Pharmacokinetics of GST-TatdMt, a recombinant fusion protein possessing potent anti-obesity activity, in mice

This study examined the absorption and pharmacokinetic disposition of 125I-GST-TatdMt, a recombinant Tat protein possessing potent anti-obesity activity, in mice after vascular and extravascular administration. GST-TatdMt was over-expressed in E. coli, purified, and radioiodinated using the IODO-GEN method. 125I-GST-TatdMt was administered to mice by i.v., i.p. and oral administration at doses of 652.7 nCi (102.3 microg). Upon i.v. injection, the average terminal elimination half-life (t1/2,lambdaz), AUC and AUMC were 6.4 h, 318.2 nCixh/mL and 2518 nCixh2/ mL, respectively. The highest radioactivity was observed in lung followed by liver, spleen, heart and kidney. The t1/2lambdaz values obtained from i.v., i.p., and oral administration were comparable from each other (range 5.8-6.4 h). The absolute bioavailability of 125I-GST-TatdMt was 42.8% and 60.5% after p.o. and i.p. administration, respectively. Given the cell-penetrating nature, 125I-GST-TatdMt may be absorbed into the systemic circulation to a relatively high extent after extravascular administration.

Comparison of femoral arterial blood pressure with radial arterial blood pressure and noninvasive upper arm blood pressure in the reperfusion period during liver transplantation

PURPOSE

The reperfusion period during liver transplantation is hemodynamically unstable. Accurate blood pressure measurements are the mainstay for the efficient management of abrupt cardiovascular changes. We sought to compare femoral arterial blood pressure (FABP) with radial arterial blood pressure (RABP) and noninvasive upper arm blood pressure (NIBP) in the reperfusion period.

METHODS

Thirty-six adult living donor liver recipients were enrolled in this prospective study. Blood pressures in 3 locations were simultaneously recorded from 1 minute before reperfusion to 15 minutes after reperfusion. We evaluated agreements between FABP and RABP and between FABP and NIBP using intraclass correlation coefficients. Also, we investigated the rates of postreperfusion syndrome (PRS) based on the measurements from 3 locations.

RESULTS

After reperfusion, the mean and diastolic RABP agreed more with the corresponding FABP than NIBP. However, systolic NIBP showed high agreement with FABP from 3 to 10 minutes after reperfusion in contrast with the moderate agreement between systolic RABP with FABP, and systolic values of NIBP than RABP were closer to FABP. The rates of PRS based on FABP, RABP, and NIBP measurements were 50.0% (18/36), 80.6% (29/36), and 50.0% (18/36), respectively.

CONCLUSIONS

We believe that NIBP in addition to RABP may be considered to be a reliable alternative when FABP is not available to evaluate hemodynamic instability in the reperfusion period during liver transplantation.

Development of LC/MS/MS assay for the determination of 5-ethyl-2-{5-[4-(2-hydroxyethyl)piperazine-1-sulfonyl]-2-propoxyphenyl}-7-propyl-3,5-dihydropyrrolo[3,2-d]pyrimidin-4-one (SK3530) in human plasma: application to a clinical pharmacokinetic study

5-Ethyl-2-{5-[4-(2-hydroxyethyl)piperazine-1-sulfonyl]-2-propoxyphenyl}-7-propyl-3,5-dihydropyrrolo[3,2-d]pyrimidin-4-one (SK3530) is a new phosphodiesterase type-5 inhibitor currently undergoing a Phase III investigation for the treatment of male erectile dysfunction. This study first describes a rapid and sensitive LC/MS/MS assay method for the quantification of SK3530 and its major metabolite, SK3541, in human plasma. The assay was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification (LLOQ), accuracy, and precision. The multiple reaction monitoring was based on the transition of m/z=532.5-->99.1 for SK3530, 488.6-->295.5 for SK3541, and 520.3-->99.1 for SK3304 (internal standard). The assay utilized a single liquid-liquid extraction and isocratic elution, and the LLOQ was 1 ng/ml using 0.2 ml human plasma. The assay was linear over a range from 1 to 1000 ng/ml for both SK3530 and SK3541, with correlation coefficients >0.9999. The mean intra- and inter-day assay accuracy ranged from 94.7 to 101.6% and 96.8 to 101.1% for SK3530 and 92.6-105.7% and 97.4-107.8% for SK3541, respectively. The mean intra- and inter-day precision was between 7.2-12.1% and 5.7-7.4% for SK3530 and 4.6-13.2% and 5.0-14.1% for SK3541, respectively. The developed assay was applied to a clinical pharmacokinetic study after oral administration of SK3530 in healthy male volunteers (dose 100 mg).

Pharmacokinetics of 125I-GST-TatdMt, a recombinant fusion protein possessing potent anti-obesity activity, after intravenous, nasal, oral, and subcutaneous administration

This study first reports the absorption kinetics of GST-TatdMt, a recombinant Tat protein possessing potent anti-obesity activity, in rats after nasal, s.c., and p.o. administration. GST-TatdMt was over-expressed in E. coli, purified, and radioiodinated using the IODO-GEN method. The radioiodinated 125I-GST-TatdMt was administered to rats by nasal, s.c., and oral routes at doses of 7.3 microg (420.7 nCi), 146.5 microg (8413.8 nCi), and 146.5 microg (8413.8 nCi), respectively. For the determination of absolute bioavailability, 125I-GST-TatdMt was also given to rats by i.v. injection (73.2 microg, 4206.9 nCi). Following administration by extravascular routes, the systemic absorption of radioactivity was prolonged, with Cmax being attained within 4.2-8.0 h. The absolute bioavailability calculated as dose-normalized AUC(extravascular)/AUC(i.v.) was 98.0, 75.8, and 87.1% after nasal, s.c., and oral administration, respectively. The majority of administered radioactivity was excreted in urine (57.5-64.7%), with fecal excretion being less (2.5-12.7%). The distribution of 125I-GST-TatdMt to various tissues was also determined at 4 and 72 h after s.c. injection. The findings of this study suggest that this protein may be absorbed into the systemic circulation when given by extravascular administration.

Determination of roxatidine in human plasma by liquid chromatography/electrospray mass spectrometry and application to a clinical pharmacokinetic study

A rapid and sensitive liquid chromatography/mass spectrometry (LC/MS) method was developed and validated for the determination of roxatidine in human plasma. Roxatidine was extracted by single liquid-liquid extraction with tert-butyl methyl ether, and the chromatographic separation was performed on a C8 column. The total analytical run time was relatively short (5 min), and the limit of assay quantification was 2 ng/mL using 0.1 mL of human plasma. Roxatidine and the internal standard, propranolol, were monitored in selected ion monitoring (SIM) mode at m/z 307.3 and 260.3, respectively. The standard curve was linear over a concentration range from 2-500 ng/mL, and the correlation coefficients were >0.999. The mean intra- and inter-day assay accuracy ranged from 103.4-108.8% and 102.3-110.0%, respectively, and the mean intra- and inter-day precision was between 3.3-8.8% and 5.3-6.2%, respectively. The developed assay method was successfully applied to a pharmacokinetic study in human volunteers after oral administration of roxatidine acetate hydrochloride at a dose of 75 mg.

Determination of clopidogrel in human plasma by liquid chromatography/tandem mass spectrometry: application to a clinical pharmacokinetic study

A rapid and sensitive LC/MS/MS assay was developed and validated for the determination of clopidogrel in human plasma. Clopidogrel was extracted by single liquid-liquid extraction with pentane, and chromatographic separations were achieved on a C(18) column. The method was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification (LLOQ), stability, accuracy and precision. The multiple reaction monitoring was based on m/z transition of 322.2 --> 211.9 for clopidogrel and 264.1 --> 125.1 for ticlopidine (internal standard). The total analytical run time was relatively short (3 min), and the LLOQ was 10 pg/mL using 0.5 mL of human plasma. The assay was linear over a concentration range from 10 to 10,000 pg/mL (r > 0.999). The intra- and inter-day accuracies were 101.3-108.8 and 98.4-103.5%, respectively, and the intra- and inter-day assay precisions were 1.9-5.5 and 4.4-8.1%, respectively. The developed assay method was applied to a pharmacokinetic study in human volunteers after oral administration of clopidogrel at a dose of 150 mg.

A Randomized Placebo-Controlled, Dose-Finding Study of Oral Lb80380 in Hbeag-Positive Patients with Chronic Hepatitis B

Background

LB80380 is potent antiviral agent against hepatitis B virus (HBV) in vitro and in the woodchuck model. It has an excellent preclinical safety profile including lower potential for renal toxicity than adefovir. It is effective against both wild-type and YMDD mutant HBV. LB80380 is converted to its parent drug, LB80331, after oral absorption, and further metabolized to its active form, LB80317.

Aims/Methods

This randomized placebo-controlled Phase I/II clinical study of LB80380 was conducted to assess the safety, antiviral activity and pharmacokinetics of its parent drug LB80331 and its active form LB80317 in 29 Asian adults with chronic hepatitis B positive for hepatitis B e antigen in four escalating dose groups (30, 60, 120 and 240 mg once per day) for 4 weeks with a 12-week follow-up period.

Results

The mean maximum HBV DNA reduction was 3.05, 4.20, 3.67 and 3.68 log10 copies/ml for 30, 60, 120 and 240 mg per day, respectively. Viral dynamic analysis suggested a high degree of inhibition of HBV replication at doses of 60 mg or higher per day. LB80380 was well tolerated at all dose groups, and no dose-related clinical or laboratory adverse event was reported.

Conclusion

LB80380 is shown to be a potent and safe antiviral agent for HBV. Marked HBV DNA suppression was observed in all dose groups. The HBV DNA suppression was approximately constant at doses of 60 mg and higher over the 28-day dosing period. The dose response of LB80380 will be evaluated further in large clinical studies.

A randomized placebo-controlled, dose-finding study of oral LB80380 in HBeAg-positive patients with chronic hepatitis B

BACKGROUND

LB80380 is potent antiviral agent against hepatitis B virus (HBV) in vitro and in the woodchuck model. It has an excellent preclinical safety profile including lower potential for renal toxicity than adefovir. It is effective against both wild-type and YMDD mutant HBV. LB80380 is converted to its parent drug, LB80331, after oral absorption, and further metabolized to its active form, LB80317.

AIMS/METHODS

This randomized placebo-controlled Phase I/II clinical study of LB80380 was conducted to assess the safety, antiviral activity and pharmacokinetics of its parent drug LB80331 and its active form LB80317 in 29 Asian adults with chronic hepatitis B positive for hepatitis B e antigen in four escalating dose groups (30, 60, 120 and 240 mg once per day) for 4 weeks with a 12-week follow-up period.

RESULTS

The mean maximum HBV DNA reduction was 3.05, 4.20, 3.67 and 3.68 log10 copies/ml for 30, 60, 120 and 240 mg per day, respectively. Viral dynamic analysis suggested a high degree of inhibition of HBV replication at doses of 60 mg or higher per day. LB80380 was well tolerated at all dose groups, and no dose-related clinical or laboratory adverse event was reported.

CONCLUSION

LB80380 is shown to be a potent and safe antiviral agent for HBV. Marked HBV DNA suppression was observed in all dose groups. The HBV DNA suppression was approximately constant at doses of 60 mg and higher over the 28-day dosing period. The dose response of LB80380 will be evaluated further in large clinical studies.

Pharmacokinetics of a novel histone deacetylase inhibitor, apicidin, in rats

This study is the first report of the pharmacokinetics of a novel histone deacetylase inhibitor, apicidin, in rats after i.v. and oral administration. Apicidin was injected intravenously at doses of 0.5, 1.0, 2.0 and 4.0 mg/kg. The terminal elimination half-life (t1/2), systemic clearance (Cl) and steady-state volume of distribution (Vss) remained unaltered as a function of dose, with values in the range 0.8-1.1 h, 59.6-68.0 ml/min/kg and 2.4-2.7 l/kg, respectively. Whereas, the initial serum concentration (C0) and AUC increased linearly as the dose was increased. Taken together, the pharmacokinetics of apicidin were linear over the i.v. dose range studied. The extent of urinary and biliary excretion of apicidin was minimal (0.017%-0.020% and 0.049% +/- 0.016%, respectively). Oral pharmacokinetic studies were conducted in fasting and non-fasting groups of rats at a dose of 10 mg/kg. The Tmax, Cl/F and Vz/F were in the range 0.9-1.1 h, 520.3-621.2 ml/min/kg and 67.6-84.4 l/kg, respectively. No significant difference was observed in the oral absorption profiles between the two groups of rats. Apicidin was poorly absorbed, with the absolute oral bioavailability of 19.3% and 14.2% in fasting and non-fasting rats.

Altered oral absorption of alcohol by combined aqueous extracts of four herbal plants in rats

This study examined the effect of combined aqueous extracts (BHR) of Ginko biloba, Mentha arvensis var. piperascens, Citrus unshiu, and Pueraria lobata var. chinensis on oral absorption of alcohol in rats. The rats were pretreated with BHR, placebo solution identical to BHR without the herbal extract, and isotonic saline. Alcohol was administered orally at 1- and 3-g/kg doses and the absorption profiles were compared. After oral administration of 1-g/kg doses, mean area under the curve (AUC) and C(max) values were significantly reduced in BHR-treated rats (16.1 +/- 10.0 and 0.3 +/- 0.1 mg/ml, respectively) as compared with saline-treated (37.9 +/- 14.4 and 0.7 +/- 0.7 mg/ml, respectively) and placebo solution-treated (63.0 +/- 46.4 and 0.7 +/- 0.4 mg/ml, respectively) rats. Similarly, after administration of 3-g/kg doses, mean AUC and C(max) values in BHR-treated rats (188.1 +/- 119.7 mg(.)min/ml and 1.0 +/- 0.4 mg/ml) were significantly reduced over those in saline-treated rats (571.4 +/- 512.4 mg(.)min/ml and 1.8 +/- 0.9 mg/ml, respectively). The relative oral bioavailability of alcohol calculated as the ratio of AUC(BHR)/AUC(Saline) was 42.5% and 32.9% at 1- and 3-g/kg doses, respectively. The reduced serum alcohol levels as well as the reduced AUC and C(max) after pretreatment with BHR appear to be a result of a reduced systemic absorption not due to an increased metabolic clearance.

Effects of aloe, aloesin, or propolis on the pharmacokinetics of benzo[a]pyrene and 3-OH-benzo[a]pyrene in rats

This study was conducted to examine the effects of aloe and aloesin on the weight gain and blood chemistry as well as the pharmacokinetics of benzo[a]pyrene (BaP) and 3-OH-BaP in rats. The rats treated with multiple doses of aloe and aloesin (100 mg/kg every 12 h for 14-19 d) did not show any significant changes in the weight gain and blood biochemical parameters. In addition, the effects of oral treatment with aloe, aloesin, and propolis on the absorption and pharmacokinetics of benzo[a]pyrene (BaP) and its metabolite, 3-OH-BaP, were studied in rats. The treatment with a single oral dose (200 mg/kg) of aloe, aloesin, and propolis did not alter the concentration-time profiles of BaP and 3-OH-BaP after iv and oral administration of BaP. At higher oral doses (500 mg/kg), the biliary excretion of BaP and the urinary excretion of 3-OH-BaP were significantly increased, but the urinary excretion of BaP and the fecal excretion of 3-OH-BaP remained unaltered. Whether high doses of aloe increase the overall elimination of BaP deserves further investigation.

In vitro investigation of the hepatic intrinsic clearance of apicidin, a histone deacetylase inhibitor, in mouse, rat, and human, with correction by nonspecific protein binding

Apicidin is a potent histone deacetylase inhibitor exhibiting broad-spectrum antiprotozoal, antiproliferative, and antiangiogenic activities. This study was conducted to calculate the intrinsic hepatic clearance of apicidin in mouse, rat, and human. The microsomal stability was determined in pooled microsomes of mouse, rat, and human. The V(max) and K(m) were 680.4 ng/min/mg protein and 10,544.1 ng/ml for mouse, 745.0 ng/min/mg protein and 24,306.0 ng/ml for rat, and 927.0 ng/min/mg protein and 62,906.0 ng/ml for human, respectively. The f(u,plasma) was extremely low, 0.369 +/- 0.034% for mouse, 0.376 +/- 0.059% rat, and 1.042 +/- 0.114% human. The unbound fraction of apicidin in microsomes (f(u,mic)) was also low, 1.731 +/- 0.237% for mouse, 0.767 +/- 0.048% for rat, and 5.751 +/- 1.575% for human. The hepatic intrinsic clearance calculated by Michaelis kinetics was further corrected by nonspecific binding to microsomal proteins. The corrected intrinsic clearance of apicidin was 1.9, 8.6, and 284.2 ml/min for mouse, rat, and human, respectively. The allometric correlation was improved when the hepatic intrinsic clearance was corrected by the nonspecific protein binding.

Rapid Screening of Blood-Brain Barrier Penetration of Drugs Using the Immobilized Artificial Membrane Phosphatidylcholine Column Chromatography

The chromatographic capacity factors (kIAM) of 23 structurally diverse drugs were measured by the immobilized artificial membrane (kIAM) phosphatidylcholine chromatography for the prediction of blood-brain barrier (BBB) penetration. The kIAM was determined using themobile phase consisting of acetonitrile:DPBS (20:80 v/v) and corrected for the molar volume of the solutes (kIAM/MWn). The correlation between kIAM/MWn and CNS penetration was highest when measured at pH 5.5 with the power function of n = 4. This in vitro predictionmethod was validated with 7 newly synthesized PDE-4 inhibitors. The relationship between in vivo plasma-to-brain concentration ratios and in vitro CNS penetration was excellent ( r= 0.959). The developed in vitro prediction method may be used as a rapid screening tool for BBB penetration of drugs with passive transport mechanism, with high success, low cost, and reproducibility.

Dose-linear pharmacokinetics, tissue distribution, and excretion of a recombinant fusion protein 125I-GST-TatdMt possessing potent anti-obesity activity

This study first examined the pharmacokinetic disposition of GST-TatdMt, a recombinant Tat protein possessing potent anti-obesity activity, in rats after i.v. injection. GST-TatdMt was over-expressed in E. coli, purified, and radioiodinated using the IODO-GEN method. The radioiodinated 125I-GST-TatdMt was administered to rats at doses of 9 microg (1640 nCi), 18 mug (3388 nCi), and 35 microg (6420 nCi). Upon administration, the total radioactivity in serum declined bi-exponentially, with the average terminal elimination half-life ranging from 13.7 to 15.7 h. There was a linear relationship between dose and AUC(INF) (r2=1.000) and between dose and Co (r2=0.999). The fraction of administered radioactivity excreted in feces was low (mean range 1.5-2.8%), while the majority of the radioactivity was excreted in urine (mean range 54.9-61.4%). The radioactivity found in the liver, lungs, spleen, and kidneys were higher than in serum, but the tissue-to-serum ratios were relatively low (<1.64). The radioactivity in testes, adipose tissue, heart, and brain was lower than in serum (tissue-to-serum ratios 0.046-0.27). The findings of this study indicate dose-linear pharmacokinetics of 125I-GST-TatdMt in rats over the i.v. dose range studied.

Nasal absorption and pharmacokinetic disposition of salmon calcitonin modified with low molecular weight polyethylene glycol

This study was performed to examine the absorption potential of polyethylene glycol (PEG)-modified salmon calcitonin (sCT) in rats administered via the nasal route. Previous studies have used relatively high molecular weight polyethylene glycols (e.g., > or =5000 daltons) for PEG-modification of sCT to provide increased metabolic stability and biological half-life. Unlike these studies, the present study utilized a low molecular weight succinimidyl-propionated monomethoxy-poly(ethylene glycol) (MW 2000). It was hypothesized that the potential for membrane transport would not be significantly altered due to a relatively small increase in the molecular size while the metabolic stability would be enhanced due to resistance to proteolytic degradation. After PEG-modification of sCT, the mono-PEG positional isomer (mono-PEG2k-sCT) was separated from di-PEG2k-sCT, tri-PEG2k-sCT, and unmodified sCT by size exclusion chromatography. The mono-PEG2k-sCT and unmodified sCT were radioiodinated, and the resulting 125I-sCT and 125I-mono-PEG2k-sCT were separated from free iodine by RP HPLC and confirmed by MALDI-TOF MS. The 125I-sCT and 125I-mono-PEG2k-sCT were administered to rats via the nasal route, and serial blood, tissue, and urine samples were taken for up to 36 h for the determination of radioactivity. Mono-PEG2k-sCT exhibited significantly increased AUC (20,638 vs. 3,650 ng.min/ml), tmax (520 vs. 77 min), and t1/2,lambdaz (923 vs. 199 min) compared with unmodified sCT. This study demonstrates that mono-PEG2k-sCT is absorbed systemically when given by the intranasal route, exhibiting altered absorption kinetics compared with unmodified sCT.

Development of a liquid chromatography/electrospray tandem mass spectrometry assay for the quantification of apicidin, a novel histone deacetylase inhibitor, in rat serum: application to a pharmacokinetic study

Apicidin, a fungal metabolite isolated from Fusarium pallidoroseum, is a cyclic tetrapeptide that exhibits potent anti-protozoal and anti-angiogenic activities. Although extensive studies have been recently conducted to examine the biological and pharmacological action, no information is available on the quantitative analysis of apicidin. To our knowledge, this study is the first to describe a rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) assay method for the quantification of apicidin in rat serum. The method was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification (LLOQ), accuracy, and precision. The multiple reaction monitoring was based on the transitions m/z 624.7 --> 84.3 and 372.1 --> 176.1 for apicidin and trazodone, respectively. The assay utilized a single liquid-liquid extraction and isocratic elution, and the LLOQ was 0.5 ng/mL using 0.1 mL of rat serum. The assay was linear over a range from 0.5-1000 ng/mL, with correlation coefficients >0.9994. The mean intra- and inter-day assay accuracy ranged from 99.9-101.5% and 94.8-102.1%, respectively, and the mean intra- and inter-day precision was between 2.7-5.9% and 1.6-11.5%, respectively. The developed assay method was applied to a pharmacokinetic study after intravenous injection of apicidin in rats at a dose of 1 mg/kg.

Physiologically based pharmacokinetics of bisphenol A

A physiologically based pharmacokinetic (PBPK) model consisting of vein, artery, lung, liver, spleen, kidneys, heart, testes, muscle, brain, adipose tissue, stomach, and small intestine was developed to predict the tissue distribution and blood pharmacokinetics of bisphenol A in rats and humans. To demonstrate the validity of the developed PBPK model, bisphenol A was administered to rats by multiple iv injections to steady state. The PBPK model predicted the steady-state levels of bisphenol A in blood and various tissues observed in rats after multiple iv injections. The PBPK model was further applied to predict blood and various tissue levels of bisphenol A in a 70 kg-human after single iv injection (5-mg dose) and multiple oral administrations to steady state (100-mg doses every 24 h). The simulated steady-state human blood levels (0.9-1.6 ng/ml) were comparable to basal blood levels of bisphenol A reported in literature (1.49 ng/ml). Furthermore, pharmacokinectic parameters of CL (116.6 L/h), Vss (141.8 L), and t1/2 (76.8 min) predicted for humans were comparable to those previously predicted by simple allometric scaling. This PBPK model may provide insights into the tissue distribution characteristics as a result of human exposure to bisphenol A.

Oral Absorption and Pharmacokinetics of Rebamipide and Rebamipide Lysinate in Rats

Rebamipide is an anti-ulcer agent exhibiting a low aqueous solubility and a poor oral bioavailability. This study was conducted to examine if the rebamipide lysinate salt form would exhibit improved solubility profiles and higher oral bioavailability compared with rebamipide free acid. Both compounds showed pH-dependent solubility profiles, with the solubility of rebamipide lysinate dramatically improved at a median pH of 5.1 (17-fold increases) over free acid, but the improvement in the solubility was not as pronounced in artificial gastric and intestinal fluids (1.4- and 1.9-fold increases, respectively). The Cl, V(ss) and t1/2 in rats after i.v. injection of rebamipide (0.5 mg/kg) averaged 21.0 +/- 3.2 ml/min/kg, 0.3 +/- 0.0 L/kg, and 0.4 +/- 0.1 hr, respectively. No significant difference was observed in these parameters between rebamipide and rebamipide lysinate. Despite improved solubility profiles, the absolute oral bioavailability of rebamipide lysinate was not increased (5.1 vs. 4.8%) nor did AUC (407.8 vs. 383.6 ng x hr/ml) and C(max) (87.4 vs. 77.0 ng/ml) compared with rebamipide free acid. Rebamipide lysinate, however, showed a more rapid absorption, and initial serum drug concentrations were higher than those found for rebamipide free acid.

Pharmacokinetic scaling of bisphenol A by species-invariant time methods

1. The study was performed to predict the pharmacokinetic disposition of bisphenol A in humans using simple allometry and several species-invariant time methods based on animal data. Bisphenol A was injected intravenously to mouse, rat, rabbit and dog (1-2 mg kg(-1) doses). 2. The obtained serum concentration-time profiles were best described by bi-exponential equations in all these animal species, with the mean Cl, V(ss) and t(1/2) of 0.3 l h(-1), 0.1 litres and 39.9 min in mouse, 1.9 l h(-1), 1.3 litres and 37.6 min in rat, 12.6 l h(-1), 7.1 litres and 40.8 min in rabbit, and 27.1 l h(-1), 20.0 litres and 43.7 min in dog, respectively. 3. The human pharmacokinetic parameters of Cl, V(ss) and t(1/2) were predicted by simple allometry as well as by normalization according to species-invariant times of kallynochrons, apolysichrons and dienetichrons. 4. The simple allometric scaling and different time transformation methods predicted the human Cl, V(ss) and t(1/2) ranging from 46.0 to 127.1 l h(-1), 125.3 to 229.7 litres and 43.6 to 196.2 min, respectively. Species-invariant time transformations showed that all animal data from the four species were superimposable. These preliminary parameter values may be useful in interpreting toxicity data in humans on environmental exposure to bisphenol A.

Interspecies comparison of the oral absorption of itraconazole in laboratory animals

The oral absorption and disposition of itraconazole were studied in rats, rabbits and dogs. Serum levels of itraconazole and its active metabolite, hydroxyitraconazole, were determined by a validated HPLC method. The absorption of itraconazole was relatively rapid in rats and dogs but was slower in rabbits. The terminal elimination half-life (T 1/2lambda(z)), time to the peak concentration (Tmax), dose and weight normalized area under the curve (AUC) and the peak concentration (Cmax) of itraconazole found in the dog were comparable to those reported in humans. As in humans, the metabolite to parent drug AUC ratios in rats and dogs were greater than unity but was less in rabbits. The dog appears to be an appropriate animal model while the rat, not the rabbit, may be used as an alternative animal model in predicting the oral absorption of itraconazole in humans.

Maternal-fetal disposition of bisphenol a in pregnant Sprague-Dawley rats

This study describes the maternal-fetal disposition of bisphenol A and its distribution into the placenta and amniotic fluid after iv injection (2 mg/kg) to pregnant Sprague-Dawley rats. Bisphenol A was distributed extensively to the placenta and fetus, with their respective AUC values 4.4- and 2.2-fold greater than AUC for the maternal serum. In contrast, the distribution of bisphenol A into the amniotic fluid was low, with the mean amniotic fluid-to-maternal serum AUC ratio of 0.2. The decay curves of bisphenol A in the placenta, fetus, and amniotic fluid paralleled that of the maternal serum during the terminal elimination phase. A five-compartment open model consisting of the maternal central, maternal peripheral, placental, fetal, and amniotic fluid compartments was used to describe the disposition of bisphenol A in pregnant rats, with the elimination occurring from the maternal central and fetal compartments. Based on this model, bisphenol A delivered to the placenta was transferred primarily to the fetus [kpf/(kpf + kpc + kpa) = 65.4 %], with the remaining fraction transported to the maternal central (33.2%) and amniotic fluid (1.4%) compartments. Bisphenol A was eliminated from the amniotic fluid by the fetal (63.9%) and placental (36.1%) routes. On the other hand, bisphenol A was eliminated from the fetus primarily by the placental route back to mother [kfp/(kfp + kfa + kfo) = 100%], with the amniotic route playing an insignificant role in fetal elimination. The percent contribution of the fetal elimination to the total elimination in the maternal-fetal unit was 0.0% [CLfoAUCfetus/(CLcoAUCmaternal serum + CLfoAUCfetus)]. The pharmacokinetic model used in this study provides insights into the routes of elimination of bisphenol A in the maternal-fetal rat upon maternal administration.

TCDD-up-regulation of IGFBP-6 and IL-5R alpha subunit genes in vivo and in vitro

Although the potent environmental contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been well known for its immunosuppressive activity, the mechanisms of its action have been difficult to elucidate. This is partly due to its inability to exert its effects in vitro. To further elucidate the underlying mechanisms of TCDD effects, we screened for genes that are regulated by the in vivo TCDD treatment of mice that are challenged with allogeneic tumor cells. RNA, collected from lymphoid organs including the thymus, draining lymph nodes, and bone marrow, was reverse-transcribed to cDNA and hybridized to DNA arrays that consisted of 588 genes (ClonTech, USA). The expression of the NF-kappaB p65, c-jun, and p27(Kip1) genes was increased by the TCDD treatment, as previously reported. In addition, we found that the expression of several genes, which were not reported as regulated by TCDD, were modulated by TCDD. Some genes, including insulin-like growth factor-binding protein-6 (IGFBP-6) and IL-5R alpha, were upregulated; while other genes, including CD14, were down-regulated. The expression of the IGFBP-6 and IL-5R alpha subunit genes by TCDD in the thymus was confirmed by RT-PCR and Western blot analyses. Furthermore, TCDD effects on the expression of the IGFBP-6 gene was also observed with EL4 mouse thymoma cells. This suggests that IGFBP-6 may be involved in thymic atrophy, and EL4 cells may be used as an in vitro model for studying molecular mechanisms of thymic atrophy.

Engaging the ribosome: universal IFs of translation

Eukaryotic initiation factor 1A (eIF1A) and the GTPase IF2/eIF5B are the only universally conserved translation initiation factors. Recent structural, biochemical and genetic data indicate that these two factors form an evolutionarily conserved structural and functional unit in translation initiation. Based on insights gathered from studies of the translation elongation factor GTPases, we propose that these factors occupy the aminoacyl-tRNA site (A site) on the ribosome, and promote initiator tRNA binding and ribosomal subunit joining. These processes yield a translationally competent ribosome with Met-tRNA in the ribosomal peptidyl-tRNA site (P site), base-paired to the AUG start codon of a mRNA.

Bioavailability and mammary excretion of bisphenol a in Sprague-Dawley rats

This study reports the absolute oral bioavailability and mammary excretion of bisphenol A in rats. The oral bioavailability was determined after administration of relatively low iv (0.1 mg/kg) and oral (10 mg/kg) doses of bisphenol A to rats. After iv injection, serum levels of bisphenol A declined biexponentially, with the mean initial distribution and terminal elimination half-lives being 6.1 +/- 1.3 min and 52.5 +/- 2.4 min, respectively. The systemic clearance (Cls) and the steady-state volume of distribution (Vss) averaged 107.9 +/- 28.7 m/min/kg and 5.6 +/- 2.4 L/kg, respectively. Upon oral administration, the maximum serum concentration (Cmax) and the time to reach the maximum concentration (Tmax) were 14.7 +/- 10.9 ng/ml and 0.2 +/- 0.2 h, respectively. The apparent terminal elimination half-life of bisphenol A (21.3 +/- 7.4 h) after oral administration was significantly longer than that after iv injection, indicating the flip-flop of the absorption and elimination rates. The absolute oral bioavailability of bisphenol A was low (5.3 +/- 2.1%). To determine the extent of mammary excretion, bisphenol A was given by simultaneous iv bolus injection plus infusion to steady state at low, medium, and high doses. The steady-state serum levels of bisphenol A were linearly increased with higher dosing rates. The systemic clearance (mean range, 119.2-154.1 ml/min/kg) remained unaltered over the dosing rate studied. The levels of bisphenol A in milk exceeded those in serum, with the steady-state milk to serum concentration ratio being 2.4-2.7.

Ligand binding profiles of delta-opioid receptor in human cerebral cortex membranes: evidence of delta-opioid receptor heterogeneity

In this study, receptor binding profiles of opioid ligands for subtypes of opioid delta-receptors were examined employing [3H]D-Pen2,D-Pen5-enkephalin ([3H]DPDPE) and [3H]Ile(5,6)-deltorphin II ([3H]Ile-Delt II) in human cerebral cortex membranes. [3H]DPDPE, a representative ligand for delta1 sites, labeled a single population of binding sites with apparent affinity constant (Kd) of 2.72 +/- 0.21 nM and maximal binding capacity (Bmax) value of 20.78 +/- 3.13 fmol/mg protein. Homologous competition curve of [3H]Ile-Delt II, a representative ligand for delta2 sites, was best fit by the one-site model (Kd = 0.82 +/- 0.07 nM). Bmax value (43.65 +/- 2.41 fmol/mg) for [3H]Ile-Delt II was significantly greater than that for [3H]DPDPE. DPDPE, [D-Ala2,D-Leu5]enkephalin (DADLE) and 7-benzylidenaltrexone (BNTX) were more potent in competing for the binding sites of [3H]DPDPE than for those of [3H]Ile-Delt II. On the other hand, deltorphin II (Delt II), [D-Ser2,Leu5,Thr6]enkephalin (DSLET), naltriben (NTB) and naltrindole (NTI) were found to be equipotent in competing for [3H]DPDPE and [3H]Ile-Delt II binding sites. These results indicate that both subtypes of opioid delta-receptors, delta1 and delta2, exist in human cerebral cortex with different ligand binding profiles.

Involvement of acetyl phosphate in the in vivo activation of the response regulator ComA in Bacillus subtilis

Development of genetic competence in Bacillus subtilis is regulated by ComP--ComA, a two-component signal transduction system. The response regulator ComA is primarily activated by ComP, a histidine kinase that mediates response to nutrient conditions and cell density, and the activated ComA is required for transcription of the srf operon, which is essential for the development of genetic competence and surfactin production. In this study we suggested that the ComA could also be activated by a small molecule phospho-donor, acetyl phosphate. Examination of srfA-lacZ expression indicated that a significant amount of srfA expression still occurs in the comP mutant during growth in a sporulation medium containing excess glucose. Analysis of a comP and pta mutant suggests that srfA activation seen in the comP mutant is dependent on the expression of pta, which encodes phosphotransacetylase (Pta). As Pta is responsible for the catalysis for conversion of acetyl coenzyme A to acetyl phosphate, we conclude that the expression of srfA seen in the comP mutant is mainly due to the activation of ComA by acetyl phosphate.

Pharmacological effects of naltriben as a ligand for opioid mu and kappa receptors in rat cerebral cortex

Naltriben (NTB) has been used to differentiate the subtypes of delta opioid receptors, delta1 and delta2. However, there is considerable evidence suggesting that NTB may act on other types of opioid receptors too. We examined the effects of NTB on the specific binding of radiolabeled ligands for opioid mu and kappa2 receptors, and the effects on the release of [3H]norepinephrine ([3H]NE) in rat cerebral cortex slices. NTB displaced the specific binding of [3H]DAMGO with Ki value of 19.79 +/- 1.12 nM in rat cortex membranes. Specific binding of [3H]diprenorphine ([3H]DIP) was inhibited by NTB with Ki value of 82.75 +/- 6.32 nM in the presence of DAMGO and DPDPE. High K+ (15 mM)-stimulated release of [3H]NE was attenuated by DAMGO in rat cerebral cortex slices. NTB (30 nM) shifted the dose-response curve of DAMGO to the right and attenuated the maximal effect. In the meantime, NTB inhibited high K+-stimulated [3H]NE release at concentrations above 100 nM. The inhibitory effect of NTB was not attenuated by CTAP (10 nM) and naloxone (3 nM) but by higher concentration of naloxone (30 nM), nor-BNI (300 nM) and bremazocine (3 nM). These results indicate that NTB, depending on the dosage, could acts not only as an antagonist at delta but also as a noncompetitive antagonist for mu receptors, and as an agonist for kappa2 receptors in rat cerebral cortex.

Pharmacokinetic disposition of polyethylene glycol-modified salmon calcitonins in rats

This study first reports the pharmacokinetic disposition of polyethylene glycol (PEG)-modified salmon calcitonin (sCT) based on the number of attached PEG molecules. PEG-modified sCT was prepared by covalent linkage with succinimidyl carbonate monomethoxy polyethylene glycol. Mono- and di-PEG-sCTs were separated by size exclusion and reverse phase HPLC, and radioiodinated by the chloramine-T method with Na125I. 125I-mono-PEG sCT, 125I-di-PEG-sCT and unmodified 125I-sCT were administered to rats by i.v. injection. Serial blood samples, urine and various tissue samples were taken for the determination of radioactivity. Di-PEG-sCT exhibited significantly reduced systemic clearance (2.3 vs. 11.1 ml/min/kg) and steady-state volume of distribution (229.9 vs. 603.1 ml/kg), while mono-PEG-sCT showed a prolonged elimination half-life (189.1 min vs. 59.8 min) compared with unmodified sCT. The extent of urinary excretion of the PEG-modified sCTs was higher than for the unmodified sCT, but all these chemicals were excreted in urine in small quantities (< or = 0.6%). There was a tendency toward reduced accumulation of PEGylated sCTs in tissues, with its reduction being inversely proportional to the molecular size. Accumulation of the total radioactivity of the unmodified and PEG-modified sCTs was highest in the liver, followed by kidneys, lungs, spleen, heart and thyroid. When expressed per tissue gram weight, however, the highest radioactivity was found in the kidneys. PEGylated sCTs may have greater therapeutic potential via reduced systemic clearance and prolonged elimination half-life over unmodified sCT.

Insulin reverses bupivacaine-induced cardiac depression in dogs

We tested the hypothesis that an insulin infusion would effectively treat bupivacaine-induced cardiac depression in dogs. In 24 mongrel dogs anesthetized with pentobarbital (5 mgkg(-1)h(-1), IV), 0.5% bupivacaine was administrated at a rate of 0.5 mgkg(-1)min(-1) until the mixed venous oxygen saturation decreased to 60% or less. The bupivacaine infusion induced a decrease in mean arterial pressure, cardiac output, and heart rate. The dogs were randomly assigned to one of four groups after the end of bupivacaine infusion. The Control (C, n = 6) and Glucose (G, n = 6) groups received an IV infusion of normal saline (2 mL/kg) and glucose (2 mL/kg of 50% dextrose in water) for 15 min, respectively. The Insulin-Glucose (IG, n = 6) group received an IV bolus of regular insulin (1 U/kg), plus a glucose infusion (2 mL/kg of 50% dextrose in water) for 15 min. The Insulin-Glucose-Potassium (IGK, n = 6) group received the same dose of insulin and glucose as the IG group, plus potassium (1-3 mEqkg(-1)h(-1)). Mean arterial pressure, cardiac output, heart rate, and mixed venous oxygen saturation recovered toward baseline level more rapidly in the IG and IGK groups than in the C group (within 5 min versus more than 20 min). These results suggest that the infusion of insulin and glucose might reverse bupivacaine-induced cardiac depression in dogs.

IMPLICATIONS

We found that insulin and glucose rapidly reversed hemodynamic abnormality in dogs with bupivacaine-induced cardiac depression. This study implies a possible clinical application of insulin treatment for bupivacaine-induced cardiac depression.

Pharmacokinetic disposition and tissue distribution of bisphenol A in rats after intravenous administration

This study examined the dose-linearity pharmacokinetics of bisphenol A, a U.S. Environmental Protection Agency (EPA) classified endocrine disruptor, in rats following iv administration. Upon iv injection of 0.2, 0.5, 1, or 2 mg/kg, serum levels of bisphenol A declined biexponentially, with mean initial distribution and elimination half-life ranges of 4-8.2 min and 38.6-62.2 min, respectively. There were no significant alterations in the systemic clearance rate (mean range 90.1-123.6 ml/min/kg) and the steady-state volume of distribution (mean range 4.6-6.0 L/kg) as a function of the administered dose. In addition, the area under the serum concentration-time curve linearly rose as the dose was increased. In a second study, bisphenol A was given by simultaneous iv bolus injection plus infusion to steady state, and levels were measured in serum and various organs. When expressed in concentration terms (e.g., amount accumulated per gram organ weight), bisphenol A was found predominantly in the lung, followed by kidneys, thyroid, stomach, heart, spleen, testes, liver, and brain. Ratios of the organ to serum bisphenol A concentrations exceeded unity for all the organs examined (ratio range 2.0-5.8) except for brain (ratio 0.75). Given the high systemic clearance and short elimination half-life, bisphenol A is unlikely to accumulate significantly in the rat.

Analysis of tnrA alleles which result in a glucose-resistant sporulation phenotype in Bacillus subtilis

Bacillus subtilis cells cannot sporulate in the presence of catabolites such as glucose. During the analysis of Tn10-generated mutants, we found that deletion of the C-terminal region of the tnrA gene, which encodes a global regulator that positively regulates a number of genes in response to nitrogen limitation, results in a catabolite-resistant sporulation phenotype. Analyses of nrg-lacZ and nasB-lacZ, which are activated by TnrA under nitrogen limitation, showed that C-terminally truncated TnrA activates nitrogen-regulated genes constitutively. The relief of catabolite repression of sporulation may result from the uncontrolled expression of the TnrA-regulated genes.

Cloning of a new Bacillus thuringiensis cry1I-type crystal protein gene

A new cry1I-type gene, cry1Id1, was cloned from a B. thuringiensis isolate, and its nucleotide sequence was determined. The deduced amino acid sequence of Cry1Id1 is 89.7%, 87.2%, and 83.4% identical to the Cry1Ia, Cry1Ib, and Cry1Ic proteins, respectively. The upstream sequence of the cry1Id1 structural gene was not functional as promoter in B. subtilis. The Cry1Id1 protein, purified from recombinant E. coli cells, had a toxicity comparable to that of Cry1Ia against Plutella xylostella, but it was significantly less active than Cry1Ia against Bombyx mori. Cry1Id1 was not active against the coleopteran insect, Agelastica coerulea.

The p53 tumor suppressor stimulates the catalytic activity of human topoisomerase IIalpha by enhancing the rate of ATP hydrolysis

DNA topoisomerase II is an essential nuclear enzyme for proliferation of eukaryotic cells and plays important roles in many aspects of DNA processes. In this report, we have demonstrated that the catalytic activity of topoisomerase IIalpha, as measured by decatenation of kinetoplast DNA and by relaxation of negatively supercoiled DNA, was stimulated approximately 2-3-fold by the tumor suppressor p53 protein. In order to determine the mechanism by which p53 activates the enzyme, the effects of p53 on the topoisomerase IIalpha-mediated DNA cleavage/religation equilibrium were assessed using the prototypical topoisomerase II poison, etoposide. p53 had no effect on the ability of the enzyme to make double-stranded DNA break and religate linear DNA, indicating that the stimulation of the enzyme catalytic activity by p53 was not due to alteration in the formation of covalent cleavable complexes formed between topoisomerase IIalpha and DNA. The effects of p53 on the catalytic inhibition of topoisomerase IIalpha were examined using a specific catalytic inhibitor, ICRF-193, which blocks the ATP hydrolysis step of the enzyme catalytic cycle. Clearly manifested in decatenation and relaxation assays, p53 reduced the catalytic inhibition of topoisomerase IIalpha by ICRF-193. ATP hydrolysis assays revealed that the ATPase activity of topoisomerase IIalpha was specifically enhanced by p53. Immunoprecipitation experiments revealed that p53 physically interacts with topoisomerase IIalpha to form molecular complexes without a double-stranded DNA intermediary in vitro. To investigate whether p53 stimulates the catalytic activity of topoisomerase II in vivo, we expressed wild-type and mutant p53 in Saos-2 osteosarcoma cells lacking functional p53. Wild-type, but not mutant, p53 stimulated topoisomerase II activity in nuclear extract from these transfected cells. Our data propose a new role for p53 to modulate the catalytic activity of topoisomerase IIalpha. Taken together, we suggest that the p53-mediated response of the cell cycle to DNA damage may involve activation of topoisomerase IIalpha.

Absorption, first-pass metabolism, and disposition of itraconazole in rats

This study examined the pharmacokinetic disposition, oral absorption and hepatic extraction of itraconazole and its active metabolite, hydroxyitraconazole, in rats. After i.v. injection, serum itraconazole concentrations decreased biexponentially, with an average terminal elimination half-life, volume of distribution and systemic clearance of 4.9 h, 6.0 l/kg and 14.2 ml/min/kg, respectively. When given orally, its absorption was low, with a mean absolute bioavailability of 16.6%. The metabolite to parent drug area under the curve (AUC) ratio was higher after oral administration compared with i.v. injection (mean ratio, 2.7 vs. 0.9). The hepatic drug extraction ratio determined after femoral and portal vein administration averaged 18.5%. When hydroxyitraconazole was injected i.v., the elimination half-life, volume of distribution and systemic clearance of itraconazole averaged 10.0 h, 2.4 l/kg and 3.4 ml/min/kg, respectively. The fraction of the systemically available itraconazole that was metabolized to hydroxyitraconazole was 21.0% and 76.0% after i.v. and oral administration, respectively. In summary, this study is the first reporting the hepatic extraction of itraconazole and the i.v. disposition characteristics of hydroxyitraconazole in rats. Itraconazole is a drug with a low hepatic extraction ratio and its systemic clearance appears to be largely accounted for by hepatic metabolism.

Usefulness of MR imaging for diseases of the small intestine: comparison with CT

OBJECTIVE

To evaluate the usefulness of MR imaging for diseases of the small intestine, emphasizing a comparison with CT.

MATERIALS AND METHODS

Thirty-four patients who underwent both CT and MR imaging using FLASH 2D and HASTE sequences were analyzed. All patients had various small bowel diseases with variable association of peritoneal lesions. We compared the detectabilities of CT and MR imaging using different MR pulse sequences. The capability for analyzing the characteristics of small intestinal disease was also compared.

RESULTS

MR imaging was nearly equal to CT for detecting intraluminal or peritoneal masses, lesions in the bowel and mesentery, and small bowel obstruction, but was definitely inferior for detecting omental lesions. The most successful MR imaging sequence was HASTE for demonstrating bowel wall thickening, coronal FLASH 2D for mesenteric lesions, and axial FLASH 2D for omental lesions. MR imaging yielded greater information than CT in six of 12 inflammatory bowel diseases, while it was equal to CT in six of seven neoplasms and inferior in five of seven mesenteric ischemia. In determining the primary causes of 15 intestinal obstructions, MR imaging was correct in 11 (73%) and CT in nine (60%) patients.

CONCLUSION

MR imaging can serve as an alternative diagnostic tool for patients with suspected inflammatory bowel disease, small intestinal neoplasm or obstruction.

Regulation of the Bacillus subtilis phosphotransacetylase gene

The enzyme, phosphotransacetylase (Pta), catalyzes the conversion of acetyl coenzyme A to acetyl phosphate. The putative pta gene of Bacillus subtilis, which had been sequenced as part of the Genome Project, was cloned and overexpressed in Escherichia coli. We confirmed that the gene encodes Pta by measuring the enzymatic activity of the purified protein. Insertional mutagenesis of the pta gene resulted in complete loss of the Pta activity, indicating that B. subtilis contains only one kind of pta gene. Expression of a pta-lacZ fusion was induced in the presence of excess glucose in the growth medium, and the intact ccpA gene was required for this activation. The transcriptional start site of the pta gene was located at 37 nucleotides upstream of the pta start codon, and a cre (catabolite responsive element) sequence, a cis-acting element that is responsible for the catabolite repression of a number of carbon utilization genes in B. subtilis, was identified upstream of the tentative promoter site. Experiments involving oligonucleotide-directed mutagenesis showed that the cre sequence is involved in glucose-mediated transcriptional activation.

A role for a highly conserved protein of unknown function in regulation of Bacillus subtilis purA by the purine repressor

Regulation of the purine biosynthetic gene purA was examined by using a transcriptional fusion to a luciferase reporter gene. Transcription was repressed about 10-fold by the addition of adenine and increased approximately 4.5-fold by the addition of guanosine. This regulation is mediated by a purine repressor (PurR). In a purR mutant, basal expression was increased 10-fold, and there was no further stimulation by guanosine or repression by adenine. An open reading frame, yabJ, immediately downstream from purR was found to have a role in the repression of purA by adenine. Repression by adenine was perturbed in a purR+ yabJ mutant, although guanosine regulation was retained. Mutations in the PurR PRPP binding motif abolished guanosine regulation in the yabJ mutant. Thus, PRPP appears to be required for upregulation by guanosine. The amino acid sequence of YabJ is homologous to the YER057c/YjgF protein family of unknown function.

Usefulness of CT in patients with intestinal obstruction who have undergone abdominal surgery for malignancy

OBJECTIVE

The purpose of this study was to evaluate the usefulness of CT in determining the causes of intestinal obstruction in patients who have undergone abdominal surgery for malignancy.

MATERIALS AND METHODS

We analyzed the CT scans of 55 patients with benign (n = 26) or malignant (n = 29) intestinal obstruction that developed after abdominal surgery for malignancy. After calculating the diagnostic accuracy of interpretations by three radiologists, we compared CT findings for benign and malignant intestinal obstructions with respect to peritoneal involvement patterns and other ancillary findings. Multivariate logistic regression analysis was used to determine the diagnostic performance of CT in revealing causes of obstruction.

RESULTS

Diagnostic accuracies of the three radiologists were 67%, 75%, and 78%. CT findings indicating malignant obstruction were a mass at the site of obstruction or prior surgery, lymphadenopathy, or an abrupt transition zone and irregular bowel wall thickening at obstructed sites (p < .05). Conversely, the chance for benign obstruction increased when CT revealed mesenteric vascular changes, a large amount of ascites, or a smooth transition zone and smooth bowel wall thickening at the obstructed site (p < .05). With multivariate logistic regression analysis using two variables (a mass at the site of obstruction or prior surgery and lymphadenopathy), we calculated the overall accuracy of CT as 84% (46/55 patients).

CONCLUSION

CT is useful in differentiating benign from malignant intestinal obstructions in patients who have undergone abdominal surgery for malignancy. However, CT has limitations in patients not having a demonstrable peritoneal mass.

Sequence analysis of the Bacillus subtilis 168 chromosome region between the sspC and odhA loci (184 degrees-180 degrees)

The nucleotide sequence of 45,389 bp in the 184 degrees-180 degrees region of the Bacillus subtilis chromosome, containing the cge cluster, which is controlled by the sporulation regulatory protein GerE, was determined. Fifty-four putative ORFs with putative ribosome-binding sites were recognized. Seven of them correspond to previously characterized genes: cgeB, cgeA, cgeC, cgeD, cgeE, ctpA, and odhA. The deduced products of 25 ORFs were found to display significant similarities to proteins in the data banks. We have identified genes involved in detoxification, cell walls, and in the metabolism of biotins, purines, fatty acids, carbohydrates and amino acids. The remaining 22 ORFs showed no similarity to known proteins. Both an attachment site of the SPbeta prophage and 2 new putative DNA replication terminators were identified in this region.

An 8 kb nucleotide sequence at the 3' flanking region of the sspC gene (184 degrees) on the Bacillus subtilis 168 chromosome containing an intein and an intron

As part of the Bacillus subtilis genome sequencing project, we determined the complete nucleotide sequence of an 8000-bp fragment downstream of the sspC gene (184 degrees) of the B. subtilis 168 chromosome. The sequence analysis shows that the sspC gene is located inside of the SP beta region, which differs from the current genetic map of B. subtilis 168. This region contains 12 putative ORFs (yojQ through yojZ and sspC). A homology search for the deduced products of the ORFs shows significant similarities to enzymes involved in deoxyribonucleotide metabolism: ribonucleotide reductase (Nrd) E, NrdF, thioredoxin and dUTPase. Interestingly, this DNA fragment includes two split genes, yojP containing conserved motifs of an intein and yojQ and yojS with an 808-bp intervening sequence for a putative intron structure. In addition, the yojR gene includes a putative new DNA replication terminator.

Vasculature in hepatocellular carcinoma after transcatheter arterial chemoembolization: comparison of power and color Doppler sonography

The purpose of this study was to compare power Doppler sonography with conventional color Doppler sonography for the detection of the vascularity of hepatocellular carcinomas after transcatheter arterial chemoembolization. Of the 93 embolized hepatocellular carcinomas, hypervascularity was demonstrated in 36 on angiography; power Doppler sonography correctly identified pulsatile flow signals in 33 (92%) of these 36, whereas color Doppler sonography identified flow signals in 24 (67%). A statistically significant difference was noted when the sizes of the nodules were 30 mm or less. Despite technical difficulties, such as flash artifact, power Doppler sonography is superior to color Doppler sonography for detection of hypervascularity, especially in small embolized nodules of hepatocellular carcinoma (30 mm or less in diameter).

Interaction of Bacillus subtilis purine repressor with DNA

A purine repressor (PurR) mediates adenine nucleotide-dependent regulation of transcription initiation of the Bacillus subtilis pur operon. This repressor has been purified for the first time, and binding to control site DNA was characterized. PurR binds in vitro to four operons. Apparent Kd values for binding were 7 nM for the pur operon, 8 nM for purA, 13 nM for purR, and 44 nM for the pyr operon. In each case, DNase I footprints exhibited a pattern of protected and hypersensitive sites that extended over more than 60 bp. A GAAC-N24-GTTC sequence in the pur operon was necessary but not sufficient for the PurR-DNA interaction. However, this motif, which is conserved in the four binding sites, was not required for binding of PurR to purA. Thus, the common DNA recognition element for binding of PurR to the four operons is not known. Multiple PurR-pur operon DNA complexes having a binding stoichiometry that was either approximately two or six repressor molecules per DNA fragment were detected. The results of a torsional constraint experiment suggest that control site DNA forms one right-handed turn around PurR.

The complete genome sequence of the gram-positive bacterium Bacillus subtilis

Bacillus subtilis is the best-characterized member of the Gram-positive bacteria. Its genome of 4,214,810 base pairs comprises 4,100 protein-coding genes. Of these protein-coding genes, 53% are represented once, while a quarter of the genome corresponds to several gene families that have been greatly expanded by gene duplication, the largest family containing 77 putative ATP-binding transport proteins. In addition, a large proportion of the genetic capacity is devoted to the utilization of a variety of carbon sources, including many plant-derived molecules. The identification of five signal peptidase genes, as well as several genes for components of the secretion apparatus, is important given the capacity of Bacillus strains to secrete large amounts of industrially important enzymes. Many of the genes are involved in the synthesis of secondary metabolites, including antibiotics, that are more typically associated with Streptomyces species. The genome contains at least ten prophages or remnants of prophages, indicating that bacteriophage infection has played an important evolutionary role in horizontal gene transfer, in particular in the propagation of bacterial pathogenesis.

Cross-resistance of the diamondback moth indicates altered interactions with domain II of Bacillus thuringiensis toxins

We compared responses to six insecticidal crystal proteins from Bacillus thuringiensis by a Cry1A-resistant strain (NO-QA) and a susceptible strain (LAB-P) of the diamondback moth, Plutella xylostella. The resistant strain showed > 100-fold cross-resistance to Cry1J and to H04, a hybrid with domains I and II of Cry1Ab and domain III or Cry1C. Cross-resistance was sixfold to Cry1Bb and threefold to Cry1D. The potency of Cry1I did not differ significantly between the resistant and susceptible strains. Cry2B did not kill resistant or susceptible larvae. By combining these new data with previously published results, we classified responses to 14 insecticidal crystal proteins by strains NO-QA and LAB-P. NO-QA showed high levels of resistance to Cry1Aa, Cry1Ab, and Cry1Ac and high levels of cross-resistance to Cry1F, Cry1J, and H04. Cross-resistance was low or nil to Cry1Ba, Cry1Bb, Cry1C, Cry1D, Cry1I, and Cry2A. Cry1E and Cry2B showed little or no toxicity to susceptible or resistant larvae. In dendrograms based on levels of amino acid sequence similarity among proteins, Cry1F and Cry1J clustered together with Cry1A proteins for domain II, but not for domain I or III. High levels of cross-resistance to Cry1Ab-Cry1C hybrid H04 show that although Cry1C is toxic to NO-QA, domain III or Cry1C is not sufficient to restore toxicity when it is combined with domains I and II of Cry1Ab. Thus, diamondback moth strain NO-QA cross-resistance extends beyond the Cry1A family of proteins to at least two other families that exhibit high levels of amino sequence similarity with Cry1A in domain II (Cry1F and Cry1J) and to a protein that is identical to Cry1Ab in domain II (H04). The results of this study imply that resistance to Cry1A alters interactions between the insect and domain II.

Cloning of a novel crystal protein gene cry1K from Bacillus thuringiensis subsp. morrisoni

A novel crystal protein gene cry1K has been cloned and sequenced from a Bacillus thuringiensis subsp. morrisoni BF190 isolated from phylloplane. The upstream promoter region of cry1K was almost identical with that of cry1B. The deduced amino acid sequence of Cry1K contains 1215 amino acid residues with an estimated molecular mass of 137 kDa. Comparison of the amino acid sequence of the Cry1K with that of Cry proteins revealed that Cry1K is most closely related to Cry1B and Cry1I. Cry1K has a high degree of identity with Cry1B in the region between initiator codon and conserved sequence block 1, and with Cry1F in the region between conserved block 3 and 5. Protein inclusion purified from a recombinant strain of B. thuringiensis expressing the cry1K gene was found to have a different insect-host specificity from Cry1B, Cry1I and Cry1F, Cry1K was found to be selectively toxic to Artogeia rapae and not active to Plutella xylostella.

Distribution of cryV-type insecticidal protein genes in Bacillus thuringiensis and cloning of cryV-type genes from Bacillus thuringiensis subsp. kurstaki and Bacillus thuringiensis subsp. entomocidus

DNA dot blot hybridizations with a cryV-specific probe and a cryI-specific probe were performed to screen 24 Bacillus thuringiensis strains for their cryV-type (lepidopteran- and coleopteran-specific) and cryI-type (lepidopteran-specific) insecticidal crystal protein gene contents, respectively. The cryV-specific probe hybridized to 12 of the B. thuringiensis strains examined. Most of the cryV-positive strains also hybridized to the cryI-specific probe, indicating that the cryV genes are closely related to cryI genes. Two cryV-type genes, cryV1 and cryV465, were cloned from B. thuringiensis subsp. kurstaki HD-1 and B. thuringiensis subsp. entomocidus BP465, respectively, and their nucleotide sequences were determined. The CryV1 protein was toxic to Plutella xylostella and Bombyx mori, whereas the CryV465 protein was toxic only to Plutella xylostella.