Larger Posterior Revascularization Associated with Reduction of Choroidal Anastomosis in Moyamoya Disease: A Quantitative Angiographic Analysis.

BACKGROUND AND PURPOSE: Choroidal anastomosis, a hemorrhage-prone periventricular collateral manifestation in Moyamoya disease, outflows to the cortex posterior to the central sulcus. The objective of the present study was to test whether the angiographic extent of revascularization posterior to the central sulcus contributes to the postoperative reduction of choroidal anastomosis. MATERIALS AND METHODS: This retrospective cohort study included choroidal anastomosis-positive hemispheres before direct bypass surgery. The postoperative reduction of choroidal anastomosis was determined by a consensus of 2 raters according to the previous research. An imaging software automatically traced the angiographic revascularization area, which was subsequently divided into anterior and posterior parts by an anatomic line corresponding to the central sulcus. Each area was quantitatively measured as a percentage relative to the whole supratentorial area. RESULTS: Postoperative reduction of choroidal anastomosis was achieved in 68 (85.0%) of the 80 included hemispheres. The revascularization area posterior to the central sulcus was significantly larger in the hemispheres with reduction than in those with no reduction (mean, 15.2% [SD, 7.1%] versus 4.2% [SD, 3.4%], P < .001), whereas no significant difference was observed in the revascularization area anterior to the central sulcus. Multivariate analysis revealed that the revascularization area posterior to the central sulcus was the only significant factor associated with reduction (OR, 1.57; 95% CI, 1.21-2.03, for every 1% increase). CONCLUSIONS: The results suggest that a larger revascularization posterior to the central sulcus is associated with postoperative reduction of choroidal anastomosis regardless of the extent of anterior revascularization. It might facilitate optimal selection of the revascularization site for preventing hemorrhage.

Pharmacokinetic study of the oral administration of procaterol hydrochloride hydrate 50 µg in healthy adult Japanese men.

BACKGROUND: The pharmacokinetics of procaterol, a selective beta2-adrenergic agonist with a high intrinsic efficacy in man, could not be determined in humans when the drug was launched because of the low therapeutic dose and the low sensitivity of the analytical methods available at the time. However, a recently established analytical method using LC-MS/MS has been refined to enable the determination of the pharmacokinetic profile of procaterol and its metabolites in humans. METHODS: Procaterol hydrochloride hydrate 50 µg was administered orally to 8 healthy adult Japanese men. Plasma and urine samples collected from the subjects were analyzed by use of LC-MS/MS for procaterol and its metabolites. RESULTS: Following the oral administration of procaterol hydrochloride hydrate 50 µg, the plasma concentration of procaterol reached a Cmax of 136.4 pg/ml at ~1.44 h post-dose. The mean apparent terminal elimination half-life was ~3.83 h. DM-251 and DM-252, glucuronides of the optical isomers of procaterol, were the main metabolites and both were present in plasma at higher levels than procaterol in the plasma. The 24 h urinary excretion rates of unchanged procaterol, DM-251 and DM-252 were 15.7%, 12.4% and 11.2% of the procaterol administered, respectively. CONCLUSION: This study describes the pharmacokinetic profiles of procaterol and its metabolites following the oral administration of procaterol hydrochloride hydrate 50 µg. Procaterol and its glucuronides were found at high levels in the plasma and urine.

Cortical Distribution of Fragile Periventricular Anastomotic Collateral Vessels in Moyamoya Disease: An Exploratory Cross-Sectional Study of Japanese Patients with Moyamoya Disease.

BACKGROUND AND PURPOSE: Collateral vessels in Moyamoya disease represent potential sources of bleeding. To test whether these cortical distributions vary among subtypes, we investigated cortical terminations using both standardized MR imaging and MRA. MATERIALS AND METHODS: Patients with Moyamoya disease who underwent MR imaging with MRA in our institution were enrolled in this study. MRA was spatially normalized to the Montreal Neurological Institute space; then, collateral vessels were measured on MRA and classified into 3 types of anastomosis according to the parent artery: lenticulostriate, thalamic, and choroidal. We also obtained the coordinates of collateral vessel outflow to the cortex. Differences in cortical terminations were compared among the 3 types of anastomosis. RESULTS: We investigated 219 patients with Moyamoya disease, and a total of 190 collateral vessels (lenticulostriate anastomosis, n = 72; thalamic anastomosis, n = 21; choroidal anastomosis, n = 97) in 46 patients met the inclusion criteria. We classified the distribution patterns of collateral anastomosis as follows: lenticulostriate collaterals outflowing anteriorly (P < .001; 95% CI, 67.0-87.0) and medially (P < .001; 95% CI, 11.0-24.0) more frequently than choroidal collaterals; lenticulostriate collaterals outflowing anteriorly more frequently than thalamic collaterals (P < .001; 95% CI, 34.0-68.0); and choroidal collaterals outflowing posteriorly more frequently than thalamic collaterals (P < .001; 95% CI, 14.0-34.0). Lenticulostriate anastomoses outflowed to the superior or inferior frontal sulcus and interhemispheric fissure. Thalamic anastomoses outflowed to the insular cortex and cortex around the central sulcus. Choroidal anastomoses outflowed to the cortex posterior to the central sulcus and the insular cortex. CONCLUSIONS: Cortical distribution patterns appear to differ markedly among the 3 types of collaterals.

Identification of the Bleeding Point in Hemorrhagic Moyamoya Disease Using Fusion Images of Susceptibility-Weighted Imaging and Time-of-Flight MRA.

BACKGROUND AND PURPOSE: The location of intracerebral hemorrhage in Moyamoya disease is a prognostic factor for rebleeding and the degree of preventive effects obtainable with bypass surgery. We evaluated whether the bleeding point and responsible vessel were detectable using fusion images of SWI and time-of-flight MRA performed during chronic-phase hemorrhage. MATERIALS AND METHODS: We retrospectively enrolled 42 patients with hemorrhagic Moyamoya disease (48 hemorrhagic events). Fusion images of SWI and MRA were made using workstations, and we defined the bleeding point as the point at which the signal of an abnormally extended artery on MRA overlapped the hypointense area on SWI. Two independent raters identified the bleeding point, and classified the location and responsible vessels. RESULTS: The bleeding point was detectable at a frequency of 79.2% by rater 1. Agreement for the presence of a bleeding point was high (interrater κ = 0.83; 95% CI, 0.65-1; intrarater κ = 0.86; 95% CI, 0.68-1). The frequency of a periventricular location of the bleeding point was 65.8% by rater 1, and agreement on the location was again high (interrater κ = 0.92; 95% CI, 0.82-1; intrarater κ = 0.85; 95% CI, 0.72-0.99). The choroidal artery was the most frequent responsible vessel (57.9% by rater 1), and agreement on the responsible vessel was high (interrater κ = 0.84; 95% CI, 0.69-1; intrarater κ = 0.90; 95% CI, 0.78-1). CONCLUSIONS: Detection of the bleeding point in hemorrhagic Moyamoya disease using SWI and MRA fusion images offers highly reproducible results.

Estimation of kinetic parameters in the inactivation of an enzyme by a suicide substrate.

A method was developed to estimate the extended Michaelis constant and maximum velocity of a suicide substrate from the time-course of remaining enzyme activity with the use of simulation data calculated from the representative kinetic model for a suicide substrate proposed by Walsh et al. (Walsh, C., Cromartie, T., Marcotte, P. and Spencer, R. (1978) Methods Enzymol. 53, 437-448). For this purpose an analytical equation for the time-course of remaining enzyme activity, based on the suicide kinetic model, was derived by the steady-state method reported by Tatsunami et al. (Tatsunami, S., Yago, N. and Hosoe, M. (1981) Biochim. Biophys. Acta 662, 226-235). The accuracy of this analytical solution was proved by comparing the result with the exact solution obtained by numerical computation. A method was also developed to estimate the most important factor for a suicide substrate, the partition ratio, from the time-course of remaining enzyme activity.

The behavior of remaining enzyme activity in a suicidal enzyme system.

We derived an equation which describes the plot of the remaining enzyme activity versus ratio of initial concentration of suicide substrate to that of enzyme to obtain a partition ratio from the time-course of remaining enzyme activity. The simulation data calculated from the representative kinetic model for a suicide substrate were used to verify this equation, which approximated steady state kinetics. Although the time-dependent loss of enzyme activity is usually characterized by pseudo-first-order kinetics, the present results show that pseudo-first-order kinetics are followed only when the ratio of initial concentration of suicide substrate to that of enzyme is greater than the partition ratio. Our results also show that the present method can be used to obtain the partition ratio of a suicide substrate from the time-course of the remaining enzyme activity when the suicide substrate is given an arbitrary concentration of one, where the ratio of initial concentration of suicide substrate to that of enzyme is less than the partition ratio. The theoretically verified equation was also checked against reported experimental data for a microsomal enzyme system.

Quantification of allospecific and nonspecific corneal endothelial cell damage after corneal transplantation.

PURPOSE: To investigate the effect of host immunity (allospecific) and surgical manipulation (non-allospecific) on corneal endothelial cells (CECs) in corneal transplantation. METHODS: Draining lymph nodes and grafted C57BL/6 corneas were harvested from syngeneic recipients, allograft acceptors, and allograft rejectors (BALB/c) 1, 3, and 8 weeks after transplantation. We analyzed CEC apoptosis using an ex vivo cornea-in-the-cup assay, and visualized cell-to-cell junctions using immunohistochemical staining (ZO-1). Automatic cell analysis using Confoscan software was used to measure CEC density as well as changes in CEC morphology by quantifying the coefficient of variation in cell size (polymegethism) and shape (pleomorphism). RESULTS: The cornea-in-the-cup assay showed that allogeneic acceptor T cells and to an even greater extent rejector T cells (but not syngeneic T cells) induced CEC apoptosis. CEC density after corneal transplantation was significantly reduced in allogeneic acceptors compared with syngeneic grafts (P<0.001), and CEC density was even further reduced in the allo-rejector group compared with the allo-acceptor group. Allogeneic grafts showed a greater increase in the coefficient of variation in cell size (polymegethism) when compared with syngeneic grafts 1 week after transplantation (P=P<0.001). However, pleomorphism was not significantly different between syngeneic and allo-acceptor grafts, indicating that polymegethism (but not pleomorphism or cell density) is a sensitive indicator of the effect of alloimmunity on CECs. CONCLUSIONS: Our data demonstrate that host alloimmunity rather than surgical manipulation alone is the major cause of CEC damage in corneal transplantation, and such morphologic changes of CECs can be detected before the clinically visible onset of allograft rejection.

Clinical pharmacokinetics of 2'-deoxy-2'-methylidenecytidine (DMDC), a deoxycytidine analogue antineoplastic agent.

This article reviews the clinical pharmacokinetics of a deoxycytidine analogue of cytarabine, 2'-deoxy-2'-methylidenecytidine (DMDC). DMDC belongs to the antimetabolite class of anticancer drugs and is phosphorylated into its active, triphosphate, form within the tumour cell. Cancer cell death appears to be a result of the impairment of DNA synthesis by the triphosphate form. DMDC undergoes deamination to the inactive 2'-deoxy-2'-methylideneuridine (DMDU), its main plasma metabolite. Following intravenous administration at 30 to 450 mg/m2, DMDC has low systemic clearance (10 to 15 L/h/m2), moderate volume of distribution (nominally similar to total body water) and a short elimination half-life of between 2 and 6 hours. Renal clearance of DMDC accounts for approximately 30 to 50% of total clearance. Following oral administration of DMDC at 12 to 50 mg/m2, mean maximum DMDC plasma concentrations are within the 100 to 400 microg/L range and are generally reached within 2 hours. Oral bioavailability of DMDC is in the order of 40%, largely as a result of first-pass metabolism in the gut and liver. This first-pass effect results in considerable interpatient variability in systemic exposure to DMDC after oral administration. The systemic availability of DMDC is proportional to the administered dose and, although there was evidence that systemic exposure to DMDC decreased on repeated administration, there are no excessive time-dependent changes in systemic exposure to DMDC. Following oral administration, DMDC is metabolised in the gut wall and liver by deamination to DMDU. The kidneys eliminate DMDC and DMDU, with up to 50% of the administered dose recovered in urine, on average, as parent drug and metabolite. Dose escalation to the maximum tolerated dose was facilitated by a pharmacokinetically guided dose escalation strategy. DMDC has shown activity in non-small-cell lung cancer and colorectal cancers following oral administration. Several tumour responses are observed at the highest doses of DMDC, indicating a possible dose-response relationship with this drug. The main clinical adverse event of DMDC therapy is myelotoxicity. The haematological toxicity of DMDC was schedule dependent; twice daily administration was associated with greater toxic effects than a once daily regimen. A pharmacokinetic-pharmacodynamic model characterised the relationship between plasma DMDC concentrations and the time-dissociated toxicity. This model-dependent approach may be used to predict the consequences of as-yet-untested therapy as well as relating acceptable risks of haematological toxicity to target drug exposure.

In vivo oxidative cleavage of a pyridine-carboxylic acid ester metabolite of nifedipine.

The pharmacokinetics of the primary pyridine metabolite of nifedipine (2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinecarboxylic acid dimethylester) (M-0) and its [2H6]dimethylester analog ([2H6]M-0) were studied in male rats. A large, 5.8-fold deuterium isotope effect for the formation clearance of the monomethylester (M-1) was observed, which is strongly indicative for an oxidative reaction mechanism involving the abstraction of a hydrogen atom, presumably by cytochrome P-450. M-0 exhibited a high systemic blood clearance (104 +/- 27 ml/min/kg) (mean +/- SD) which was not significantly influenced by deuterium substitution (125 +/- 13 ml/min/kg). Its systemic clearance is presumably flow limited, and extrahepatic metabolism can be anticipated. The major metabolic pathway for M-0 in male rats seems to be a direct oxidation at the 2-methyl position and subsequently a rapid conversion of the unstable 2-hydroxymethyl-dimethylester to the lactone of the monomethylester (M-2), as has been shown by others in vitro. Non-oxidative ester cleavage of M-0 in our rats was negligible. Deuterium substitution of M-0 at the ester methyl groups induced "metabolic switching" in favor of the direct oxidation of M-0 to M-2.

Combined use of percutaneous ethanol injection and radiofrequency ablation for the effective treatment of hepatocelluar carcinoma.

Radiofrequency ablation (RFA) and percutaneous ethanol injection (PEI) therapy are currently used for the treatment of hepatocellular carcinoma (HCC). The purpose of this study was to evaluate the usefulness of combination therapy of PEI and RFA (PEI-RFA). Seventy-three patients with biopsy-proven HCC and liver cirrhosis underwent RFA after a bolus injection of ethanol into HCC. The volume of coagulated necrosis in the liver caused by PEI-RFA was estimated and compared with that by RFA alone. Coagulated necrosis areas in the liver of patients treated with PEI-RFA were significantly larger than those of patients treated with RFA alone. In PEI-RFA group, the volume of coagulated necrosis was significantly correlated with the amounts of ethanol injected into HCC. No major complications were observed during and after the PEI-RFA treatment. These results indicate that PEI-RFA is more effective than RFA alone and can make dramatic improvement of therapeutic effects in RFA therapy for HCC with fewer sessions of treatments. Therefore, PEI-RFA is considered to be a practical and promising option and may open up new avenues for the treatment of HCC.

Immunological characterization of human vitronectin and its binding to glycosaminoglycans.

The cell-adhesive glycoprotein vitronectin in human plasma was characterized with a monospecific anti-vitronectin antibody. Vitronectin, a mixture of monomeric 75 and 65 kDa polypeptides, was found to have different ratios of amounts of 75 and 65 kDa polypeptides in immunoblots of sera from various healthy human donors. Two states of vitronectin were previously reported; the open state binds to heparin, but the cryptic state does not (Hayashi et al. (1985) J. Biochem. 98, 1135-1138). The anti-vitronectin antibody was suggested to react more strongly with the open state of vitronectin than with the cryptic state. To quantitate all vitronectin regardless of its state, an enzyme-linked immunosorbent assay of vitronectin was developed based on prior boiling of vitronectin-containing samples in 2% (w/v) sodium dodecyl sulfate and 40 mM dithiothreitol to destroy conformational differences. About 12-20% of the vitronectin molecules in plasma were found to bind to heparin-Sepharose under physiological conditions. Vitronectin in plasma bound 30-fold more efficiently to heparin immobilized by amino groups than by carboxyl groups. Its affinity for heparin was higher than for chondroitin sulfate A or C, or dermatan sulfate. Vitronectin was also found to contain covalently-linked small polypeptides of 15 and 13 kDa. These light chains seemed to be disulfide-bonded to the 65 kDa polypeptide, and might be endogenously derived from nicks in the carboxy-terminal portion of the 75 kDa polypeptide in plasma.

Fluorescence assay of nitrofurantoin with o-aminothiophenol in plasma and urine.

A fluorescence method is presented for the determination of nitrofurantoin based on conversion of the drug to a fluorescent substance. The method requires 0.1-0.5 ml of plasma or diluted urine and is 10 times more sensitive than the commonly used colorimetric method.

Simultaneous determination of a new anticancer drug galocitabine and its metabolites in blood by high-performance liquid chromatography.

A relatively simple and sensitive high-performance liquid chromatographic (HPLC) method is described for measuring galocitabine (Ro 09-1390) and its meatbolites, i.e. 5'-deoxy-fluorocytidine (5'-DFCR), 5'-deoxy-fluorouridine (5'-DFUR) and 5-fluorouracil (5-FU), in blood for the purpose of studying pharmacokinetics and toxicokinetics in small animals. The procedure for blood includes deproteinization with acetonitrile. Blood components were separated on a reversed-phase C18 column with a linear gradient of acetonitrile and water and detected at a wavelength of 270 nm. The between-day relative standard deviation (RSD) was less than 10% for all compounds at concentrations of 10-100 micrograms ml-1. The calibration curves obtained from the analysis of blood samples were linear and the correlation coefficients ranged from 0.997 to 0.999. The calculated determination limits were 6.9 micrograms ml-1 for galocitabine, 3.0 micrograms ml-1 for 5'-DFCR, 4.0 micrograms ml-1 for 5'-DFUR and 3.7 micrograms ml-1 for 5-FU.

Enterohepatic circulation model for population pharmacokinetic analysis.

An enterohepatic circulation model based on physiological aspects of biliary excretion has been developed for population pharmacokinetic analysis. Mycophenolate mofetil was selected as a model drug for validation of the model. As a secondary objective, the model was used for pharmacokinetic comparison among different races. The post-hoc plasma concentration-time course was well described by the newly developed enterohepatic model and a secondary peak arising from enterohepatic circulation was also well defined. The covariates predicted by the model agreed well with literature results. The model is useful for evaluation of the covariates of an enterohepatically circulated drug. The population pharmacokinetic approach is of benefit for evaluating racial differences for a pharmacokinetic bridging package.

Lack of an effect of Madopar on the disposition of tolcapone and its 3-O-methylated metabolite in rats.

The effect of Madopar (benserazide and L-dopa, 1:4) on the disposition of the new selective inhibitor of catechol-O-methyltransferase, tolcapone, in rats was investigated. There was no statistically significant difference in the pharmacokinetic parameters of tolcapone in the presence or absence of Madopar except for a change in the mean residence time after oral administration. Thus, we rejected the hypothesis that the consumption of S-adenyl-L-methionine by Madopar would change the disposition of tolcapone. There were no statistically significant differences in the cumulative amount absorbed of drug and the absorption rate in the presence or absence of Madopar. We concluded that there was no interaction between tolcapone and Madopar.

The disposition of the tolcapone 3-O-methylated metabolite is affected by the route of administration in rats.

Catechol-O-methyltransferase (COMT) catalyses the transfer of the methyl group from S-adenyl-L-methionine (SAM) to one of the hydroxy groups of a catechol, usually the hydroxy group in position 3. COMT is present mainly in a soluble form (S-COMT) in the cytosol, but a small fraction is bound to cell membranes (MB-COMT). MB-COMT has higher affinity for the catechol substrate than does S-COMT by a factor of > 10, and high MB-COMT activity is observed in the intestinal muscle layer. The present study investigates the effect of the administration route on the disposition of the tolcapone 3-O-methylated metabolite following intravenous and oral tolcapone administration in rats. Tolcapone is a substrate for COMT although the 3-O-methylated metabolite produced has no pharmacological actions. The 3-O-methylated metabolite was eliminated very slowly following oral administration of tolcapone, and its concentration approached a plateau level, which was in contrast to the situation following intravenous administration of tolcapone. It is thought that the oral dose of tolcapone receives a high exposure to MB-COMT in the intestinal muscle layer during its absorption, and tolcapone seems to form a complex with MB-COMT having a high affinity constant (i.e. a very low Ki). The fraction of the intravenous dose of tolcapone metabolized to the 3-O-methylated metabolite at 10 mg kg-1 was 2.6%, whereas those of the oral doses, which were corrected by the bioavailability, were 5.4% for 20 mg kg-1 and 2.7% for 40 mg kg-1.

Study of diffuse source pollution management for land use and drainage system planning.

This study aims to clarify the mass balance of pollutants during both dry periods and storm events and to discuss the effects of some strategies such as pollutant removal, land use planning and new drainage systems by simulation. Three subjects are discussed in this paper. First, the amount of pollutants entering Lake Biwa from an urban area have been roughly estimated by using data collected by the local government. Second, many additional samples were collected from road surfaces, house roofs and parking lots to consider the role of land use in pollutant runoff. Third, some ongoing BMP projects in an urban area are introduced. As a result, some ideas on how to solve the problem of diffuse pollution in urban areas have been obtained.