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M Hanano

Publications and source records attributed to M Hanano.

At least 145 records · Page 8Linked to original sources
PubMed1987

Transport of benzylpenicillin by the rat choroid plexus in vitro.

To characterize the transport system by which benzylpenicillin, an organic anion, is accumulated by the isolated rat choroid plexus, kinetic analysis of benzylpenicillin transport was performed. Accumulation of benzylpenicillin was against an electrochemical potential gradient via a saturable process (Km = 58 microM and Vmax = 84 nmol/ml of tissue per min) that was inhibited by sulfhydryl reagents (p-hydroxymercuribenzoate and N-ethylmaleimide), metabolic inhibitors (KCN and 2,4-dinitrophenol) and anion exchange inhibitors (4-acetamide-4'-isothiocyanatostilbene-2,2'-disulfonic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid), but is major transport system did not require the inward Na+ gradient. Organic anions, such as 5-hydroxyindoleacetic acid, homovanillic acid, p-aminohippuric acid and probenecid inhibited the accumulation of benzylpenicillin, whereas dipeptides did not affect it. Kinetic analysis of the accumulation of benzylpenicillin suggests that both phenoxymethylpenicillin and cefpiramide are also transported via the benzylpenicillin transport system. Other penicillin and cephalosporin derivatives inhibited the accumulation of benzylpenicillin with different affinities. Penicillin derivatives without dissociating groups in the side chain had the higher affinity for the benzylpenicillin transport system than other beta-lactam antibiotics did. Among penicillin derivatives examined, a good correlation (r = 0.92) was observed between the lipophilicity and the affinity for the benzylpenicillin transport system, whereas no correlation was observed among the cephalosporin derivatives. These findings suggest that the major transport system of benzylpenicillin in the rat choroid plexus is via a carrier-mediated active anion transport process which is distinct from that of dipeptides, and does not require the inward Na+ gradient.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Anion exchanger mediates benzylpenicillin transport in rat choroid plexus.

Transport characteristics of benzylpenicillin in the central nervous system was examined using ATP-depleted rat choroid plexus. In the presence of an outwardly directed Cl- gradient, accumulation of benzylpenicillin was stimulated markedly compared with the accumulation in the absence of Cl- gradient. Under Cl- gradient conditions, benzylpenicillin was accumulated transiently at a concentration approximately 1.7-fold higher than at equilibrium ("overshoot") implying the uphill transport. The Cl- gradient-stimulated accumulation of benzylpenicillin was not solely due to the changes in the membrane potential or in the intracellular pH. Accumulation of benzylpenicillin in choroid plexuses preloaded with HCO3-, SCN- or benzylpenicillin also was stimulated compared with the accumulation in unpreloaded choroid plexuses. The Cl- gradient-stimulated benzylpenicillin accumulation was saturable (Km = 13.6 microM and Vmax = 3.76 nmol/ml of tissue per min), and was reduced by sulfhydryl reagents (p-hydroxymercuribenzoic acid, p-chloromercuribenzoic acid, p-chloromercuribenzenesulfonic acid and N-ethylmaleimide). Probenecid and anionic exchange inhibitors (furosemide, 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonic acid and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid) inhibited the Cl- gradient-stimulated benzylpenicillin accumulation in a dose-dependent fashion. An inwardly directed Na+ gradient did not stimulate the accumulation of benzylpenicillin. These findings suggest that the principal mechanism for the uphill transport of benzylpenicillin in the rat choroid plexus is via an anionic exchanger.

4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid↗
PubMed1986

Na+-dependent p-aminohippurate transport at the basolateral side of the isolated perfused rat kidney.

The uptake of p-amino[3H]hippurate by isolated perfused rat kidney was studied to characterize the mechanism which was responsible for organic anion transport process. A rapid injection multiple indicator dilution technique and the distributed two-compartment model of Sawada et al. (Computer Methods Programs Biomed., 20 (1985) 51) were employed. Some characteristics of a carrier-mediated transport from the antiluminal space to the intracellular space for p-aminohippurate at the basolateral side were demonstrated: the uptake was stimulated by the countertransport effect and showed Na+ dependency. These findings are consistent with p-amino[3H]hippurate's being taken up into the isolated rat basolateral membrane vesicle by Na+-dependent carrier-mediated transport (J. Pharmacol. Exp. Ther. 227 (1983) 122). It is suggested that the multiple indicator dilution technique is a sensitive new method to study the mechanisms of renal tubular transport in the living kidney as an organ.

Aminohippuric Acids↗
PubMed1986

Factor VIII lability, protein C and other vitamin K-dependent proteins.

The stability of factor VIII was studied in plasmas from patients on long-term warfarin therapy. The percent residual factor VIII activity (F.VIII:C) after incubation at 37 degrees C for 4 hr was higher in warfarinized patients than in normal subjects; 76.9 +/- 10.8% (mean +/- SD) of the initial F.VIII:C in the patients versus 61.6 +/- 5.8% in normal subjects (p less than 0.001). On the whole, neither protein C nor vitamin K-dependent coagulation factors except factor VII activity (F.VII:C) correlated with the residual F.VIII:C. There was a negative and weak correlation between the residual F.VIII:C at 4 hr and either the initial F.VIII:C or F.VII:C. Another experiment using protein C depleted plasma showed a relatively enhanced stability of F.VIII:C in the protein C deficiency. These results indicate that factor VIII is more stable in warfarinized plasma, and that protein C and vitamin K-dependent coagulation factors are not the sole, main factor responsible for such a phenomenon.

Blood Coagulation Factors↗
PubMed1986

Further studies on aggregation of platelet-type von Willebrand's disease platelets by human von Willebrand factor.

Platelet-type von Willebrand's disease (vWD) is a bleeding disorder characterized by a heightened interaction between platelets and von Willebrand factor (vWF) as the result of an intrinsic platelet abnormality (probably in GPIb). Platelet aggregability was nearly normal in response to thrombin, wheat germ agglutinin and Ricinus communis agglutinin in this disorder. Unmodified platelets showed no aggregation upon the addition of peanut agglutinin. Partially purified human vWF induced little aggregation of washed patient platelets, but the aggregation was greatly enhanced in the presence of plasma devoid of vWF. Monoclonal antibodies directed against GPIb and GPIIb/IIIa as well as EDTA completely inhibited vWF-induced aggregation. These results indicate that human vWF induces aggregation of platelet-type vWD platelets in the presence of divalent cations and some plasma cofactor(s), and that both GPIb and GPIIb/IIIa are involved in this aggregation.

Antibodies, Monoclonal↗
PubMed1986

Determination of kinetic parameters of a carrier-mediated transport in the perfused intestine by two-dimensional laminar flow model: effects of the unstirred water layer.

The kinetic parameters of a carrier-mediated transport for D-glucose and for taurocholate were determined from rat in situ intestinal single perfusion experiments. The true parameters were obtained by the two-dimensional laminar flow model, in which the solute concentration at the aqueous-intestinal membrane interface can be calculated numerically without assuming the aqueous diffusion layer, discriminating the effects of the unstirred water layer. The true Michaelis constant was 4.5 mM for D-glucose and 1.5 mM for taurocholate. The true maximal transport velocity was 3.4 nmol/s per cm2 for D-glucose and 0.29 nmol/s per cm2 for taurocholate. The apparent Michaelis constant was raised by the factor of 6.6 for D-glucose and 3.6 for taurocholate due to the effects of the unstirred water layer. The maximal transport velocity was relatively unaffected by the unstirred water layer in both compounds. The values of the effective (operational) thickness of the unstirred water layer were compatible with those reported previously by employing various experimental methods. The kinetic parameters obtained in vitro everted sacs, for comparison, almost coincided with the true ones in situ. Therefore, the two-dimensional laminar flow model is shown to be valid not only for determining the kinetic parameters of a carrier-mediated transport in situ but also for predicting the absorption rate in situ from the uptake rate in vitro.

Animals↗
PubMed1986

Intestinal absorption by carrier-mediated transports: two-dimensional laminar flow model.

The two-dimensional laminar flow model was adapted to the intestinal absorption of drug and biological substances by carrier-mediated transports in the single perfusion experiments and we investigated the effects of the unstirred water layer on the Michaelis constant and the maximum transport velocity. According to the calculated values, the half saturation concentration at the inlet was larger than the true Michaelis constant at the intestinal wall. The apparent values of the Michaelis constant and the maximum transport velocity obtained by the Lineweaver-Burk plots were larger than the true ones, and the relations were not linear. These deviations increased as the ratio of the maximum transport velocity to the Michaelis constant increased and as the perfusion rate decreased. In the concurrent presence of a passive transport, underestimation of the carrier-mediated transport component of the absorption rate (at steady state) was predicted. It is considered to cause the underestimation of the maximum transport velocity. When water was absorbed (or secreted), the absorption rate increased (or decreased) and did not saturate. This two-dimensional laminar flow model would enable us to analyze the experimental data to determine the true values of the Michaelis constant and the maximum transport velocity.

Absorption↗
PubMed1986

Determination of the membrane permeability coefficient and the reflection coefficient by the two-dimensional laminar flow model for intestinal perfusion experiments.

We performed single perfusion experiments in the small intestine of rats in order to prove that the two-dimensional laminar flow model is suitable to determine the membrane permeability coefficient and the reflection coefficient. We used progesterone as an aqueous-diffusion-limited drug, urea as a membrane transport-limited drug and the tritiated water as an intermediate substance. The membrane permeability coefficient for progesterone was calculated to be 3.6 X 10(-4) cm/s. This value did not change when the thickness of the aqueous diffusion layer was altered by increasing the perfusion rate 10-fold. It was directly demonstrated that the two-dimensional laminar flow model was suitable to analyze the data of intestinal perfusion experiments. Membrane permeability coefficients for urea and tritiated water were determined to be 3.4 X 10(-5) cm/s and 8.9 X 10(-5) cm/s, respectively. In the presence of water absorption with the hypotonic perfusion solution, the reflection coefficient for urea was 0.84. This value is thought to be theoretically reasonable, suggesting the usefullness of the two-dimensional laminar flow model to obtain the reflection coefficient in the intestinal membrane.

Animals↗
PubMed1986

DDAVP in acquired von Willebrand syndrome associated with multiple myeloma.

The response to a single intravenous infusion of 1-deamino-8-D-arginine vasopressin (DDAVP, desmopressin) was studied in two patients with acquired von Willebrand syndrome associated with IgG-kappa myeloma. Following infusion of DDAVP (0.3-0.4 micrograms/kg), prolonged bleeding time was normalized; plasma ristocetin cofactor activity, von Willebrand factor antigen, and factor VIII activity were remarkably increased; and high-molecular-weight forms of von Willebrand factor were demonstrated by crossed immunoelectrophoresis in both patients. Excellent hemostasis was achieved following administration of DDAVP in one patient when it was used for the treatment of gum bleeding and for the prophylaxis of bleeding during and after dental extractions. These observations suggest that DDAVP is an effective alternative to blood products for at least some patients with acquired von Willebrand syndrome in addition to patients with inherited von Willebrand disease, hemophilia A, and uremia.

Blood Coagulation Tests↗
PubMed1986

Excessive fibrinolysis in suspected amyloidosis: demonstration of plasmin-alpha 2-plasmin inhibitor complex and von Willebrand factor fragment in plasma.

We performed a hemostatic evaluation in detail in a patient with suspected amyloidosis who was suffering from several bleeding episodes. He had a shortened euglobulin clot lysis time, decreased alpha 2-plasmin inhibitor (alpha 2-PI), decreased plasminogen, elevated tissue-type plasminogen activator (t-PA), elevated plasmin-alpha 2-PI complex, and decreased ratio of ristocetin cofactor to von Willebrand factor (vWF) antigen. Fibrinogen and fibrin/fibrinogen degradation products levels fluctuated, with abnormal values on several occasions. On crossed immunoelectrophoresis, plasmin-alpha 2-PI complex and vWF fragment were demonstrated in the patient plasma. These abnormal findings and bleeding symptoms improved following the administration of tranexamic acid. Discontinuation of tranexamic acid resulted in deterioration of these parameters. These observations indicate that pathologic fibrinolysis (continuous intravascular plasmin generation) characterized by the consumption of alpha 2-PI and plasminogen, formation of plasmin-alpha 2-PI complex, and fragmentation of vWF contributed to the bleeding in this patient. It is important to recognize excessive fibrinolysis as the underlying cause of bleeding in these patients, since specific treatment with antifibrinolytic agents is effective in controlling the bleeding.

Amyloidosis↗
PubMed1986

A simulation study on the effect of a uniform diffusional barrier across hepatocytes on drug metabolism by evenly or unevenly distributed uni-enzyme in the liver.

The effect of a uniform diffusional barrier on hepatic extraction of the parent drug by evenly or unevenly distributed uni-enzyme was quantitatively determined by the present simulation study. Five models of enzymic distribution were defined with regard to the hepatic blood flow path, and the extraction ratios were calculated or simulated under the various conditions of average intrinsic clearances and diffusion clearances across hepatocytes. Differences in the extraction ratios among the five models were evaluated by the "relative extraction ratios," which are the extraction ratios in each model divided by that in the model where the enzymatic activity is evenly distributed. It was found that when a diffusion clearance was high compared to the intrinsic clearance, enzymic distribution was not an important determinant of the extent of hepatic extraction. By contrast, when a diffusional barrier across hepatocytes exists, i.e., the diffusion clearance is low or intermediate compared to the intrinsic clearance, extraction ratios differed widely among the models of enzymic distribution, especially at intermediate average intrinsic clearances. In the presence of a diffusional barrier, the more skewed the distribution of the enzymatic activity is, the lesser the amount of drug eliminated at steady state. The most efficient metabolism occurred when the enzymatic activity was evenly distributed.

Diffusion↗
PubMed1986

Biliary excretion and enterohepatic cycling of glycyrrhizin in rats.

The enterohepatic cycling of glycyrrhizin was examined using rats with and without biliary fistulization. The plasma decay in the control rats without fistulization following an iv dose of 100 mg/kg of glycyrrhizin, was generally biphasic. However, secondary peaks were observed in all rats in the elimination phase, i.e., 0.5 to 12 h following dosing. The plasma concentrations in the rats with biliary fistulization administered the same dose showed a biexponential decline. The AUC and CLtot were significantly higher and lower in the control rats, respectively. The biliary excretion was 80.6 +/- 9.9% of the administered dose, and intestinal absorption was confirmed by using the bile collected after iv dosing. From these results, we concluded that glycyrrhizin was predominantly secreted from the liver into the bile, and that the secondary peaks in the elimination phase, the higher AUC, and the lower CLtot in the control rats were due to the effects of enterohepatic recycling of glycyrrhizin. Furthermore, the transport of the drug from the liver to the bile appears to be a saturable process.

Animals↗
PubMed1986

Effects of potential damaging agents on the microclimate-pH in the rat jejunum.

This study was designed to determine the pH of the intestinal surface in the rat jejunum in an attempt to investigate the effect of potential damaging agents on the microclimate-pH. A significant pH gradient was observed between the mucosal surface and the bulk phase; however, the microclimate-pH usually ranged from 6.5 to 7.5, irrespective of the wide range in the bulk pH. When the bulk pH was either 7.3 or 4, the microclimate-pH was approximately 6.7, while the microclimate-pH was approximately 7.4 when the bulk pH was raised to 9. The distance of the pH gradient was found to be approximately 900-1300 microns. After treatment with ouabain (10 mM) or amiloride (8 mM), or replacement of Na+ with Li+, the microclimate-pH significantly increased compared with the control (buffer solution). Chlorpromazine (2 mM) and ouabain also significantly increased the microclimate-pH, but at the same time, chlorpromazine decreased the bulk pH so that a more marked pH gradient was observed. Both aspirin (10 mM) and acetazolamide (80 mg/kg, iv) significantly decreased the microclimate-pH under the condition of the acidic bulk phase pH. N-Acetyl-L-cysteine (5%) induced marked changes in microclimate-pH, the direction depending upon the bulk phase pH. Neither taurocholic acid (10 mM) nor glucose (10 mM) significantly changed the microclimate pH.

Acetazolamide↗
PubMed1986

Effect of albumin on hepatic uptake of warfarin in normal and analbuminemic mutant rats: analysis by multiple indicator dilution method.

Multiple indicator dilution studies of warfarin uptake were carried out on isolated perfused rat livers in the presence and absence of bovine serum albumin (BSA) in the perfusate using normal rats and Nagase analbuminemic rats (NAR). A distributed model was fitted to the dilution data and estimates of influx, efflux, and sequestration rate constants were obtained. In both groups of rats, the intrinsic clearance for unidirectional hepatic uptake (CLint,influx) of warfarin in the presence of 1.6 g/dl BSA was approximately 37-45% of that in the absence of BSA, while the unbound fraction of warfarin with 1.6 g/dl BSA in the perfusate was only 4.2% of that in the absence of BSA. Thus the degree of BSA-induced reduction of the value of CLint,influx and that of the unbound fraction are different. From these observations, it was found that the hepatic uptake of warfarin is not driven solely by the unbound concentration of warfarin, supporting the recent concepts of albumin-mediated transport for tightly albumin bound ligands as reported by Ockner et al. In addition, the fact that the same hepatic uptake mechanism of warfarin was also observed in NAR suggested that the hepatic uptake of warfarin may not necessarily require a special albumin receptor on the hepatocyte surface.

Animals↗
PubMed1986

A defect of platelet release reaction in a patient with SLE: impaired platelet aggregation induced by phorbol ester with a normal phosphorylation of 40K protein.

A 37-year-old female who suffered from SLE had a bleeding disorder. At the time of initial evaluation, the main disease demonstrated was a delta-storage pool deficiency. After this improved, a marked decrease of aggregation still remained, when induced by either ADP, epinephrine, collagen, A23187, thrombin, or PAF-acether. Although arachidonate-induced aggregation was slightly decreased, thromboxane B2 was produced normally in response to exogenous arachidonate. The patient's endoperoxides and/or thromboxane A2 aggregated aspirin-treated platelets, though her platelets were themselves unresponsive. Impaired aggregability induced by TPA (12-0-tetradecanoylphorbol-13-acetate) or OAG (1-oleoyl-2-acetyl-glycerol) was also found. However, the phosphorylation of P43 and P20 induced by several stimulators including CA++ ionophore was normal, using 32P-labelled platelets. It is suggested that TPA or OAG-induced platelet aggregation requires not only the phosphorylation of those proteins, but also another unknown mechanism after the phosphorylation, and that the platelet dysfunction of this patient was due to a defect of some mechanism involving Ca++ uptake or mobilization of cytoplasmic Ca++ from intracellular storage sites.

Adenosine Diphosphate↗
PubMed1986

Effect of quinidine on the tissue binding of digoxin in guinea-pigs.

The mechanism of quinidine-induced decrease in the tissue distribution of digoxin to heart, liver and skeletal muscle has been examined in guinea-pigs. Quinidine, in the presence of adenosine-5'-triphosphate (ATP), inhibited the specific binding of digoxin in homogenates of heart, liver and muscle, while in the absence of ATP the inhibition was observed only in heart. The decrease in the tissue-to-plasma unbound concentration ratios (Kpu) of heart and muscle determined from in-vitro binding studies was comparable to that in the Kpu values observed in-vivo, while in liver it was not sufficient to account for the fall in Kpuin-vivo values. It is concluded that quinidine-induced decrease in the tissue distribution of digoxin in heart and muscle is due to inhibition of tissue binding of this drug, while that in liver could be partially attributed to the decrease in the tissue binding.

Adenosine Triphosphate↗
PubMed1986

Kinetic analysis of rat renal tubular transport based on multiple-indicator dilution method.

New methods, based on the multiple-indicator dilution (MID) technique, to study the kinetic relations between the renal tubular cell entry process and the secretory process of drugs are proposed. [3H]Cimetidine was used as a model drug. T-1824-labeled albumin (a vascular reference), [14C]creatinine (an extracellular reference), and [3H]cimetidine were rapidly injected into the renal artery of isolated perfused rat kidney, and normalized outflow-time patterns were secured from rapidly sampled renal venous perfusate. A distributed two-compartment model was fitted to the dilution data by nonlinear least-squares regression, and the influx, efflux, and sequestration rate constants were estimated. Both the influx and the sequestration process (based on the unbound cimetidine concentration) had two transport systems (i.e., Michaelis-Menten-type saturable transport and linear-type passive transport), whereas the efflux process was independent of the intracellular cimetidine concentration. At the low dose of cimetidine the influx clearance was larger than those of the efflux and sequestration, whereas at the high dose no remarkable difference was observed among these three clearances due to the large decrease in the influx clearance. Thus the MID technique is a sensitive new method to study the rate-limited process of renal tubular transport in rats.

Animals↗