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At least 1,405 records · Page 78Linked to original sources
PubMed1997

Flow quantification using fast cine phase-contrast MR imaging, conventional cine phase-contrast MR imaging, and Doppler sonography: in vitro and in vivo validation.

OBJECTIVE: Our purpose was to assess the accuracy of measurements of flow velocity and volume flow rate in an in vitro phantom and in healthy human volunteers using a cardiac-gated, segmented K-space, fast cine phase-contrast (PC) MR imaging technique with view sharing (fast PC). We compared this method with conventional cine PC MR imaging and Doppler sonography. SUBJECTS AND METHODS: Pulsatile flow was generated in a flow phantom that consisted of a cylindric tube having various degrees of tapered stenosis. Phase-encoded velocity maps were obtained using cine PC and fast PC MR imaging. Doppler sonography was also performed. Measurements of aortic and pulmonary artery peak systolic and minimum diastolic velocity and volume flow rate were then compared in eight healthy volunteers using the three imaging techniques. RESULTS: We found excellent agreement between fast PC and cine PC measurements of peak systolic velocity when regions of interest were drawn to exclude vessel margins (r > .99 for phantom studies, and r = .80 for human studies). Correlation between minimum diastolic velocity measurements by MR imaging was limited by noise that resulted from high encoding velocity settings. However, such correlation improved with signal averaging. When compared with predicted values of volume flow rates, both cine PC (r > .99) and fast PC (r = .97) MR imaging were more accurate than Doppler sonography (r = .78) in vitro. Measurements of cardiac output were adversely affected by low signal to noise, especially during diastole; estimates based on systolic forward flow resulted in better agreement between the two MR imaging methods. CONCLUSION: Fast PC MR flow quantification may prove to be a useful adjunct to routine MR studies for measurements of peak flow velocity. However, estimates of volume flow rate using fast PC MR imaging are limited because of increased noise during low diastolic flow as well as edge artifacts.

Adult↗
PubMed1983

S-phase cell distribution in the small intestine irradiated at different times of the day. II. Recovery phase.

Modifications occurring during recovery in the small intestine of animals exposed to the same radiation dose given at different times of the day were evaluated. S-phase cell distribution along the crypts and invertase activity were evaluated to ascertain the functional capacity of epithelial cells. In animals killed between 5 and 6 days after exposure, S-phase cell distribution and functional conditions tended towards normality although recovery was not complete. Labelled cells occurred also at villus junctions, demonstrating limitation in size of the differentiating compartment. This was confirmed by reduced activity of the brush border enzymes. Animals irradiated at the end of the dark period recovered more quickly and efficiently. In this group, labelled cell distribution was almost the same as in the controls starting from 120 h, and invertase activity was also closer to the controls than in any other group.

Animals↗
PubMed1982

Hazardous waste management program: phase I interim authorization for Nebraska--Environmental Protection Agency, region VII. Phase I interim authorization.

The State of Nebraska has applied for interim authorization of its hazardous waste program under Subtitle C of the Resource Conservation and Recovery Act and EPA guidelines for the approval of State hazardous waste programs [40 CFR Part 123]. EPA has determined that the State's program meets all applicable statutory and regulatory requirements and is granting Phase I interim authorization to Nebraska to operate in its jurisdiction a hazardous waste program in lieu of Phase I of the Federal hazardous waste program.

Environmental Health↗
PubMed1982

Illinois, phase I interim authorization of state hazardous waste management program--Environmental Protection Agency, Region V. Granting of phase I interim authorization to state hazardous waste program.

The State of Illinois has applied for Interim Authorization of its hazardous waste program under Subtitle C of the Resource Conservation and Recovery Act of 1976, as amended (RCRA) and EPA guidelines for the approval of State hazardous waste programs (40 CFR Part 123, Subpart F). USEPA has reviewed the Illinois hazardous waste program and has determined that the Illinois hazardous waste program is substantially equivalent to the Federal program. USEPA is hereby granting Phase I Interim Authorization to Illinois to operate a hazardous waste program in lieu of Phase I of the Federal hazardous waste program in its jurisdiction.

Environmental Health↗
PubMed1998

Phase I and phase II xenobiotic biotransformation in different inbred strains of rats: study in immobilized perfused hepatocytes.

The present study was designed to compare phase I and phase II biotransformation reactions in immobilized perfused hepatocytes as a cellular system obtained from inbred rat strains which represent models for some cardiovascular diseases, namely, spontaneously hypertensive rats (SHR), rats sensitive and resistant to isoprenaline-induced myocardial lesions (IS and IR, respectively) as compared to Wistar rats (W). The biotransformation kinetics for hexobarbital (HX), 7-ethoxycoumarin (7-EC), 1-chloro-2,4-dinitrobenzene (CDNB) and 4-nitrophenol (4-NP) were followed up in the hepatocyte perfusate. W and SHR rat hepatocytes have metabolized HX at a higher rate than those of the IR and IS strains. Hepatocytes from the W strain exhibited a higher rate of 7-EC deethylation activity compared to hepatocytes obtained from the IR or IS strains. Hepatocytes obtained from SHR and IR rats showed the highest glutathione-S-transferase (GST) activity towards CDNB compared to the IS or W strain. 4-NP disappearance was higher in the perfusion medium of hepatocytes obtained from the W and IS strains compared to the IR strain. These significant differences in drug biotransformation between various studied strains, which may be genetically determined, can be well demonstrated by using an efficient drug metabolizing model of the immobilized perfused hepatocytes. The importance of these differences should be considered during the study of the experimental therapy of the relevant disease as obtained from the specific experimental strain, where it may be expected that the pharmacokinetic profile of a drug in vivo and consequently its pharmacodynamic or toxic effects will be strain dependent.

Animals↗
PubMed2000

Disruption of dioxin-inducible phase I and phase II gene expression patterns by cadmium, chromium, and arsenic.

Recent work suggesting that cellular oxidative stress exerts an inhibitory effect on aromatic hydrocarbon receptor (AHR)-dependent gene expression led us to test the hypothesis that pro-oxidant environmental pollutants might alter the induction of detoxification genes by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an AHR ligand. We found that, in mouse hepatoma Hepa-1 cells, TCDD-inducible cytochrome P450, Cyp1a1, and nicotinamide adenine dinucleotide phosphate-quinone oxidoreductase (Nqo1) mRNA accumulation were differentially affected by cadmium (Cd(2+)), chromium (Cr(6+)), and arsenic (As(3+)). Cadmium or arsenic did not change Cyp1a1 mRNA levels but did enhance TCDD-inducible levels of Nqo1 mRNA, an effect that paralleled the ability of these metals to activate a beta-galactosidase gene reporter system regulated by an electrophile response promoter element. Chromium inhibited mRNA accumulation for both Cyp1a1 and Nqo1. Manipulation of cellular thiol status did not modify the response to combined chromium-TCDD exposure, suggesting that the response was not caused by oxidative stress. Chromium did not block DNA-binding competence of the AHR and did not have an effect on mRNA stability, but it inhibited Cyp1a1 gene transcription and the expression of an AHR-dependent luciferase reporter. These data indicate that coexposure to pro-oxidant metals and AHR ligands, which is common in the environment, can disrupt the regulation of phase I and phase II detoxification genes, leading to imbalances in gene expression that may have important consequences for the toxicity of complex mixtures.

Animals↗
PubMed1975

Rhinosporidium seeberi. An ultrastructural study of its endosporulation phase and trophocyte phase.

The endosporulation phase of Rhinosporidium seeberi is the part of the life cycle most vulnerable to drug therapy. The laminated body formed from the precleavage sporangium has double-membraned tubular and vesicular structures within concentric layers. Similar tubular structures are also found in the developing sporoblast. The development of trophocytes involves three distinct phases. The early trophocyte retains many of the characteristics of the sporoblast as well as endoplasmic reticulum and other radiating filamentous structures in the cell wall. The itermediate tropocyte is larger (20 mug to 30mug m) and contains lipid bodies and microbodies, whereas the mature trophocyte is smaller (7mug m to9mug m) and microbodies are sparse or absent.

Cell Nucleus↗
PubMed2001

Mechanisms affecting the dissolution of nonaqueous phase liquids into the aqueous phase in slow-stirring batch systems.

Understanding the kinetics of the exchange processes between nonaqueous phase liquids (NAPLs) and water is important in predicting the fate of anthropogenic compounds such as petroleum hydrocarbons, i.e., benzene, toluene, ethylbenzene, and xylene (BTEX) as well as polynuclear aromatic hydrocarbons (PAHs). Exchange processes occurring in the environment resemble the experimental setup of the slow-stirring method (SSM) designed to determine solubilities and octanol-water partition coefficients. Data obtained from SSM experiments for diesel fuel compounds are interpreted by a linear transfer model that is characterized by an aqueous molecular boundary layer and the water/NAPL equilibrium partition coefficient. For the chosen experimental setup, the boundary layer thickness is 2.42 x 10(-2) cm. Typical equilibration times lie between 1 and 2 d. Due to the temperature dependence of the aqueous diffusivity, this time increases with decreasing temperature. Transport within the NAPL phase can slow down the exchange process for the more water-soluble compounds (e.g., benzene) provided that the stirring rate exceeds a critical value.

Alkanes↗
PubMedDate not supplied

Phase behavior of the alpha-hydroxyoctanoic acid/Laureth 4/white oil/water system and preliminary evaluation of the phase changes during evaporation of its emulsion.

The phase diagram was determined for the alpha-hydroxyoctanoic acid/Laureth 4/white oil/water system using visual observation with an optical microscope. Typical emulsions were evaporated to determine the structural changes. These were compared to those predicted from the phase diagram. Small-angle x-ray diffraction was used to determine the location of the alpha-hydroxyoctanoic acid in the lamellar liquid crystal. The most important result is the fact that irrespective of initial composition, the final result was a suspension of solid acid particles with dissolved oil and surfactant in a surfactant/oil liquid with only minute amounts of solubilized acid.

Caprylates↗
PubMed2003

[The detection methods for antiplatelet autoantibodies (phase II and phase III assay)].

A variety of methods are utilized to detect antiplatelet autoantibodies nowadays, platelet-associated immunoglobulin G(PAIgG) is a phase II assay of limited value in the meaning of its sensitivity and specificity for the diagnosis of idiopathic thrombocytopenic purpura(ITP), although it has been ordered in many occasions. The newer antigen-specific assays(phase III), which can identify autoantibodies against platelet glycoprotein(GP)s, such as GP IIb/IIIa, with greater specificity but lower sensitivity are rarely performed in clinical situations in Japan. Development of novel systems to detect clinically more relevant markers, including specific antiplatelet autoantibodies, is necessary for the diagnosis of ITP.

Autoantibodies↗
PubMed1992

Comparison of mouse and human colon tumors with regard to phase I and phase II drug-metabolizing enzyme systems.

Since human colorectal tumors are insensitive to most chemotherapeutic agents, there is a need for the discovery of new drugs that would show activity against this disease. In an attempt to better appreciate the relevance of a widely used mouse colon tumor (colon adenocarcinoma Co38) as a screening model for human colorectal tumors, we compared the main phase I and phase II drug-metabolizing enzyme systems in both tumoral and nontumoral colon tissues. The following enzymes were assayed by Western blot: cytochromes P-450 (1A1/A2, 2B1/B2, 2C, 2E1, and 3A), epoxide hydrolase, and glutathione-S-transferases (GST-alpha, -mu, and -pi). The activities of the following enzymes or cofactors were determined by spectrophotometric or fluorometric assays: total cytochrome P-450, 1-chloro-2,4-dinitrobenzene-GST, selenium-independent glutathione peroxidase, 3,4-dichloronitrobenzene-GST, ethacrynic acid-GST, total glutathione, epoxide hydrolase, UDP-glucuronosyltransferase, beta-glucuronidase, sulfotransferase, and sulfatase. Results obtained by Western blot showed that mouse colon adenocarcinoma Co38 did not express any of the probed cytochromes P-450, whereas human colorectal tumors expressed only low levels of cytochrome P-450 3A. GST-alpha and GST-pi were detected in all tumoral and nontumoral tissues of both species. The neutral GST-mu was expressed in all murine tissues investigated and was found to be polymorphic in human tissues. For human peritumoral and tumoral colorectal tissues there was no significant difference between GST isoenzyme levels, whereas mouse colon adenocarcinoma Co38 had a lower expression of GST-mu and GST-pi, compared to normal mouse colon. Enzymatic activities for glutathione peroxidase, 3,4-dichloronitrobenzene-GST, and ethacrynic acid-GST confirmed the Western blot results for GST-alpha, GST-mu, and GST-pi, respectively. Total GSH levels were similar between murine and human tumors but were 3-fold higher in human tumors than in peritumoral tissues, whereas they were 7-fold lower in mouse colon tumor Co38, compared to normal mouse colon. Epoxide hydrolase was not expressed in either mouse colon adenocarcinoma Co38 or normal mouse colon tissues, whereas it was expressed in human colon peritumoral and tumoral tissues at similar levels. No significant difference was observed between human tumors and peritumoral tissues for UDP-glucuronosyltransferase, beta-glucuronidase, sulfotransferase, and sulfatase. For murine colon tissues, the conjugation pathways (UDP-glucuronosyltransferase and sulfotransferase) were lower in colon adenocarcinoma Co38, whereas the converse was observed for the corresponding hydrolytic enzymes (beta-glucuronidase and sulfatase).(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMed1992

[Phase 3 and phase 4 bundle of branch block].

Intermittent left bundle branch blocks are present in the ECGs of 1 patient with mitral valve disease. By occurring either after short or long cycles they represent respectively phase 3 and phase 4 blocks. Such mechanisms emphasize the relationship between automatism and conduction. The occurrence of block and of normal conduction during cycles of the same length, its correlation with the conduction of the previous cycle, demonstrate the presence of a functional linking between successive impulses. This linking may occur every time a potential or active macroreentry circuit exist. In our case the circuit is formed by the 2 bundle branches which join distally in the ventricular septum.

Bundle-Branch Block↗
PubMedDate not supplied

Comparison of solid-phase extraction and micro-solid-phase extraction for liquid chromatography/mass spectrometry analysis of pesticides in water samples.

Our recent on-line solid-phase extraction (SPE) device for micro-liquid chromatography, known as micro-solid-phase extraction (microSPE), was compared with traditional SPE for the analysis, from aqueous samples, of 4 pesticides belonging to different classes. Two different kinds of adsorbents, C18 and graphitized carbon black, were tested. A 2-stage ion trap mass spectrometer, equipped with homemade microflow electrospray ion (ESI) source, was used. Detection limits with a signal-to-noise ratio of 3:1 for both extraction methods were in the range of 0.1 microg/L for all compounds. However, better recoveries were obtained when microSPE traps were used.

Adsorption↗
PubMed2005

Energy expenditure during walking in amputees after disarticulation of the hip. A microprocessor-controlled swing-phase control knee versus a mechanical-controlled stance-phase control knee.

We have compared the energy expenditure during walking in three patients, aged between 51 and 55 years, with unilateral disarticulation of the hip when using the mechanical-controlled stance-phase control knee (Otto Bock 3R15) and the microprocessor-controlled pneumatic swing-phase control knee (Intelligent Prosthesis, IP). All had an endoskeletal hip disarticulation prosthesis with an Otto Bock 7E7 hip and a single-axis foot. The energy expenditure was measured when walking at speeds of 30, 50, and 70 m/min. Two patients showed a decreased uptake of oxygen (energy expenditure per unit time, ml/kg/min) of between 10.3% and 39.6% when using the IP compared with the Otto Bock 3R15 at the same speeds. One did not show any significant difference in the uptake of oxygen at 30 m/min, but at 50 and 70 m/min, a decrease in uptake of between 10.5% and 11.6% was found when using the IP. The use of the IP decreased the energy expenditure of walking in these patients.

Artificial Limbs↗
PubMed2005

3D-CT arteriography and 3D-CT venography: the separate demonstration of arterial-phase and venous-phase on 3D-CT angiography in a single procedure.

Although 3D-CT angiography provides valuable anatomic information regarding lesion and their surrounding vessels and bony structures, it cannot demonstrate lesions, arteries, and veins, separately. The separate demonstration of arterial-phase 3D-CT angiography (3D-CT arteriography) and venous-phase 3D-CT angiography (3D-CT venography) will facilitate the understanding of the vascular anatomy within lesions, thus, allowing improvement of diagnostic accuracy and potentially a safer surgical approach. We describe 3D-CT arteriography and 3D-CT venography by using a multidetector row helical CT.

Adult↗
PubMed2005

Class II deep bite faces: one-phase or two-phase treatment?

Timing is the key for successful and stable results in Class II patients. Most low-angle patients are treated during the mixed dentition in two phases: orthopedics, then orthodontics. The vertical discrepancy differentiates the patient who will need extraction, the high-angle case, from those who should be treated through nonextraction, the low-angle case. Treatment of these latter patients necessitates expansion of the soft tissues. In the authors' practice, 70% of cases are treated nonextraction. This new concept for Class II treatment makes the Class II mechanics less traumatic because the occlusal correction requires less anchorage preparation. Most low-angle cases treated with two-phase treatment do not require surgical procedures. Orthodontics for tomorrow will necessitate more concept and less mechanics.

Cephalometry↗
PubMed1991

[Phase II study of lung cancer--evaluation of new drug in small cell lung cancer (SCLC) and phase II testing of analogues].

The purpose of this report is to review the problems in the evaluation of new drugs in SCLC and phase II testing of analogues in lung cancer. SCLC is one of the most chemotherapy-sensitive solid tumours and patients (pts) who relapse after their first-line treatment are likely to have resistant tumors, precluding the appropriate evaluation of new drugs, especially analogues. However, it is ethically difficult to evaluate new drugs in untreated pts with SCLC. Based on many issues, We recommended that new drugs should be evaluated in "good" pts with extensive-stage SCLC and that the trial design should include early stopping rules as well as a crossover to an active alternative regimen such as etoposide and cisplatin for non-responders. Also, I recommended that the endpoint for a positive phase II study with an analogue depends upon which of the following four ways the analogue's superiority is hope for; (1) superior efficacy in responsive tumors; (2) broader spectrum; (3) cross-over resistance to the parent structure; (4) diminished toxicity.

Antineoplastic Agents↗
PubMed1978

Phase I and preliminary phase II study of neocarzinostatin.

Neocarzinostatin is a protein antitumor antibiotic isolated from cultures of Streptomyces carzinostaticus var.F41. The drug has undergone extensive clinical trial in Japan, and has been reported active against a variety of human tumors. A phase I and preliminary phase II evaluation of the drug has been performed, using an iv bolus daily x 5 schedule. Ninety-six patients have been treated at doses from 500 to 2250 units/m2/day. Courses were repeated at 4-week intervals if allowed by bone marrow recovery. Dose-limiting toxicity was myelosupppression, which occurred late (median nadir, Day 27). Myelosuppression was more pronounced in patients who had received previous chemotherapy. In nine patients (9%) thrombocytopenia was prolonged (greater than or equal to 45 days) or irreversible. Acute administration of the drug was associated with rigors in approximately half the patients. Gastrointestinal side effects were mild. Three patients had a severe acute reaction resembling anaphylaxis. The maximally tolerated dose for this dose schedule is approximately 2250 units/m2/day. Antitumor activity has been seen in hepatoma and hematologic malignancies. Activity in lung and colorectal carcinoma appears limited with this dose schedule.

Adolescent↗