Biomedical subjects

M Maeda

Publications and source records attributed to M Maeda.

At least 847 records · Page 47Linked to original sources

PubMed1991

Chemical stimulation of the ventrolateral medullary depressor area decreases ipsilateral cerebral blood flow in anesthetized rats.

In anesthetized (chloralose and urethane), paralyzed and artificially ventilated rats, the neurons in the ventrolateral medullary depressor area (VLDA) were chemically stimulated by microinjections of L-glutamate (2.5-5 nmole in 100 nl of 0.9% sodium chloride solution) and the cerebral blood flow (CBF) was determined using a combination of labeled microspheres (57Co, 113Sn and 46Sc). Unilateral chemical stimulation of the VLDA (n = 11) produced a significant (P less than 0.05) decrease in CBF of the cerebral cortex ipsilateral to the stimulated VLDA; the CBF was 41 +/- 5 (mean +/- S.E.M.) and 29 +/- 4 ml.min-1.(100 g)-1 before and during the chemical stimulation of VLDA. The decrease in CBF was not due to the decrease in arterial blood pressure (ABP) caused by the chemical stimulation of the VLDA because the CBF during the chemical stimulation of the VLDA was significantly smaller (P less than 0.01) than the CBF during controlled hemorrhagic hypotension (n = 10). In another group of rats (n = 6), moderate hypertension was induced by blood transfusion. Unilateral chemical stimulation of the VLDA in these rats decreased ABP but it remained within normotensive range. A significant (P less than 0.05) decrease in CBF (from 46 +/- 12 to 29 +/- 7 ml.min-1.(100 g)-1) and a significant (P less than 0.01) increase in cerebrovascular resistance (from 2.7 +/- 0.4 to 4.3 +/- 0.6 mmHg per [ml.min-1.(100 g)-1]) was observed in the ipsilateral cerebral cortex of these rats. Chemical stimulation of the VLDA did not affect the reactivity of the cerebral vessels to hypercapnea (n = 5).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

The reduction of nonspecific binding in chemiluminescent sandwich enzyme immunoassays.

The reduction in nonspecific binding obtained in EIA procedures based on glucose oxidase (GO)-labelled antibody is determined by the origin of the antibodies used for both the solid phase and for GO labelling. We have examined the relationship between nonspecific binding and various antibody combinations for the purpose of establishing highly sensitive chemiluminescent sandwich enzyme immunoassays. It was shown that nonspecific binding could be reduced by the following combination of solid phase and GO labelled antibodies: (i) guinea pig IgG-guinea pig IgG, (ii) goat IgG-rabbit IgG, (iii) goat IgG-rabbit Fab'. On the basis of these results, we succeeded in establishing highly sensitive chemiluminescent sandwich enzyme immunoassays for human chorionic gonadotropin (hCG) and alpha-fetoprotein (AFP). The detection limit was 2.5 mIU/ml for hCG using combination (i), 1 ng/ml for AFP using combination (ii), and 0.05 ng/ml (70 amol/assay) for AFP using combination (iii).

Animals↗

PubMed1991

Mechanism of action of ginsenoside Rh2: uptake and metabolism of ginsenoside Rh2 by cultured B16 melanoma cells.

The uptake and metabolism of ginsenoside Rh2 (Rh2) by B16 melanoma cells were studied. In a medium containing 2% fetal calf serum, the uptake of Rh2 reached a maximum of 3 nmol/10(6) cells at 3-6 h after Rh2 (12.5 microM) was added, but gradually decreased to 0.8 nmol/10(6) cells. In these cells, protopanaxadiol (PPD), which is an aglycon of Rh2, increased inversely with the decrease in Rh2 as a result of deglycosylation by the cells. When PPD (8 microM) was added to the medium, the uptake reached a plateau of 2.4 nmol/10(6) cells, within 0.5 h. The association constant of Rh2 (1.74 +/- 1.08 x 10(6) M-1) for bovine serum albumin (BSA) was significantly higher than that of PPD (9.90 +/- 1.10 x 10(4) M-1). In a serum-free medium, both Rh2 and PPD were incorporated within 1.5 h. The uptake rate constant of Rh2 (1.20 +/- 0.20 h-1) was not significantly different from that of PPD (1.02 +/- 0.15 h-1), but the release rate constant of PPD (2.12 +/- 0.38 h-1) was significantly lower than that of Rh2 (3.03 +/- 0.57 h-1). These differences in affinity for BSA and the release rate constants were thought to be the cause of the difference in uptake kinetics between these drugs. The effects of Rh2 and PPD on the cells were identical, and there was no difference in the lag periods before the appearance of their effects, despite their differing rates of uptake.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

A case of melena caused by a hepatic aneurysm ruptured into the intrahepatic bile duct in a patient with allergic granulomatous angiitis.

A 46 year old woman was admitted to our institute in June, 1987 with an attack of asthma, as well as remittent fever and leukocytosis accompanied by hypereosinophilia. She was found to have melena from an unknown source upon gastrointestinal examination. Four low-density areas were found in the liver on computed tomography and one of the intrahepatic foci formed a large extrahepatic abscess communicating with the intrahepatic duct on tubography. Resection of the four hepatic segments, including the large abscess, and cholecystectomy were performed. Healed necrotizing arteritis was histopathologically observed in the resected liver specimen, with the four low-density areas on CT scan having all been necrotic foci. One of them formed an intrahepatic biliary fistula and rupture of a hepatic aneurysm into a biliary duct was found to be the cause of melena. Although eosinophil infiltration and extravascular granuloma were not observed, a diagnosis of allergic granulomatous angiitis was made from the characteristic clinical course, systemic vasculitis and peripheral blood eosinophilia. To the best of our knowledge, this is the first report of intrahepatic duct perforation most probably being caused by hepatic aneurysm rupture in a patient with allergic granulomatous angiitis.

Aneurysm↗

PubMed1991

Manometric evaluation of esophageal function in progressive systemic sclerosis with special regard to the disease severity.

A study was conducted to elucidate the relation between the severity of progressive systemic sclerosis (PSS) and the grade of esophageal function disorder, the extent of which was estimated using esophageal manometry. Fifty two patients with PSS were divided into the mild, moderate and severe groups according to the severity score established by the PSS Research Group supported by The Ministry of Health and Welfare of Japan. Primary peristaltic pressure in the esophageal body at 25 to 35cm from the incisors as well as lower esophageal sphincter pressure (LESP), which represents the function of the smooth muscle of the esophagus, were significantly decreased in parallel with the increasing severity of PSS. In contrast, there was no significant difference in upper esophageal sphincter pressure (UESP) or in primary peristaltic pressure at 20cm from the incisors, indicating that the function of striated muscle of the esophagus was not impaired. In addition, even in the mild PSS group without dysphagia (19 cases), primary peristaltic pressure in the esophageal body at 25 to 35cm from incisors was found to be significantly decreased in comparison with the control. Hence, esophageal manometry was useful for early detection of the pathophysiological state of the esophageal function in PSS.

Deglutition Disorders↗

PubMed1991

Successful treatment of a case of hepatocellular carcinoma with tumor necrosis factor and local hyperthermia.

A case of unresectable hepatocellular carcinoma which responded favorably to combined therapy with tumor necrosis factor (TNF) and local hyperthermia is reported. A 58-year-old man was admitted to our hospital in June 1988 for treatment of hepatocellular carcinoma affecting S4 and S8. After three sessions of transcatheter arterial embolization (TAE) therapy, the serum alpha 1-fetoprotein level decreased, and a reduction in the size of the lesions was also noted. Thereafter, the patient received local hyperthermia once a week (60 minutes of irradiation from a Thermotron-RF8 at 1,100W), but the alpha 1-fetoprotein level increased again in February 1989. On examination, enlargement of the S8 lesion and a new nodule in S7 were recognized. Since TAE was contraindicated due to liver dysfunction, human recombinant TNF (1 x 10(6)U) was given by intravenous infusion together with local hyperthermia once a week. Eight sessions of the combined therapy reduced the serum alpha 1-fetoprotein level markedly (7,512.0 to 2,782.0 pg/ml) and after eighteen sessions, 58.1% regression of tumor size (partial response) on computed tomography scans was observed. This anecdotal case supports previous experimental evidence suggesting that TNF plus hyperthermia may be effective for treating unresectable hepatocellular carcinoma.

Carcinoma, Hepatocellular↗

PubMed1991

Chemiluminescent assay of various enzymes using indoxyl derivatives as substrate and its applications to enzyme immunoassay and DNA probe assay.

Chemiluminescent assays of various enzymes have been developed using indoxyl derivatives as substrates. The principle of the method is as follows: an enzyme causes hydrolysis of an indoxyl derivative to an intermediate indoxyl that is readily oxidized to indigo dye and simultaneously produces hydrogen peroxide (H2O2). Hydrogen peroxide is detected chemiluminescently using isoluminol-microperoxidase. Alkaline phosphatase (ALP), beta-D-galactosidase (beta-gal), and beta-glucosidase were assayed by this method using 5-bromo-4-chloro-3-indolyl phosphate (BCIP), 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal), and 5-bromo-4-chloro-3-indolyl-beta-D-glucoside, respectively, as substrates. Using BCIP and X-Gal substrates, we have been able to detect 10(-19) mol of ALP and beta-gal, respectively. This assay system can be applied to enzyme immunoassay and DNA probe assay.

Alkaline Phosphatase↗

PubMed1991

Vanadate-sensitive ATPase from chromaffin granule membranes formed a phosphoenzyme intermediate and was activated by phosphatidylserine.

Vanadate-sensitive ATPase (115 kDa molecular weight) in adrenal chromaffin granules is an intrinsic membrane enzyme with its catalytic site located at the outer surface of the granules. Upon incubation with [gamma-32P]ATP, the purified ATPase formed an alkaline-labile phosphoenzyme intermediate, which was inhibited by vanadate but not by Na+ or K+. Ratio of ATPase or phosphatase activity and formation of phosphoenzyme intermediate was constant during purification after the first glycerol density gradient centrifugation. Phosphatidylserine specifically activated the enzyme about three-fold by increasing the Vmax value without changing the Km for ATP. Other phospholipids, including phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine, as well as lysophospholipids and detergents, had no effect. These results indicated that the vanadate-sensitive ATPase belongs to the P-type ATPases, which differ from known cation-translocating P-type ATPases.

Adenosine Triphosphatases↗

PubMed1991

Role of the carboxyl terminal region of H(+)-ATPase (F0F1) a subunit from Escherichia coli.

The effects of amino acid substitutions in the carboxyl terminal region of the H(+)-ATPase a subunit (271 amino acid residues) of Escherichia coli were studied using a defined expression system for uncB genes coded by recombinant plasmids. The a subunits with the mutations, Tyr-263----end, Trp-231----end, Glu-219----Gln, and Arg-210----Lys (or Gln) were fully defective in ATP-dependent proton translocation, and those with Gln-252----Glu (or Leu), His-245----Glu, Pro-230----Leu, and Glu-219----His were partially defective. On the other hand, the phenotypes of the Glu-269----end, Ser-265----Ala (or end), and Tyr-263----Phe mutants were essentially similar to that of the wild-type. These results suggested that seven amino acid residues between Ser-265 and the carboxyl terminus were not required for the functional proton pathway but that all the other residues except Arg-210, Glu-219, and His-245 were required for maintaining the correct conformation of the proton pathway. The results were consistent with a report that Arg-210 is directly involved in proton translocation.

Arginine↗

PubMed1991

Continuous local intra-arterial infusion of antithrombotic agents for replantation (comparison with intravenous infusion).

The success rate of replantation of amputated digits and limbs appears to be improved by local continuous intra-arterial infusion of urokinases, heparin and PGE1 at a daily dose of 240,000 I.U., 10,000 U, and 40 micrograms, respectively, for ten days, in comparison to intravenous infusion of the drugs. The purpose of this study was to investigate the difference between the haematological effects of intra-arterial and intravenous infusion. Accordingly coagulation and fibrinolytic enzyme levels were examined before, and at 4 and 12 hours after the start of infusion and on the 3rd and 10th postoperative days. Intra-arterial infusion was advantageous over intravenous infusion probably because the effect of general metabolism on drug levels was small, drugs exhibited immediate action and efficacy was localised. No particular side effects were demonstrated.

Blood Coagulation Factors↗

PubMed1991

The sliding venous flap for covering skin defects with poor blood supply on the lateral aspects of fingers.

For the treatment of skin defects with poor blood supply on the lateral aspects of the fingers, particularly the radial side of the index finger and the ulnar side of the little finger which have been difficult to cover conventionally, we have developed the sliding venous flap. The flap can be moved by using the "sag" obtained from the dissected dorsal veins of the same finger. We have applied this technique in six cases with excellent results. The indications are limited to cases with only slight crushing of the dorsum of the finger. We consider this technique safe and effective in covering skin defects with poor blood supply on the lateral aspects of fingers.

Adolescent↗

PubMed1991

Hepatocyte growth inhibitory factor derived from HTLV-I(+) T cell lines: effect on the epidermal growth factor-dependent proliferation of rat hepatocytes.

A human T cell leukemia virus-I infected T cell line, ATL-2, produces an interleukin-2 receptor inducing factor, adult T cell leukemia (ATL)-derived factor (ADF). In the conditioned medium (CM) of ATL-2, we found an inhibitory activity on the epidermal growth factor (EGF)-dependent proliferation of primary cultured rat hepatocytes, measured by cell number and [3H]thymidine incorporation. ATL-2 CM dose-dependently inhibited hepatocyte proliferation. This activity was fractionated by gel filtration at a molecular size of 15,000 to 40,000 and was tentatively called hepatocyte growth inhibitory factor (HGI). Further fractionation with the ion-exchange column indicated that HGI was separable from ADF. Nevertheless, there was a positive correlation between HGI and ADF production, because the HGI activity was also detected in the CM of another ADF producer cell line (HUT102), while no significant HGI activity was detected in the CM of low ADF producer cell lines, ED and MOLT4.

Animals↗

PubMed1991

Aquatic toxicity testing for multicomponent compounds with special reference to preparation of test solution.

An adequate method of determining the toxicity of a compound consisting of multiple components, such as creosote, coal tar, and coal tar pitch, was studied for different test solution preparation methods, i.e., direct dosing without filtration, diluting the stock solution of saturated concentration, and dispersing with acetone. Killifish, Oryzias latipes, as a freshwater fish; red sea bream, Pagrus major, as a saltwater fish; and daphnia, Daphnia magna, as a representative crustacean, were used for testing. The chemical analysis of each preparation of test solution with gas chromatography revealed an entirely different profile of the components. The highest toxicity was obtained with preparation by acetone dispersion. That was followed by the preparations with direct dosing method and with the method of dilution of saturated concentration stock solution. Considering the results obtained, the direct dosing method with a suitable settling time may provide useful information enabling extrapolation of the test results to the natural environment for complex multicomponent compounds.

Acetone↗

PubMed1991

Complexation of thiomalic acid with mercury (II) and lead (II) under physiological conditions.

The complex formation of thiomalic acid (H3L) with Hg(II) and Pb(II) was investigated under physiological conditions of 37 degrees C and 0.15 mol dm-3 NaCl by potentiometric titrations using glass electrodes. From the analysis of the emf data in the two systems by use of computer program MIQUV it was concluded that the species formed in the two systems are [HgH4L2], [HgH3L]-, [HgH2L2]2-, [HgHL2]3-, [HgHL], [HgL]-, [HgL2]4-, [Hg(OH)L]2-, [Hg(OH)L2]5-, [PbH2L2]2-, [PbH2L]+, [PbHL2]3-, [PbHL], [PbL]-, [Pb(OH)L]2-, and [Pb(OH)2L]3-. The hydrolytic reactions of Hg(II), data on which were used in the analysis of the above system, were also studied by separate potentiometric titrations. Measurements of 13C NMR spectra of [HgL2]4- and [PbL]- and [PbHL2]3- in D2O solutions suggested that the ligand coordinates with both the metal ions through the sulfhydryl group and one of the two carboxylate groups in such a way that the five-membered chelate ring is formed within the complexes.

Binding Sites↗

PubMed1991

Hyperperfusion of the rat brain during reflex hypertension induced by sudden lowering of the cutaneous temperature.

In anesthetized and artificially ventilated rats, passive or reflex hypertension was produced by ligation of the abdominal aorta (12 rats), or sudden lowering of the cutaneous temperature to 25-30 degrees C achieved by exposure to cold water (26 rats), respectively. Cold exposure increased the blood flow (microsphere method) in all of the brain regions studied by 54-174% in the face of a reflex increment in the arterial pressure by 40% on average. The vascular resistance was changed by 0-(-)32%. Such hemodynamic alterations were greater in almost all of the brain regions than would be anticipated from the autoregulatory function of the brain circulation, as evidenced by a comparison with those observed during passive hypertension. Exposure to thermoneutral water resulted in the minimal changes in the hemodynamic states of the systemic as well as brain circulations (5 rats). The sympathetic nerves innervating the cranial vessels were strongly activated during the cold exposure, as confirmed by the observation of a large increase in flow in the temporalis muscle after acute surgical sympathectomy. However, sympathetic denervation did not alter the degree of hemodynamic changes occurring in the brain regions during cold exposure. We conclude that, in the face of reflex hypertension induced by cold exposure, the powerfully activated sympathetic nerves failed to exert their well-known effect on the brain blood flow which prevents it from rising to an excessively high level.

Animals↗

PubMed1991

Hyperperfusion and enhanced metabolic state of the brain during sudden lowering of the cutaneous temperature in rats.

Forty-eight anesthetized and artificially ventilated rats were pretreated with the ganglion blocking agent, pentolinium (5 mg/kg, i.v.), followed by continuous phenylephrine infusion for maintenance of normotension. The rats were subjected to mock treatment (16 rats), to sudden exposure to thermoneutral water (34-36 degrees C, 16 rats), or to cold water (16 degrees C, 16 rats). The latter treatment lowered the cutaneous temperature to 25-30 degrees C. Neither one of these treatments produced any significant changes in arterial pressure or heart rate. Exposure to cold elicited hyperperfusion (microsphere method) in each of the brain regions studied. The increase in cerebral cortical blood flow (by 59 +/- 8%, mean +/- SEM) was most significant. The cerebral cortical metabolic rate for oxygen was increased by 46 +/- 10%. During the cold exposure, excellent tight coupling between the metabolic rate and blood flow was observed in the cerebral cortex. Mock treatment and exposure to thermoneutral water resulted in only trivial increases in blood flow and in metabolic rate. Thus, during cold exposure, an enhanced metabolic state of the brain represented the primary determinant increasing the brain blood flow, provided that normotension was maintained.

Animals↗

PubMed1991

An investigation of venous pressure and oxygen tension in human extremities: an experimental study of survival in pedicled venous flaps.

The pedicled venous flap is used at various sites, such as the finger, forearm, and leg. The authors previously reported that the reasons for the viability of such flaps, based on the digital dorsal vein and used for repairing digital skin defects in the earlier study, were high venous pressure or oxygen tension, as well as the possible effects of plasmatic imbibition and outflow through the draining vein. To investigate the importance of venous pressure and oxygen tension in the survival of these flaps at other sites in the body, measurements were made comparing these parameters in the digital vein, cephalic vein, and greater saphenous vein, which are all used clinically as draining veins in pedicled venous flaps. Although measurements in other sites were consistently lower than in the digital dorsal vein, since these other venous flaps are nevertheless viable in the clinical situation, their viability may not be due only to relatively high venous pressure and oxygen tension. The authors intend to carry out further comparative studies on plasmatic imbibition in the flap and outflow through the draining vein.

Adolescent↗

PubMed1991

Combined therapy with antithrombotic agents and radical scavengers for reperfusion injury of flaps.

The usefulness of combining antithrombotic agents and radical scavengers in the treatment of reperfusion injury (an almost ideal approach) was substantiated using an ischemic flap model. The cause(s) of reperfusion injury was hypothesized on the basis of differences in effects between antithrombotic agents and radical scavengers in the experimental groups. Flap specimens were also obtained regularly for histologic examination. The experiment was conducted in nine rabbit groups. For continuous treatment with intraarterial antithrombotic agents, both heparin and urokinase were continuously injected at respective administration rates of 20 U/kg/hr and 200 IU/kg/hr for seven consecutive days immediately before reperfusion. For intraarterial radical scavenger treatment, a solution of both 30,000 U/kg SOD and 30,000 U/kg catalase in 5 ml of a lactated Ringer's solution was injected over a period of about 30 min immediately before reperfusion. The ischemic time of the flaps was 10 hr for Group I and 12 hr for Group II. Each group was comprised of subgroups a, b, c, and d: a = control; b = continuous intraarterial antithrombotic agent injection; c = intraarterial lactated Ringer's solution alone; and d = intraarterial radical scavenger injection. For Group II, an additional subgroup e was established, which received continuous injection of both intraarterial antithrombotic agents and injected intraarterial radical scavenger. In the 10-hr ischemic treatment group, an effect was obtained by continuous intraarterial antithrombotic agents alone. In the 12-hr ischemic treatment group, a significant improvement in flap-take ratio was obtained using intraarterial radical scavenger, in combination with antithrombotic agents. Observation of the flaps that survived in subgroups Ib and IIe revealed skin thinning, vascular wall thickening, and muscular tissue degeneration, although the skin architecture was well preserved.

Animals↗