Colonic tumour cells possess a cell surface protease capable of binding 9-aminoacridine to its active centre, thus locating cells when viewed under a fluorescence microscope. In vivo and in frozen ...sections, the enzyme is masked by a protein inhibitor. This inhibitor can be displaced by formaldehyde fixation of the tissue and then replaced by adding a fresh extract of colon or lung tissue. The inhibitor is modified by oxidation; provided by air, oxidized glutathione or potassium permanganate, resulting in a change in conformation in the inhibitor and this then results in the enzyme binding the fluorescent probe. The effect of oxidation can be reversed by dithiothreitol. It is proposed that these changes are brought about by a disulphide exchange acting on the inhibitor which indirectly controls the activity of the cell surface enzyme in vivo. The steps described above can be conveniently followed on sections of tissue mounted on a microscope slide; this has the advantage that the same cells can be monitored during a sequence of reactions. It is believed that these techniques could well be applied to other enzyme systems than the tumour protease described in this study.
IntroductionA major knowledge gap in the treatment of complicated Staphylococcus aureus bacteraemia (SAB) is the optimal duration of antibiotic therapy. Safe shortening of antibiotic therapy has the ...potential to reduce adverse drug events, length of hospital stay and costs. The objective of the SAFE trial is to evaluate whether 4 weeks of antibiotic therapy is non-inferior to 6 weeks in patients with complicated SAB.Methods and analysisThe SAFE-trial is a multicentre, non-inferiority, open-label, parallel group, randomised controlled trial evaluating 4 versus 6 weeks of antibiotic therapy for complicated SAB. The study is performed in 15 university hospitals and general hospitals in the Netherlands. Eligible patients are adults with methicillin-susceptible SAB with evidence of deep-seated or metastatic infection and/or predictors of complicated SAB. Only patients with a satisfactory clinical response to initial antibiotic treatment are included. Patients with infected prosthetic material or an undrained abscess of 5 cm or more at day 14 of adequate antibiotic treatment are excluded. Primary outcome is success of therapy after 180 days, a combined endpoint of survival without evidence of microbiologically confirmed disease relapse. Assuming a primary endpoint occurrence of 90% in the 6 weeks group, a non-inferiority margin of 7.5% is used. Enrolment of 396 patients in total is required to demonstrate non-inferiority of shorter antibiotic therapy with a power of 80%. Currently, 152 patients are enrolled in the study.Ethics and disseminationThis is the first randomised controlled trial evaluating duration of antibiotic therapy for complicated SAB. Non-inferiority of 4 weeks of treatment would allow shortening of treatment duration in selected patients with complicated SAB. This study is approved by the Medical Ethics Committee VUmc (Amsterdam, the Netherlands) and registered under NL8347 (the Netherlands Trial Register). Results of the study will be published in a peer-reviewed journal.Trial registration numberNL8347 (the Netherlands Trial Register).
Operational longline fishery characteristics, bycatch information, and loggerhead turtle satellite tracks were all used in conjunction with remotely sensed sea surface temperature data to identify ...the environmental area where the majority of loggerhead turtle bycatch occurred in the Hawaii-based longline fishery during 1994 to 2006. In the first quarter of each calendar year from 1994 to 2006, the majority of shallow longline sets and associated loggerhead turtle bycatch were above 28 N, which corresponds to the area near the North Pacific Subtropical Frontal Zone. Based on the thermal ranges of bycatch, sets and the satellite-tagged turtles, it was recommended that shallow sets should only be deployed in waters south of the 18.5C (65.5F) isotherm to decrease loggerhead turtle bycatch. This recommendation formed the basis for the TurtleWatch tool, a map providing up-to-date information about the thermal habitat of loggerhead sea turtles in the Pacific Ocean north of the Hawaiian Islands. TurtleWatch was released to fishers and managers in electronic and paper formats on December 26, 2006, to assist in decision making during the first quarter of 2007. Fishery information from 2007 was later compared with data for the years 2005 to 2006 to assess the response of the fishery to TurtleWatch. The observed fleet movement during the first quarter of 2007 was to the north of the 18.5C (65.5F) isotherm (i.e. in the area recommended for avoidance by the TurtleWatch product) with increased effort and lower bycatch rates. We discuss possible reasons for this decrease in turtle bycatch north of the frontal zone together with future research directions which may lead to refinement of the TurtleWatch product.
Acetabular labral tears and associated intra-articular pathology of the hip have been recognised as a source of symptoms. However, it is now appreciated that there is a relatively high prevalence of ...asymptomatic labral tears. In this study, 70 young asymptomatic adult volunteers with a mean age of 26 years (19 to 41) were recruited and underwent three tesla non-arthrographic MR scans. There were 47 women (67.1%) and 23 men (32.9%). Labral tears were found in 27 volunteers (38.6%); these were an isolated finding in 16 (22.9%) and were associated with other intra-articular pathology in the remaining 11 (15.7%) volunteers. Furthermore, five (7.1%) had intra-articular pathology without an associated labral tear. Given the high prevalence of labral pathology in the asymptomatic population, it is important to confirm that a patient's symptoms are due to the demonstrated abnormalities when considering surgery.
Background
Although the antidiarrheal loperamide is a potent opiate, it does not produce opioid central nervous system effects at usual doses in patients. On the basis of in vitro studies ...demonstrating that loperamide is a substrate for the adenosine triphosphate–dependent efflux membrane transporter P‐glycoprotein, we postulated that inhibition of P‐glycoprotein with quinidine would increase entry of loperamide into the central nervous system with resultant respiratory depression.
Methods
To test this hypothesis, a 16‐mg dose of loperamide was administered to eight healthy male volunteers in the presence of either 600 mg quinidine, a known inhibitor of P‐glycoprotein, or placebo. Central nervous system effects were measured by evaluation of the respiratory response to carbon dioxide rebreathing as a measure of opiate‐induced respiratory depression.
Results
Loperamide produced no respiratory depression when administered alone, but respiratory depression occurred when loperamide (16 mg) was given with quinidine at a dose of 600 mg (P < .001). These changes were not explained by increased plasma loperamide concentrations.
Conclusion
This study therefore demonstrates first the potential for important drug interactions to occur by a new mechanism, namely, inhibition of P‐glycoprotein, and second that the lack of respiratory depression produced by loperamide, which allows it to be safely used therapeutically, can be reversed by a drug causing P‐glycoprotein inhibition, resulting in serious toxic and abuse potential.
Clinical Pharmacology & Therapeutics (2000) 68, 231–237; doi: 10.1067/mcp.2000.109156
Nanostructuring of Fe/ZSM-5 results in significantly higher phenol productivity during benzene oxidation with nitrous oxide. Optimal performance is obtained at low iron content. Display omitted
► ...Nanometer-thin ZSM-5 nanosheets functionalized by iron. ► High hydrothermal stability of the Fe/ZSM-5 nanosheets. ► Improved catalyst stability in the benzene to phenol oxidation reaction. ► Deactivation mainly due to coke deposition in the mesopores. ► Lower Fe content results in less coke formation in micropores.
Hierarchical Fe/ZSM-5 zeolites were synthesized with a diquaternary ammonium surfactant containing a hydrophobic tail and extensively characterized by XRD, Ar porosimetry, TEM, DRUV–Vis, and UV-Raman spectroscopy. Their catalytic activities in catalytic decomposition of N2O and the oxidation of benzene to phenol with N2O as the oxidant were also determined. The hierarchical zeolites consist of thin sheets limited in growth in the b-direction (along the straight channels of the MFI network) and exhibit similar high hydrothermal stability as a reference Fe/ZSM-5 zeolite. Spectroscopic and catalytic investigations point to subtle differences in the extent of Fe agglomeration with the sheet-like zeolites having a higher proportion of isolated Fe centers than the reference zeolite. As a consequence, these zeolites have a somewhat lower activity in catalytic N2O decomposition (catalyzed by oligomeric Fe), but display higher activity in benzene oxidation (catalyzed by monomeric Fe). The sheet-like zeolites deactivate much slower than bulk Fe/ZSM-5, which is attributed to the much lower probability of secondary reactions of phenol in the short straight channels of the sheets. The deactivation rate decreases with decreasing Fe content of the Fe/ZSM-5 nanosheets. It is found that carbonaceous materials are mainly deposited in the mesopores between the nanosheets and much less so in the micropores. This contrasts the strong decrease in the micropore volume of bulk Fe/ZSM-5 due to rapid clogging of the continuous micropore network. The formation of coke deposits is limited in the nanosheet zeolites because of the short molecular trafficking distances. It is argued that at high Si/Fe content, coke deposits mainly form on the external surface of the nanosheets.
HIV protease inhibitors have proven remarkably effective in treating HIV-1 infection. However, some tissues such as the brain and testes (sanctuary sites) are possibly protected from exposure to HIV ...protease inhibitors due to drug entry being limited by the membrane efflux transporter P-glycoprotein, located in the capillary endothelium. Intravenous administration of the novel and potent P-glycoprotein inhibitor LY-335979 to mice (1-50 mg/kg) increased brain and testes concentration of (14)Cnelfinavir, up to 37- and 4-fold, respectively, in a dose-dependent fashion. Similar effects in brain levels were also observed with (14)C-labeled amprenavir, indinavir, and saquinavir. Because (14)Cnelfinavir plasma drug levels were only modestly increased by LY-335979, the increase in brain/plasma and testes/plasma ratios of 14- to 17- and 2- to 5-fold, respectively, was due to increased tissue penetration. Less potent P-glycoprotein inhibitors like valspodar (PSC-833), cyclosporin A, and ketoconazole, as well as quinidine and verapamil, had modest or little effect on brain/plasma ratios but increased plasma nelfinavir concentrations due to inhibition of CYP3A-mediated metabolism. Collectively, these findings provide "proof-of-concept" for increasing HIV protease inhibitor distribution into pharmacologic sanctuary sites by targeted inhibition of P-glycoprotein using selective and potent agents and suggest a new therapeutic strategy to reduce HIV-1 viral replication.
Summary
Structured illumination microscopy (SIM) for the imaging of alpha particle tracks in fluorescent nuclear track detectors (FNTD) was evaluated and compared to confocal laser scanning ...microscopy (CLSM). FNTDs were irradiated with an external alpha source and imaged using both methodologies. SIM imaging resulted in improved resolution, without increase in scan time. Alpha particle energy estimation based on the track length, direction and intensity produced results in good agreement with the expected alpha particle energy distribution. A pronounced difference was seen in the spatial scattering of alpha particles in the detectors, where SIM showed an almost 50% reduction compared to CLSM. The improved resolution of SIM allows for more detailed studies of the tracks induced by ionising particles. The combination of SIM and FNTDs for alpha radiation paves the way for affordable and fast alpha spectroscopy and dosimetry.
Lay description
Alpha radiation therapy is a form of cancer treatment where alpha radiation, a heavy form of radiation, is used. This type of radiation therapy is becoming more popular, as it can be used as an alternative for treating tumours resistant to conventional radiation therapy. However, research on alpha radiation is severely hampered, because alpha particles can only travel very short distances before losing their energy (less than 100 micron in water). A new type of detector called the fluorescent nuclear track detector (FNTD) is able to measure this radiation. The particles that travelled through the detector create tracks, which can be visualised using fluorescence microscopy techniques. Currently, confocal laser scanning microscopy (CLSM) is mostly used for 3D imaging of these nuclear tracks. In this work we used structured illumination microscopy (SIM) as an alternative to CLSM, in an attempt to reach beyond the diffraction limit and thereby increase the spatial resolution of FNTD imaging. We showed that the length, the direction and the energy of the alpha particle tracks in the detector could be measured with very good accuracy using this technique. The detector can therefore be used for measuring the radiation dose induced by alpha radiation. Researchers could thus combine this detector with biological studies to increase our knowledge on the effects that this type of radiation has on (cancer) tissue. The increased resolution also showed less scattering, which is a measure for how much an alpha particle ‘bounces around’ against atoms, than was reported by previous studies. This leads us to believe that the combination of SIM and FNTD can also help to increase our understanding of the physical interactions of alpha particles on a very small scale. From these findings, it is our opinion that SIM is an excellent candidate for large scale commercial super‐resolution imaging of these detectors.
Ethnicity is an important demographic variable contributing to interindividual variability in drug metabolism and response. In this rapidly expanding research area many genetic factors that account ...for the effects of ethnicity on pharmacokinetics, pharmacodynamics, and drug safety have been identified. This review focuses on recent developments that have improved understanding of the molecular mechanisms responsible for such interethnic differences. Genetic variations that may provide a molecular basis for ethnic differences in drug metabolizing enzymes (CYP 2C9, 2C19, 2D6, and 3A4), drug transporter (P-glycoprotein), drug receptors (adrenoceptors), and other functionally important proteins (eNOS and G proteins) are discussed. A better understanding of the molecular basis underlying ethnic differences in drug metabolism, transport, and response will contribute to improved individualization of drug therapy.
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