No abstract

ClC-3 is a voltage-gated Cl−channel that is highly conserved and widely expressed, although its function, localization, and properties remain a matter of considerable debate. In this study, we have shown that heterologous expression of ClC-3 in either Chinese hamster ovary (CHO-K1) or human hepatoma (Huh-7) cells results in the formation of large, acidic vesicular structures within cells. Vesicle formation is prevented by bafilomycin, an inhibitor of the vacuolar ATPase, and is not induced by an E224A mutant of ClC-3 with altered channel activity. This demonstrates that vesicle formation requires both proton pumping and Cl−channel activity. Manipulation of the intracellular Cl−concentration demonstrated that the ClC-3-associated vesicles shrink and swell consistent with a highly Cl−-permeable membrane. The ClC-3 vesicles were identified as lysosomes based on their colocalization with the lysosome-associated proteins lamp-1, lamp-2, and cathepsin D and on their failure to colocalize with fluorescently labeled endosomes. We conclude that ClC-3 is an intracellular channel that conducts Cl− when it is present in intracellular vesicles. Its overexpression results in its appearance in enlarged lysosome-like structures where it contributes to acidification by charge neutralization.

Equivalent performances were observed in the comparison between GSI 65 keV monochromatic images and images from a regular abdomen scan protocol. This suggests the possibility of GSI to be employed in routine abdominal scans, which would potentially offer more information through its capabilities of material decomposition.

ClC-3 is a highly conserved voltage-gated chloride channel, which together with ClC-4 and ClC-5 belongs to one subfamily of the larger group of ClC chloride channels. Whereas ClC-5 is localized intracellularly, ClC-3 has been reported to be a swelling-activated plasma membrane channel. However, recent studies have shown that native ClC-3 in hepatocytes is primarily intracellular. Therefore, we reexamined the properties of ClC-3 in a mammalian cell expression system and compared them with the properties of endogenous swellingactivated channels. Chinese hamster ovary (CHO)-K1 cells were transiently transfected with rat ClC-3. The resulting chloride currents were Cl ؊ > I ؊ selective, showed extreme outward rectification, and lacked inactivation at positive voltages. In addition, they were insensitive to the chloride channel blockers, 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and 4,4-diisothiocyanostilbene-2,2-disulfonic acid (DIDS) and were not inhibited by phorbol esters or activated by osmotic swelling. These properties are identical to those of ClC-5 but differ from those previously attributed to ClC-3. In contrast, nontransfected CHO-K1 cells displayed an endogenous swelling-activated chloride current, which was weakly outward rectifying, inactivated at positive voltages, sensitive to NPPB and DIDS, and inhibited by phorbol esters. These properties are identical to those previously attributed to ClC-3. Therefore, we conclude that when expressed in CHO-K1 cells, ClC-3 is an extremely outward rectifying channel with similar properties to ClC-5 and is neither activated by cell swelling nor identical to the endogenous swelling-activated channel. These data suggest that ClC-3 cannot be responsible for the swelling-activated chloride channel under all circumstances.

The method is suitable for tomographic imaging systems with flat-panel detectors.

Phosphinidenes have been proposed as short-lived intermediates in several reaction systems. ' We have reported products from the photodecomposition of 1 -mesitylphosphirane that are in accord with the formation of free mesitylphosphinidene (2) as a reactive intermediate.2 Product structures suggest that mesitylphosphinidene adds to ?r-bonds in a fashion similar to that for carbenes and silylenes.*J But, heeding Mathey's warning regarding the invocation of phosphinidene intermediates without physical evidence: it was recognized that spectroscopic studies were n d e d in order to fully establish the formation of phosphinidenes.Theoretical studies predict that many phosphinidenes have triplet ground electronic statesS and that the ground triplet state of arylphosphinidenes is lower in energy by more than 40 kcal/ mol than the lowest excited (singlet) states6 It thus seemed likely that a triplet arylphosphinidene could be detected by ESR spectroscopy, as in the case of carbenes and nitrenes.' While ESR experiments on the photolysis of proposed phosphinidene precursors in frozen matrices have been reported previously,* the (1) (a) Schmidt,U. Angew. Chem., Int. Ed. Engl. 1975,14,523. (b) Weber, B.; Reaitz. M. Houben-Wevl, p 34: "The effective generation of these transient phosphinidenes from appropriate precursors is deduced from the isolation of products whose formation can be explained by a mechanism involving such intermediates. However, in almost every case as will be demonstrated later, it is possible to conceive alternate mechanisms which do not involve phosphinidenes. Thus, only a thorough physiwchemicalstudy of the generating systems can provide a firm basis for the actual formation of phosphinidenes." ( 5 ) For H P (a) Nguyen, M. T. Mol. Phys. 1986, 59, 547. (b) Droege, A.T.; Engelking, P. C. Scheme 1 CH3( cCH3 1. MesP(H)LI, THF TsO' OTs Z.wBuLl,MF -H * .C-cFH I Scheme 2 1 2 3 2 4detection by ESR of a triplet phosphinidene was not achieved. We report here the observation of triplet mesitylphosphinidene. trans-2,3-Dimethyl-1 -mesitylphosphirane (1) was synthesized from MesPHz9 and (*)-2,3-butanediol ditosylatelo in 52% yield as shown in Scheme 1.11Compound 1 was found to decompose more easily and cleanly than the previously reported l-mesitylphosphirane.Z Room temperature photolysis of compound 1 in the presence of 3-hexyne gave a 64% yield of 2,3-diethyl-1 -mesitylphosphirene (4)12 (Scheme 2).When frozen solutions of compound 1 (0.01-0.1 M) in methylcyclohexane were irradiated at 77 K with a 254 nm light source, the methylcyclohexane glass became yellow. After thawing, trimesitylcyclotriphosphine (3) was observed in 30% yield in the absence of trapping agent;l3 in the presence of 3-hexyne, 2,3-dimethyl-1-mesitylphosphirene (4) was formed in yields of 2240% based on the initial amount of compound 1. The formation of these products strongly suggests that mesitylphosphinidene (2) was formed in the matrix.A methylcyclohexane solution of compound 1 (0.1 M, 0.6 mL) was placed in a quartz ESR tube, degassed, and se...

The mathematical model can represent the DIL∕DI∞ curve from a single axial CT scan. Generally, n ≠ 1. The equilibrium dose, α, n, and Leq exhibit strong dependencies on phantom diameter and location in the phantom. On the other hand, α, n, and Leq have relatively weak dependencies on material (PMMA or water), tube voltage (80-140 kVp), and bowtie filter, and Leq is also insensitive to beam width (≤4 cm). A weak dependency of the DIL∕DI∞ curve on CT scanner using 80-140 kVp and beam width up to 4 cm is consistent with the results of this study and previous publications. The dose equilibration data provided in this paper can be useful for CT dose evaluation. A framework is presented for assessing dose at any point in infinitely long PMMA and water cylinders undergoing multidetector CT examinations.

Objective To assess excess all cause and cause specific mortality during the three months (1 January to 31 March 2020) of the coronavirus disease 2019 (covid-19) outbreak in Wuhan city and other parts of China. Design Nationwide mortality registries. Setting 605 urban districts and rural counties in China’s nationally representative Disease Surveillance Point (DSP) system. Participants More than 300 million people of all ages. Main outcome measures Observed overall and weekly mortality rates from all cause and cause specific diseases for three months (1 January to 31 March 2020) of the covid-19 outbreak compared with the predicted (or mean rates for 2015-19) in different areas to yield rate ratio. Results The DSP system recorded 580 819 deaths from January to March 2020. In Wuhan DSP districts (n=3), the observed total mortality rate was 56% (rate ratio 1.56, 95% confidence interval 1.33 to 1.87) higher than the predicted rate (1147 v 735 per 100 000), chiefly as a result of an eightfold increase in deaths from pneumonia (n=1682; 275 v 33 per 100 000; 8.32, 5.19 to 17.02), mainly covid-19 related, but a more modest increase in deaths from certain other diseases, including cardiovascular disease (n=2347; 408 v 316 per 100 000; 1.29, 1.05 to 1.65) and diabetes (n=262; 46 v 25 per 100 000; 1.83, 1.08 to 4.37). In Wuhan city (n=13 districts), 5954 additional (4573 pneumonia) deaths occurred in 2020 compared with 2019, with excess risks greater in central than in suburban districts (50% v 15%). In other parts of Hubei province (n=19 DSP areas), the observed mortality rates from pneumonia and chronic respiratory diseases were non-significantly 28% and 23% lower than the predicted rates, despite excess deaths from covid-19 related pneumonia. Outside Hubei (n=583 DSP areas), the observed total mortality rate was non-significantly lower than the predicted rate (675 v 715 per 100 000), with significantly lower death rates from pneumonia (0.53, 0.46 to 0.63), chronic respiratory diseases (0.82, 0.71 to 0.96), and road traffic incidents (0.77, 0.68 to 0.88). Conclusions Except in Wuhan, no increase in overall mortality was found during the three months of the covid-19 outbreak in other parts of China. The lower death rates from certain non-covid-19 related diseases might be attributable to the associated behaviour changes during lockdown.