Diazachlorin and diazabacteriochlorin for one- and two-photon photodynamic therapy

Diazachlorin and diazabacteriochlorin have been prepared through reduction of diazaporphyrin and their in vitro and in vivo activity in photodynamic therapy has been investigated.

Chemo- and Regioselective Reduction of 5,15-Diazaporphyrins Providing Antiaromatic Azaporphyrinoids

Reagent-controlled chemo- and regioselective reduction of 5,15-diazaporphyrins has been developed. The selective reduction of carbon-carbon double bonds of diazaporphyrins provides 18 π aromatic isobacteriochlorin-type products, whereas the reduction of carbon-nitrogen double bonds leads to selective formation of 20 π N,N'-dihydrodiazaporphyrins in excellent yields. The distinct antiaromatic character of N,N'-dihydrodiazaporphyrins has been revealed. The free-base N,N'-dihydrodiazaporphyrin exhibits slower inner NH tautomerism than that in the corresponding 18 π porphyrins.

Salmonella prevalence and total microbial and spore populations in spices imported to Japan

A total of 259 samples of 40 types of spices were tested for Salmonella prevalence and total microbial and spore populations. Salmonella enterica serotypes Weltevreden and Senftenberg were isolated from a black- and red-pepper sample, respectively. Because Salmonella was not detected by the most-probable-number method, it indicated that at least one cell of the microorganism was present in 25 g of sample. The mean aerobic bacterial count was greater than 5.39 log CFU/g in turmeric, garam masala, curry powder, and paprika. The mean bacterial spore counts were greater than 4.33 log CFU/g in turmeric and curry powder. The mean aerobic bacterial count in the two Salmonella-isolated samples was 6.93 log CFU/g. These results indicate that spices can be a source of contamination in the products where they are used as ingredients, and methods to reduce the microbial load in spices should be used.

Tissue-equivalent TL sheet dosimetry system for X- and gamma-ray dose mapping

To measure dose distribution for X- and gamma rays simply and accurately, a tissue-equivalent thermoluminescent (TL) sheet-type dosemeter and reader system were developed. The TL sheet is composed of LiF:Mg,Cu,P and ETFE polymer, and the thickness is 0.2 mm. For the TL reading, a square heating plate, 20 cm on each side, was developed, and the temperature distribution was measured with an infrared thermal imaging camera. As a result, linearity within 2% and the homogeneity within 3% were confirmed. The TL signal emitted is detected using a CCD camera and displayed as a spatial dose distribution. Irradiation using synchrotron radiation between 10 and 100 keV and (60)Co gamma rays showed that the TL sheet dosimetry system was promising for radiation dose mapping for various purposes.

Unusual hypersensitivity to warfarin in a critically ill patient

A patient was admitted to the intensive care unit because of respiratory failure, and warfarin therapy was started at 2 mg/day for the treatment of pulmonary embolism, together with other medications. Despite the low dosage of warfarin, international normalized ratio (INR) was markedly elevated from 1.15 to 11.28 for only 4 days, and bleeding symptoms concurrently developed. Vitamin K2 was infused along with discontinuation of warfarin. One day later, the INR was found to have decreased, and bleeding was also improved. An objective causality assessment indicated a probable relationship between clotting abnormality and warfarin administration, although the degree of elevation of the INR was unusual in the light of the daily warfarin dose and duration of its exposure. Based on the clinical status of the patient, it was suspected that several conditions contributed to the abnormal hypersensitivity to warfarin. Contributory factors probably included pharmacokinetic interactions with co-administrated drugs, vitamin K deficiency caused by decreased dietary intake, reduced gut bacterial production, impaired intestinal absorption and hepatic synthetic capacity, and increased consumption of clotting factors. In view of our experience in the present case, it should be stressed that close monitoring of coagulation capacity is necessary in critically ill patients in order to avoid fatal haemorrhage after initiating warfarin therapy regardless of the dosage.

Serum carvedilol concentration and its relation to change in plasma brain natriuretic peptide level in the treatment of heart failure: a preliminary study

OBJECTIVE

To examine the influence of carvedilol dose and concentration in serum on plasma brain natriuretic peptide (BNP), a measure of heart failure progression.

METHODS

12 patients with New York Heart Association (NYHA) functional class II-III chronic heart failure were enrolled in the study. They received carvedilol at daily doses of 1-20 mg with a 1-2 weekly adjustment. Serum carvedilol trough concentrations were measured in steady-state using a specific fluorescence HPLC method. The degree of improvement in heart failure was assessed from the ratio of change in the plasma BNP concentration, 2 weeks, 1 month and 3 months after the commencement of carvedilol administration.

RESULTS

From the pharmacokinetic aspect, there was no valid correlation between the trough serum carvedilol concentration (Cmin) and daily dose per body weight (Dd/BW), indicating that there was a wide difference in the carvedilol elimination capacity among individuals. A significant decrease in the BNP was observed at the 3rd month in patients treated with the high dose (> 750 mg/3 months). On the other hand, in patients with a mean serum carvedilol level (Cmin) of less than 2.5 nmol/l up to 2 weeks after the start ofcarvedilol therapy, the degree of reduction in the BNP value after the 3rd month was significantly larger, relative to the patient group with Cmin over 2.5 nmol/l.

CONCLUSIONS

The total carvedilol dose was confirmed to be one of the determinants for improvement in heart failure, and it was suggested that the initial serum level also plays an important role in therapeutic outcome. Therefore, it may be important to monitor the serum carvedilol level at the introductory period to determine the daily dose requirements because of the wide inter-individual variability in its metabolic clearance.

Predictive performance of serum digoxin concentration in patients with congestive heart failure by a hyperbolic model based on creatinine clearance

OBJECTIVES

To formulate a simple equation for determining the daily dose requirements of digoxin by inclusion of creatinine clearance (Ccr) values as an explanatory variable.

METHODS

We included 235 routine monitoring and clinical laboratory test data (steady-state serum digoxin concentration and Ccr values), obtained from hospitalized patients receiving digoxin for treatment of congestive heart failure. The 107 data sets were fitted to a hyperbolic model to account for the relation between the ratio of serum digoxin level to the daily dose (L/D) and the Ccr values determined by six methods. Their correlation coefficients (r) were computed by non-linear regression analysis. To evaluate the validity of the best-fitting model, the predictive performance of the L/D ratios was compared with those given by seven reference models previously published, using another 128 data sets.

RESULTS

The hyperbolic model involving the Ccr values estimated by Cockcroft and Gault's equation showed the closest correlation (r = 0.81) between the actual and estimated Ccr values. Mean prediction error (ME), a measure of bias, of the L/D ratio (0.018 ng/mL) was almost negligible when other data were fitted to the proposed model, and this ME value proved to be much smaller than those calculated from the previously published prediction models. Mean absolute prediction error, a measure of precision, by the proposed model was also satisfactory for prediction.

CONCLUSION

The newly developed model provided good predictive performance of serum digoxin level. Taking simplicity in practical use into account, the clinical application of the proposed model will allow for accurate and rapid determination of the initial maintenance dosing regimen of digoxin based on the individual Ccr value, without actual measurement of its serum concentration.

An open study of a lotion formulation to improve tolerance of tacrolimus in facial atopic dermatitis

BACKGROUND

We identified 19 patients with facial atopic eczema who failed to respond to tacrolimus (FK506) ointment, although tacrolimus ointment has shown excellent benefit for the treatment of recalcitrant facial erythema in most patients with atopic dermatitis.

OBJECTIVES

We attempted to determine the efficacy of an original lotion formulation of tacrolimus for facial atopic dermatitis resistant to tacrolimus ointment.

PATIENTS/METHODS

Recalcitrant facial erythema of these 19 patients was treated with an original tacrolimus lotion preparation for 6 months. Patch testing with white petrolatum was performed in both the 19 patients and in 30 other atopic dermatitis patients who had experienced excellent results with tacrolimus ointment.

RESULTS

Of the 19 resistant patients, those whose symptoms were greatly or moderately improved by the lotion were 95%, 89% and 89% after 2 weeks, 3 months and 6 months of treatment, respectively. Further, patch testing to petrolatum showed positive reactions in several (six of 19) patients, compared with none of 30 controls with atopic eczema that had responded to topical tacrolimus ointment.

CONCLUSIONS

The tacrolimus lotion had a significant effect on the recalcitrant facial erythema in adult patients with atopic dermatitis who were resistant to tacrolimus ointment. We suggest that one reason for the unresponsiveness to tacrolimus ointment may be because of contact sensitivity to white petrolatum.

Lysenin-sphingomyelin binding at the surface of oligodendrocyte lineage cells increases during differentiation in vitro

We have investigated the relationship between the developmental expression of sphingomyelin, a major component of myelin, and oligodendrocyte lineage. Using lysenin as a cytochemical probe for membrane sphingomyelin, we have now determined the distribution pattern of sphingomyelin on the plasma membrane of rat cultured oligodendrocytes. Although lysenin does not bind to A2B5(+)/NG2(+) bipolar oligodendrocyte progenitors, lysenin recognizes sphingomyelin on the cell bodies of multipolar A2B5(+) cells, but not on their processes. O4(+) and O1(+) immature and MBP(+) mature oligodendrocytes are strongly labeled by lysenin from cell bodies to the tips of processes. The content of sphingomyelin in immature and mature oligodendrocytes is approximately 2-fold higher than that in oligodendrocyte progenitors. These findings show that sphingomyelin increases during differentiation of cells in the oligodendrocyte lineage. In multipolar oligodendrocyte progenitors exposed to Triton X-100 at 4 degrees C, lysenin labels cell processes in addition to cell bodies. In contrast, Triton X-100 extraction does not alter the distribution of lysenin binding on O4(+), O1(+) and MBP(+) cells, although the immunocytochemical intensities of the lysenin bindings increase. Our data suggest that the alteration in sphingomyelin content and distribution in the oligodendrocyte lineage cells could have important consequences for cell recognition and downstream signaling events through sphingomyelin-rich domains.

Bactericidal activity of catechin-copper (II) complexes against Staphylococcus aureus compared with Escherichia coli

The bactericidal activity of catechin-copper (II) complexes against Staphylococcus aureus compared with Escherichia coli was investigated in relation to the generation of hydrogen peroxide and the binding of Cu(II) ion onto the bacteria. The bactericidal activity of catechin-Cu(II) complexes against Staph. aureus (Gram-positive) was much lower than that against E. coli (Gram-negative), suggesting that the binding of copper ions to the surface of bacterial cells plays an important role in the bactericidal activity of catechin-Cu(II) complexes.

Factors that affect absorption behavior of cyclosporin a in gentamicin-induced acute renal failure in rats

Factors that affect the absorption of cyclosporin A (CsA) were examined in gentamicin-induced acute renal failure (ARF) rats. In ARF rats, the area under the blood CsA concentration-time curve after oral administration was significantly decreased in comparison with that of control rats; 5.81 +/- 0.55 vs 11.30 +/- 1.59 mg h mL(-1)(mean+/-s.e.m.), respectively, and the relative bioavailabilities in ARF and control rats after oral administration were 15.2% and 43.4%, respectively. The flow rate of bile and the amount of bile acids in ARF rats were markedly decreased to about 61% of control, and 41% of control, respectively. The amount of CsA uptaken into the evened sac of jejunum, transferred to serosal side, and metabolized in tissues was significantly decreased in ARF rats without verapamil, while with 0.3 mM verapamil, the amount in ARF rats recovered to the levels of control rats. The absorption clearance of CsA in ARF rats was significantly decreased, however it was significantly improved by adding bile or bile acid. Adenosine triphosphate released from enterocytes in ARF rats was significantly decreased in the presence of 2.0 microM CsA, 0.3 mM verapamil, or both, in comparison with control rats. From these findings, we concluded that a reduction of CsA bioavailability during ARF is caused by depression in bile excretion and renal function-dependent depression of uptake from intestinal tract via maybe P-gLycoprotein in enterocytes. They are main two factors that reduce the absorbed fraction of CsA in ARF rats.

Adsorption and pharmacokinetics of cyclosporin A in relation to mode of infusion in bone marrow transplant patients

Two main factors that affect the pharmacokinetics of cyclosporin A (CsA) during 24-h durable intravenous (DIV) administration have been reported, namely physiological changes after bone marrow transplantation, and blood sampling through indwelling lines. In addition, it has been found that infusion sets made of polyvinyl chloride (PVC) markedly adsorb CsA. We conducted in vitro adsorption studies of CsA on infusion sets, and the administration routes that are used in the treatment of patients with bone marrow transplantation. We also examined the effects of administration route on CsA pharmacokinetics in clinical practice. The in vitro adsorption study using 30-mm segments of lumen from commercially available infusion sets showed that the degree of CsA adsorption per area of lumen made of PVC was significantly higher than that in those made of polyethylene (PE) or polybutadiene (PB), which showed no adsorption of CsA. Due to its adsorption, use of infusion sets made of PVC resulted in about a 40-50% loss of CsA dose, which affected the pharmacokinetic parameters during 24-h DIV, while those made of PE and PB did not. The use of non-PVC infusion sets should allow for accurate monitoring of CsA results, and provide cost benefit in the treatment of bone marrow transplantation.

Damage to the cytoplasmic membrane of Escherichia coli by catechin-copper (II) complexes

In the presence of a nonlethal concentration of Cu(II), washed Escherichia coli ATCC11775 cells were killed by (-)-epigallocatechin (EGC) and (-)-epicatechin (EC). Cell killing was accompanied by a depletion in both the ATP and potassium pools of the cells, but the DNA double strand was not broken, indicating that the bactericidal activity of catechins in the presence of Cu(II) results from damage to the cytoplasmic membrane. Induction of endogenous catalase in E. coli cells increased their resistance to being killed by the combination of catechins and Cu(II). In all cases studied, EGC and EC with Cu(II) were found to generate hydrogen peroxide, but its concentration was too low to account for the bactericidal activity. The bactericidal activity of EGC in the presence of Cu(II) was completely suppressed by ethylenediaminetetraacetate, bathocuproine, catalase, superoxide disumutase (SOD), heated catalase, and heated SOD, but not by dimethyl sulfoxide. When catalase, either heated or unheated, was added to the cells incubated with EGC in the presence of Cu(II), it completely inhibited further killing of the cells. These findings suggest that recycling redox reactions between Cu(II) and Cu(I), involving catechins and hydrogen peroxide on the cell surface, must be important in the mechanism of the killing.

Influence of glycerol-induced acute renal failure on the pharmacokinetics of cyclosporin in rats

Although it is widely believed that renal dysfunction has no effect on the pharmacokinetics of cyclosporin, many clinical reports suggest that renal dysfunction after renal transplantation is closely related to the pharmacokinetics of cyclosporin. To clarify the relationship between renal dysfunction and the pharmacokinetics of cyclosporin, we examined the influence of acute renal failure (ARF) on its pharmacokinetics in glycerol-induced ARF rats. The values of indicators of renal function (serum creatinine, blood urea nitrogen), but not those of indicators of hepatic function, were significantly increased in ARF rats that received glycerol compared with values for control rats. The area under the blood cyclosporin concentration-time curve after oral administration (AUCpo) were 4.976+/-0.847 mghL(-1) for ARF rats and 9.684+/-1.100 mghL(-1) for control rats; AUCpo in ARF was significantly reduced in a manner dependent on renal function. The oral clearance of cyclosporin in ARF and control rats was 1.172+/-0.207 and 0.544+/-0.062Lh(-1) kg(-1), respectively, whereas total body clearance in ARF and control rats was 0.151+/-0.008 and 0.183+/-0.010Lh(-1)kg(-1), respectively. The relative bioavailability of cyclosporin in ARF and control rats was 0.118 and 0.336, respectively. In an in-vitro study using everted sac and liver-slice methods, the apparent first-order rate constants for cyclosporin uptake (k(uptake)) and metabolism (k(metab)) in gut tissues were reduced, whereas k(uptake) and k(metab) in liver were increased. Gastric emptying, measured by use of paracetamol, was significantly reduced in ARF rats. These results suggest that glycerol-induced ARF results in several changes in the pharmacokinetics of cyclosporin in rats. From these results, we conclude that reduction of the absorbed fraction of cyclosporin strongly contributes to the decrease in AUCpo in the presence of ARF.

Preferential inhibition of CYP1A enzymes in hepatic microsomes by mexiletine

We examined the inhibitory behavior of theophylline oxidations and a variety of cytochrome P450 (P450)-dependent metabolism in the presence of mexiletine (MEX), using hepatic microsomes from both control mice and mice exposed to beta-naphthoflavone (beta-NF). Theophylline metabolism, which is mainly catalyzed by CYP1A2, was susceptible to competitive inhibition by MEX. The calculated inhibition constants (Ki) for theophylline 3-demethylation and its 8-hydroxylation were 4.3 microM and 8.3 microM, respectively, which are comparable to the recommended therapeutic serum range for MEX. The inhibitory potency of MEX on cytochrome P450-dependent enzyme activities diverged among the several metabolic reactions, which were probes for CYP1A, 2A, 2C, 2D, 2E and 3A subfamilies. The Ki value (6.7 microM) for methoxyresorufin O-demethylation mediated by CYP1A2 agreed with those from theophylline oxidations. These metabolic reactions exhibited the smallest Ki values, 1-3 orders of magnitude lower than activities of other constitutive cytochrome P450 species. Similar degrees of inhibition were observed in CYP1A1, a beta-NF-inducible isoform with a relatively high conformity to CYP1A2. These results indicate that MEX acts as a selective and potent inhibitor of the CYP1A enzymes responsible for oxidative biotransformation of chemicals such as theophylline. This evidence provides a fundamental explanation for the pharmacokinetic interactions experienced in clinical practice.

Mammalian cell mutants resistant to a sphingomyelin-directed cytolysin. Genetic and biochemical evidence for complex formation of the LCB1 protein with the LCB2 protein for serine palmitoyltransferase

Lysenin, a hemolytic protein derived from the earthworm Eisenia foetida, has a high affinity for sphingomyelin. Chinese hamster ovary (CHO) cells exhibited a high cytolytic sensitivity to lysenin, but treatment with sphingomyelinase rendered the cells resistant to lysenin. Temperature-sensitive CHO mutant cells defective in sphingolipid synthesis were resistant to lysenin, and this lysenin resistance was suppressed by metabolic complementation of sphingolipids. Selection of lysenin-resistant variants from mutagenized CHO cells yielded two types of sphingomyelin-deficient mutants, both of which showed less lysenin binding capability than wild-type cells. One mutant strain was severely defective in sphingomyelin synthesis but not glycosphingolipid synthesis, and another strain (designated LY-B) was incapable of de novo synthesis of any sphingolipid species and had no activity of serine palmitoyltransferase (SPT; EC 2.3.1.50) catalyzing the first step of sphingolipid biosynthesis. LY-B cells lacked the LCB1 protein, a component of SPT, and transfection of LY-B cells with the hamster LCB1 cDNA restored both SPT activity and sphingolipid synthesis to the cells. Expression of an affinity peptide-tagged LCB1 protein in LY-B cells caused the endogenous LCB2 protein to adsorb to a tag affinity matrix. In addition, an anti-hamster LCB2 protein antibody co-immunoprecipitated both SPT activity and the wild-type LCB1 protein with the LCB2 protein. Thus, cell surface sphingomyelin is essential for lysenin-induced cytolysis, and lysenin is a useful tool for isolation of sphingomyelin-deficient mutants. Moreover, these results demonstrate that the SPT enzyme comprises both the LCB1 and LCB2 proteins.

Bactericidal activity of catechin-copper (II) complexes on Escherichia coli ATCC11775 in the absence of hydrogen peroxide

Washed Escherichia coli ATCC11775 cells were killed by (-)-epigallocatechin (EGC) in the presence of a non-lethal concentration of Cu2+ (1 mumol l-1) without additional H2O2, but not by (-)-epicatechin (EC). EGC alone (< 0.1 mmol l-1) did not reduce the viability of the cells. The survival curve obtained in the presence of EGC and Cu2+ was similar to that obtained in the presence of (-)-adrenaline (EN) and Cu2+.

Relationship between area under the concentration versus time curve of cyclosporin A, creatinine clearance, hematocrit value, and other clinical factors in Japanese renal transplant patients

We evaluated the relationship between the area under the concentration versus time curve (AUC) of cyclosporin A (CsA) and several other clinical factors, because the clinical utility of AUC monitoring has been ambiguous. Fifty-four clinical time courses from 14 Japanese renal transplant patients during hospitalization, in the period from April 1990 to March 1997, were examined. In a bivariate regression analysis there was no correlation between the AUC and the daily dose of CsA (mg/kg/day) when the individual data or total series data were analyzed. In a chi-square test, the donor type of kidney (chi(2) = 25.254, df = 1, p = 0.0000) and renal function-related episodes, i.e. acute tubular necrosis, hemodialysis, hypertension, nephrotoxicity, or rejection (chi(2) = 13.982, df = 1, p = 0.0002) directly affected posttransplant renal function assessed by creatinine clearance, while episodes of hepatic function as assessed by the glutamate-pyruvate transaminase (GPT) activity level had no correlation with the posttransplant renal function evaluated according to creatinine clearance. In contrast, the renal function-related episodes significantly affected the AUC after renal transplantation (chi(2) = 4.934, df = 1, p = 0.0263), while hepatic function assessed by GPT did not. In a multivariate analysis, the creatinine clearance and obesity had significant positive correlations with the AUC, whereas the hematocrit had a significant negative correlation with the AUC. From these observations, we concluded that the dosage adjustment of CsA cannot be performed using the linear relationship between the daily oral dose and the AUC, and that renal function, obesity, and the CsA blood distribution properties affect the CsA pharmacokinetics after renal transplantation. Posttransplant renal function as well as obesity and CsA blood distribution properties are important factors to be considered when therapeutic monitoring is performed.

Simultaneous determination of glucocorticoids in plasma or urine by high-performance liquid chromatography with precolumn fluorimetric derivatization by 9-anthroyl nitrile

A new method for simultaneous determination of glucocorticoids (GCs) in plasma or urine by high-performance liquid chromatography (HPLC) with fluorimetric detection has been developed. Following extraction with ethyl acetate using a reversed-phase disposable cartridge, the six GCs [cortisol (F), cortisone (E), prednisolone (PL), prednisone (PN), 6beta-hydroxycortisol (6beta-OHF) and 6beta-hydroxyprednisolone (6beta-OHP)] and an internal standard (6beta-hydroxycotortisone) were derivatized by treatment with 9-anthroyl nitrile (9-AN) in a mixture of basic catalysts (triethylamine and quinuclidine) to give the fluorescent esters through the 21-hydroxyl group. The GC derivatives so obtained were then cleaned by a straight-phase disposable cartridge and chromatographed on a straight-phase column with an isocratic HPLC technique. The fluorescence derivatives of the GCs, including the internal standard, were separated as clear single peaks and no interfering peaks were observed on the chromatograms. The lower limits of detection for F, E, PL and PN in plasma or urine were 0.1 ng/ml and those for 6beta-OHF and 6beta-OHP in plasma or urine were 0.5 ng/ml, at a signal-to-noise ratio of 3. The analytical recovery of known amounts of the GCs added to plasma or urine were almost 100%. This method can be applied to the determination of plasma or urinary F in renal transplant patients who received PL and can be applied for other metabolic investigations in relation to the change in blood pressure via 11beta-hydroxysteroid dehydrogenase or in hepatic metabolizing via CYP3A4.

Lysenin, a novel sphingomyelin-specific binding protein

Lysenin, a novel 41-kDa protein purified from coelomic fluid of the earthworm Eisenia foetida, induced erythrocyte lysis. Preincubation of lysenin with vesicles containing sphingomyelin inhibited lysenin-induced hemolysis completely, whereas vesicles containing phospholipids other than sphingomyelin showed no inhibitory activity, suggesting that lysenin bound specifically to sphingomyelin on erythrocyte membranes. The specific binding of lysenin to sphingomyelin was confirmed by enzyme-linked immunosorbent assay, TLC immunostaining, and liposome lysis assay. In these assays, lysenin bound specifically to sphingomyelin and did not show any cross-reaction with other phospholipids including sphingomyelin analogs such as sphingosine, ceramide, and sphingosylphosphorylcholine, indicating that it recognized a precise molecular structure of sphingomyelin. Kinetic analysis of the lysenin-sphingomyelin interaction by surface plasmon resonance measurements using BIAcoreTM system showed that lysenin associated with membrane surfaces composed of sphingomyelin (kon = 3.2 x 10(4) M-1 s-1) and dissociated extremely slowly (koff = 1.7 x 10(-4) s-1), giving a low dissociation constant (KD = 5.3 x 10(-9) M). Incorporation of cholesterol into the sphingomyelin membrane significantly increased the total amount of lysenin bound to the membrane, whereas it did not change the kinetic parameters of the lysenin-membrane interaction, suggesting that lysenin specifically recognized sphingomyelin and cholesterol incorporation changed the topological distribution of sphingomyelin in the membranes, thereby increasing the accessibility of sphingomyelin to lysenin. Immunofluorescence staining of fibroblasts derived from a patient with Niemann-Pick disease type A showed that lysenin stained the surfaces of the fibroblasts uniformly, whereas intense lysosomal staining was observed when the cells were permeabilized by digitonin treatment. Preincubation of lysenin with vesicles containing sphingomyelin abolished lysenin immunostaining. This study demonstrated that lysenin bound specifically to sphingomyelin on cellular membranes and should be a useful tool to probe the molecular motion and function of sphingomyelin in biological membranes.

A predictive model for area under the concentration versus time curve of cyclosporin A using several routine monitoring results in renal transplant patients

We created a predictive model for the area under the concentration versus time curve (AUC) of cyclosporin A (CsA) using routine monitoring results, and examined its clinical utility. Based on 48 clinical time courses accumulated from renal transplant patients, the AUC predictive model was created. An estimate of the AUC0-8 (integrated from time zero to 8 h) was then given as follows: AUC0-8 = 5673.1 x log(TL) + 9342.8 x log(OB) + 64.1 x Dprd x 869.4 x DTK - 168.9 x HCT - 161.2 x SCr - 11.3 x GPT + 3.0 x PL - 588.6 x SEX - 24794.5. In this model, the AUC0-8(ng.h/ml) is given as a function of the CsA through levels (TL, ng/ml), obesity (OB, %), daily dose of prednisolone (Dprd, mg/d), donor type of kidney (DTK), hematocrit (HCT, %), serum creatinine (SCr, mg/dl), glutamate-pyruvate transaminase activity (GPT, IU/l), plasma lipids (PL, mg/dl) and sex distinction (SEX). The Statistical significance of the multiple regression was p < 0.00001 (R2 = 0.862, n = 48), and the day after transplantation, neither the administered oral dose of CsA, or the patient's age had any contribution to the regression. The predictive performance of this model was almost equal to that of the existing method which used 3-point data on the concentration versus time curve. In clinical adaptation for renal transplant patients, the steady-state concentration of CsA (Css) based on the AUC0-8 predictive model was significantly decreased during acute gastroenteritis or before acute rejection, whereas nephrotoxicity was increased, even though CsA trough levels were within a normal therapeutic range (100-200 ng/ml). These findings suggest that the created AUC0-8 predictive model using routine monitoring results, i.e., the trough level of CsA, biochemical tests, a daily dose of predorinsolone (PRD), and basic patient information, is convenient as a monitoring device for CsA therapy, and is satisfactory in clinical practice.

Relationship between erythrocyte-to-plasma distribution ratio of cyclosporin and lymphocyte proliferation in renal transplant patients

OBJECTIVE

The aim of this study was to examine the relationship between erythrocyte-to-plasma distribution ratio of cyclosporin (CsA-EP) and lymphocyte proliferation as an indicator of immunosuppressive activity in renal transplant patients.

METHODS

A total of 113 whole blood samples obtained from 6 inpatients with renal transplantation were analysed. CsA concentrations in blood and plasma at trough were measured by fluorescence polarization immunoassay using monoclonal antibody, lymphocyte proliferation in response to phytohaemagglutinin was evaluated by the fluorimetric derivatization method using ethidium bromide and the stimulation index (SI) was calculated.

RESULTS

There was no correlation between CsA dose and trough levels (vs blood CsA, r2 = 0.052; vs plasma CsA, r2 = 0.054, n = 113). A significant negative correlation between the SI and the CsA-EP was found in individual or all samples (r2 = 0.224, p < 0.0001, n = 113), whereas CsA trough levels in blood or plasma had no correlation with the SI.

CONCLUSION

Although the degree of contribution of CsA-EP to the SI was 22%, the CsA-EP is a more useful predictor of changes in immunosuppressive response than CsA concentration in blood or plasma. The adoption of the CsA-EP as a monitoring index could be helpful in assessing the appropriateness of CsA immunosuppressive therapy.

Redistribution of phosphatidylethanolamine at the cleavage furrow of dividing cells during cytokinesis

Ro09-0198 is a tetracyclic polypeptide of 19 amino acids that recognizes strictly the structure of phosphatidylethanolamine (PE) and forms a tight equimolar complex with PE on biological membranes. Using the cyclic peptide coupled with fluorescence-labeled streptavidin, we have analyzed the cell surface localization of PE in dividing Chinese hamster ovary cells. We found that PE was exposed on the cell surface specifically at the cleavage furrow during the late telophase of cytokinesis. PE was exposed on the cell surface only during the late telophase and no alteration in the distribution of the plasma membrane-bound cyclic peptide was observed during the cytokinesis, suggesting that the surface exposure of PE reflects the enhanced scrambling of PE at the cleavage furrow. Furthermore, cell surface immobilization of PE induced by adding the cyclic peptide coupled with streptavidin to prometaphase cells effectively blocked the cytokinesis at late telophase. The peptide-streptavidin complex treatment had no effect on furrowing, rearrangement of microtubules, and nuclear reconstitution, but specifically inhibited both actin filament disassembly at the cleavage furrow and subsequent membrane fusion. These results suggest that the redistribution of the plasma membrane phospholipids is a crucial step for cytokinesis and the cell surface PE may play a pivotal role in mediating a coordinate movement between the contractile ring and plasma membrane to achieve successful cell division.

Effect of morphine on secretion of amylase from isolated parotid acini

The effect of morphine on amylase secretion was studied in isolated rat parotid acinar cells. It was found that aluminum fluoride (AlCl3/NaF) and dibutyryl-cyclic AMP but not by cyclic AMP, enhanced amylase secretion. Cyclic AMP was effective in enhancing secretion following permeabilization of cells with alpha-toxin. Following treatment of cells with alpha-toxin, both GTP and GTP-gamma-S also enhanced secretion. Morphine reduced AlCl3/NaF- or GTP-induced secretion of amylase, but was without effect on GTP-gamma-S-induced secretion. Photoaffinity labeling by the use of [32P] 4-azidoanilido GTP revealed its incorporation into 43 kDa and 31 kDa proteins. Incorporation was further enhanced with AlCl3/NaF. Morphine reduced labeling of the 43 kDa protein. Immunoblot analysis identified the 43 kDa GTP binding protein as Gs. When [gamma 32P] GTP was preloaded into permeabilized acinar cells and its hydrolysis measured, morphine stimulated and AlCl3/NaF inhibited GTPase activity. These results suggested the involvement of Gs in secretion of amylase. Furthermore, morphine reduced secretion of amylase by stimulating GTPase activity and by reducing the incorporation of GTP into Gs.

Involvement of CYP2E in 8-hydroxylation of theophylline in mouse hepatic microsomes-difference from its N-demethylations

We examined which cytochrome P-450 (P-450) species other than CYP1A participates in the oxidative metabolism of theophylline (TP) in mouse hepatic microsomes. Among the three metabolic pathways of TP, only 8-hydroxylation was selectively enhanced by acetone, a potent inducer of CYP2E. We assumed that two P-450 populations with different metabolic ability were involved in this metabolic process, and kinetic analyses revealed that the enhancement was due to the induction of a high-capacity P-450 population. The 8-hydroxylation at a substrate concentration, where most of the total activity was attributed to the catalysis of the high-capacity phase, was markedly impaired by CYP2E inhibitors such as 4-methylpyrazole and aminoacetonitrile, whereas the N-demethylations were little affected by these agents. The activity of TP 8-hydroxylation was significantly correlated with that of p-nitrophenol hydroxylation, a probe for CYP2E, in untreated microsomes. The activities of these oxidative reactions were modified to a similar degree by known enzyme inhibitors with a range of inhibitory potencies and affinity for P-450 isoforms. On the other hand, a relationship between TP N-demethylations and p-nitrophenol hydroxylation was not apparent, but there was a behavioral similarity between the two types of N-demethylations. The results indicated that TP 8-hydroxylation, which accounts for a large portion of TP oxidations, involves CYP2E, and that its N-demethylations are mediated by a common or closely similar P-450 species distinct from CYP2E.

A novel phosphatidylserine-binding peptide motif defined by an anti-idiotypic monoclonal antibody. Localization of phosphatidylserine-specific binding sites on protein kinase C and phosphatidylserine decarboxylase

A monoclonal anti-idiotypic antibody, Id8F7, previously shown to bind to a phosphatidylserine (PS)-specific binding site on protein kinase C (PKC) has been used to identify a 12-amino acid consensus sequence shared by PKC and phosphatidylserine decarboxylase (PSD). The 14-amino acid synthetic peptide derived from the corresponding region of PSD (amino acids 351-364 of the enzyme from Chinese hamster ovary cells) bound effectively and specifically to PS, and that derived from rat PKC gamma (amino acids 227-240) bound weakly but specifically to PS. Analysis of binding of Id8F7 to various synthetic peptides revealed that the consensus sequence motif, FXFXLKXXXKXR, is responsible for the interaction with both Id8F7 and PS. The results suggest that the conserved amino acid residues represent a basic structural motif for the specific interaction with PS, and the corresponding regions of PKC and PSD form the PS-specific binding sites of these enzymes.

A nomogram for predicting optimal dosage of cyclosporine in renal transplant patients: taking physiological factors into consideration for regimen during immunosuppressive therapy

We constructed a nomogram for determining the optimal regimen of cyclosporine (CyA), based on physiological changes that occur during immunosuppressive therapy. The nomogram consists of a fixed model and a variable model. In the fixed model, the oral dose of CyA (D, mg/kg) is given by the multiple linear function of logarithmic CyA trough level (TL, ng/ml), the surrogate apparent total body clearance of CyA (CL/fsu, l/h/kg, being equal to D/TL/12), and the erythrocyte-to-plasma distribution ratio of CyA (CyA-EP), as defined by: D = 4.938 x log(TL) + 1.5037 x CL/fsu - 0.0326 x CyA-EP - 10.7156. In the variable model, the CL/fsu is given by the CyA-EP and the patient's intrinsic parameters (P1, P2), using a nonlinear equation: CL/fsu = P1 x exp(P2 x CyA-EP)/CyA-EP. An optimal CyA dose to maintain a desired trough level was calculated, and the validity of the nomogram was found satisfactory for clinical use. This offers a very concise and practical method for the therapeutic monitoring of CyA. Because the pharmacokinetics of CyA depends on physiological changes due to several disease states, and because the CyA-EP reflects the pharmacokinetics of CyA and the patient's disease state, the proposed nomogram is believed to provide an optimal dosage adjustment, taking physiological factors into consideration.

Multiplicity of cytochrome P-450 species involved in theophylline metabolism in mouse hepatic microsomes

To ascertain the multiplicity of the cytochrome P-450 (P-450) species participating in the individual metabolic conversion of theophylline by 8-hydroxylation, 3-demethylation and 1-demethylation in mice, kinetics were studied under various conditions using untreated and inducer-treated mouse hepatic microsomes. Eadie-Hofstee plots of 1-demethylation in untreated microsomes exhibited a straight line, whereas those of 8-hydroxylation and 3-demethylation were curved lines. The biphasic kinetics indicated the contribution of two P-450 populations to the respective metabolic pathways; one characterized by high affinity and low capacity, the other by low affinity and high capacity. The high affinity population was efficiently induced by beta-naphthoflavone (beta-NF), and was highly susceptible to inhibition by a specific CYP1A inhibitor. The low affinity population was sensitive to induction by phenobarbital (PB), and was markedly inhibited by preferential inhibitors for PB-inducible P-450 species. The present results indicated that two P-450 populations contributed to the theophylline metabolism in mouse hepatic microsomes, and that the high and low affinity populations corresponded, respectively, to CYP1A, and a PB-inducible P-450 species having a much higher capacity than CYP1A.

Changes in the serum protein binding of vancomycin in patients with methicillin-resistant Staphylococcus aureus infection: the role of serum alpha 1-acid glycoprotein levels

The relationship between albumin or alpha 1-acid glycoprotein (AAG) levels and vancomycin (VCM) protein binding was studied in 44 serum samples from the 10 patients with methicillin-resistant Staphylococcus aureus (MRSA) infection receiving VCM therapy. Eighty serum samples from 80 healthy subjects were used as a control for albumin and AAG levels. The protein binding percentage of VCM in the serum of the patients varied widely from 27 to 62%. The mean albumin level (34 g/L) was significantly lower than that in healthy subjects (46 g/L). There was no correlation between the binding percentage and serum albumin level in the patients (r = -0.25, p > 0.1). The mean AAG level in the patients (1.51 g/L) was significantly higher than in healthy subjects (0.59 g/L). There was a significant correlation between the binding percentage of VCM and serum AAG level (r = 0.63, p < 0.001). The binding percentage of VCM individual patients changed in parallel to serum AAG and C-reactive protein (CRP) levels, which is a useful marker of acute phase response. There were also significant correlations between AAG, albumin, and CRP levels. The present results indicate that the increased AAG level in serum of the patients appeared to have a significant effect on the protein-binding characteristics of VCM.

Relationship between apparent total body clearance of cyclosporin A and its erythrocyte-to-plasma distribution ratio in renal transplant patients

To establish an optimal method for determining a cyclosporin A (CyA) regimen based on physiological changes that occur during immunosuppressive therapy, the relationship between apparent CyA body clearance (CL/f) and the CyA erythrocyte-to-plasma distribution ratio (CyA-EP) was examined using clinical time courses obtained during routine monitoring. The CyA-EP, which was calculated by a multiple regression formula using routine data, was increased during renal dysfunction involving the normal recovery phase after transplantation, during nephrotoxicity, during acute tubular necrosis, and during acute renal rejection. CyA total body clearance (CLt), calculated by multiplying CL/f and converted bioavailability, fc (which is equal to 0.009 x LD, where LD represents the CyA level in blood per dose ratio), showed hyperbolic decay with increasing CyA-EP (the mean CLt was defined as follows: CLt = 0.937/CyA-EP), whereas fc showed exponential decay with increasing CyA-EP (the mean fc was defined as follows: fc = 0.593 x exp(-0.155 x CyA-EP)). These findings suggest that total CyA body clearance and its bioavailability were suppressed during the renal dysfunction phase. Hence, the mean CL/f as a function of the CyA-EP was given by the following equation: CL/f = 1.390 x exp(0.204 x CyA-EP)/CyA-EP. Since the CyA-EP reflects a patient's disease state and alterations in the CyA pharmacokinetic profile, these model formulae should provide an adequate method for determining a CyA dosage regimen for several disease states after renal transplantation.

Measurement of theophylline metabolites produced by reaction with hepatic microsome by high performance liquid chromatography following solid phase extraction

An analytical method has been developed with which to measure the microsomal enzyme activities responsible for oxidative theophylline metabolism. Three metabolites: 3-Methylxanthine (3-MX); 1-methylxanthine (1-MX); 1,3-dimethyluric acid (1,3-DMU), with acetaminophen as an internal standard (IS), were separated by solid phase extraction using a Sep-Pak C18 cartridge, followed by high performance liquid chromatography on a reversed-phase column with isocratic elution using 25 mM acetate buffer containing 4% acetonitrile and 2.5 mM tetra-n-butylammonium hydrogen sulphate (pH 5.25) as the mobile phase. The analytes were clearly resolved and no interference with foreign peaks was observed. A linear relationship was obtained for the metabolites over the concentration range of 0.5-5.0 micrograms/mL, and their analytical recovery was almost 100%. This method can be used to assess drug interactions involving alterations in the biotransformation of theophylline.

A simple method for predicting the cyclosporin A erythrocyte-to-plasma distribution ratio in blood, and its clinical assessment

To adapt the monitoring of cyclosporin A (CyA) to clinical practice, we have developed a model to predict the CyA erythrocyte-to-plasma distribution ratio (CyA-EP), and evaluated its utility in clinical practice. We monitored CyA trough concentrations in whole blood and performed a series of biochemical tests during disease states in patients undergoing immunosuppressive therapy with CyA after transplantation. An estimate of CyA-EP (EPpr) was thus given by the following equation: EPpr = 6.0831 - 0.2944 x (TG+CHO) - 0.0037 x (CyAblood) - 0.0553 x (HCT) + 0.0463 x (BW) + 0.4447 x (CRE) - 0.0366 x (AGE). In this predictive model, EPpr is given as a function of the plasma lipid levels (TG+CHO, mM), the CyA concentration in whole blood (CyAblood, ng/ml), and the hematocrit (HCT, %), as well as the patient's body weight (BW, kg), serum creatinine (CRE, mg/dl) and age (AGE, years). The parameters TG+CHO, CyAblood, HCT, and AGE were negatively correlated with the CyA-EP, whereas BW and CRE exhibited a positive correlation. The predictive performance of this model was satisfactory for clinical use and changes in CyA-EP in transplant patients were obtained from monitoring CyA in whole blood and routine biochemical tests, without directly measuring CyA-EP. Since CyA-EP is an useful indicator for predicting a shift of CyA into tissues and its systemic clearance in plasma, our model to predict the CyA-EP will help the physician select a CyA regimen during immunosuppressive therapy in a variety of disease states after transplantation.

Stereoselectivity in the hydroxylation of propafenone enantiomers in mouse hepatic microsomes

Stereoselectivity in the oxidative metabolism of propafenone (PPF) enantiomers to 5-hydroxypropafenone was studied with untreated and inducer-treated mouse hepatic microsomes. In the untreated microsomes, Lineweaver-Burk plots of the 5-hydroxylation of R(-)- and S(+) PPF. single lines, and the intrinsic clearance (Vmax/Km) value of R(-)-PPF was 1.3-fold higher than that of S(+)-PPF. When racemic PPF was used as a substrate, the plot was shifted to the upper region, in comparison with that estimated from the sum of the individual 5-hydroxylase activities of each enantiomer, suggesting enantiomer/enantiomer interaction. In phenobarbital-induced microsomes, the Lineweaver-Burk plot for R(-)-PPF was a single line, but that for S(+)-PPF was biphasic. When racemic PPF was used as a substrate, the plot was biphasic and was shifted to the upper region in comparison with that estimated from the sum of the individual 5-hydroxylase activities of each enantiomer. The observed value of intrinsic clearance of the PPF racemate at lower concentrations (Vmax/Km1) was consistent with the estimated value, suggesting no interaction between R(-)- and S(+)-PPF. These findings indicate that most of the 5-hydroxylation of R(-)- and S(+)-PPF is catalyzed by common cytochrome P-450 species, but a part of S(+)-PFF 5-hydroxylation is catalyzed by another phenobarbital inducible cytochrome P-450 species, particularly at lower substrate concentrations.

Changes in the concentration of serum alpha 1-acid glycoprotein in epileptic patients

Factors leading to elevation of the serum level of alpha 1-acid glycoprotein (AAG), the principal binding protein of cationic drugs in the systemic circulation, were investigated in 142 epileptic patients receiving long-term therapy with carbamazepine (CBZ), phenytoin (DPH), phenobarbital (PB), or valproate (VPA). The mean serum activity of gamma-glutamyl transpeptidase (gamma-GTP), an indicator of enzyme induction, in the groups of patients receiving enzyme inducers such as CBZ, DPH, and/or PB was at least some 5-fold higher than in patients receiving VPA alone, which is well known to be a non-inducer. There was no significant difference in the mean serum level of AAG between the former and the latter groups, i.e. there was no correlation between AAG and gamma-GTP levels in serum, and it is unlikely that the enzyme inducing properties of CBZ, DPH and PB are associated with an increased level of AAG. The mean serum level of AAG in the patients with poorly controlled seizures was significantly higher than in those with well controlled seizures (0.81 vs. 0.56 milligram). The serum AAG level in individual patients changed in parallel with the frequency of seizures. The present results strongly suggest that elevation of serum AAG level in epileptic patients may not be associated with the enzyme-inducing activities of anticonvulsants, but with the epileptic seizures per se.

Effect of fluconazole on theophylline disposition in humans

The effect of fluconazole, an antimycotic that inhibits cytochrome P-450-mediated drug metabolism, on theophylline kinetics and the production of its metabolites were compared with those of enoxacin in 5 healthy subjects. All subjects received a single oral dose of 240 mg theophylline (aminophylline, 300 mg) after they had been given oral fluconazole 100 mg every 12 h or enoxacin 200 mg every 8 h for three consecutive days. Pretreatment with enoxacin decreased the total clearance (CLT) and elimination rate constant (Kel) of theophylline by 50% and 46%, respectively, without changing the volume of distribution (Vd), but there were no significant change in any pharmacokinetic parameter when fluconazole was administered. Enoxacin led to a 50% reduction in the metabolic clearance (CLM) of theophylline and to decreases of 69%, 59% and 38% in the formation clearance of the three theophylline metabolites, 3-methylxanthine (3-MX), 1-methyluric acid (1-MU), and 1,3-dimethyluric acid (1,3-DMU), respectively, accompanied by significant changes in the urinary recovery of theophylline and its metabolites. In contrast, treatment with fluconazole led only to a slight decrease in the CLM of theophylline (16%) and in the formation clearance of its metabolites (15%-18%), and there was no change in the renal clearance (CLR) of theophylline. The results indicate that fluconazole is a minor inhibitor of theophylline disposition compared with enoxacin, and they suggest that the inhibitory action of fluconazole is selective for certain cytochrome P-450 isozymes, but not for the cytochrome P-4501A involved in theophylline metabolism.

Pharmacokinetics of cyclosporin A after intravenous administration to rats in various disease states

We examine the pharmacokinetic profile of cyclosporin A (CyA) after intravenous administration to rats prepared as models of various disease states found in patients who receive organ transplantations. After intravenous bolus administration to normal rats, the total blood clearance (CLt) of CyA showed a dose-dependent increase. The CLt was reduced in anemic (ANE) rats prepared by venesection, in carbon tetrachloride-induced acute hepatic failure (AHF) rats, and in glycerol-induced acute renal failure (ARF) rats. On the other hand, the volume of distribution at a steady state (Vss) of CyA increased significantly in ANE and aged (AGE) rats. CyA distribution was tissue-specific, and the tissue CyA concentration was disease state-dependent. Linear relationships between the CyA concentration in whole blood and various tissues (liver, kidney and heart) were found in AGE, ANE and AHF animals. However, in ARF rats, tissue concentration was not increased to a great extent in comparison with the other disease models, even though the whole blood CyA concentration was increased. The tissue per blood concentration ratio (Kb), which represented the CyA tissue transfer from systemic circulation, was influenced by the disease state. In the liver, in particular, the Kb increased in the AHF and AGE groups, whereas it decreased in the ANE and ARF rats. The CLt of CyA was negatively related to the erythrocyte per plasma concentration ratio (E/P), and the E/P exhibited disease state-dependent changes, suggesting that this ratio is a valuable indicator for predicting variations in CyA total blood clearance in organ transplant patients during episodes of anemia, nephrotoxicity and hepatotoxicity.

Erythrocyte uptake and protein binding of cyclosporin A (CyA) in human blood: factors affecting CyA concentration in erythrocytes

To further the understanding of the complexity of cyclosporin A (CyA) pharmacokinetics, we conducted an erythrocyte uptake and efflux study, and a protein binding study in human blood. The uptake study showed that the transport of CyA from the extracellular fraction to erythrocytes was retarded by increased human serum albumin (HSA) and lipid levels in this fraction. In addition, the concentration of CyA in erythrocytes increased with increases in CyA concentration in blood and reductions in hematocrit. The efflux study showed that the transport of CyA from erythrocytes to the extracellular fraction was essentially enhanced by increases of HSA and lipid levels in that fraction, but that these effects were relatively small. There were two affinity binding sites for CyA in ghost-free erythrocyte hemolysate, but not in the plasma fraction. The affinity binding constants for these binding sites were reduced by elevations in temperature, and under physiological conditions, 37 degrees C, almost all the CyA in erythrocytes was bound to a CyA binding protein, namely, cyclophillin. These findings suggest that CyA distribution in blood is of two different types which are present in the erythrocyte and plasma fractions, respectively. Monitoring of blood biochemistry variables showed that the concentration of CyA in erythrocytes had an interlocking relationship with these physiological factors, which were related to patient disease state, i.e., hematocrit, lipids, albumin, and total protein; the concentration of CyA in erythrocytes could be predicted from these physiological factors.