Quick-scanning x-ray absorption spectroscopy system with a servo-motor-driven channel-cut monochromator with a temporal resolution of 10 ms

We have developed a quick-scanning x-ray absorption fine structure (QXAFS) system and installed it at the recently constructed synchrotron radiation beamline BL33XU at the SPring-8. Rapid acquisition of high-quality QXAFS data was realized by combining a servo-motor-driven Si channel-cut monochromator with a tapered undulator. Two tandemly aligned monochromators with channel-cut Si(111) and Si(220) crystals covered energy ranges of 4.0-28.2 keV and 6.6-46.0 keV, respectively. The system allows the users to adjust instantly the energy ranges of scans, the starting angles of oscillations, and the frequencies. The channel-cut crystals are cooled with liquid nitrogen to enable them to withstand the high heat load from the undulator radiation. Deformation of the reflecting planes is reduced by clamping each crystal with two cooling blocks. Performance tests at the Cu K-edge demonstrated sufficiently high data quality for x-ray absorption near-edge structure and extended x-ray absorption fine-structure analyses with temporal resolutions of up to 10 and 25 ms, respectively.

MULTI-SITE AEROSOL MONITORING USING MINI STEP SAMPLER

We developed mini step samplers with low manufacturing and running costs for application in multi-site air-pollution monitoring. The miniaturization of the sampler was achieved by reducing the suction nozzle size. We tested the samplers with suction nozzle diameters of 2 and 4 mm through simultaneous exposure in the same site. Elemental concentrations of aerosol collected by these samplers were consistent within ±20% during comparison and the sample uniformity did not differ significantly. Sampling with small suction nozzle did not adversely affect aerosol collection. Aerosol samples were collected simultaneously at two sites in our laboratory and in the hall outside for 3 days and analyzed subsequently by PIXE. The time variation of elemental concentrations was high during daytime and low at night time and also during the weekend. Elemental concentrations in the hall were always higher than those in the laboratory. In our laboratory, we change shoes at the entrance and therefore, elemental concentrations inside the lab are lower than in the hall. In a second field experiment, we carried out simultaneous multi-site aerosol sampling during two periods in correlation with meteorological data (wind direction and velocity). It was observed that elemental concentrations of some soil origin elements changed periodically. On the other hand, the concentration of Cu and Zn showed irregular concentration spikes whose pattern showed a variation with the sites. Analysis using the data of wind directions showed that Cu had been transported to the sites from northeasterly direction and that the concentration of Zn was influenced by two big factories nearby. In conclusion, it has been demonstrated that the multi-site sampling system combined with meteorological data is well suited to identify sources of pollution.

AN ATTEMPT TO DETERMINE POSITIONS OF AEROSOL SOURCE BY THE PIXE ANALYSIS

Aerosols were continuously collected for 2 or 3 hours during the periods of 4-27 August 1997 and of 23 March-2 April 1998 at a suburb of Sendai City (east 10 km from Sendai), and meteorological data such as wind directions, wind velocities, etc were measured at the same time. The collected aerosol samples were analyzed by the particle-induced X-ray emission (PIXE) method. Fourteen elements (S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Hg and Pb) were contained in these samples. The elemental concentrations increased in the daytime and decreased at night. It coincided with the time variation of people movement. The concentrations of Mn, Fe, Zn and Pb elements depended strongly on the direction of wind and their distributions for wind directions reflected to the position of aerosol sources. This result suggests that the position of aerosol source can be determined by measuring aerosols and wind directions at the many positions.

Preparation of Thin Polycarbonate Film and Its Application to PIXE Analysis of Anionic Elements in Water Samples

A polycarbonate film of thin and uniform thickness was prepared. A casting solution for film-formation was made up by diluting a solution of poly (bisphenol A carbonate) in chloroform by a factor of two to three with benzene. A uniform film was created by dropping 0.2-0.3 cm3 of the casting solution slowly on a water surface within an aperture (20 mm diameter) of Mylar target frame floating on 50 wt% sucrose aqueous solution. Films of 0.14-0.27 mg/cm2 thickness thus prepared offer a good combination of mechanical strength and low continuum backgrounds. To test PIXE analysis of anionic species in water, targets containing SO 42-, Cr 2 O 72-, AsO 43-, and Ga 3+-internal standard were prepared by depositing 100 μl of the test solutions onto the polycarbonate film, and irradiated in vacuum by 3 MeV proton beams. The difference between the nominal and the analyzed concentrations seldom exceeded ± 15 % in the range from 10 to 2000 ppb.

Successful treatment of Trichosporon fungemia in a patient with refractory acute myeloid leukemia using voriconazole combined with liposomal amphotericin B

Trichosporon fungemia is a rare and fatal fungal infection that occurs in patients with prolonged neutropenia associated with hematologic malignancies. A 21-year-old male developed Trichosporon fungemia during remission induction therapy for acute myeloid leukemia (AML). Although two courses of induction therapy failed to induce a remission of AML, combination therapy with voriconazole and liposomal amphotericin B (L-AmB) followed by monocyte colony-stimulating factor ameliorated the Trichosporon fungemia and enabled the patient to receive reduced-intensity bone marrow transplantation (BMT) from his human leukocyte antigen-A one-locus mismatched mother. The patient achieved a durable remission after BMT without exacerbation of Trichosporon fungemia. The combination therapy with voriconazole and L-AmB may therefore be useful in controlling Trichosporon fungemia associated with prolonged neutropenia after remission induction therapy for AML.

Population pharmacokinetics of fluconazole after administration of fosfluconazole and fluconazole in critically ill patients

WHAT IS KNOWN AND OBJECTIVE

Fluconazole is an antifungal agent that is commonly used to treat patients with serious systemic fungal infections in intensive care units. Fosfluconazole is a phosphate prodrug of fluconazole, which was developed to reduce the volume of fluid required to administer fluconazole by intravenous injection. The objective of this study was to characterize the pharmacokinetics of the antifungal fluconazole after the intravenous administration of the prodrug fosfluconazole or fluconazole in critically ill patients with serious systemic fungal infections, by population pharmacokinetic analysis using the nonmem software package.

METHODS

Clinical biochemical data including serum fluconazole levels were obtained from 57 patients treated in the intensive care unit along with two naïve pooled patients gleaned from previous reports. The pharmacokinetic model of fluconazole was estimated using a one-compartment model. The probability that the area under the concentration-time curve is higher than 800 μg h/mL was determined by simulation.

RESULTS

It was assumed that all the administered fosfluconazole was converted to fluconazole with an estimated fosfluconazole-fluconazole conversion rate constant of 2·05/h. The significant covariates for clearance for fluconazole (CL) and volume of distribution for fluconazole (Vd) were resulted in creatinine clearance (CLcr) and body weight (BW), respectively, in the final pharmacokinetic model equations: CL (L/h) = 0·799 × [CLcr (mL/min)/92·7](0·685) and Vd (L) = 48·1 × [BW (kg)/65](1·40) , where the interpatient variabilities in CL and Vd and the intrapatient variability were 44·8%, 79·7% and 19·8%, respectively. On the basis of the results of the Monte Carlo simulation, the probabilities of target attainment were 60%, 26% and 11% for 400 mg/day administration as fluconazole equivalent at CLcr values of 40, 70 and 100 mL/min, respectively.

WHAT IS NEW AND CONCLUSION

The present population pharmacokinetic analysis strongly indicates that fosfluconazole (and fluconazole) dosage should be optimized in terms of CLcr in critically ill patients.

Steady and transient behaviors of protoplasmic streaming in Nitella internodal cell

Steady and transient behaviors of protoplasmic streaming in Nitella internodal cell have been investigated for various temperatures from 30 degrees C to near 0 degrees C. It has been found that steady velocity of the streaming linearly decreases with increasing inverse temperature but its proportionality coefficient changes at approximately 10 degrees C. Velocity distribution, which reflects temporal fluctuations of the protoplasmic streaming, is nonGaussian and its half width becomes larger at higher temperatures. On the other hand, recovery of the protoplasmic streaming, which is observed after stopping the streaming with a current stimulus to the internodal cell, has been found to show more clear sigmoidal time courses at higher temperatures.

Increased distribution of carboplatin, an anti-cancer agent, to rat brains with the aid of hyperbaric oxygenation

1. The distribution of an anti-cancer agent carboplatin to brains was investigated in combination with hyperbaric oxygenation treatment in rats. 2. After intravenous administration of carboplatin (30 mg kg(-1)) to male Wistar rats, elimination curves of plasma drug concentrations plotted against a time of 45 min were not different with or without hyperbaric oxygenation (at 0.20-0.25 MPa for last 20 min) treatments. 3. Carboplatin concentrations of livers, lungs and kidneys in each group were similar at the endpoint of hyperbaric oxygenation treatment. 4. Under these atmosphere conditions (at 0.10 MPa), carboplatin concentration was at an undetectable level in rat brains (<0.1 microg g(-1) tissue, n = 6). On the contrary, carboplatin was detected in all brains tested at the levels of 0.5 +/- 0.3 microg g(-1) tissue (mean and standard deviation (SD), n = 6), 0.8 +/- 0.5 microg g(-1) tissue, and 0.4 +/- 0.2 microg g(-1) tissue in combination with hyperbaric oxygenation at 0.20, 0.22, and 0.25 MPa, respectively, at the endpoint of hyperbaric oxygenation treatment. 5. The results suggest that carboplatin could be uptaken into rat brains at the detectable levels by the aid of hyperbaric oxygenation, consistently with the reported findings of enhanced transendothelial permeability and improved clinical efficacy of carboplatin combined hyperbaric oxygenation therapy.

Results of tenolysis for flexor tendon adhesion after phalangeal fracture

There are only three reports of the surgical outcomes of flexor tendon tenolysis after phalangeal fractures. The fracture type, the time to mobilisation following injury and the time between the injury and tenolysis did not affect the results of tenolysis. The outcome only correlated significantly to the total passive range of motion before tenolysis.

Prediction ofin vivodrug clearance fromin vitrodata. II: Potential inter-ethnic differences

Potential differences in drug clearance between Japanese and Caucasians were investigated by integrating data on demography, liver size, the abundance of the major cytochromes P450 and in vitro metabolic parameters. Eleven drugs (alprazolam, caffeine, chlorzoxazone, cyclosporine, midazolam, omeprazole, sildenafil, tolbutamide, triazolam, S-warfarin and zolpidem) fulfilled the entry criteria of the study (i.e. the necessary in vitro metabolism data were available and clearance values had been reported both in Caucasians and Japanese). Values of relevant biological variables were obtained from the literature, and clearance predictions were made using the Simcyp Population-Based ADME Simulator. The ratios of observed oral clearance (CLp.o.) values in Caucasians compared with Japanese ranged from 0.6 to 2.8 (integrating data from 82 sources). The CLp.o. values for alprazolam, caffeine and zolpidem were not statistically different between Caucasian and Japanese (p>0.05), whereas those for chorzoxazone, cyclosporine, omeprazole, tolbutamide and triazolam were higher in Caucasians (p<0.05), and those for midazolam, sildenafil and S-warfarin were higher in Japanese (p<0.05). CLp.o. values, predicted from in vitro data, were within 3-fold of observed in vivo values for seven of the 11 drugs in Japanese. Values for the predicted ratios ranged from 1.6 to 4.9. The predicted ratios were not significantly different from observed ratios for cyclosporine, omeprazole, tolbutamide and triazolam. Only partial success in predicting ethnic differences in clearance indicates the need for larger and more reliable databases on relevant variables. With such information, in silico predictions might be used with more confidence to decrease the need for repeating pharmacokinetic studies in different ethnic groups.

Species differences in hydrolase activities toward OT-7100 responsible for different bioavailability in rats, dogs, monkeys and humans

OT-7100 (5-n-butyl-7-(3,4,5-trimethoxybenzoylamino)pyrazolo[1,5-a] pyrimidine) is an amide moiety-bearing pyrazolopyrimidine derivative with a potential analgesic effect. To determine the factors responsible for observed species differences in the bioavailability of this drug, human and experimental animal samples were used to investigate in vitro microsomal and cytosolic hydrolase activities in the liver and small intestine vis-à-vis the pharmacokinetics of OT-7100. The AUC(0-t) values of OT-7100 after oral administration in rats, dogs and monkeys were 0.163, 0.0383 and 0.00147 microg h ml(-1) divided by mg kg(-1), respectively. The bioavailabilities of OT-7100 after oral administration in rats, dogs and monkeys were 36, 17 and 0.3%, respectively. The plasma concentration-time profiles of intravenously administrated OT-7100 in rats, dogs and monkeys were similar. The hydrolase activities toward OT-7100 in liver microsomes or cytosol were approximately similar in rats, dogs, monkeys and humans. In contrast, hydrolase activities of small intestinal microsomes from monkeys were higher (36.1 ng mg protein(-1) min(-1)) than those of rats, dogs and humans (5.4, 1.4 and 4.3 ng mg protein(-1) min(-1), respectively). These results suggest that the primary factor influencing first-pass metabolism for the OT-7100 is enzymatic hydrolysis in the small intestine. This information provides an important index for extrapolating the pharmacokinetics of drugs in humans using studies on monkeys.

Ethnic differences between Japanese and Caucasians in the expression levels of mRNAs for CYP3A4, CYP3A5 and CYP3A7: lack of co-regulation of the expression of CYP3A in Japanese livers

Using a newly developed real-time reverse transcriptase-polymerase chain reaction method, mRNAs were quantitated for CYP3A4, CYP3A5 and CYP3A7 in adult livers from 24 Japanese and 24 Caucasian subjects to elucidate the potential ethnic differences in the expression levels of human cytochrome P450 (CYP) 3As. The expression level of CYP3A4 mRNA in Japanese livers (n = 24) was approximately three times higher than that in Caucasian livers (n = 24, p < 0.001). The mean level of CYP3A5 mRNA was approximately twice higher in Japanese (n = 9) than in Caucasians (n = 5) heterozygous for the CYP3A5 *1 allele (p = 0.057). The CYP3A7 mRNA level was twice higher in Japanese (n = 24) than in Caucasians (n = 22) carrying the CYP3A7 *1A/ *1A genotype (p = 0.042). The level of CYP3A4 mRNA did not correlate with those of CYP3A5 (r = 0.044, n = 24) or CYP3A7 (r = 0.21, n = 24) mRNAs in Japanese livers in contrast to co-regulatory expression of CYP3A4, CYP3A5 and CYP3A7 in Caucasian livers. The results indicate that there are ethnic differences in the expression levels of adult liver CYP3A mRNAs between Japanese and Caucasians, and that the mechanism(s) regulating the hepatic CYP3A expression may be different between these ethnic groups.

Involvement of human cytochrome P450 2B6 in theω- and 4-hydroxylation of the anesthetic agent propofol

Human liver microsomal cytochrome P450s (P450s or CYP) involved in the oxidative biotransformation of the anesthetic agent propofol were investigated. Of six cDNA-expressed human P450 enzymes tested, CYP2B6 and CYP1A2, followed by CYP3A4, had high catalytic activities at a 20 microM propofol concentration, corresponding to clinical plasma levels. K(m) and k(cat) values for propofol omega- and 4-hydroxyation were 27 microM and 21 nmol omega-hydroxypropofol formed/min/nmol CYP2B6 and 30 microM and 42 nmol 4-hydroxypropofol formed/min/nmol CYP2B6, respectively. CYP2B6 expressed in HepG2 cells also effectively catalyzed propofol omega- and 4-hydroxylation. In a panel of individual human liver microsomes, propofol omega- and 4-hydroxylation activities (at the substrate concentration of 20 microM) were highly correlated with CYP2B6 contents, and moderately with CYP3A4 contents. Anti-CYP2B6 antibody inhibited both omega- and 4-hydroxylation activities in human liver samples that contained relatively high levels of CYP2B6, whereas alpha-naphthoflavone and an anti-CYP1A2 antibody showed inhibitory effects on the 4-hydroxylation activity in a liver microsomal sample in which the CYP1A2 level was relatively high. These results suggest that CYP2B6 has an important role in propofol omega- and 4-hydroxylation in human livers and that the hepatic contents of CYP2B6, CYP3A4, and CYP1A2 determine which P450 enzymes play major roles in propofol oxidation in individual humans.

Increased transendothelial permeability of anti-cancer agent carboplatin with the aid of hyperbaric oxygenation

1. The objective was to investigate the transport of an anticancer agent carboplatin across the blood-brain barrier in combination with hyperbaric oxygenation treatment. An in vitro well-validated model of bovine brain capillary endothelial cells was used. 2. A transendothelial transport of doxorubicin, a known P-glycoprotein substrate, was enhanced 1.5-fold by verapamil for 2-h incubation at 37 degrees C. A transendothelial permeability coefficient of carboplatin (1.29 x 10(-3)cm min-1) was also increased 1.8-fold by verapamil. 3. Under the hyperbaric oxygenation conditions (at 0.2 MPa for the first 10 min), the transendothelial transport for 2 h of doxorubicin and carboplatin were increased 1.3- to 1.8-fold by hyperbaric oxygenation, like the suppressive effects of verapamil on P-gp function, without increase of the transport of lucifer yellow, a non P-glycoprotein substrate. 4. Combination of hyperbaric oxygenation treatment and verapamil could not further increase the permeability coefficients of these drugs that were already enhanced by either treatment, implying the P-glycoprotein-mediated carboplatin efflux transport similarly as doxorubicin. 5. Together with our reported high efficacy of carboplatin combined with hyperbaric oxygenation therapy on brain tumours, the present results suggest that carboplatin could be transported by P-glycoprotein, but that this efflux mechanism would be reduced by the hyperbaric oxygenation with the consequences of clinical efficacy.

Extensor tendon rupture associated with osteoarthritis of the distal radioulnar joint

Non-rheumatoid osteoarthritis of the distal radioulnar joint can cause extensor tendon rupture. We analysed the radiographic morphology of the distal radioulnar joint to identify the risk factors for this complication. Forty-one wrist X-rays of 37 patients with extensor tendon rupture caused by distal radioulnar joint osteoarthritis were evaluated retrospectively for the severity of osteoarthritis by the Kellgren/Lawrence scoring system. Measurements were obtained from posteroanterior views. All but one wrist had severe osteoarthritic changes exceeding grade 3. The radiographic features that were different from those of the contralateral wrists included deepening and widening of the sigmoid notch, radial shift of the ulnar head and dorsal inclination of the sigmoid notch. There was no significant association between tendon rupture and the morphology of the ulnar head or ulnar variance. The scallop sign, dorsal inclination of the sigmoid notch and radial shift of the ulnar head are radiological risk factors for extensor tendon ruptures.

Restriction enzyme digestion analysis of PCR-amplified DNA of Blastocystis hominis isolates

Genomic DNA of Blastocystis isolates released into 0.1% Triton X-100 was suitable for amplification and yielded similar results as the genomic DNA extracted with standard kit. The specific B. hominis primers (BH1: GCT TAT CTG GTT GAT CCT GCC AGT and BH2: TGA TCC TTC CGC AGG TTC ACC TAC A) successfully produced the PCR product of about 1,770 bp with all the 7 Blastocystis isolates tested. The restriction fragment length polymorphism (RFLP) patterns yielded by 13 out of 25 restriction endonucleases showed that the 7 isolates could be grouped into 4 subgroups: subgroup-1 consisted of isolate C; subgroup-2 of isolates H4 and H7; subgroup-3 of isolates KP1, Y51 and M12; and subgroup-4 of isolate 27805. The differences between subgroups manifested as clear-cut RFLP patterns. A common band of 230 bp was revealed by Eco R1 in all the Blastocystis isolates tested. The band of about 180 bp was revealed by Alu I, differentiated symptomatic from asymptomatic isolates of this parasite, and might indicate the pathogenicity of this parasite.

Enhanced enamel remineralization under acidic conditions in vitro

We conducted this study to test the hypothesis that acidic solutions undersaturated with respect to enamel and supersaturated with respect to fluorapatite can enhance enamel remineralization by reducing preferential remineralization of the outer lesion and promoting mineral ion penetration. We used quantitative microradiography to assess mineral changes in artificial surface-softened and subsurface lesions in human enamel in vitro, induced by such an acidic solution and by a neutral remineralizing solution. For surface-softened lesions, the extent of remineralization was similar for both solutions, although preferential remineralization of the outer lesion was observed with the neutral solution. For subsurface lesions, preferential remineralization of the outer lesion was not observed with either solution. However, the extent of subsurface lesion remineralization by the acidic solution was significantly greater than that observed with the neutral solution. Results obtained are noted to reflect inherent differences in lesion type and the properties of the solutions studied.

Cooperative updating in the Hopfield model

We propose a new method for updating units in the Hopfield model. With this method two or more units change at the same time, so as to become the lowest energy state among all possible states. Since this updating algorithm is based on the detailed balance equation, convergence to the Boltzmann distribution is guaranteed. If our algorithm is applied to finding the minimum energy in constraint satisfaction and combinatorial optimization problems, then there is a faster convergence than those with the usual algorithm in the neural network. This is shown by experiments with the travelling salesman problem, the four-color problem, the N-queen problem, and the graph bi-partitioning problem. In constraint satisfaction problems, for which earlier neural networks are effective in some cases, our updating scheme works fine. Even though we still encounter the problem of ending up in local minima, our updating scheme has a great advantage compared with the usual updating scheme used in combinatorial optimization problems. Also, we discuss parallel computing using our updating algorithm.

Long pulse production of high current D(-) ion beams in the JT-60 negative ion source

The first long pulse production of high power D(-) ion beams has been demonstrated in the JT-60 U negative ion sources, each of which was designed to produce 22 A, 500 keV D(-) ion beams. Voltage holding capability and the grid power loading were examined for long pulse production of high power D(-) ion beams. From the correlation between voltage holding and the light intensity of cathodoluminescence from the Fiber Reinforced Plastic insulators, the acceleration voltage for stable voltage holding capability was found to be less than 320-340 kV where the light was sufficiently suppressed. By tuning the extraction voltage, the grid power loadings in the ion sources were decreased to the allowable levels for long pulse injection without a significant reduction of the beam power. After tuning the acceleration and extraction voltages, D(-) ion beams of 12.5 and 9.8 A were produced at 340 keV with cesium seeding at a rate of approximately 14 microg/s into the ion sources. The pulse duration of these D(-) ion beams was extended step by step, and then was successfully extended up to 18 s without degradation of the negative ion production. The D(-) ion beams were neutralized to yield 3.6 MW D(0) beams by a gas cell, and then injected into the JT-60 U plasma. Further, a slight reduction of D(-) ion beam power allowed the longer injection duration of 21 s at a D(0) beam power of 3.2 MW. The success in the long pulse production of a high power D(-) ion beam shows that negative ion beams can be produced during a few tens of seconds without degradations of negative ion production and the voltage holding in a large Cs-seeded negative ion source.

Depositional records of plutonium and (137)Cs released from Nagasaki atomic bomb in sediment of Nishiyama reservoir at Nagasaki

In a sediment core of Nishiyama reservoir at Nagasaki city, depth profiles of (240)Pu/(239)Pu isotopic ratio, (239+240)Pu and (137)Cs activities were determined. Sediments containing plutonium and (137)Cs, which were deposited immediately after a detonation of Nagasaki atomic bomb, were identified in the core. Observed below the sediments were macroscopic charcoals, providing evidence for initial deposit of the fallout of the Nagasaki atomic bomb. This is the first entire depositional records of plutonium and (137)Cs released from the Nagasaki atomic bomb together with those from atmospheric nuclear tests.

Closed rupture of the flexor tendons caused by carpal bone and joint disorders

We analysed 21 patients with closed rupture of the flexor tendons caused by carpal bone and joint disorders. The tendon that ruptured depended on the location of the bone perforation into the carpal tunnel. Radiocarpal arthrography was performed in 13 patients and capsular perforation was demonstrated by contrast medium leakage into the carpal canal in 11 patients. This proved a useful diagnostic test. The flexor tendon(s) were reconstructed with free tendon graft in 17 patients, cross-over transfer of flexor tendons from adjacent digits in two and buddying to an adjacent flexor tendon in one patient. Postoperative total active range of motion in the fingers after 13 free tendon graft reconstructions averaged 213 degrees (range 170-265 degrees ). The active range of motion of the thumb-interphalangeal joint after free tendon graft reconstruction in three cases improved from 0 degrees to 33 degrees on average (range 10 degrees -40 degrees ).

Disparity in holoprotein/apoprotein ratios of different standards used for immunoquantification of hepatic cytochrome P450 enzymes

An analysis of reported hepatic abundances of CYP3A4 and 3A5 indicated that values determined by immunoquantification using commercially available, unpurified recombinant enzymes as standards are significantly lower than those determined using purified enzymes or human liver microsomes characterized with lysosomal peptides (CYP3A4: mean 45 versus 121 pmol/mg protein, p < 0.01; CYP3A5: mean 28 versus 83 pmol/mg protein, p < 0.05). When immunoquantifying cytochromes P450 (P450s), it is assumed that the holoprotein (holo)/apoprotein ratio is the same in the samples and the standard. Estimates of holo/apoprotein ratios from data reported for a range of P450s purified from human liver and non-commercial recombinant systems indicated less than complete and variable heme coupling dependent on enzyme and system.