[Interpretation of thoracic radiographs re-examined and corrected with tomodensitometry].
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Adult↗
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Stereocontrol in Diels-Alder cycloaddition to unsaturated sugars: reactivities of cis-dienophiles with cyclopentadiene.
Cycloaddition of cyclopentadiene with a D-arabinose-derived cis-dienophile, methyl (Z)-4,5,6,7-tetra-O-acetyl-2,3-dideoxy-D-arabino-hept-2-enonate (2), under thermal conditions gave essentially a single norbornene adduct, isolated crystalline in 81% yield and identified by NMR spectroscopy and X-ray crystallography as methyl (5R,6S)-6-endo-(1,2,3,4-tetra-O-acetyl-D-arabino-tetritol-1-yl)bic yclo [2.2.1]-hept-2-ene-5-endo-carboxylate (3). The diene adds exclusively from the si-face of the dienophile and give only the endo product. The same sequence starting from L-arabinose gave the enantiomer (7) of 3. In contrast, a related cis-dienophile (9) having a butenolide ring reacts with cyclopentadiene from the opposite (re) face giving mainly the endo adduct (5S,6R)-6-endo-(2,3,4-tri-O-acetyl)-D-arabino-tetritol-1-yl)bicycl o [2.2.1]hept-2-ene-5-endo-carboxylic acid 1,4-lactone (10), isolated crystalline in 70% yield, whose structure was again established by NMR spectroscopy, and firmly consolidated by X-ray crystallography. The minor (11%) product was the exo(5S,6R) isomer 11. A cis-enonate 14, analogous to 2 but deoxygenated at the allylic position, showed negligible diastereofacial selectivity and reacted with cyclopentadiene to give a mixture of all four possible adducts. A 6-membered ring dienophile 16 was also subjected to the same cycloaddition for comparison with the butenolide 9; it gave principally the two endo products 17 and 19 in 31 and 38% yields, respectively, accompanied by 12% of a mixture of the two exo products (18 and 20). The quantitative distribution of cycloaddition products as a function of dienophile stereochemistry is discussed. The high degree of asymmetric induction observed, especially with the readily accessible dienophiles 2 and 7, provides a valuable route of access to enantiomerically pure tetra-C-substituted cycloalkanes.
Carbohydrate Conformation↗
A neutral organometallic fluoro complex can be a good ligand.
The reaction of the complex [Mo(OTf)(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (1) (OTf = trifluoromethylsulfonate; phen = 1,10-phenanthroline) with tetrabutylammonium fluoride trihydrate afforded the fluoride complex [MoF(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)] (2). The IR spectrum and the oxidation potential of 2 reflect the fact that its metal center is more electron-rich than that of the chloro analogue [MoCl(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)]. Compound 2 reacted with 1 affording the homobinuclear complex [[Mo(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)](2)(mu-F)][OTf] (3), with a fluoride bridge. Compound 2 also reacts with the species generated in situ by triflate abstraction from [M(OTf)(CO)(3)('N-N')] (M = Mn, Re; 'N-N' = 2,2'-bipyridine (bipy), phen) using NaBAr'(4) (Ar' = 3,5-bis(trifluoromethyl)phenyl), affording the heterobinuclear complexes [[Mo(eta(3)-C(3)H(4)-Me-2)(CO)(2)(phen)](mu-F)[M(CO)(3)('N--N')]][BAr'(4)] (M = Mn, 'N-N' = bipy (4); M = Re, 'N-N' = phen (5)). All new compounds have been characterized by spectroscopic methods (IR and NMR) and, in the case of 1, 2, 3, and 4, also by means of X-ray diffraction analysis.
Journal Article↗
Mathematical model for pre-operative planning of linear and closing-wedge metatarsal osteotomies for the correction of hallux valgus.
First-metatarsal osteotomy is performed for an abnormal intermetatarsal angle and severe hallux valgus deformity. The metatarsal head is slid along the osteotomy and fixed with a Kirschner wire to achieve angular and linear realignment with respect to the other metatarsals. When reduction of joint subluxation is also sought, a bone wedge is removed. A mathematical model and a corresponding computer-based tool were developed for pre-operative planning of the optimum surgical solution. Standard intermetatarsal angle correction, head-to-sesamoids re-alignment, joint subluxation reduction and metatarsal length adjustment were all pursued. A standard pre-surgical dorso-plantar radiograph of the patient, with an additional metal ball for calculation of X-ray magnification, was necessary to analyse the original and final geometrical configurations. For the first time, expected bone loss and wire diameter were also considered. The angles of bone cuts and the amount of sliding along these cuts were calculated by the model according to the surgical goal. All the resulting geometrical parameters, both in the pre- and planned post- operative configuration, were provided in graphical and tabular form. In a change from former qualitative analysis of radiograms, the surgeon can now enter the operating theatre with a detailed plan of the goal to be achieved.
Hallux Valgus↗
Colorectal cancer screening: the potential role of virtual colonoscopy.
Virtual colonoscopy is a promising new technique that combines rapid spiral CT scanning of the abdomen with advanced computer programs capable of re-creating two- and three-dimensional views of the colon and rectum. Recent studies comparing this method with conventional colonoscopy show that virtual colonoscopy already is more accurate than barium enema X-ray studies for the detection of colorectal polyps, and that it approaches the accuracy of colonoscopy for diagnosing advanced lesions. Before virtual colonoscopy can be promoted for population-based screening for colorectal cancer, a number of issues discussed in this review need to be addressed. These include questions of accuracy, availability, acceptability, and cost-effectiveness.
Colonography, Computed Tomographic↗
Cytotoxic constituents from the stem bark of Dichapetalum gelonioides collected in the Philippines.
Fractionation of an ethyl acetate-soluble extract of the stem bark of Dichapetalum gelonioides, collected in the Philippines, using the LNCaP (hormone-dependent human prostate) cell line as a monitor, led to the purification of three dichapetalin-type triterpenoids [dichapetalins A (1), I (2), and J (3)], along with two dolabrane norditerpenoids (6, 7), and the additional triterpenoids zeylanol (8), 28-hydroxyzeylanol (9), and betulinic acid. Since compounds 1-3 exhibited promising selectivity against the SW626 (human ovarian cancer) cell line, a re-collection of the plant material was carried out, to obtain more of these compounds for additional biological testing. Two further phenylpyranotriterpenoids [dichapetalins K (4) and L (5)] were isolated from the re-collected plant material. The structures of the new compounds 2-5 and 9 were determined on the basis of spectroscopic data interpretation, and the relative configuration of 6 was confirmed using X-ray crystallography. Compounds 4-6 and the methyl ester, 6a, exhibited broad cytotoxic activity when tested against a panel of human tumor cell lines. Dichapetalin A (1) was not active when evaluated in an in vivo hollow fiber assay in the dose range 1-6 mg/kg.
Antineoplastic Agents, Phytogenic↗
The neoplastic transformation potential of mammography X rays and atomic bomb spectrum radiation.
Considerable controversy currently exists regarding the biological effectiveness of 29 kVp X rays which are used for mammography screening. This issue must be resolved to enable proper evaluation of radiation risks from breast screening. Here a definitive assessment of the biological effectiveness of 29 kVp X rays compared to the quality of radiation to which the atomic bomb survivors were exposed is presented for the first time. The standard radiation sources used were (a) an atomic bomb simulation spectrum and (b) 2.2 MeV electrons from a strontium-90/yttrium-90 (90Sr/90Y) radioactive source. The biological end point used was neoplastic transformation in vitro in CGL1 (HeLa x human fibroblast hybrid) cells. No significant difference was observed for the biological effectiveness of the two high-energy sources for neoplastic transformation. A limiting relative biological effectiveness (RBE(M)) of 4.42 +/- 2.02 was observed for neoplastic transformation by 29 kVp X rays compared to these two sources. This compares with values of 4.67 +/- 3.93 calculated from previously published data and 3.58 +/- 1.77 when the reference radiation was 200 and 220 kVp X rays. This suggests that the risks associated with mammography screening may be approximately five times higher than previously assumed and that the risk-benefit relationship of mammography exposures may need to be re-examined.
Cell Transformation, Neoplastic↗
Cystic lung disease in Sjögren's syndrome.
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Adult↗
[Efficacy of chest CT on the staging and re-staging in patients with small cell lung cancer].
Chest CT revealed to be effective to improve the quality of the staging of lung cancer concerning with the evaluation of intrathoracic lesion. The numbers of patients who had thoracic lesion as the first relapse site were higher in the group which were re-staged without the information of chest CT. The extramural review of the multi-center trial showed the inter-center bias to evaluate CR in spite of using the same X-ray imaging modalities.
Carcinoma, Small Cell↗
[Format and image contents of x-ray picture (author's transl)].
This article is essentially on the lines of the paper read at the German Congress of Radiologists ("Deutscher Röntgenkongress") at Münster. It deals with the visual interpretation of the contents of roentgenographic films of widely different origin. On going deeper into the subject, it was found that by examining the pictures for structural contents as far as the image permits, it becomes possible to obtain a survey of all the usually prepared x-ray photographs--a viewpoint which has so far been greatly neglected. Knowledge of the conditions of observation and of the prerequisites is promoted at the same time. The need for radiation protection is re-emphasized from a new angle.
Humans↗
Re-expansion of atelectasis during general anaesthesia: a computed tomography study.
Formation of atelectasis is one mechanism of impaired gas exchange during general anaesthesia. We have studied manoeuvres to re-expand such atelectasis in 16 consecutive, anaesthetized adults with healthy lungs. In group 1 (10 patients), the lungs were inflated stepwise to an airway pressure (Paw) of 10, 20, 30 and 40 cm H2O. In group 2 (six patients), three repeated inflations up to Paw = 30 cm H2O were followed by one inflation to 40 cm H2O. Atelectasis was assessed by analysis of computed x-ray tomography (CT). In group 1 the mean area of atelectasis in the CT scan at the level of the right diaphragm was 6.4 cm2 at Paw = 0 cm H2O, 5.9 cm2 at 20 cm H2O, 3.5 cm2 at 30 cm H2O and 0.8 cm2 at 40 cm H2O. A Paw of 20 cm H2O corresponds approximately to inflation with twice the tidal volume. In group 2 the mean area of atelectasis was 9.0 cm2 at Paw = 0 cm H2O and 4.2 cm2 after the first inflation to 30 cm H2O. Repeated inflations did not add to re-expansion of atelectasis. The final inflation (Paw = 40 cm H2O) virtually eliminated the atelectasis. We conclude that, after induction of anaesthesia, the amount of atelectasis was not reduced by inflation of the lungs with a conventional tidal volume or with a double tidal volume ("sigg"). An inflation to vital capacity (Paw = 40 cm H2O), however, re-expanded virtually all atelectatic lung tissue.
Adult↗
Biophysical characterisation of lysozyme binding to LPS Re and lipid A.
The binding of lysozyme to bacterial deep rough mutant lipopolysaccharide (LPS) Re and to its lipid moiety lipid A, the 'endotoxic principle' of LPS, was investigated using biophysical techniques. The beta<-->alpha gel to liquid crystalline phase transition, the nature of the functional groups of the endotoxins, the secondary structure of lysozyme, and competition with polymyxin B were studied by Fourier-transform infrared spectroscopy (FTIR); the supramolecular aggregate structure of the endotoxins was determined with synchrotron radiation X-ray diffraction and the binding stoichiometry with microcalorimetry. The results were compared with those found with zwitterionic and negatively charged phospholipids. It can clearly be shown that lysozyme binds electrostatically to charged groups of the endotoxin molecules with the consequence of acyl-chain rigidification and an initiation of a transition from inverted cubic to multilamellar structures. The binding stoichiometry of endotoxin and lysozyme is a 3:1 molar ratio for both LPS Re and lipid A, indicating a dominant binding of lysozyme to the lipid A-phosphates. This could be confirmed by the analysis of a phosphate vibration and by the use of a dephospho LPS. Parallel to lysozyme binding to endotoxin, a conformational change of the secondary structure in the protein from mainly alpha helix to more unordered structures takes place, while the residual beta-sheet substructure does not exhibit a clear concentration dependence. Binding is found to be specific for the endotoxins since, for the zwitterionic phosphatidylcholine, no binding is observed and, for the negatively charged phosphatidylglycerol, only very weak binding is found. The results are discussed in the context of the ability of lysozyme to reduce endotoxicity.
Calorimetry↗
Preparation and X-ray crystallographic analysis of rubredoxin crystals from Desulfovibrio gigas to beyond ultra-high 0.68 A resolution.
Rubredoxin (D.g. Rd), a small non-heme iron-sulfur protein shown to function as a redox coupling protein from the sulfate reducing bacteria Desulfovibrio gigas, has been crystallized using the hanging-drop vapor diffusion method and macroseeding method. Rubredoxin crystals diffract to an ultra-high resolution 0.68 A using synchrotron radiation X-ray, and belong to the space group P2(1) with unit-cell parameters a=19.44 A, b=41.24 A, c=24.10 A, and beta=108.46 degrees. The data set of single-wavelength anomalous dispersion signal of iron in the native crystal was also collected for ab initio structure re-determination. Preliminary analysis indicates that there is one monomer with a [Fe-4S] cluster in each asymmetric unit. The crystal structure at this ultra-high resolution will reveal the details of its biological function. The crystal character and data collection strategy for ultra-high resolution will also be discussed.
Crystallography, X-Ray↗
Aqueous synthesis of derivatized cyclopentadienyl complexes of technetium and rhenium directed toward radiopharmaceutical application.
Half-sandwich complexes of the type [(RCOCp)M(CO)(3)] with M = Re and (99(m))Tc were synthesized from [M(OH(2))(3)(CO)(3)](+) in water. The R group can be an organic residue or a receptor binding biomolecule with a spacer to cyclopentadienyl (Cp). This provides a general route to Cp complexes of technetium without the need for starting from [TcBr(CO)(5)]. The X-ray structure of [(C(6)H(5)CH(2)COC(5)H(4))Tc(CO)(3)] has been elucidated. The compound crystallizes in the monoclinic space group P2(1)/c with a = 16.1454(9), b = 7.6300(6), and c = 12.3922(7) A and beta = 107.792(6) degrees. We have chosen a serotonergic receptor ligand (WAY) as an example for the derivatization of Cp with a bioactive molecule. WAY is linked to Cp by an aliphatic chain of variable length. The half-sandwich complexes were prepared from water and organic solvents. The structure of [(WAY4-Cp)Re(CO)(3)] could be elucidated. The compound crystallizes in the monoclinic space group P2(1)/c with a = 15.7112(6), b = 6.8775(3), and c = 25.5217(12) A and beta = 103.778(5) degrees. Quantification of inhibition constants gave a clear structure-activity relationship. A single methylene group between the receptor binding site and the half-sandwich complex gave an IC(50) of 217 nM for HT(1A), whereas a butylene linker resulted in retention of the inhibition constant with an IC(50) of 6 nM with respect to underivatized WAY. For use as radiopharmaceuticals, the compounds have also been prepared with (99m)Tc in quantitative yield.
Catalysis↗
A New Family of Nonstoichiometric Layered Rare-Earth Tin Antimonides, RESn(x)()Sb(2) (RE = La, Ce, Pr, Nd, Sm): Crystal Structure of LaSn(0.75)Sb(2).
A new class of nonstoichiometric layered ternary rare-earth tin antimonides, RESn(x)()Sb(2) (RE = La, Ce, Pr, Nd, Sm), has been synthesized through reaction of the elements at 950 degrees C. In the lanthanum series LaSn(x)()Sb(2), tin can be incorporated from a maximum content of x approximately 0.7 or 0.8 to as low as x approximately 0.10. The structure of lanthanum tin diantimonide with the maximum tin content, LaSn(0.75)Sb(2), has been determined by single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group -Cmcm with a = 4.2425(5) Å, b = 23.121(2) Å, c = 4.5053(6) Å, and Z = 4. The isostructural rare-earth analogues were characterized by powder X-ray diffraction. The structure of LaSn(0.75)Sb(2) comprises layers of composition "LaSb(2)" in which La atoms are coordinated by Sb atoms in a square-antiprismatic geometry. Between these layers reside chains of Sn atoms distributed over three crystallographically independent sites, each partially occupied at about 20%. The structure of LaSn(0.75)Sb(2) can be regarded as resulting from the excision of RE-Sb and Sb-Sb bonds in the related structures of binary rare-earth diantimonides, RESb(2), and then intercalation of Sn atoms between layers.
Journal Article↗
Determination of the absolute configuration of (+)-neopentyl-1-d alcohol by neutron and x-ray diffraction analysis.
The absolute configuration of (+)-neopentyl-1-d alcohol, prepared by the reduction of 2,2-dimethylpropanal-1-d by actively fermenting yeast, has been determined to be S by neutron diffraction. The neutron study was carried out on the phthalate half ester of neopentyl-1-d alcohol, crystallized as its strychnine salt. The absolute configuration of the (-)-strychninium cation was first determined by an x-ray anomalous dispersion study of its iodide salt. The chiral skeleton of strychnine then served as a reference from which the absolute configuration of the -O-CHD-C(CH3)3 group of neopentyl phthalate was determined. Difference Fourier maps calculated from the neutron data showed unambiguously that the -O-CHD-C(CH3)3 groups of both independent molecules in the unit cell had the S configuration. This work proves conclusively that the yeast system reduces aldehydes by delivering hydrogen to the re face of the carbonyl group. Crystallographic details: (-)-strychninium (+)-neopentyl-1-d phthalate, space group P2(1) (monoclinic), a = 18.564(6) A, b = 7.713(2) A, c = 23.361(8) A, beta = 94.18(4) degrees, V = 3336.0(5) A3, Z = 2 (T = 100 K). Final agreement factors are R(F) = 0.073 for 2768 reflections collected at room temperature (x-ray analysis) and R(F) = 0.144 for 960 reflections collected at 100 K (neutron analysis).
Crystallography, X-Ray↗
The binding ability of iron bonded to porphodimethene: structural, magnetic, and electronic relationship to iron porphyrin complexes.
The availability of the parent compound, meso-hexaethylporphodimetheneiron(II), [(Et6N4)Fe] (2), of this report results from a novel synthetic methodology that makes [Et6N4Li2] (1) easily available. The major focus is on how the axial positions, which are the key reactive sites in metalloporphyrins, and the electronic configuration of the metal can be affected by the breakdown of the aromaticity of the porphyrin skeleton and by the nonplanar conformation of the ligand. DFT calculations indicate a 3B1(dz2)1(dyz)1 ground state for 2 versus the 3A2(dxz)1(dyz)1 ground state in the porphyrin analogue. The intermediate-spin state (S = 1) of 2 changed drastically upon addition of one or two axial ligands, as hexacoordination is preferred by iron(II). The hexacoordinate complexes [(Et6N4)Fe(L)(L')] (L = L' = THF, 3; L = L' = Py, 4; L = PhNO, L' = Py, 14) have been isolated and structurally characterized. Strong-field ligands lead to a low-spin diamagnetic state for iron(II), namely for complexes 4-7, 9, and 14, whereas 3 is a typical d6 high-spin complex, as is the pentacoordinate [(Et6N4)Fe(CN)]Bu4N (8). The structural analysis showed common features for 6, 7, 9, and 14: i) a small displacement of the metal from the N4 plane, and ii) an N4 cavity, larger than that in the corresponding porphyrins, affecting the Fe-N bond lengths. The 1H NMR spectrum is quite diagnostic of the two-fold symmetry in the diamagnetic hexacoordinate complexes, revealing either a D2h or a C2v symmetry. The CO stretching frequency (1951 cm(-1)) in complex 6 probes the good electron density at the metal. The one-electron oxidation of 2 led to pentacoordinate iron(III) derivatives [(Et6N4)Fe(Cl)] (10), [(Et6N4)2Fe2(mu-O)] (11), and [(Et6N4)2Fe2(mu-p-OC6H4-O)] (12). Complex 10 is a typical high-spin iron(III) (5.85muB at 298 K), while 11 and 12 behave as antiferromagnetic coupled iron(III) (J = -9.4cm(-1), 12, and J = -115cm(-1), 11). In complexes 10, 11, and 12 iron is sitting in a quite distorted square pyramidal geometry, in which the ligand displays a very distorted roof conformation with different degrees of ruffling. Distinctive structural and magnetic features have been found for the nitrosyl derivative [(Et6N4)Fe-NO], which has a low-spin state (S = 1/2) and the following structural parameters: Fe-N-O, 147.3(2) degrees; Fe-N, 1.708(2) A; N-O, 1.172(3) A. A comparative structural, magnetic, and theoretical analysis of the compounds listed above has been made with the analogous porphyrin derivatives. The detailed structural investigation has been mapped through the X-ray analysis of 2, 7, 8, 9, 11, 13, and 14.
Journal Article↗
Diazenide and hydrazide(2-) derivatives of the [Re(CO)3]+ core.
Reaction of [ReBr3(CO)3]2- with aryldiazonium salts gives the Re(iii) diazenide complexes [ReBr2(NNC6H4R-4)(CO)2]-. The attachment of a PhNHCS tethering group to pyridyl hydrazine generates a HYNIC related proligand which gives a stable chelated pyridyliumthiocarbazide(2-) derivative of the [Re(I)(CO)3]+ core.
Carbon Monoxide↗