolished by treatment with cycloheximide or 17 alpha-methyltestosterone, whereas the immediate inhibition produced by U-67590A administered 10 min before challenge was not affected by this treatment. 6. U-67590A administered 10 min or 3 h before challenge did not affect the bronchoconstriction induced by histamine or leukotriene D4.7. Release of histamine from lung fragments of sensitized guinea-pigs in vitro was inhibited by U-67590A.8. The present experiments indicate that U-67590A demonstrated dual, immediate and late, inhibitory effects. The former are independent of protein synthesis and may be associated with non-genomic direct action on the mediator-releasing process without affecting mediator-induced reactions. The latter share common inhibitory actions with other glucocorticoids which are dependent on protein synthesis through gene expression.

Airway Resistance↗