Blockade of fatty acid signalling inhibits lipopolysaccharide-induced macrophage recruitment and progression of apical periodontitis.

AIM: To examine the role of palmitic acid in lipopolysaccharide (LPS)-stimulated chemotaxis of macrophages and the potential contribution of saturated fatty acid in signalling during the pathogenesis of apical periodontitis. METHODOLOGY: J774, a mouse macrophage cell line, was used in the experiments. After treatment with LPS, proteolytic maturation of sterol regulatory element-binding protein-1c (SREBP-1c) and expression of fatty acid synthase (FASN) were examined by Western analysis. Levels of palmitic acid were measured by reverse phase-high performance liquid chromatography-mass spectrometry. Knockdown of SREBP-1c and FASN was accomplished by small interfering RNA technology. Secretion of CC-chemokine ligand 2 (CCL2) and cellular chemotaxis were assessed by enzyme-linked immunosorbent assay and transwell migration assay, respectively. Sulfo-N-succinimidyl oleate (SSO) treatment was used to inhibit fatty acid signalling in vitro and also in a rat model of apical periodontitis. All data were first subjected to Levene's test. In vitro data were then analysed using ANOVA followed by Tukey's multiple comparison test. Data from animal experiments were analysed by independent t-tests. The significant level was set at 0.05. RESULTS: LPS stimulated proteolytic maturation of SREBP-1c and FASN expression in macrophages and significantly enhanced palmitic acid synthesis (P < 0.05). Knockdown of SREBP-1c attenuated LPS-enhanced FASN expression. Knockdown of FASN significantly suppressed LPS-enhanced palmitic acid synthesis (P < 0.05). LPS and exogenous palmitic acid significantly enhanced CCL2 secretion and macrophage chemotaxis (all P < 0.05). Inhibition of FASN expression significantly alleviated LPS-augmented CCL2 secretion (P < 0.05). SSO significantly suppressed CCL2 secretion and macrophage chemotaxis augmented by LPS and palmitic acid (all P < 0.05). In a rat model of induced apical periodontitis, SSO treatment significantly attenuated progression of apical periodontitis and macrophage recruitment (all P < 0.05). CONCLUSIONS: LPS/SREBP-1c/FASN/palmitic acid signalling contributed to tissue destruction caused by bacterial infection. Modulation of lipid metabolism and signalling may be helpful for the management of apical periodontitis.

Simvastatin alleviates bone resorption in apical periodontitis possibly by inhibition of mitophagy-related osteoblast apoptosis.

AIM: To assess the connection between mitophagy and hypoxia-induced apoptosis in osteoblasts and whether simvastatin alleviates bone resorption in apical periodontitis through modulation of mitophagy-related apoptosis. METHODOLOGY: Hypoxia-induced generation of reactive oxygen species in mitochondria and changes in mitochondrial membrane potential were evaluated, respectively, by MitoSOX and JC-1 fluorescence dye signalling. Accumulation of mitophagy markers PTEN-induced putative kinase 1 (PINK1) and Parkin in mitochondria was examined by Western blotting and immunofluorescence microscopy. Osteoblast apoptosis was assessed by Western analysis of cleaved-poly (adenosine diphosphate ribose) polymerase (PARP). In a rat model of induced apical periodontitis, the therapeutic effect of simvastatin and its action on osteoblast mitophagy and apoptosis were examined. anova, Fisher's and Student's t-test were used for data analysis. RESULTS: Hypoxia-induced mitochondrial dysfunction and stimulated mitophagy in osteoblasts. Hypoxia also provoked apoptosis in osteoblasts and inhibition of mitophagy decreased hypoxia-augmented apoptotic activity. Simvastatin alleviated hypoxia-induced mitochondrial dysfunction, mitophagy and apoptosis. The protective action of simvastatin against apoptosis was related to its antimitophagy activity. Experiments in the rat model of induced apical periodontitis supported the laboratory findings. Simvastatin treatment mitigated periapical bone loss and reduced the activities of apoptosis and mitophagy in regional osteoblasts. CONCLUSIONS: The results suggest that modulation of osteoblast mitophagy may help diminish bone loss associated with inflammation and has potential as an auxiliary therapy for apical periodontitis.

Sirtuin 6 attenuates periapical lesion propagation by modulating hypoxia-induced chemokine (C-C motif) ligand 2 production in osteoblasts.

AIM: To investigate the attenuating effect of sirtuin 6 (SIRT6) on hypoxia-induced production of chemokine (C-C motif) ligand 2 (CCL2) by osteoblasts and the relevance of this action on the pathogenesis of periapical lesions. METHODOLOGY: Sirtuin 6 was overexpressed in MC3T3-E1 murine osteoblasts by lentivirus-mediated gene transfer. The relationship between the antiglycolytic/antioxidative activities of SIRT6 and its effect on hypoxia-induced CCL2 production were examined. Pathogenetic relevance of the actions of SIRT6 was assessed in a rat model of induced apical periodontitis. The data were analysed statistically using Student's t-test or one-way analysis of variance (anova) and then a Tukey's multiple comparison test. RESULTS: In cultured murine osteoblasts, 24-h hypoxic treatment significantly enhanced the generation of reactive oxygen species (P = 0.003), expression of lactate dehydrogenase A (LDHA) and production of lactate (P = 0.007). A reciprocal effect between hypoxia-induced redox imbalance and hypoxia-enhanced glycolysis was noted which in turn augmented the secretion of CCL2. Through its antiglycolytic and antioxidative effects, SIRT6 blocked the vicious cycle to suppress CCL2 production. In normal periapical tissues of rats, strong expression of SIRT6 and low levels of LDHA and 8-OHdG (a marker of oxidative DNA damage) were found in osteoblasts. In induced apical periodontitis, osteoblastic expression of SIRT6 was significantly suppressed (P = 0.001) which was associated with significantly elevated levels of LDHA (P = 0.003) and 8-OHdG (P = 0.004) and significantly enhanced recruitment of macrophages (P = 0.004). CONCLUSIONS: Sirtuin 6 has a therapeutic effect on periapical lesions through suppression of CCL2 synthesis. The anti-inflammatory action of SIRT6 is closely related to its regulatory activities in cellular metabolism and redox homoeostasis.

HLA-DPB1 and anti-HBs titer kinetics in hepatitis B booster recipients who completed primary hepatitis B vaccination during infancy.

Previously we reported significant associations of the human leukocyte antigen (HLA)-DPB1 05:01 with memory against hepatitis B (HB) vaccination. However, the effects of HLA-DPB1 on antibodies to hepatitis B surface antigen (anti-HBs) kinetics were not explored. We followed up a cohort of 1974 HB booster recipients and quantified their 1-month and 1-year post-booster anti-HBs titers. A total of 681 subjects were randomly selected and typed for HLA-DPB1. We found that male subjects, undetectable pre-booster titers, and 05:01 homozygotes led to significantly lower post-booster anti-HBs titers. The geometric means (95% confidence interval (CI)) of 1-month post-booster anti-HBs titers were 4.68 (2.69-8.12), 23.01 (14.96-35.40) and 50.06 (27.20-92.13) mIU ml(-1) for subjects carrying two, one and no HLA-DPB1 05:01 allele. The corresponding figures for 1-year post-booster anti-HBs titers were 1.26 (0.73-2.18), 4.72 (3.08-7.25) and 7.32 (3.75-13.56) mIU ml(-1). There were significant associations of post-booster anti-HBs titers with the number of HLA-DPB1 risk and protective alleles. Among booster responders, anti-HBs decay rates were significantly reduced in subjects who had detectable pre-booster anti-HBs titers and the HLA-DPB1 05:01 allele. Our results indicated that HLA-DPB1 influences the kinetics of anti-HBs. The long-term memory against hepatitis B surface antigen (HBsAg) and the residual serum titers of anti-HBs after HB vaccination may be influenced by different mechanisms as evidenced by their inverse trend of associations with the 05:01 allele.

Tunneled island pedicle flap reconstruction for upper lateral cutaneous lip defects.

BACKGROUND: Esthetic upper lateral cutaneous lip reconstruction preserves the apical triangle, nasolabial fold symmetry, and free margin position. The tunneled island pedicle flap (IPF) is a novel single-stage reconstruction to achieve these goals. OBJECTIVES: Describe the technique and patient and surgeon-reported outcomes for the tunneled IPF reconstruction of upper lateral cutaneous lip defects. METHODS: Retrospective chart review of consecutive tunneled IPF reconstruction following Mohs micrographic surgery (MMS) at a tertiary care center between 2014 and 2020. Patients rated their scars using the validated Patient Scar Assessment Scale (PSAS), and independent surgeons rated scars using the validated Observer Scar Assessment Scale (OSAS). Descriptive statistics were generated for patient demographics and tumor defect characteristics. RESULTS: Twenty upper lateral cutaneous lip defects were repaired with the tunneled IPF. Surgeons rated scars with a composite OSAS score of 11.83 ± 4.29 (mean, SD) [scale of 5 (normal skin) to 50 (worst scar imaginable)] and an overall scar score of 2.81 ± 1.11 [scale of 1 (normal skin) to 10 (worst scar imaginable)]. Patients rated their scars with a composite PSAS score of 10 ± 5.39 [scale of 6 (best possible score) to 60 (worst)] and with an overall score of 2.2 ± 1.78 [scale of 1 (normal skin) and 10 (very different from normal skin)]. One flap was surgically revised for pincushioning, but none experienced necrosis, hematoma, or infection. CONCLUSIONS: The tunneled IPF is a single-stage reconstruction for upper lateral cutaneous lip defects with favorable scar ratings by patients and observers.

Circular RNA circ_0067934 functions as an oncogene in glioma by targeting CSF1.

Since this article has been suspected of research misconduct and the corresponding authors did not respond to our request to prove originality of data and figures, "Circular RNA circ_0067934 functions as an oncogene in glioma by targeting CSF1, by X.-L. Cui, X.-D. Wang, S.-K. Lin, C.-M. Miao, M. Wu, J.-G. Wei, published in Eur Rev Med Pharmacol Sci 2019; 23 (19): 8449-8455-DOI: 10.26355/eurrev_201910_19157-PMID: 31646575" has been withdrawn. The Publisher apologizes for any inconvenience this may cause. https://www.europeanreview.org/article/19157.

In situ preparation of an ultra-thin nanomask on a silicon wafer.

Porous nanomasks have been prepared in situ on an insulating silicon wafer by anodization of an aluminum film grown on it. Ultra-thin nanomasks, around 50 nm thick, were fabricated by utilizing a stop signal, a vivid color appearing at the air-electrolyte interface, and the process involved showed excellent repeatability. Finally, 2D nanoscale p-n junction arrays were fabricated on a silicon on insulator (SOI) wafer using the ultra-thin nanomasks prepared. The experimental results are in good agreement with the simulated results on the characteristics of the anodization process involved.

Circular RNA circ_0067934 functions as an oncogene in glioma by targeting CSF1.

OBJECTIVE: The importance of circular RNAs in malignant tumors increases the attention of researchers. The role of circ_0067934 in glioma remains unclear. Our study aims to uncover how circ_0067934 functions in glioma development. PATIENTS AND METHODS: Real Time-quantitative Polymerase Chain Reaction (RT-qPCR) was utilized to determine the level of circ_0067934 in glioma tissues. Circ_0067934 was knocked down in glioma cells. Cell migrated and invaded ability was detected through functional assay in vitro and in vivo. Further mechanism assays were performed to explore the potential targets of circ_0067934. RESULTS: The circ_0067934 was highly expressed in glioma tissues compared with adjacent samples. The expression of circ_0067934 was upregulated in glioma cell lines. The cell migrated and invaded ability of glioma cells was inhibited after circ_0067934 was knocked down. Besides, CSF1 expression was decreased via knockdown of circ_0067934. Furthermore, tumor metastasis was inhibited after circ_0067934 was knocked down in nude mice. CONCLUSIONS: The circ_0067934 could suppress cell migration and invasion of glioma by upregulating CSF1.

Correction to: CCN2 inhibits lung cancer metastasis through promoting DAPK-dependent anoikis and inducing EGFR degradation.

Following publication of their article "CCN2 inhibits lung cancer metastasis through promoting DAPK-dependent anoikis and inducing EGFR degradation", the authors reported an error in Fig.6b. α-Tubulin image of rCCN2 treatment  (upper panel in CL1-5) only showed eight lanes, when there should be nine.

Clinical relevance of musical murmurs in color-coded carotid and transcranial duplex sonographies.

BACKGROUND AND PURPOSE: Musical murmurs (MMs), sometimes called seagull cry, goose cry, honks, or cooing murmur, are murmurs with a single frequency that sounds like a musical tone. Doppler detections usually show mirror-image parallel strings or bands of low to moderate frequency. Musical murmurs are mostly described in cardiac murmurs and have seldom been mentioned in cerebrovascular disease. METHODS: A retrospective review of 12,000 patients from our neurosonographic data base of the past 7 years was conducted to find patients who had MMs during color-coded carotid and transcranial duplex sonographies. RESULTS: Sixty-six musical murmurs were found in 60 patients (0.5% of all studied patients). There were 44 men and 16 women with a mean age of 63.8 years. Musical murmurs may occur with or without simultaneous turbulent flows, or very close to a high-intensity frequency (with systolic spindles) turbulent flow. Musical murmurs are detected more frequently in intracranial vessels (94%) than in extracranial cervical arteries. The pathologic changes corresponding to the area of MMs were high-grade stenosis of the arteries (58 MMs), small arteries serving as collateral circulation (5 MMs), carotid cavernous sinus fistulas (2 MMs), and Moyamoya disease (1 MM). Fifty (88%) of 57 patients with stenotic arterial lesions had histories of cerebral infarction or transient ischemic attack, and 64% of the cerebrovascular events occurred on the side appropriate to the MMs. CONCLUSIONS: The presence of MMs in color-coded carotid duplex and transcranial color-coded duplex sonography imply severe underlying vascular diseases that require prompt treatment. Further cerebral angiographic study is warranted to clarify the underlying pathology in patients with MMs.

Pharmacodynamics and pharmacokinetics of haloperidol and reduced haloperidol in schizophrenic patients.

Twelve male chronic schizophrenic inpatients, neuroleptic-free for at least 4 weeks, were given an oral test dose of 10 mg haloperidol (HAL) and reduced HAL (RHAL) in a random order, with a 2-week interval. Two weeks after the last test dose, the patients were given HAL, 5 mg orally twice daily for 7 days. Blood samples were drawn at baseline and between 0.5 and 24 hr after the test doses, and during HAL treatment as well. Plasma drug concentrations and homovanillic acid (HVA) levels were measured with high-performance liquid chromatography using electrochemical detection. HAL, but not RHAL, produced increments in plasma HVA (pHVA) levels at 24 hr after a test dose. pHVA levels remained higher than baseline during HAL treatment. Detectable interconversion between HAL and RHAL was observed in eight patients. The capacity of the reductive drug-metabolizing enzyme system, however, was greater than that of the oxidative processes. The plasma RHAL:HAL ratios on days 6 and 7 were higher than and positively correlated with those at Tmax after a single dose of HAL and were negatively correlated with the HAL:RHAL ratios at Tmax after a single dose of RHAL. Thus, both reductive and oxidative drug-metabolizing systems probably contribute to individual differences in plasma RHAL:HAL ratios in HAL-treated schizophrenic patients.

Plasma catecholamine metabolites in schizophrenics: evidence for the two-subtype concept.

Plasma homovanillic acid (pHVA) and plasma methoxyhydroxyphenyl glycol (pMHPG), as well as plasma haloperidol, were measured in 33 schizophrenic patients before and during 6 weeks of haloperidol treatment. Good responders had higher baseline pHVA values compared with poor responders (17.4 +/- 8.8 ng/ml, n = 22 versus 11.4 +/- 5.0 ng/ml, n = 11, p less than 0.05). A higher than 15 ng/ml pretreatment pHVA level was associated with a more consistent clinical response to the subsequent treatment. Differential pHVA changes during treatment were also found between good and poor responders. Within the good responder group, a significant decline in pHVA over time was found. By contrast, pHVA showed a transient increase in the poor responder group. Plasma MHPG changes showed a similar pattern during treatment in good responders, although no significant differences in baseline values were found between the good (n = 13) and poor (n = 9) responders, and pMHPG showed no change during treatment in poor responders. Significant correlations between baseline pHVA and pMHPG values were found in 22 patients. Good responders and poor responders did not differ significantly in terms of age, duration of illness, severity of presenting symptoms, haloperidol dose, or plasma drug concentration. Two hypothetical subtypes of schizophrenia and both dopamine and norepinephrine systems involved in schizophrenic psychopathology are proposed.

An evaluation of whole blood testing for Helicobacter pylori in general practice.

BACKGROUND: Rapid whole blood tests for Helicobacter pylori infection were developed to assist in the management of patients with dyspepsia in general practice. However, they have not been extensively tested in this setting. AIM: To investigate the test characteristics of the BM-Test (Helisal Quick Test) when used in general practice. METHOD: One hundred and ten dyspeptic patients attending local general practitioners were recruited into the study. The BM-Test was administered by the general practitioner at the screening visit according to standard instructions supplied with the test kit. The patient was then referred to Nepean or Mornington Peninsula Hospitals for further assessment. including a 14C-urea breath test. The test kit was forwarded to the appropriate hospital centre for an independent, blinded reading. The sensitivity and specificity of the BM-Test were evaluated against the results of the 14C-UBT. RESULTS: Based on general practitioner readings, the BM-Test had a sensitivity of 59.3% and a specificity of 90.2%. The positive and negative predictive values were 87.5% and 65.7%, respectively. When based on independent readings, sensitivity rose to 71.2% and specificity fell to 88.2%. The BM-Test was more sensitive for older patients than for younger patients when based on both the general practitioner and independent readings. CONCLUSION: The BM-Test performs below the generally recommended sensitivity and specificity of 90% required for clinical practice.

A rapid-release 50-mg tablet-based 13C-urea breath test for the diagnosis of Helicobacter pylori infection.

BACKGROUND: Recently, a rapid-release 100-mg 13C-urea tablet with citrate supplement (Diabact UBT) showed excellent performance in a European population. AIM: To investigate the accuracy of a 50-mg tablet-based 13C-urea breath test protocol. METHODS: : Consecutive dyspeptic patients referred for upper endoscopy were recruited. 13C-Urea breath test was performed using a 50-mg 13C-urea tablet (Diabact UBT) and compared with the gold standard (rapid urease test and histology). Baseline, 10-min, 20-min and 30-min breath samples were collected in all cases. The cut-off values at each measurement interval were determined by three standard deviations above the mean excess delta 13CO2 excretion of Helicobacter pylori-negative patients. RESULTS: Two hundred patients (150 before therapy and 50 after therapy) were available for analysis, with a mean age of 48.4 years, and 99 patients (50%) were H. pylori positive. The sensitivity and specificity of the 50-mg tablet-based 13C-urea breath test at 10 min, 20 min and 30 min were 100% and 98%, 100% and 100%, and 100% and 98%, respectively. CONCLUSION: A 20-min, 50-mg tablet-based 13C-urea breath test (Diabact UBT) protocol is highly accurate for the diagnosis of H. pylori infection.

Effects of gender and age on plasma levels of clozapine and its metabolites: analyzed by critical statistics.

BACKGROUND: Previous reports concerning the effects of gender and age on steady-state plasma concentrations of clozapine and its major metabolites, norclozapine and clozapine-N-oxide, have been controversial. Since the frequency distribution of the plasma levels is asymmetrical and skewed to the right, the statistical methods (such as analysis of variance and regression analysis) used earlier are actually inappropriate for analyzing the effects of the variables on the concentrations and might contribute to the inconsistent results. The goal of the present study, with befitting statistics, is to measure the potential effect of dose, gender, age, and body weight on plasma levels of clozapine and its 2 major metabolites. METHOD: We retrospectively analyzed data from a therapeutic drug monitoring study for steady-state plasma clozapine, norclozapine, and clozapine-N-oxide levels that was conducted in a large group of Chinese schizophrenic inpatients (male:female ratio = 83:79; age range, 33.8 +/- 9.3 years). The daily doses of clozapine had ranged from 100 to 900 mg, with a mean +/- SD value of 379.5 +/- 142.2 mg. Plasma concentrations had been measured using high-performance liquid chromatography with ultraviolet detection. Multiple linear regression was adopted to quantify the effects of various factors on the plasma levels. The natural logarithm of the plasma level was used as the dependent variable to overcome the skewness problem. RESULTS: After adjusting the effects of gender, age, and body weight by multiple linear regression, each 1-mg increment in the daily dose could raise the clozapine level by 0.31%, norclozapine by 0.27%, and clozapine-N-oxide by 0.16%. Female patients had 34.9% higher clozapine levels and 36.3% higher norclozapine, with other variables being controlled. No sex differences were demonstrated for clozapine-N-oxide levels. Each 1-year increment in age would elevate the clozapine level by 1.1%, norclozapine by 1.0%, and clozapine-N-oxide by 1.0%. Body weight could not influence the levels of these compounds. CONCLUSION: The present results suggest that women possess higher plasma levels (about one third higher) of clozapine and norclozapine, but not the N-oxide metabolite. Each addition of 1 year in age elevated clozapine and either metabolite's levels by about 1%. Furthermore, every 1-mg increase in the daily dose raised clozapine and norclozapine concentrations by approximately 0.3%. These findings could assist clinicians in optimizing clozapine dosing strategies.

Gastrointestinal radiology. Pharmacokinetics of iopanoate and iodoxamate in rhesus monkeys.

The pharmacokinetics, biliary excretion, plasma protein binding, enterohepatic circulation, and biotransformation of iopanoic acid and iodoxamic acid in the rhesus monkey were evaluated by a dynamic infusion method. The dynamic method has the advantage that the pharmacokinetic parameters involved in the hepatic uptake and biliary excretion can be evaluated from a single infusion experiment. The percentage of iodoxamic acid not bound to plasma protein varied from 6.1-41.2% as iodoxamic acid plasma levels were from 42 microM to 912 microM. Using the Freundlich isotherm approach, more than one class of binding site for iodoxamic acid was found. A saturable biliary excretion mechanism or hepatic uptake mechanism was determined with a Vmax of 1.03 microM/kg/min. Less than 1% of iodoxamic acid injected into the duodenum was recovered in the bile in 12 hours. Iodoxamic acid was found to exist in blood as an unchanged species. Iopanoic acid was extremely highly bound to monkey plasma protein. As blood concentration increased from 18.9 to 464 microM, the percentage unbound in plasma protein varied from 0.1-2.8%. Biliary excretion rates of iopanoic acid were fitted by a computer to the Michaelis-Menten equation against unbound plasma concentration and the average Vmax value was found to be 0.85 microM/kg/min with an average Kmax value of 0.253. Iopanoic acid was found to exist in monkey blood as unchanged species and in the bile mainly as an ester glucuronide. Coadministration experiments revealed that the interaction of iodoxamic acid and iopanoic acid in the monkey is complex. The compounds appear to compete for plasma protein binding sites as well as for binding sites on intrahepatic protein. The biliary excretion data seem to fit the ligant exclusion model, in which iopanoic acid acts as an inhibitor and competes with iodoxamic acid for binding to either of two identical sites in the liver, which, presumably, is the rate-limiting step in the liver's overall elimination of these radiographic agents.

Saturation kinetics of iodipamide.

To characterize the saturation kinetics of iodipamide, timed samples of blood, urine, and bile were taken from two unanesthetized dogs infused with iodipamide at increasing rates to achieve various steady state blood concentrations. Biliary excretion rate of iodipamide reached an asymptote with increasing blood concentration, indicating a biliary transport maximum (Tm) of 15.2 to 16.2 mgI/min. Urinary excretion was not a pure, first order process and urinary excretion rate was higher than the glomerular filtration rate corrected for plasma protein binding, suggesting that active tubular secretion may play a part. Extrarenal elimination followed Michaelis-Menten kinetics. Estimates of maximum rate (Vm) and Michaelis-Menten constant (Km) were obtained graphically. The estimated values of Vm were 4 to 6 times that of biliary Tm. In acute infusion experiments the iodipamide excreted in the bile and urine and that remaining in the organs analyzed accounted for only a fraction of the dose administered; no significant accumulation of iodipamide was found in the liver.

Recirculation of iopanoic acid after conjugation in the liver.

The purpose of the investigation was to determine if an enterohepatic recirculation occurred for the metabolite of iopanoic acid. The major metabolite of iopanoic acid (Telepaque) in dog bile is the glucuronide conjugate. The identification and quantitation of glucuronide conjugate was accomplished by elemental analysis, paper chromatography, thin layer chromatography, fluorescent excitation analysis, and high pressure liquid chromatography. The stability of iopanoic acid glucuronide in refrigerated dog bile was confirmed. Known amounts of the glucuronide conjugate were instilled into the duodenum of 8 awake adult dogs, and bile collected for 8 hours. Between 19% and 53% (average 31%) of the administered dose was recovered in bile, thereby documenting the presence of an enterohepatic recirculation of conjugated iopanoic acid. The slow rise and plateau of the excretion curve suggests that either the compound is absorbed slowly, or that absorption depends upon deconjugation in the gut. The implications are discussed.

Pharmacokinetics of iopanoic acid in the rhesus monkey: biliary excretion, plasma protein binding and biotransformation.

A dynamic infusion method, originally developed for the pharmacokinetic studies of Iodoxamic acid, was applied to the kinetic studies of the biliary excretion of another cholecystographic agent, iopanoic acid. This dynamic method has an important advantage in that the pharmacokinetic parameters involved in the hepatic uptake or biliary excretion can be evaluated from a single infusion experiment. Using the equilibrium dialysis technique, iopanoic acid was found to be highly bound to the plasma proteins. A linear relationship was found when the logarithm of unbound plasma concentration of iopanoic acid was plotted vs. the logarithm of its blood concentration. When the biliary excretion rates of iopanoic acid were fitted by a computer to the Michaelis-Menten equation against its unbound plasma concentration, the average Vm value was found to be 0.85 micron/kg/min and the average Km value was found to be 0.253 micron. Iopanoic acid was found to exist in monkey blood as unchanged species and in the bile mainly as the ester glucuronide.

Observation on the metabolism of iopanoyl (Telepaque) glucuronide in dogs treated with antibiotics.

The purpose of our investigation was to determine whether iopanoyl glucuronide, the major metabolite of iopanoic acid (Telepaque), undergoes hydrolysis by bacterial beta-glucuronidase in dogs. The conjugated compound was identified and quantitated by elemental analysis, fluorescent excitation analysis, thin-layer chromatography, and high pressure liquid chromatography. The experiments were performed before and after combined antibiotic treatment with neomycin and vancomycin. It was first determined that reabsorption and excretion of sodium iopanoate was only minimally diminished during antibiotic treatment. Known amounts of iopanoyl glucuronide were infused into the small bowel of 4 awake dogs with chronic bile fistula, and bile was collected for 5--8 hours. The excretion of the recirculated conjugated compound was 4--5 times lower during antibiotic treatment. Incubation of ileal fluid with bile containing iopanoyl glucuronide suggested that beta-glucuronidase hydrolyzes the conjugated compound. Hydrolysis was markedly decreased after pretreatment with antibiotics. These findings suggest that the beta-glucuronidase produced by bacteria may be a major mechanism in enterohepatic recirculation of iopanoyl glucuronide. Mechanisms and possible implications are discussed.