Fluctuations in complex networks with variable dimensionality and heterogeneity.

Synchronizing individual activities is essential for the stable functioning of diverse complex systems. Understanding the relation between dynamic fluctuations and the connection topology of substrates is therefore important, but it remains restricted to regular lattices. Here we investigate the fluctuation of loads, assigned to the locally least-loaded nodes, in the largest-connected components of heterogeneous networks while varying their link density and degree exponents. The load fluctuation becomes finite when the link density exceeds a finite threshold in weakly heterogeneous substrates, which coincides with the spectral dimension becoming larger than 2 as in the linear diffusion model. The fluctuation, however, diverges also in strongly heterogeneous networks with the spectral dimension larger than 2. This anomalous divergence is shown to be driven by large local fluctuations at hubs and their neighbors, scaling linearly with degree, which can give rise to diverging fluctuations at small-degree nodes. Our analysis framework can be useful for understanding and controlling fluctuations in real-world systems.

Comparative protein binding of taxotere and SID530, a new docetaxel formulation with hydroxypropyl-beta-cyclodextrin, in human plasma in vitro.

The purpose of this study was to evaluate the plasma-protein binding of docetaxel in two different formulations, Taxotere and SID530, a new docetaxel formulation with hydroxypropyl-beta-cyclodextrin (HP-beta-CD), in human plasma in vitro, using equilibrium dialysis. Unbound docetaxel concentration in the human plasma was determined by LC-MS/MS analysis. SID530 showed a plasma-protein binding profile comparable to that of Taxotere in the clinically relevant concentration range of docetaxel. In both formulations, the unbound fraction of docetaxel increased in a concentration-dependent biphasic manner. The resulting data indicate that the excipient used in SID530, HP-beta-CD, generates similar effects as polysorbate 80 of Taxotere in terms of plasma-protein binding of docetaxel.

Validated LC-MS/MS method for the determination of mirodenafil in rat plasma and its application to a comparative pharmacokinetic study of the free base and hydrochloride salt forms of mirodenafil.

In this study, the pharmacokinetics of 2 forms of mirodenafil, namely the base form and the hydrochloride salt form, were investigated in rats. The 2 forms were orally administered to rats and the plasma concentrations of mirodenafil were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The mirodenafil base and hydrochloride salt forms showed similar pharmacokinetic profiles in terms of their maximum plasma concentration (Cmax) and area under the concentration-time curve (AUC). The time to peak concentration (Tmax) of the base form was slightly greater than that of the salt form, but this difference was not statistically significant. These results suggest that the mirodenafil base and hydrochloride forms are pharmacokinetically equivalent in rats, and thus the base form could be used in various mirodenafil formulations as a substitute for the existing mirodenafil hydrochloride form.

Pharmacokinetic equivalence of Taxotere and SID530, a novel docetaxel formulation containing hydroxypropyl-beta-cyclodextrin in monkeys.

SID530 is a new parenteral formulation of docetaxel containing hydroxypropyl-beta-cyclodextrin (HP-ß-CD). In this study, a comparative pharmacokinetic study of 2 docetaxel parenteral solutions, SID530 and Taxotere, was carried out. In a crossover experimental design, 6 male cynomolgus monkeys received each formulation by intravenous infusion of a single dose. The concentration of docetaxel in whole blood and plasma was determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The 2 formulations showed similar pharmacokinetic parameters in both whole blood and plasma, and displayed comparable values for maximum serum concentration (Cmax), time to peak concentration (Tmax), and area under the concentration-time curve (AUC). The 90% confidence intervals for the ratios of Cmax and AUC values for SID530 to Taxotere were within the acceptable range of 0.80-1.20 in both plasma and whole blood. These findings indicate that SID530 and Taxotere are comparable in terms of their distribution in the blood and their plasma profile; consequently, these drugs are bioequivalent in the monkey.

Effects of an aqueous-ethanolic extract of ginger on cytochrome P450 enzyme-mediated drug metabolism.

Ginger has been extensively used as a herbal medicine for thousands of years in Asia; it has also been used as a seasoning agent in several foods and beverages worldwide. In this study, the effect of an aqueous-ethanolic extract of ginger on CYP450-mediated drug metabolism was investigated in vitro to elucidate the herb-drug interactions. A CYP450-specific substrates mixture was incubated with an aqueous-ethanolic extract of ginger in human liver microsomes fortified with an NADPH-generating system, and the metabolites generated from each of the CYP450-specific metabolic reactions were measured by liquid chromatography-tandem mass spectrometry. The ginger extracts were tested at concentrations of 0.05-5 microg/mL. The resulting data showed that the ginger extract inhibited CYP2C19-mediated drug metabolism in a concentration-dependent manner with an IC50 value of 3.8 microg/mL. When the ginger extract was pre-incubated and assessed, the inhibition pattern did not change, indicating that the inhibition of CYP2C19 was competitive rather than mechanism-based. The effects on other CYP isozyme activity were negligible at the concentrations tested. In conclusion, this inhibitory effect of ginger extract could affect the pharmacokinetics and lead to interactions with drugs that are metabolized by CYP2C19.

Flavin-containing monooxygenase 1-catalysed N,N-dimethylamphetamine N-oxidation.

N,N-dimethylamphetamine (DMA) is a methamphetamine analogue known to be a weaker central nervous system stimulant than methamphetamine. Although a major metabolite of DMA is known to be DMA N-oxide (DMANO), which may be catalysed by flavin-containing monooxygenase (FMO), the specific enzyme(s) involved in this biotransformation has not been identified. In this study, the specific enzyme(s) involved with DMA N-oxidation was characterized by several assays. When DMA was incubated with different human recombinant drug-metabolizing enzymes, including FMOs and cytochrome P450s (CYPs), the formation of DMANO by FMO1 was the most predominant. The Michaelis-Menten kinetic constants for DMA N-oxidation by FMO1 were: K(m) of 44.5 microM, V(max) of 7.59 nmol min(-1) mg(-1) protein, and intrinsic clearance of 171 microl min(-1) mg(-1) protein, which was about twelve-fold higher than that by FMO3. Imipramine, an FMO1-specific inhibitor, selectively inhibited DMA N-oxidation. The resulting data showed that DMA N-oxidation is mainly mediated by FMO1.

Characterization of human cytochrome P450 enzymes involved in the biotransformation of eperisone.

Eperisone is a centrally acting muscle relaxant widely used for the therapeutic treatment of spastic patients to relieve muscle stiffness and back pain. The objective of this study was to characterize the metabolic pathway involved in the biotransformation of eperisone mediated by human cytochrome P450 (CYP) enzymes. Eperisone was metabolized to seven metabolites via oxidation and carbonyl reduction in human liver microsome. Among them, M3 and M4 were found to be primary major metabolites which were generated by CYPs. The kinetics study with (-)-R- and (+)-S-eperisones revealed that CYPs-mediated hydroxylation did not have significant stereoselectivity for metabolic clearance of eperisone. Incubation with recombinant CYP isozyme, chemical inhibition assay, and immuno-inhibition assay showed that multiple CYPs were involved in M4 formation, but mainly CYP2J2 in M3 formation. In addition, intestinal microsomes metabolized eperisone to M3 and M4 via CYP2J2- and CYP3A4-mediated reactions, which are supposed to contribute to presystemic metabolism of eperisone.

Disposition and metabolism of (2S,3S,4R)-N''-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxy methyl-2H-benzopyran-4-yl)-N'-benzylguanidine, a novel neuroprotective agent for ischemia-reperfusion damage, in rats.

The metabolism and disposition of KR31378 (a benzopyran derivative and a novel neuroprotective agent) were investigated following single oral or intravenous administration of [(14)C]-KR31378 to rats. [(14)C]-KR31378 was rapidly absorbed after oral dosing with an oral bioavailability of greater than 71%. The maximum plasma concentration and area under the curve of total radioactivity in rat plasma increased proportionally to the administered dose. KR31378 was distributed over all organs and tissues except for brain, eyeball and testis, and declined by first order kinetics up to 24 h after dosing. Excretion of the radioactivity was 29.5% of the dose in the urine and 58.5% in the feces within 2 days after oral administration. Biliary excretion of the radioactivity in bile duct-cannulated rats was about 66.0% for the first 24 h. KR31378 was extensively metabolized by ring hydroxylation, O-demethylation, oxidation and reduction with subsequent N-acetylation and O-glucuronide conjugation. N-acetylated conjugates (M2, M10, M11, M12, M14, and M15) were identified as the predominant metabolites in rats.

Testicular microlithiasis: what is its association with testicular cancer?

PURPOSE: To determine the prevalence of testicular microlithiasis in patients who were referred for scrotal ultrasonography (US) at a tertiary care cancer center and to evaluate the association between microlithiasis and cancer. MATERIALS AND METHODS: Testicular sonograms obtained in 528 men were retrospectively reviewed to identify patients with US findings suggestive of microlithiasis, intratesticular masses, and intratesticular heterogeneous changes. The association of US findings with medical records and with histopathologic findings that were available in 95 patients was evaluated. Statistical analysis was performed to determine the relationship of testicular cancer, intratesticular mass, and microlithiasis. RESULTS: Forty-eight (9%) of the 528 patients had microlithiasis; 13 of these (27%) had testicular cancers. Of the 480 patients without microlithiasis, 38 (8%) had testicular cancer. Ninety patients had an intratesticular mass, of whom 23 (26%) had microlithiasis. Forty-three (12 with microlithiasis) patients with a mass had testicular cancer, 43 (10 with microlithiasis) had benign findings or nontesticular malignant histopathologic findings, and four (one with microlithiasis) had no pathologic findings. CONCLUSION: Intratesticular microlithiasis is highly associated with confirmed testicular cancer, as well as with US evidence of testicular mass.

Breast cancer: assessing the use of routine pelvic CT in patient evaluation.

OBJECTIVE: The purpose of this study was to determine the benefit of routine pelvic CT in the evaluation of patients with primary breast cancer and to assess the frequency with which equivocal or abnormal findings on pelvic CT prompted the performance of additional studies or procedures that yielded results relevant to patient care. MATERIALS AND METHODS: The reports of 6628 body CT scans that included images of at least the pelvis in 2426 patients with breast cancer during a 9-year period were reviewed. The presence and sites of reported definite or probable metastases or pelvic tumors were recorded for each scan. Also, the types and results of diagnostic examinations and procedures prompted by equivocal or abnormal findings on pelvic CT were recorded. RESULTS: Pelvic metastases shown on CT were the only known site of metastasis in 13 (0.5%) of 2426 patients, and four other patients (0.2%) had new or enlarging pelvic metastases despite the presence of stable extrapelvic metastases. The pelvic metastases in these 17 patients were located in bone only in 11 patients, in adnexa only in five patients, and in adnexa, endometrium, and bone in one patient. In addition, pelvic CT led to the performance of 204 additional radiologic examinations, including 186 pelvic sonographic examinations, and 50 surgical procedures; 215 (84.6%) of these 254 additional examinations and procedures yielded normal, benign, or indeterminate results. CONCLUSION: The routine use of pelvic CT in the evaluation of patients with breast cancer has an extremely low yield and often prompts performance of pelvic sonographic or surgical procedures, the results of which were rarely relevant to cancer therapy.

Use of phosphorous-31 nuclear magnetic resonance spectroscopy to determine safe timing of chemotherapy after hepatic resection.

Liver resection induces accelerated growth of residual hepatic micrometastases. Adjuvant chemotherapy may improve outcome if administered early after resection but may prove lethal if initiated prior to completion of DNA synthesis in regenerating liver. This study investigates phosphorus-31 nuclear magnetic resonance ((31)P-NMR) as a noninvasive tool for measuring energy changes reflective of hepatic DNA synthesis and for predicting safe timing of chemotherapy after 70% hepatectomy. To evaluate metabolic changes in regenerating liver, quantitative three-dimensional (31)P-NMR was performed, using the technique of chemical shift imaging at various time points after 70% hepatectomy in adult male Fischer rats. Animals receiving a course of 2'-deoxy-5-fluorouridine (FUDR; 100 mg/kg, i.p. four times per day x 5), initiated at the time of operation, were also evaluated to observe the effects of chemotherapy on liver regeneration. Forty-eight hours after resection, hepatic nucleoside triphosphate (NTP), which reflects ATP content, fell 37% (P < 0.03) in animals undergoing hepatectomy alone. By contrast, animals receiving FUDR after hepatectomy demonstrated a mitigated NTP response, with a drop of only 17% (P = not significant), suggesting that interruption of DNA synthesis leads to a reduced consumption of ATP. Direct measures of DNA synthesis and nuclear proliferation were correlated with NMR findings. [(3)H]Thymidine incorporation and Ki67 immunohistochemistry were performed on liver samples from rats undergoing 70% hepatectomy with and without FUDR. Both [(3)H]thymidine incorporation and Ki67 expression were inhibited significantly at 48 h in animals receiving hepatectomy and FUDR, compared with those not treated with FUDR. To determine whether NMR changes could be used to identify safe timing of chemotherapy after hepatectomy, rats were treated with a 5-day course of FUDR initiated either prior to or after NMR changes normalized. Animals treated with FUDR at the point of NTP normalization (72 h) showed significantly improved survival over those that began treatment at operation (75 % versus 17 %; P = 0.0005, log rank test). FUDR inhibits hepatic DNA synthesis and influences mortality if administered too early after hepatectomy. Chemical shift imaging is a noninvasive tool that can identify metabolic changes coinciding with DNA synthesis and nuclear proliferation after hepatectomy. (31)P-NMR may be useful for determining safe timing of chemotherapy after liver resection.

Idiopathic pulmonary hemosiderosis with cystic lesions: a rare presentation.

This report describes a case of a 49-year-old man with cough, recurrent hemoptysis, and dyspnea during 18 months, presenting with radiological findings of alveolar infiltrate and cystic lesions in left upper lobe. Laboratory studies revealed normocytic hypochromic anemia and normal coagulation tests. C-reactive protein and mucoproteins were negative. Serum protein electrophoresis and complement, urinalysis, serum creatinine, creatinine clearance, and 24-hour urine protein were normal. Tests for antineutrophil cytoplasmic antibodies and anti-glomerular-basement membrane antibodies were negative. Tests for connective tissue diseases were all negative. Histological findings were consistent with those of idiopathic pulmonary hemosiderosis. Radiological findings are discussed.

The in vivo effect of bryostatin-1 on paclitaxel-induced tumor growth, mitotic entry, and blood flow.

Pretreatment of tumor cells with the protein kinase C (PKC) inhibitor bryostatin-1 enhances the cytotoxicity of most chemotherapeutic agents. However, in the case of paclitaxel, this effect has been shown in vitro to be best achieved when bryostatin-1 follows (rather than precedes) paclitaxel treatment. With combination trials of bryostatin-1 and paclitaxel planned for clinical trials and with only in vitro data available regarding drug sequence, we elected to undertake an in vivo study evaluating the effect of sequential bryostatin-1 and paclitaxel in a tumor-bearing mouse model and to correlate this effect to cell cycle events, tumor metabolism, and tumor blood flow. At the maximum tolerated i.p. dose, bryostatin-1 at 80 microg/kg resulted in a small but significant increase in tumor doubling time (4.2 +/- 0.3 days) compared with control tumors (3.0 +/- 0.3 days; P < 0.01). Mice treated with i.v. paclitaxel, administered at a dose of 12 mg/kg every 12 h for three doses, weekly for 3 weeks, had a tumor doubling time of 23.4 +/- 1.7 days. Mice pretreated with i.p. bryostatin-1 (80 microg/kg) followed 12 h later by i.v. paclitaxel (12 mg/kg every 12h for three doses) weekly for 3 weeks had a tumor doubling time of 9.7 +/- 1.1 days. This was significantly less (P < .001) than paclitaxel alone, which indicated an inhibitory effect by bryostatin-1 on paclitaxel therapy. In comparison, tumor-bearing mice that were treated with the same dose but with the sequence of paclitaxel followed by bryostatin-1 had a tumor doubling time of 29.6 +/- 0.6 days. This was significantly greater than the tumor doubling times for any condition tested (P < 0.01), demonstrating the sequence dependence of this combination. The efficacy of paclitaxel is dependent on mitotic entry, a step that requires activation of p34cdc2 kinase activity. Treatment with paclitaxel in vivo increased p34 cdc2 kinase activity in the mouse mammary tumors, whereas administration of bryostatin-1 before paclitaxel prevented the p34cdc2 kinase activation by paclitaxel. This was further evaluated in vitro by flow cytometry in MKN-74 human gastric cancer cells. As determined by MPM-2 labeling, which identifies cells in mitosis, pretreatment with bryostatin-1 prevented paclitaxel-treated cells from entering mitosis. Bryostatin-1 has been reported to induce changes in muscle metabolism and to decrease muscle blood flow. These events could impact on the interaction of bryostatin-1 with paclitaxel. Using proton-decoupled phosphorus nuclear magnetic resonance (31P-NMR) spectroscopy in vivo, bryostatin-1 at 80 micro1g/kg induced a decrease in both intratumoral pH and high-energy phosphates. In vivo perfusion studies, using dynamic enhanced NMR imaging with gadolinium diethylenetriamine pentaacetic acid, also demonstrated decreased tumor blood flow. These studies suggest that the inhibition of tumor response to paclitaxel by bryostatin-1 is multifactorial and includes such diverse factors as inhibition of cell entry into mitosis, a decrease in pH and energy metabolism, and a decrease in tumor blood flow. These results indicate that, as this combination enters Phase I clinical trials, the sequence of paclitaxel followed by bryostatin-1 will be critical in the clinical trial design.

A quantitative assessment of liver metabolites during jaundice using three dimensional phosphorus chemical shift imaging.

Phosphorus metabolites in the jaundiced rat liver were studied by three-dimensional phosphorus chemical shift imaging (CSI). Animals were studied at 1, 2, and 3 weeks post-ligation of the common bile duct. Quantitation of metabolites was performed using an external standard. Metabolite T(1) values were assessed in CSI experiments on normal untreated animals. High-performance liquid chromatography (HPLC) was used to measure adenine nucleotides in a separate group of jaundiced rats. 3D-CSI did not detect significant changes in NTP in jaundiced animals relative to baseline controls. At two and three weeks post bile duct ligation, pH was significantly elevated. HPLC data comparing ATP levels to baseline controls also detected no change except for elevated ATP detected on Day 21. (31)P NMR chemical shift imaging may be used to assess liver metabolites under conditions of stress such as jaundice. However, absolute quantitation requires careful attention to many factors including point spread function, correct T(1) values, and adequate signal-to-noise ratio.

Pulmonary nodules resected at video-assisted thoracoscopic surgery: etiology in 426 patients.

PURPOSE: To determine the etiology of pulmonary nodules resected at video-assisted thoracoscopic surgery (VATS) and establish the probabilities that single or multiple nodules resected at VATS represent malignancy in patients with or patients without known cancer. MATERIALS AND METHODS: Pathology reports from VATS performed between January 1995 and July 1997 were searched for data on gross specimens revealing pulmonary nodules 3 cm or smaller. Findings were correlated with clinical and histologic data. RESULTS: In 254 patients with one nodule resected at VATS, the nodules were malignant in 108 patients with and in 32 patients without known cancer (P < .03). Among 172 patients with multiple nodules resected, at least one nodule was malignant in 85 patients with and in 20 patients without known cancer (P > .05). Nodules larger than 1 cm were more likely to be malignant than were smaller nodules (P < .002). In patients with known malignancy, nodules smaller than 0.5 cm were more likely to be benign, whereas nodules larger than 0.5 cm but smaller than 1 cm were more likely to be malignant (P < .001). CONCLUSION: A single pulmonary nodule resected at VATS was more likely to be malignant in patients with known cancer. Nodules larger than 1 cm but smaller than 3 cm resected at VATS were more likely to be malignant. Nodules smaller than 0.5 cm were more likely to be benign.

Hepatic sonography: comparison of tissue harmonic and standard sonography techniques.

OBJECTIVE: This study was performed to compare tissue harmonic sonography of the liver with conventional sonography of the liver. SUBJECTS AND METHODS: Forty-eight patients underwent tissue harmonic and conventional sonography of the liver, using a randomized imaging sequence. Imaging parameters were standardized, but gain varied. Techniques were compared using predetermined impact analysis categories. If a finding was revealed by only one sonographic technique, additional confirmation was obtained by another imaging technique or by surgery. In a separate image quality analysis, masked images were reviewed by two experienced radiologists to evaluate fluid-solid differentiation, near-field, far-field, and overall image quality. Rankings were correlated with field of view of images and body habitus of patients as determined by body mass index. RESULTS: Tissue harmonic sonography provided the same information as conventional sonography in 34 patients (71%) and added information in 14 patients (29%). The findings from tissue harmonic sonography resulted in altered treatment in five patients (10%). Eight patients (17%) had lesions revealed by tissue harmonic sonography only. Four patients (8%) had inadequate far-field visualization by both techniques. Both observers ranked tissue harmonic sonography the same as or better than standard sonography in 46 patients (96%) for fluid-solid differentiation, in 46 patients (96%) for near-field image quality, and in 45 patients (94%) for overall image quality. For far-field image quality, one observer ranked tissue harmonic sonography the same as or better than conventional sonography in 40 patients (83%), and the second observer, in 41 patients (85%). Image quality ratings showed no correlation with body habitus of the patients or field of view of images. CONCLUSION: Tissue harmonic sonography of the liver provides more information and better image quality than does conventional sonography of the liver.

Arthroscopic-assisted reduction of distal radius fractures.

The outcomes of seven patients with severe comminuted intraarticular fractures of the distal radius treated by arthroscopic reduction and percutaneous external fixation (ARPEF) were retrospectively reviewed. All of the fractures were classified as C3 types using the AO classification scheme. Outcomes were evaluated using the Gartland and Werley functional criteria, an objective wrist examination, a radiographic analysis, and a self-assessment outcome form at an average follow-up of 27 months (range, 12 to 45 months). All patients were free of pain and had returned to their prior occupations. No patient had articular incongruency of greater than 1 mm, and there was no evidence of radiocarpal degenerative change. Active range of motion and maximal grip strength averaged 92% and 98%, respectively, of the uninjured wrist. The technique of arthroscope-assisted reduction and percutaneous external fixation yielded excellent results in a small group of patients, with minimal complications.