Inhibition of P-glycoprotein by orange juice components, polymethoxyflavones in adriamycin-resistant human myelogenous leukemia (K562/ADM) cells

We investigated the effects of the ethyl acetate extract of grapefruit juice (GFJ), that of orange juice (OJ) and their components on the uptake of [(3)H]vincristine into adriamycin-resistant human myelogenous leukemia cells. Its uptake was increased by the extracts of GFJ and OJ up to 7- and 3-fold, respectively, as well as verapamil and cyclosporin A. OJ components, i.e. 3,3',4',5,6,7,8-heptamethoxyflavone, nobiletin and tangeretin, also increased the uptake of [(3)H]vincristine in a concentration-dependent manner. Although GFJ components, dihydroxybergamottin and bergamottin, significantly increased the uptake, their potencies were considerably weaker than those of OJ components. These data suggest that OJ components inhibit P-gp-mediated efflux of [(3)H]vincristine, resulting in the intracellular accumulation of chemotherapeutic drugs. These components may become candidates of multi-drug resistance reversing agents in cancer chemotherapy.

Human placental transport of vinblastine, vincristine, digoxin and progesterone: contribution of P-glycoprotein

To elucidate the role of P-glycoprotein in human placenta, we examined its expression in placenta, and the transcellular transport and uptake of P-glycoprotein substrates in cultured human placental choriocarcinoma epithelial cells (BeWo cells). The uptake of [(3)H]vinblastine and [(3)H]vincristine into BeWo cells was increased in the presence of a metabolic inhibitor, sodium azide. The basolateral-to-apical transcellular transport of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin was greater than the apical-to-basolateral transcellular transport. In the presence of cyclosporin A, the basolateral-to-apical transcellular transport of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin was significantly increased, and the apical-to-basolateral transcellular transport was decreased. The uptake of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin into BeWo cells was significantly enhanced in the presence of several inhibitors, such as verapamil or mouse monoclonal antibody anti-P-glycoprotein MX-MDR (MRK16) as well as cyclosporin A. Although progesterone significantly enhanced the uptake of [(3)H]vinblastine, [(3)H]vincristine and [(3)H]digoxin into BeWo cells, the uptake of [(3)H]progesterone was not affected by these inhibitors. Immunoblot analysis revealed that P-glycoprotein with a molecular weight of 172 kDa was expressed in BeWo cells and isolated trophoblast cells. Furthermore, P-glycoprotein was detected in human placental brush-border membrane vesicles, but not in human placental basolateral membrane vesicles. In conclusion, these data suggest that P-glycoprotein is expressed on the brush-border membrane (maternal side) of human placental trophoblast cells. P-Glycoprotein is considered to regulate the transfer of several substances including vinblastine, vincristine and digoxin from mother to fetus, and to protect the fetus from toxic substances.

Effect of anti-inflammatory bowel disease drug, E3040, on urate transport in rat renal brush border membrane vesicles

To confirm the assumption that 6-hydroxy-5, 7-dimethyl-2-methylamino-4-(3-pyridylmethyl)benzothiazole (E3040) acts on urate reabsorption by inhibiting urate-anion exchange at the luminal membrane of renal tubules, we investigated the inhibitory effect of E3040 and its two conjugated metabolites on hydroxyl ion (OH(-)) gradient-dependent urate uptake into brush border membrane vesicles from rat renal cortex and compared it with other uricosuric agents. The order of potency was AA193 (5-chloro-7, 8-dihydro-3-phenylfuro[2,3-g]-1,2-benzisoxazole-7-carboxylic acid)>benzbromarone>E3040>probenecid>E3040 sulfate>E3040 glucuronide. Furthermore, kinetic analysis revealed that E3040 may be a competitive inhibitor of the OH(-) gradient-dependent uptake of urate into brush border membrane vesicles.

New scheme of the biosynthesis of formononetin involving 2,7,4'-trihydroxyisoflavanone but not daidzein as the methyl acceptor

Glycyrrhiza echinata cell-free extract produced isoformononetin by the 7-O-transmethylation of daidzein from S-adenosyl-L-methionine (SAM). When the yeast microsome expressing 2-hydroxyisoflavanone synthase was mixed with the cell-free extract and incubated with liquiritigenin and SAM, formononetin emerged. Furthermore, the cell-free extract yielded formononetin on incubation with 2,7,4'-trihydroxyisoflavanone and SAM. We propose a novel pathway of formononetin biosynthesis involving 2,7,4'-trihydroxyisoflavanone as the methyl acceptor.

Diffusion and deformations of single hydra cells in cellular aggregates

Cell motion within cellular aggregates consists of both random and coherent components. We used confocal microscopy to study the center of mass displacements and deformations of single endodermal Hydra cells in two kinds of cellular aggregates, ectodermal and endodermal. We first carefully characterize the center of mass displacements using standard statistical analysis. In both aggregates, cells perform a persistent random walk, with the diffusion constant smaller in the more cohesive endodermal aggregate. We show that a simple parametric method is able to describe cell deformations and relate them to displacements. These deformations are random, with their amplitude and direction uncorrelated with the center of mass motion. Unlike for an isolated cell on a substrate, the random forces exerted by the surrounding cells predominate over the deformation of the cell itself, causing the displacements of a cell within an aggregate.

Comparative pharmacodynamic analysis of Q-T interval prolongation induced by the macrolides clarithromycin, roxithromycin, and azithromycin in rats

In order to evaluate the arrhythmogenic potency of macrolide antibiotics in a quantitative manner, we analyzed the influence of clarithromycin (CAM), roxithromycin (RXM), and azithromycin (AZM) on Q-T intervals from pharmacokinetic and pharmacodynamic points of view and in comparison with the potency of erythromycin (EM) previously reported by us for rats. Male Sprague-Dawley rats were anesthetized, and CAM (6.6, 21.6, and 43.2 mg/kg of body weight/h), RXM (20 and 40 mg/kg/h), and AZM (40 and 100 mg/kg/h) were intravenously injected for 90 min to obtain the time courses of drug concentrations in plasma and the changes in the Q-T intervals during and after the drug injections. Distinct Q-T interval prolongation of up to 10 ms was observed with CAM at its clinical concentrations. RXM and AZM evoked Q-T interval prolongation at concentrations higher than their clinical ranges. The potencies for Q-T interval prolongation, assessed as the slope of the concentration-response relationship, were 6.09, 0.536, and 0.989 ms. ml/microg for CAM, RXM, and AZM, respectively. There was hysteresis between the change in the Q-T intervals and the time course of the plasma concentration of each drug. The rank order of clinical arrhythmogenicity was estimated to be EM > CAM > RXM > AZM, as assessed from the present results and our previous report for EM. In conclusion, RXM and AZM were estimated to be less potent at provoking arrhythmia than EM and CAM. These results should be useful for making a safer choice of an appropriate agent for patients with electrocardiographic risk factors.

Influence of Helicobacter pylori infection on development of stress-induced gastric mucosal injury

Immediately after the Great Hanshin Earthquake in Kobe in 1995, the recurrence rate of peptic ulcer in patients infected with Helicobacter pylori was higher than that in patients in whom H. pylori had been eradicated. We evaluated the influence of H. pylori infection on stress-induced gastric mucosal injury in Mongolian gerbils and C57BL/6 mice. These animals were immersed in water for 30, 120, and 720 min 12 weeks after inoculation with H. pylori, and then killed to assess gastric mucosal damage, and to measure cytokine production (interleukin [IL]-1beta, IL-4, IL-6, and IL-10; interferon [IFN]-gamma; and tumor necrosis factor [TNF]-alpha) in the gastric tissue of the mice. The stress treatment for 30 min resulted in a significantly higher bleeding rate and bleeding index among infected gerbils and mice compared with results in uninfected animals. Conversely, the bleeding and ulcer indexes were significantly higher in uninfected gerbils after 720 min of the stress treatment than in infected gerbils. Prior to the stress treatment, gastric IL-1beta and IFN-gamma production was significantly higher in the infected group than in the uninfected group. After 120 min of the stress treatment, TNF-alpha production was increased in the infected group, and IL-1beta and IL-10 production was increased in the uninfected group. However, the production of these cytokines showed no change at 30 min of the stress treatment. These results suggest that H. pylori infection influences the development of gastric mucosal injury in the early phase of stress exposure; cytokines do not play a major role in this process.

Spontaneous symmetry breaking turing-type pattern formation in a confined Dictyostelium cell mass

We have discovered a new type of patterning which occurs in a two-dimensionally confined cell mass of the cellular slime mold Dictyostelium discoideum. Besides the longitudinal structure reported earlier, we observed a spontaneous symmetry breaking spot pattern whose wavelength shows similar strain dependency to that of the longitudinal pattern. We propose that these structures are due to a reaction-diffusion Turing instability similar to the one which has been exemplified by CIMA (chlorite-iodide-malonic acid) reaction. The present finding may exhibit the first biochemical Turing structure in a developmental system with a controllable boundary condition.

Comparison of blood-brain barrier permeability in mice and rats using in situ brain perfusion technique

Here we present a method for measuring the permeability coefficient-surface area product (PS) values at the blood-brain barrier in mice, using the in situ brain perfusion technique originally developed for rats by Takasato et al. (Am J Physiol Heart Circ Physiol 247: H484-H493, 1984). Retrograde infusion into the right external carotid artery increased the carotid perfusion pressure in proportion to the perfusion rate. Intravascular volume and cerebral perfusion fluid flow at a perfusion rate of 1.0 ml/min in mice were similar to those in rats. In addition, the contribution of systemic blood to total flow in the hemisphere was small (only 3. 2%). These findings indicated that this perfusion rate is suitable for mice. The PS values of more than 20 different compounds were determined in mice by using the in situ brain perfusion technique, and comparisons were made with data from rats. There was a close relationship (1:1) between the PS values in mice and rats, indicating that brain capillary permeabilities are similar in mice and rats.

Diagnosis and treatment of 6-pyruvoyl-tetrahydropterin synthase deficiency

We detected a case of 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency during a neonatal mass screening and considered the differentiation and treatment of the peripheral form of PTPS deficiency. Although single treatment of BH4 had been started, because of the lowered biopterin (B) value, elevated neopterin (N) value, and N/B ratio in the cerebrospinal fluid (CSF), the peripheral form was judged negative and combined treatment with L-dopa and 5-hydroxy tryptophan (5-HTP) was started. Follow-up study will be necessary to confirm the diagnosis of PTPS deficiency.

Thallium-201 myocardial SPET in patients with collagen disease

We analysed stress 201Tl myocardial single photon emission tomography (SPET) in collagen disease patients to evaluate abnormal uptake patterns and their clinical significance in the assessment of the cardiac status of these patients. The main purpose of the study was to evaluate the clinical significance of reverse redistribution. Twenty-two collagen disease patients (13 with progressive systemic sclerosis (PSS) and nine with systemic lupus erythematosus (SLE)) were examined by 201Tl myocardial SPET with exercise (n = 9) or dipyridamole stress (n = 13). For quantitative analysis, each 201Tl SPET polar map was divided into 17 segments, and the 201Tl uptake pattern of each segment was classified into four types. Eighteen (82%) of the patients showed abnormal findings on 201Tl SPET. Of the 374 segments analysed, 295 (79%) were classified as normal, 16 (4%) as reverse redistribution, 49 (13%) as reversible defect and 14 (4%) as fixed defect. Patients were divided into two groups: those with cardiac abnormalities on conventional testing (Group A, n = 10) and those without (Group B, n = 12). The incidences of fixed defect, reversible defect and reverse redistribution were significantly higher (P <0.01, P <0.0005, P <0.05, respectively) in Group A than in Group B. Nine (90%) of the patients in Group A and nine (75%) in Group B showed abnormal findings. No significant difference was found between the PSS and SLE patients in the incidence of the individual uptake patterns. Stress 201Tl myocardial SPET appears to be an effective method of evaluating a wide spectrum of myocardial involvement in collagen disease patients and in assessing their clinical cardiac status. Reverse redistribution is found to be a significant finding in collagen disease patients.

Induction of apoptosis in mouse brain capillary endothelial cells by cyclosporin A and tacrolimus

Although cyclosporin A and tacrolimus are used clinically as potent immunosuppressants, there have been reports of neurotoxicity and encephalopathy. A possible mechanism is that these drugs damage the blood-brain barrier (BBB), inducing dysfunction and increased permeability, and are then able to enter the brain. We studied the cytotoxicity of cyclosporin A and tacrolimus, focused on apoptosis induction, using an immortalized cell line established from BALB/c mouse cerebral microvessel endothelial cells (MBEC4). We found that these two drugs induced cell shrinkage, chromatin condensation and DNA fragmentation, which are characteristics of apoptosis. Our data suggest that the induction of apoptosis on the brain capillary endothelial cells may be at least partly involved in the occurrence of immunosuppressant-induced encephalopathy.

[Successive myocardial fatty acid metabolic imaging in patients with dilated cardiomyopathy: usefulness as a prognostic indicator]

To evaluate the prognostic value of fatty acid metabolic imaging in patients with idiopathic dilated cardiomyopathy (DCM), we performed myocardial imaging with 123I-BMIPP (BMIPP). We studied 23 patients with DCM who were admitted because of congestive heart failure (CHF) and after discharge the stable condition persisted for more than one year. BMIPP imaging was obtained when CHF recovered (first study) and the second study was performed one year after the first study. From BMIPP imaging we calculated % Uptake (percentage of cardiac uptake of isotope to total injected dose) and Defect Score (degree and extent of regional abnormality in BMIPP uptake, DS). In the first study, we performed myocardial imaging with 201T1 to calculate Uptake Ratio of BMIPP (% Uptake of BMIPP divided by % Uptake of 201T1, UR). During the follow up period of 18.2 +/- 9.5 months (4.5-39.6 months) after the second study, cardiac event developed in 8 patients (cardiac death; 4, deterioration of CHF; 4). On univariate analysis, the following indices differed significantly between the event and event-free groups; left ventricular end-systolic dimension, graded DS, UR and % Uptake of 201T1 at the first study, % Uptake of BMIPP and DS at the second study, difference of % Uptake of BMIPP and DS between the first and second study, and newly designed index from graded DS of the first study and its change in the second study (Defect Index, DI). Cox proportional hazard analysis showed that DI (p = 0.0026) and age (p = 0.0262) were independent predictors of cardiac events. In patients with DI > or = 3, the relative risk of cardiac event was 25.0 times greater than that in patients with DI < or = 2. These data suggested that the extent and degree of regional abnormality of BMIPP uptake (DS) and its changes with time were useful for evaluating the prognosis in patients with DCM even though a clinically stable condition is persisting.

Nasal reconstruction based on aesthetic subunits in Orientals

Reconstruction based on the aesthetic subunit principle has yielded good aesthetic outcomes in patients with moderate to severe nasal defects caused by trauma or tumor resection. However, the topographic subunits previously proposed are often unsuitable for Orientals. Compared with the nose in white patients, the nose in Orientals is low, lacks nasal muscle, and has a flat glabella; the structural features of the underlying cartilage and bone are not distinctly reflected in outward appearance. The authors devised aesthetic subunits suitable for Orientals, and they used these units to reconstruct various parts of the nose. The major difference between these units and those presented previously is the lack of soft triangles and the addition of the glabella as an independent unit. The authors divided the nose into the following five topographic units: the glabella, the nasal dorsum, the nasal tip, and the two alae. The border of the nasal dorsum unit was extended to above the maxillonasal suture. The basic reconstruction techniques use a V-Y advancement flap from the forehead to reconstruct the glabella, an island flap from the forehead to reconstruct the nasal dorsum and nasal tip, a nasolabial flap to reconstruct an ala, and a malar flap to reconstruct the cheek. A combination of flaps was used when the defect involved more than one unit. This concept was used for nasal reconstruction in 24 patients. In one patient undergoing reconstruction of the nasal dorsum and in one undergoing reconstruction of the nasal tip, the texture of the forearm flap did not match well, which resulted in a slightly unsatisfactory aesthetic outcome. In one patient in whom the glabella, nasal dorsum, and part of the cheek were reconstructed simultaneously, a web was formed at the medial ocular angle, and a secondary operation was subsequently performed using Z-plasty. In one patient undergoing reconstruction with a forehead flap, defatting was required to reduce the bulk of the subcutaneous flap pedicle at the glabella. However, suture lines were placed in the most inconspicuous sites in all patients, and the use of a trapdoor contraction emphasized the three-dimensional appearance of the nose. The use of these aesthetic subunits for reconstruction offers several advantages, particularly in Oriental patients. Because the nasal dorsum is reconstructed together with the side walls, tenting of the nasal dorsum is avoided, which prevents a flat appearance of the nose. A forehead flap is useful in the repair of complex defects. Defects of the alae should be separately reconstructed with a nasolabial flap to enhance the effect of the trapdoor contraction and to highlight the three-dimensional appearance of the nose. Candidates for reconstruction should be selected on the basis of nasal structure. The results suggest that these units can also be used in some white patients.

Cloning and characterization of a novel RNA-binding protein SRL300 with RS domains

AT-rich element binding factor 1 (ATBF1) mRNA encodes a transcription factor implicated in neuronal differentiation. A cDNA for the protein that can bind the 5'-noncoding sequence of the ATBF1 mRNA was cloned. The deduced protein, termed SRL300, contains a unique RNA-binding region, two large RS domains and many phosphorylation sites. SRL300 protein was detected in both human and rat cells.

Correlating the severity of paraquat poisoning with specific hemodynamic and oxygen metabolism variables

OBJECTIVE

To investigate the hemodynamics and oxygen metabolism of patients with varying degrees of severity of paraquat poisoning.

DESIGN

Prospective, observational, clinical study.

SETTING

Intensive care unit in a university hospital.

PATIENTS

Forty-three consecutive patients with paraquat and/or diquat poisoning were classified into three groups by the severity index of paraquat poisoning (SIPP; hr/mg/L).

INTERVENTIONS

Standard treatments included specific respiratory management, fluid resuscitation, and aggressive circulatory support.

MEASUREMENTS AND MAIN RESULTS

Serum paraquat and diquat levels were measured at arrival, and SIPP was calculated. The cardiac index (CI), left ventricular stroke work index (LVSWI), systemic vascular resistance index (SVRI), oxygen delivery index (DO2I), oxygen consumption index (VO2I), and oxygen extraction ratio (O2ER) were measured at 6, 12, 24, 36, 48, 72, and 96 hrs postadmission. A significant inverse correlation between SIPP and survival time was found in 31 fatal cases (r = .85; p < .001). In the SIPP 10-50 group, CI, DO2I, VO2I, and O2ER were maintained at higher levels than in the SIPP group of <10 (p < .05), whereas SVRI decreased significantly (p < .05). In the SIPP group of >50, CI, LVSWI, SVRI, DO2I, and VO2I decreased, whereas O2ER had a tendency to increase progressively. There was a significant correlation between SVRI and SIPP, O2ER and SIPP, and O2ER and SVRI 24 hrs after admission, respectively (p < .001).

CONCLUSIONS

Paraquat poisoning is characterized by high oxygen consumption with high oxygen extraction, with the degree of derangement based on the severity index. The development of a marked imbalance between increased oxygen demand and decreased oxygen supply because of myocardial depression might be a possible cause of death in circulatory failure.

Effect of bioflavonoids on vincristine transport across blood-brain barrier

Several grapefruit juice bioflavonoids, including quercetin, are reported to stimulate P-glycoprotein-mediated drug efflux from cultured tumor cells. To see whether these bioflavonoids alter the permeation of vincristine across the blood-brain barrier, we conducted experiments with cultured mouse brain capillary endothelial cells (MBEC4 cells) in vitro and ddY mice in vivo. The steady-state uptake of [3H]vincristine by MBEC4 cells was decreased by 10 microM quercetin, but increased by 50 microM quercetin. Similarly, the in vivo brain-to-plasma concentration ratio of [3H]vincristine in ddY mice was decreased by coadministration of 0.1 mg/kg quercetin, but increased by 1.0 mg/kg quercetin. Kaempferol had a similar biphasic effect on the in vitro uptake of [3H]vincristine. Other aglycones tested (chrysin, flavon, hesperetin, naringenin) increased [3H]vincristine uptake in the 10-50 microM range, and glycosides (hesperidin, naringin, rutin) were without effect. We then addressed the mechanism of the concentration-dependent biphasic action of quercetin. Verapamil, a P-glycoprotein inhibitor, inhibited the efflux of [3H]vincristine from MBEC4 cells, while 10 microM quercetin significantly stimulated it. The uptake of [3H]vincristine by MBEC4 cells was increased by inhibitors of protein kinase C, but decreased by phorbol 12-myristate-13-acetate (PMA), as well as by 10 microM quercetin. The phosphorylation level of P-glycoprotein was increased in the presence of 5 microM quercetin or 100 nM PMA, but decreased by the protein kinase C inhibitor H7 (1-(5-isoquinolinesulfonyl)-2-methylpiperazine, 30 microM). We conclude that low concentrations of quercetin indirectly activate the transport of [3H]vincristine by enhancing the phosphorylation (and hence activity) of P-glycoprotein, whereas high concentrations of quercetin inhibit P-glycoprotein. Our results indicate that patients taking drugs which are P-glycoprotein substrates may need to restrict their intake of bioflavonoid-containing foods and beverages, such as grapefruit juice.

Propiverine-induced Parkinsonism: a case report and a pharmacokinetic/pharmacodynamic study in mice

PURPOSE

We present a case report of propiverine-induced Parkinsonism. We previously reported the induction of catalepsy by amiodarone, aprindine and procaine, which possess a diethylaminomethyl moiety and demonstrated selective blockade of dopamine D2 receptors by these drugs in mice. We hypothesized that drugs possessing a diethylaminomethyl structure may generally induce Parkinsonism and/or catalepsy.

METHODS

Thus, we performed a study to examine whether oxybutynin, pentoxyverine and etafenone, as well as propiverine, induce catalepsy in mice.

RESULTS

The intensity of drug-induced catalepsy was in the order: haloperidol > etafenone > pentoxyverine > propiverine > oxybutynin. In vivo occupancy of dopamine D1, D2 and mACh receptors in the striatum was also examined. The in vitro binding affinities to the D1, D2 and mACh receptors in the striatum synaptic membrane were within the ranges of 2.4-140 microM, 380-4,200 nM, and 1.2-2,800 nM, respectively.

CONCLUSIONS

These results support the idea that any drug possessing a diethylaminomethyl moiety may contribute to the induction of catalepsy, possibly by occupying dopamine receptors.

Quantitative prediction of catalepsy induced by amoxapine, cinnarizine and cyclophosphamide in mice

Parkinsonism can be a side effect of antipsychotic drugs, and has recently been reported with peripherally acting drugs such as calcium channel blockers, antiarrhythmic agents and so on. In this study, we examined the quantitative prediction of drug-induced catalepsy by amoxapine, cinnarizine and cyclophosphamide, which have been reported to induce parkinsonism. Dose-dependent catalepsy was induced by these drugs in mice. In vivo dopamine D(1), D(2) and muscarinic acetylcholine (mACh) receptor occupancies by these drugs in the striatum were also examined. The in vitro binding affinities (K(i) values) of amoxapine and cinnarizine to dopamine D(1), D(2) and mACh receptors in rat striatal synaptic membrane were 200 and 2900 nM, 58.4 and 76.4 nM and 379 and 290 nM, respectively. Cyclophosphamide did not bind to these receptors at concentrations up to 100 microM. Twenty drugs, including those mentioned above, showed a significant correlation between the observed intensity of catalepsy and the values predicted with a pharmacodynamic model (Haraguchi K, Ito K, Kotaki H, Sawada Y, Iga T. Prediction of drug-induced catalepsy based on dopamine D(1), D(2), and muscarinic acetylcholine receptor occupancies. Drug Metab Disp 1997; 25: 675-684) based on in vivo occupancy of dopamine D(1), D(2) and mACh receptors. We conclude that occupancy of dopamine D(1) and D(2) receptors contributes to catalepsy induction by amoxapine and cinnarizine.

Learning-induced synchronization of a globally coupled excitable map system

We propose a pulse-coupled neural network model in which one-dimensional excitable maps connected in a time-delayed network serve as the neural processing units. Although the individual processing unit has simple dynamical properties, the network exhibits collective chaos in the active states. Introducing a Hebbian learning algorithm for synaptic connections enhances the synchronization of excitation timing of the units within a subpopulation. The synchronizing clusters approximately exhibit a power-law size distribution, suggesting a hierarchy of synchronization. After applying a stationary signal to a subpopulation of the units with learning, the network then reproduces the signal. The learnable time range is much longer than the inherent time scale of the processing units, i.e., the synaptic delay time. Also, the network can reproduce periodic signals with time resolution finer than the delay time. Our present network model can be considered as a temporal association device which operates in chaotic states.

Experiential assessment of endoventricular circular patch plasty in patients with depressed left ventricular function due to ischemia

A concept of volume reduction surgery for patients with end-stage dilated cardiomyopathy was introduced to the surgical aspect. We started consequently to employ this operation for patients with ischemic cadiomyopathy. Between October 1997 and April 1999, 14 patients (mean age 64 years; 12 men, 2 women) underwent endoventricular circular patch plasty (EVCPP) in our institute.

TECHNIQUE

The left ventricle (LV) is opened by placing an incision parallel to the left anterior descending (LAD) coronary artery. An endocardial purse-string suture is placed circumferentially at the root of the posterior papillary muscle. The remaining opening of the cavity is closed with a circular bovine pericardial patch. The excluded edges of LV free wall and septum are directly closed with felt strips.

RESULTS

There were no significant hemodynamic differences in heart rate, cardiac index and pulmonary capillary wedge pressure before and after the operation. Either LV end-diastolic volume index (from 134.8 +/- 30.7 to 77.1 +/- 16.3 ml/m2) or LV end-systolic volume index (from 85.0 +/- 21.8 to 40.0 +/- 12.5 ml/m2) definitely reduced postoperatively, the LV ejection fraction (EF), consequently, significantly improved from 0.31 +/- 0. 09 to 0.48 +/- 0.10 (p=0.0007). In all patients the New York Heart Association (NYHA) functional class improved from 2.8 +/- 0.7 to 1.3 +/- 0.5 after operation. We will aggressively employ this procedure for patients with ischemic cardiomyopathy in consideration of the limitations of the efficacy and the indication of this operation.

Polymethoxylated flavones in orange juice are inhibitors of P-glycoprotein but not cytochrome P450 3A4

The presence in orange juice of compounds that specifically inhibit the P-glycoprotein (P-gp) drug efflux transporter, but not the cytochrome P450 (CYP) isozyme CYP3A4, was investigated. The uptake of [(3)H]vinblastine, a substrate of P-gp, by Caco-2 cells was measured. An ethyl acetate extract of orange juice did not affect the initial uptake rate of [(3)H]vinblastine but significantly increased the steady-state uptake, as did cyclosporin A (20 microM), an inhibitor of P-gp. No significant effect on the uptake of 3-O-[(3)H]methylglucose or [(14)C]phenylalanine by Caco-2 cells was found, compared with the control. When the extract was separated on a Cosmosil column, the eluate with 70% methanol showed the most potent ability to increase [(3)H]vinblastine uptake. Additional separation of the 70% methanol eluate on a silica gel column with hexane-acetone (3:1) gave 3,3',4',5,6,7,8-heptamethoxyflavone (HMF) and 4',5,6,7,8-pentamethoxyflavone (tangeretin). HMF, tangeretin, and 3',4',5,6,7,8-hexamethoxyflavone (nobiletin), another methoxyflavone contained in orange juice, all increased the steady-state uptake of [(3)H]vinblastine by Caco-2 cells in a concentration-dependent manner. The order of potency of these compounds at the concentration of 50 microM was tangeretin > HMF > nobiletin. None of these methoxyflavones inhibited 6beta-hydroxylation of testosterone catalyzed by CYP3A4. The ethyl acetate extract of orange juice and these methoxyflavones also increased steady-state [(3)H]vinblastine uptake by LLC-GA5-COL300 cells (a cell line transfected with human MDR1 cDNA). We conclude that these methoxyflavones enhanced vinblastine uptake by specifically inhibiting drug efflux via P-gp. They may have potential as agents for reversing multidrug resistance or for recovering the bioavailability of certain drugs.

Quantitative prediction of metabolic inhibition of midazolam by erythromycin, diltiazem, and verapamil in rats: implication of concentrative uptake of inhibitors into liver

To evaluate the degree of drug-drug interaction concerning metabolic inhibition in the liver quantitatively, we tried to predict the plasma concentration increasing ratio (R) of midazolam (MDZ) by erythromycin (EM), diltiazem (DLZ), or verapamil (VER) in rats. MDZ was administered through the portal vein at the steady state of plasma concentration of these inhibitors. The R values in the area under the plasma concentration curve of MDZ in the presence of EM, DLZ, and VER were 2.02, 1.64, and 1.30, respectively. The liver to plasma unbound concentration ratios of EM, DLZ, and VER at the steady state after infusion were 20.8, 1.02, and 3.01, respectively, suggesting concentrative uptake of EM and VER into the liver. The predicted R value in the presence of EM calculated by use of plasma unbound concentration was 1.03, whereas the value calculated with liver unbound concentration was 1.61, which was very close to the observed value. These findings indicated the need to consider the concentrative uptake of inhibitors into the liver for the quantitative prediction of metabolic inhibition. However, the predicted values in the presence of DLZ or VER calculated by use of liver unbound concentration were still underestimated. This result may be due to the metabolic inhibition by the metabolites of both inhibitors. Therefore, when predicting the degree of metabolic inhibition quantitatively, the inhibitory effect by coadministered drugs and the disposition of these metabolites in the liver must also be considered.