[Clinical efficacy analysis of arthroscopic treatment for hallux ganglion cyst deriving from ankle joint].

Objective: To investigate the pathogenesis and clinical efficacy of arthroscopic treatment for hallux ganglion cyst deriving from ankle joint. Methods: The clinical data of 21 patients with ankle arthroscopic in the Department of Hand and Foot Surgery,Affiliated Hospital of Jining Medical College from January 2019 to March 2021 were analyzed retrospectively.There were 15 male and 6 female cases,aged (52.6±8.2) years (range:42 to 70 years).There were 9 cases of primary operation and 12 cases of recurrence after operation in other hospital.All the patients were examined by ankle arthrography and MRI before operation.The synovial membrane of the ankle was debrided and the tendon sheath of flexor longus was removed at the ankle canal.One year after operation,MRI was performed,and the American Orthopedic Foot and Ankle Society(AOFAS) score of forefoot function and visual analogue scale (VAS) before and after operation were compared by the paired t test or Mann-Whitney U test.The postoperative complications and recurrence were recorded. Results: All patients were operated successfully.The joint capsule at the back of the ankle joint of the patients were ruptured and communicated with the tendon sheath of the flexor longus tendon at the ankle canal.No wound infection,vascular and nerve injury occurred.The follow-up period was (15.0±2.2) months (range:12 to 18 months).During the follow-up period,there was no recurrence of toe appearance and MRI.At the last follow-up,the AOFAS score (90.8±4.3) was significantly higher than that (72.8±6.3) before operation (t=-10.810,P<0.01),and the VAS score(M(IQR)) was significantly lower than that before operation,the difference was significant (1.0(1.0) vs. 3.0(0.5), Z=-4.081,P<0.01). Conclusions: The possible mechanism of hallux ganglion cyst deriving from ankle joint is that the joint capsule at the back of the ankle joint ruptures and communicates with the tendon sheath of the flexor longus tendon at the ankle canal,and the intra-articular synovial fluid through the cylinder effect generated by sliding with the flexor tendon of the flexor longus tendon in the tendon sheath sac leads to the heel valange cyst.Ankle-synovial cleansing of the ankle joint under ankle arthroscopy and resection of the flexor tendon sheath of the flexor longus tendon at the ankle canal are effective and less invasive.

[Association between HULC gene locus rs7763881 polymorphism and recurrence and metastasis after radical resection in hepatocellular carcinoma].

Objective: To investigate the association between the expression of long non-coding RNA genes and the HULC rs7763881 polymorphism, recurrence, and metastasis after radical resection in patients with hepatocellular carcinoma (HCC). Methods: Paraffin tissue samples were selected from 426 cases diagnosed with HCC between January 2004 to January 2012. The expression of different genotypes of HULC gene locus rs7763881 in paraffin tissues was detected by PCR, and the association between different genotype expressions and clinical case characteristics of HCC [gender, age, TNM stage, alpha-fetoprotein, tumor maximum diameter (cm), vascular invasion, tumor capsule, tumor grade] was analyzed. Cox proportional risk regression model was used to analyze the correlation between different genotypes and clinicopathological features, prognosis, and recurrence. Survival analysis between different genotypes was performed using the Kaplan-Meier method for a parallel log-rank test. Results: There were 27 (6.3%) cases in the whole group who lost to follow-up. A total of 399 (93.7%) specimens were included in the study, and 105 (26.3%), 211 (52.9%) and 83 (20.8%) were included in the rs77638881 AA, AC, and CC genotypes, respectively. Kaplan-Meier curve showed that the postoperative overall survival and recurrence-free survival rate were significantly higher in patients with the AA than AC/CC genotype (P < 0.05). Univariate analysis showed that the AC/CC genotype was closely related to tumor vascular invasion and recurrence or metastasis of HCC (P < 0.05). Cox multivariate analysis results showed that patients with the AA genotype were taken as references, and the results showed that the risk of recurrence and metastasis in patients with the CA/CC genotype increased to varying degrees, with statistical significance (P < 0.05). Conclusion: The rs7763881 polymorphic loci located on the HULC gene are closely related to HCC recurrence and metastasis after radical resection. Thus, it may be an indicator for evaluating HCC recurrence and metastasis.

Nitrogen-rich Fe-N-C materials derived from polyacrylonitrile as highly active and durable catalysts for the oxygen reduction reaction in both acidic and alkaline electrolytes.

Fe-N-C catalyst with a core-graphitic shell nanostructure was synthesized by pyrolysis of polyacrylonitrile (PAN)-coated carbon black in the presence of iron salts. The attained catalyst exhibits high performance towards the oxygen reduction reaction (ORR) in both acid and alkaline electrolytes, with the half-wave potentials of 97mV negative and 39mV positive to Pt/C in 0.5M H2SO4 and 0.1M NaOH, respectively. Meanwhile, the catalyst shows high stability and remarkable tolerance towards methanol. The XRD analysis demonstrates that both the introduction of iron and an increase of the pyrolysis temperature promote the growth of layers in the graphitic shell. With the rise of pyrolysis temperature, increases of the catalytic activity and Fe3+ reduction potential are observed, as well as the relative content of nitrogen of Fe-Nx type and N 1s binding energy. Moreover, a linear relationship between the logarithm of ORR turnover number and the Fe3+ reduction potential is observed. Based on these findings, the enhanced ORR performance of the catalyst can be attributed to the growth of π-conjugated graphitic layers, which modulates the electronic structure of embedded Fe-N4 sites. In addition, the presence of an accessible core-graphitic shell nanostructure facilitates the mass transport of ORR-relevant species between the electrolyte and the catalytic sites.

Rod-like CuMnOx transformed from mixed oxide particles by alkaline hydrothermal treatment as a novel catalyst for catalytic combustion of toluene.

Rod-like copper manganese mixed oxides (CuMnx-NR) have been synthesized from copper manganese mixed oxide particles by sodium hydroxide hydrothermal treatment, and a higher BET surface area of 221 m(2) g(-1) is obtained on the nanorod-like sample, which exhibits superior catalytic activity toward toluene combustion at 210 °C due to the increase in its oxygen mobility of the chemisorbed oxygen species as well as the increase in surface concentrations of higher valance cations, Cu(2+), Mn(3+) and Mn(4+), in the samples.

MOF-derived binary mixed metal/metal oxide @carbon nanoporous materials and their novel supercapacitive performances.

Mixed cobalt and manganese oxides embedded in the nanoporous carbon framework (M/MO@C) were synthesized by the direct carbonization of a binary mixed-metal organic framework (CoMn-MOF-74) for the first time. The unique M/MO@C carbon materials maintained the primary morphology of CoMn-MOF-74, and showed a uniform dispersibility of Co, MnO and CoO nanoparticles in the carbon matrix, and therefore greatly increased the conductivity of the M/MO@C materials. A series of M/MO@C samples were tested as the electrode materials for supercapacitors, and a remarkable specific capacitance of 800 F g(-1) was obtained using the M/MO@C-700 sample at a current density of 1 A g(-1) in 6 M KOH electrolyte. Moreover, the M/MO@C sample showed a good cycling stability with a capacitance retention of 85% after 1000 cycles. It is also found that the optimized carbonization temperature is a critical parameter to obtain such a M/MO@C nanoporous carbon framework with the best capacitive performances. The present approach is convenient and reproducible, which could be easily extended to the preparation of other M/MO@C composites with excellent electrochemical performances.

Reconstruction of atmospheric soot history in inland regions from lake sediments over the past 150 years.

Historical reconstruction of atmospheric black carbon (BC, in the form of char and soot) is still constrained for inland areas. Here we determined and compared the past 150-yr records of BC and polycyclic aromatic compounds (PACs) in sediments from two representative lakes, Huguangyan (HGY) and Chaohu (CH), in eastern China. HGY only receives atmospheric deposition while CH is influenced by riverine input. BC, char, and soot have similar vertical concentration profiles as PACs in both lakes. Abrupt increases in concentrations and mass accumulation rates (MARs) of soot have mainly occurred since ~1950, the establishment of the People's Republic of China, when energy usage changed to more fossil fuel contributions reflected by the variations in the concentration ratios of char/soot and individual PACs. In HGY, soot MARs increased by ~7.7 times in the period 1980-2012 relative to the period 1850-1950. Similar increases (~6.7 times) were observed in CH. The increase in soot MARs is also in line with the emission inventory records in the literature and the fact that the submicrometer-sized soot particles can be dispersed regionally. The study provides an alternative method to reconstruct the atmospheric soot history in populated inland areas.

Elemental carbon and polycyclic aromatic compounds in a 150-year sediment core from Lake Qinghai, Tibetan Plateau, China: influence of regional and local sources and transport pathways.

Elemental carbon (EC) and polycyclic aromatic compounds (PACs) are potential proxies for the reconstruction of change in human activities and the origin of air masses in historic times. In this study, the historic deposition of char and soot (the two subtypes of EC) and PACs in a 150-year sediment core from different topographic subbasins of Lake Qinghai on the Qinghai Tibetan Plateau (QTP) were reconstructed. The objective was to explore how the variations in the concentrations of EC and PACs, in the ratios of char to soot and of oxygenated polycyclic aromatic hydrocarbons (OPAHs) to parent PAHs, and in the composition of the PAC mixtures reflect historical changes in climate and human activity and the origin of air masses arriving at the QTP. The deposition fluxes of soot in the different subbasins were similar, averaging 0.18 (range of 0.15-0.25) and 0.16 (0.13-0.23) g m(-2) year(-1), respectively, but they varied for char (averaging 0.11 and 0.22 g m(-2) year(-1), respectively), suggesting ubiquitous atmospheric deposition of soot and local river inputs of char. The different vertical distributions of the char/soot ratios in the different subbasins can be interpreted in terms of the different transport mechanisms of char and soot. An abrupt increase in soot concentrations since 1980 coincides with results from the QTP ice cores that were interpreted to be indicative of soot transport from South Asia. Similar concentration patterns of PAHs with soot and 9,10-anthraquinone/anthracene (9,10-AQ/ANT) ratios all >2.0 suggest regional PAC sources. Increasing PAH/soot ratios and decreasing 9,10-AQ/ANT ratios since the beginning of the 1970s indicate increasing local emissions. The historical trends of these diagnostic ratios indicate an increase in the fossil-fuel contribution since the beginning of the 1970s. The increase of perylene concentrations with increasing core depth and the ratio of perylene to its penta-aromatic isomers indicate that perylene originates mainly from in situ biogenic diagenesis. We demonstrate that the concentrations of EC, char, soot, and PACs in sediments can be used to reconstruct local, regional, and remote sources and transport pathways of pollutants to the QTP.

Haemoglobin, neutrophil to lymphocyte ratio and platelet count improve prognosis prediction of the TNM staging system in nasopharyngeal carcinoma: development and validation in 3,237 patients from a single institution.

AIMS: To improve prediction efficiency by incorporating complete blood count (CBC) into the TNM system on 5 year disease-specific survival (DSS) for patients with nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS: The CBC of 3237 patients undergoing radiotherapy was retrospectively evaluated. In total, 2820 patients treated with non-intensity-modulated radiotherapy (IMRT) were randomly divided into development (1895 patients) and validation cohorts (925 patients). The association of potential risk factors with 5 year DSS was tested by Cox proportional hazards analysis and a prognostic index was created by assigning weighted scores proportional to a regression coefficient to each factor. Each cohort was divided into low, intermediate and high prognostic index. The prognostic index was validated in the validation cohort and compared with the TNM system on prediction of 5 year DSS. Validation was repeated in another independent group of 417 patients treated with IMRT. RESULTS: Eight independent prognostic factors were identified: gender, age, T or N stages, anaemia or thrombocytosis during radiotherapy, continuous reduction in haemoglobin, high neutrophil-lymphocyte ratio before radiotherapy. Each was assigned a number of points. The area under curve (AUC) of the prognostic index was larger than that of Union Internationale Contre le Cancer/American Joint Cancer Committee TNM system 2009 (0.697 versus 0.619, P < 0.001). CONCLUSION: A CBC-based prognostic index was developed and had a higher prediction efficiency on 5 year DSS in NPC than the TNM system alone.

Bacterial diversity in Malan ice core from the Tibetan Plateau.

Three ice core samples were collected from the Malan ice core drilled from the Tibetan Plateau, and three 16S rDNA clone libraries by direct amplification from the ice-melted water were established. Ninety-four clones containing bacterial 16S rDNA inserts were selected. According to restriction fragment-length polymorphism analysis, 11 clones were unique in the library from which they were obtained and used for partial sequence and phylogenetic analysis, and compared with 8 reported sequences from the same ice core at depth 70 m. Differences among the samples were apparent in clone libraries. The phylotypes were dominated by the Proteobacteria group, Acinetobacter sp. and Cytophaga-Flavobacterium-Bacteroides (CFB) group. They accounted for 92.5% (Proteobacteria), 100% (Acinetobacter sp.), 34.4% (CFB) and 100% (beta-Proteobacteria) in the clone libraries from the samples at ice depths 35, 64, 70, and 82 m, respectively. The Acinetobacter sp. was only found in the deposition at ice depth 82 m and closely clustered with gamma-Proteobateria. Two members (Malan A-21 and 101) of alpha-Proteobacteria from the sample of 35 m and two (Malan B-26 and 48) of beta-Proteobacteria of 64 m were loosely clustered (< 95% similarity) with known bacteria, represented new genera in ice bacteria.

Interaction of plasma proteins with cytochromes P450 mediated metabolic reactions: inhibition by human serum albumin and alpha-globulins of the debrisoquine 4-hydroxylation (CYP2D) in liver microsomes of human, hamster and rat.

The effect of human serum albumin (HSA), alpha1-acid glycoprotein (alpha1-AGP), and alpha- and gamma-globulins on the in vitro metabolism of debrisoquine in human, hamster and rat liver microsomes was studied. Interaction of albumin with cytochrome P450 mediated phenytoin metabolism has been reported. Since plasma protein binding of phenytoin is high, in the present study a weakly protein bound drug, debrisoquine, was studied. Debrisoquine is a substrate of CYP2D6. The debrisoquine 4-hydroxylation was measured using a radio-TLC method. Among the four plasma proteins, alpha-globulins had the strongest inhibitory effect on the debrisoquine 4-hydroxylase activity. The inhibition with 2% alpha-globulins was 42+/-18% for human and higher for hamster and rat liver microsomes (65-71%). HSA had less effect than alpha-globulins. In the presence of HSA, the decrease in activity was between 18 and 35% for all liver microsomes studied. The debrisoquine 4-hydroxylase activity was not significantly changed by alpha1-AGP or gamma-globulins. Using an ultra-filtration method, the protein binding of debrisoquine to 4% HSA, 0.5% alpha1-AGP, 2% alpha-globulins and 2% gamma-globulins was found to be 22, 20, 22 and 5%, respectively. Since the observed inhibition is inconsistent with level of protein binding, it appears, particularly in the case of alpha-globulins, that the plasma proteins interact with CYP2D directly.

[Expression of bcl-2 protein in uterine leiomyomas and normal myometrium].

OBJECTIVE: To study the expression of the apoptosis regulatory protein bcl-2 in the uterine leiomyomas and in the normal myometrium. METHODS: The expression of bcl-2 protein was examined by immunohistochemical ABC staining in 40 cases of uterine leiomyomas and normal myometrium. RESULTS: bcl-2 expression was higher in the uterine leiomyomas than that in the normal myometrium, both in the proliferative phase and in the secretory phase of the menstrual cycle (P < 0.01); bcl-2 expression in leiomyomas in the secretory phase was stronger than that in the proliferative phase of the menstrual cycle (P < 0.01). CONCLUSIONS: The increase of apoptosis inhabiting gene bcl-2 may play an important role in the growth of the uterine leiomyomas. This action may be regulated by progesterone.

Effects of ethanol on ethylmorphine metabolism in isolated rat hepatocytes: characterization by means of a multicompartmental model.

Hepatic cytochrome P-450 enzymes mediate at least two important biotransformation pathways of codeine and ethylmorphine starting with either N-demethylation or O-dealkylation, producing polar metabolites which are then subsequently glucuronidated. The present study was designed to characterise the acute effects of ethanol on the metabolism of ethylmorphine and to compare it with the effects on codeine in suspensions of freshly isolated rat hepatocytes. Isolated rat hepatocytes from male Wistar rats were prepared by a collagenase perfusion method. Ethylmorphine, codeine and their metabolites were quantified by HPLC with UV detection. The total ethylmorphine elimination rate was reduced by 12% at 5mM and 38% at 100 mM ethanol. The corresponding percentages for codeine were 16 and 43%. In the presence of ethanol the concentrations of several intermediate and end products of ethylmorphine and codeine changed markedly from the control situation. The experimental data were applied to a mathematical compartmental linear model to estimate the influence of ethanol on the separate reaction rates in the two main metabolic pathways. The ratios between reaction rate constants in the ethylmorphine experiments at 100 and 0 mM ethanol were 0.65 for ethylmorphine-->norethylmorphine, 0.63 for norethylmorphine-->normorphine, 0.56 for ethylmorphine-->morphine, 0.49 for morphine-->normorphine, 0.31 for normorphine-->normorphine-3-glucuronide and 0.49 for morphine-->morphine-3-glucuronide. Almost similar effects of ethanol on codeine metabolism were found. In additional experiments, norethylmorphine or norcodeine (50 microM) was incubated with 5 mM to 100 mM of ethanol and the metabolism of both norethylmorphine and norcodeine was found to be inhibited by ethanol in a concentration-dependent manner. The glucuronidation of morphine and normorphine added in separate experiments was also inhibited by ethanol, from 22 to 36% for morphine-3-glucuronide and 30 to 60% for normorphine-3-glucuronide, respectively, in the presence of 5 mM to 100 mM of ethanol. It was concluded that all steps in the metabolism of ethylmorphine (and codeine) leading to the end products morphine-3-glucuronide and normorphine-3-glucuronide were inhibited by ethanol, and that the glucuronidation process were the ones most affected by ethanol.

Evidence for CYP2D1-mediated primary and secondary O-dealkylation of ethylmorphine and codeine in rat liver microsomes.

The purpose of the present study was to investigate the role of specific CYPs responsible for the O-dealkylation of ethylmorphine (EM) and codeine (CD) to morphine (M), as well as that of norethylmorphine (NEM) and norcodeine (NCD) to normorphine (NM) in rat liver microsomes. Liver microsomes metabolize EM and CD to M, and NEM and NCD to NM, in the presence of an NADPH-generating system. The metabolites of EM and CD were determined by HPLC with UV and electrochemical detection. In the present study, the role of CYP2D1 in O-dealkylation of EM/NEM and CD/NCD was investigated by use of specific antiCYP antibodies. When testing rabbit antirat CYP2D1, 2E1, 2C11, and 3A2 antibodies, only the antiCYP2D1 antibody inhibited the EM/NEM and CD/NCD O-dealkylase activities significantly. The maximum inhibition achieved was approximately 80% at a protein ratio (IgG to microsomes) of 10:1, p = 0.001. The contribution of CYP2D1 to the O-dealkylation of EM/NEM and CD/NCD was further confirmed by use of the specific CYP2D1 inhibitors quinine and propafenone. Five microM of quinine inhibited the EM/NEM and CD/NCD O-dealkylase activities by approximately 80%. The CYP3A inhibitor troleandomycin (TAO) failed to inhibit the CYP2D1 catalyzed reaction, but did inhibit the N-demethylation of EM and CD. The O-dealkylation of NEM and NCD was also impaired in Dark Agouti rat (DA) liver microsomes. Taken together, the immunoinhibition and chemical-inhibitor studies of rat liver microsomes provided convincing evidence for the involvement of CYP2D1, the rat counterpart of human CYP2D6, in the metabolism of EM/NEM and CD/NCD to the corresponding O-dealkylated metabolites.

Biotransformation and pharmacokinetics of ethylmorphine after a single oral dose.

1. The pharmacokinetics of ethylmorphine after administration of a single dose of the cough mixture Cosylan were investigated in 10 healthy subjects. 2. The median urinary recovery of ethylmorphine and measured metabolites was 77% over 48 h. The median tmax of unchanged ethylmorphine was 45 min, and the terminal elimination t1/2 was 2 h. Ethylmorphine-6-glucuronide was found to be the major metabolite. 3. Two subjects had significantly lower urinary recovery (0.48 h) of morphine and morphine-glucuronides than the remainder. Furthermore, these two had urinary metabolic ratios (MRO) and partial metabolic clearances (CLmO) for O-deethylation of ethylmorphine tentatively classifying them phenotypically as poor metabolisers of the debrisoquine/sparteine type. 4. Genotyping for cytochrome P450 (CYP) 2D6 alleles revealed five homozygote (wt/wt) and five heterozygote subjects. Two subjects phenotypically classified as poor metabolisers were genotypically CYP2D6A/wt and CYP2D6D/wt, respectively. 5. Serum and urine samples taken more than 8 and 24 h after administration of ethyl-morphine respectively, contained morphine and morphine-glucuronides, but no ethylmorphine, ethylmorphine-6-glucuronide or (serum only) norethylmorphine. Norethylmorphine could be detected after hydrolysis of urine samples in all subjects. The urinary recovery of the active metabolites morphine and morphine-6-glucuronide after administration of ethylmorphine varied by a factor of 9 between individuals. 6. The wide variation in recovery of morphine and morphine-glucuronides after oral administration of ethylmorphine could not be explained simply by a difference in CYP2D6 genotype. Constitutional variation in other enzymatic pathways involved in ethylmorphine metabolism is probably crucial. Ratios of morphine to parent drug cannot be used to distinguish the source of morphine after administration of ethylmorphine. Norethylmorphine should be included in urine assays for opiates in forensic toxicology, and no firm conclusions about the source of morphine are possible based on serum samples obtained more than 24 h after drug administration.

Ethylmorphine O-deethylation in isolated rat hepatocytes. Involvement of codeine O-demethylation enzyme systems.

The O-dealkylation of ethylmorphine (EM) and codeine (CD) to morphine (M) co-segregates with debrisoquine/sparteine genetic polymorphism in man. CD O-demethylation is catalysed by cytochrome P450 2D1 (CYP2D1) in rats. In the present study, the O-deethylation of EM was examined and compared with that of CD in suspensions of freshly-isolated hepatocytes prepared by a collagenase method from Wistar rats with and without CYP2D1 inhibitors. Isolated hepatocytes were also prepared from Dark Agouti (DA) rats deficient in CYP2D1, and were incubated with EM or CD. EM, CD and their metabolites were quantified by HPLC with UV detection. EM had a similar pattern of metabolism to that of CD in suspensions of hepatocytes from Wistar rats. Both EM and CD were O-dealkylated to form M plus morphine-3-glucuronide (M3G) and N-demethylated to form norethylmorphine (NEM) or norcodeine (NCD), respectively, which were further metabolized to normorphine (NM) and finally glucuronidated to normorphine-3-glucuronide (NM3G). As compared to hepatocytes from Wistar rats, DA rats were characterized by a markedly decreased formation (70 approximately 75% reduction) of M plus M3G from both EM and CD. Quinine, quinidine, propafenone and sparteine all inhibited EM O-deethylation as well as CD O-demethylation. Quinine was the most potent inhibitor of both these O-dealkylations (Ki = 0.2 microM for both EM and CD, respectively). Quinine as well as the other inhibitors inhibited both EM and CD O-dealkylation competitively and with small differences in Ki versus EM and CD, respectively. The metabolism of EM to M plus M3G and that of CD to M plus M3G was highly correlated when results from the various separate cell suspensions were plotted. In conclusion all findings indicated that the enzyme responsible for O-demethylation of CD, CYP2D1 was also responsible for the O-deethylation of EM to M.

Ethylmorphine metabolism in isolated rat hepatocytes.

The metabolism of ethylmorphine has been studied in suspensions of isolated rat hepatocytes. Early during incubation, the two major metabolic intermediates detected were morphine and norethylmorphine following N- and O-dealkylation of ethylmorphine, respectively. During subsequent incubation the concentration of the second metabolic intermediate, normorphine increased, before the concentration peaked at approximately 20 microM (100 microM ethylmorphine). Both morphine and normorphine were glucuronidated to form morphine-3-glucuronide and normorphine-3-glucuronide, respectively, which appeared to be the major metabolic end products. The percentage of ethylmorphine metabolized to morphine-3-glucuronide was found to be dependent on the initial concentration of ethylmorphine. With increasing initial ethylmorphine concentration the relative formation of morphine-3-glucuronide was reduced (29 +/- 10% at 5 microM, 18 +/- 5% at 20 microM, and 15 +/- 4% at 100 microM mean +/- S.D., n = 10). The concentrations of ethylmorphine and its metabolites were found to be higher in liver cells than in medium. Thus the ratios between the intra-/extra-cellular concentrations of ethylmorphine increased somewhat from an initial value of 4 during the period for which ethylmorphine could be detected intracellularly. The drug metabolites all exhibited ratios above 10 for the initial 100 min. of incubation. With time these ratios showed a decline, but even for prolonged incubation the ratios were 5 or higher for the end products. Thus considerable drug concentration gradients existed across the cell membrane of isolated rat hepatocytes.