Neuroimaging and head injuries: where we've been--where we're going.
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Brain↗
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Electron tunneling in single crystals of Pseudomonas aeruginosa azurins.
Rates of reduction of Os(III), Ru(III), and Re(I) by Cu(I) in His83-modified Pseudomonas aeruginosa azurins (M-Cu distance approximately 17 A) have been measured in single crystals, where protein conformation and surface solvation are precisely defined by high-resolution X-ray structure determinations: 1.7(8) x 10(6) s(-1) (298 K), 1.8(8) x 10(6) s(-1) (140 K), [Ru(bpy)2(im)(3+)-]; 3.0(15) x 10(6) s(-1) (298 K), [Ru(tpy)(bpy)(3+)-]; 3.0(15) x 10(6) s(-1) (298 K), [Ru(tpy)(phen)(3+)-]; 9.0(50) x 10(2) s(-1) (298 K), [Os(bpy)2(im)(3+)-]; 4.4(20) x 10(6) s(-1) (298 K), [Re(CO)3(phen)(+)] (bpy = 2,2'-bipyridine; im = imidazole; tpy = 2,2':6',2' '-terpyridine; phen = 1,10-phenanthroline). The time constants for electron tunneling in crystals are roughly the same as those measured in solution, indicating very similar protein structures in the two states. High-resolution structures of the oxidized (1.5 A) and reduced (1.4 A) states of Ru(II)(tpy)(phen)(His83)Az establish that very small changes in copper coordination accompany reduction but reveal a shorter axial interaction between copper and the Gly45 peptide carbonyl oxygen [2.6 A for Cu(II)] than had been recognized previously. Although Ru(bpy)2(im)(His83)Az is less solvated in the crystal, the reorganization energy for Cu(I) --> Ru(III) electron transfer falls in the range (0.6-0.8 eV) determined experimentally for the reaction in solution. Our work suggests that outer-sphere protein reorganization is the dominant activation component required for electron tunneling.
Azurin↗
Crystalline beta-cyclodextrin.12H2O reversibly dehydrates to beta-cyclodextrin.10.5 H2O under ambient conditions.
In contact with mother liquor, crystalline beta-cyclodextrin (beta-CD) hydrate has composition approximately beta-CD.12H2O. If crystals are dried at ambient conditions (18 degrees C, approximately 50% humidity), the unit cell volume diminishes approximately 30 to 50 A3. X-ray structure analysis of a dry crystal (0.89 A resolution, 4617 data, R = 0.059) showed the composition beta-CD.10.5 H2O, with approximately 5.5 water molecules in the beta-CD cavity (7 partially and 2 fully occupied sites) and approximately 5.0 between the beta-CD molecules. The positions of the beta-CD host and of most of the hydration waters are conserved during dehydration, but the occupancies of the waters in the beta-CD cavity diminish. Dry crystals put into solvent re-hydrate to the original form. The mechanism of de- and re-hydration is not evident.
Crystallization↗
Reactivity of a Vanadium(III) Center over an Oxo Surface Modeled by Calix[4]arene.
Metalation of the monomethoxycalix[4]arene [p-Bu(t)-calix[4]-(OMe)(OH)(3)], 1, using [VMes(3).THF] led to the coordinatively unsaturated V(III)-d(2) fragment [p-Bu(t)-calix[4]-(OMe)(O)(3)V] collapsing to the dimer [{&mgr;-p-Bu(t)-calix[4]-(OMe)(O)(3)}V](2), 2, where each calix[4]arene shares a bridging oxygen donor atom. The dimeric complexity remains intact in the reaction with Bu(t)NC and PhCN, which bond to the metal inside the cavity of the calix[4]arene leading to [{&mgr;-p-Bu(t)-calix[4]-(OMe)(O)(3)}(V-L)](2) [L = Bu(t)NC, 3; L = PhCN, 4]. In contrast, the reaction of 2 with pyridine and 4,4'-dipyridyl cleaves the dimeric form into a monomeric complex [{&mgr;-p-Bu(t)-calix[4]-(OMe)(O)(3)}V(Py)], 5, or to a different dimer containing a bridging 4,4'-dipyridyl, [{p-Bu(t)-calix[4]-(OMe)(O)(3)}(2)V(2)(&mgr;-4,4'-dipyridyl)], 6. Complex 2 undergoes one electron oxidation by I(2) to the corresponding vanadium(IV) dimer [{&mgr;-p-Bu(t)-calix[4]-(O)(4)}(2)V(2)], 7, and by p-benzoquinone to [{p-Bu(t)-calix[4]-(OMe)(O)(3)}V](2)(&mgr;-C(6)H(4)O(2)), 8. A two-electron oxidation of the V(III)-d(2) to vanadium(V) derivatives has been achieved using styrene epoxide and diphenyldiazomethane. In the former case the oxovanadium(V) derivative was obtained [p-Bu(t)-calix[4]-(OMe)(O)(3)V=O], 9, and in the latter case a metallahydrazone complex [p-Bu(t)-calix[4]-(OMe)(O)(3)V&tbd1;N-N=CPh(2)], 10. The dimeric d(2) and d(1) derivatives display significant antiferromagnetic couplings between the two metal centers, namely as follows: 2, J = -74.6 cm(-)(1); 3, J = -17 cm(-)(1); 4, J = -33.4 cm(-)(1); 7, J = -131.7 cm(-)(1). The extended Hückel calculations gave an appropriate picture of the two-electron reduction of the diphenyldiazomethane substrate. The proposed structures have been supported by X-ray analyses on 3, 7, 9, and 10.
Journal Article↗
Cobalt-60: the heart of gamma-radiation sterilization.
Currently, more than three million cubic metres of single-use medical devices are sterilized by gamma radiation each year. The wide use of this method of sterilization is a result of the lethal effects of ionizing radiation on microbial populations and the penetrative powers of cobalt-60. This article describes how cobalt-60 is produced and used in gamma-radiation sterilization, and how it is disposed of once it has reached the end of its useful life. Cobalt-60 sources typically have a life of 20 years, at which point they are returned to the suppliers for re-encapsulation, reprocessing, recycling, or disposal.
Cobalt Radioisotopes↗
DEB test for Fanconi anemia detection in patients with atypical phenotypes.
Pancytopenia, hyperpigmentation, small stature, congenital abnormalities, and predisposition to neoplasia characterize Fanconi anemia (FA). The clinical phenotype is extremely variable, therefore the diagnosis is frequently delayed until the pancytopenia appears, making diagnosis difficult on the basis of clinical manifestations alone. Hypersensitivity of FA cells to the clastogenic effect of diepoxybutane (DEB) provides a unique marker for the diagnosis before the beginning of hematological manifestations. Our aim in this study was to detect FA in children with atypical manifestations to define which conditions should be routinely included in the DEB test screening. We performed the chromosomal breakage test in 34 patients with probable FA and 83 patients with clinical conditions that could suggest FA, but are not usually screened by the DEB test: 20 patients with aplastic anemia, 20 patients with VACTERL association, 20 with radial ray abnormalities, 7 with tracheo-esophageal fistulae, 12 with anal atresia, and 4 with myelodysplastic syndrome. We found 18 DEB-positive patients: 12 were in the group of probable FA and 6 in the other groups. Among the last ones: three were included because of aplastic anemia, without any other sign of FA, however when re-examined, other anomalies were detected. The third patient had anal atresia, renal hypoplasia, pre-axial polydactyly, and normal blood cell counts and was diagnosed as having VACTERL association. The other two patients lacking physical or hematological signs were identified among the group of radial ray abnormalities. Thus, our results highlight the need to increase the number of abnormalities indicating need for a DEB test. Delay in the diagnosis of FA may have serious consequences for the patients and their family members.
Adult↗
[Roentgenographic study of the structural organization of the collagen fibers in the tunica media of the aorta].
X-ray diffraction tecnique was used to investigate the distribution and orientation of collagen fibers in media layer of pig aortic wall as a function of mechanical deformation. Hyistological analyses were carried out to study the behavior of smooth cells when mechanical deformation is applied to media layer. The results show a close relationship between collagen fibers and smooth cells orientation.
Animals↗
Transition metal complexes coordinated by an NAD(P)H model compound and their enhanced hydride-donating abilities in the presence of a base.
The ruthenium(II) and rhenium(I) complexes containing an NAD(P)H model compound, 1-benzyl-1,4-dihydronicotinamide (BNAH), as ligand, [Ru(tpy)(bpy)(BNAH)]2+ (1 a) and [Re(bpy)(CO)3(BNAH)]+ (1 b), were quantitatively produced by the reaction of the corresponding metal hydrido complexes with BNA(+) (1-benzylnicotinamidium cation). In the presence of base with pK(a) = 8.9, 1 a and 1 b have much greater reducing power than "free" BNAH. The oxidation potentials of 1 a in the absence and the presence of triethylamine were 0.55 V and -0.04 V, respectively, versus Ag/AgNO(3), whereas that of "free" BNAH was 0.30 V. Spectroscopic results clearly showed that the base extracts a proton from the carbamoyl group on 1 a and 1 b to give the deprotonated BNAH coordinating to the transition-metal complexes [Ru(tpy)(bpy)(BNAH-H+)]+ (3 a) and [Re(bpy)(CO)3(BNAH-H+)] (3 b); this deprotonation underlies the enhancement in reducing ability. The deprotonated forms 3 a and 3 b can efficiently reduce other NAD(P) models to give the corresponding 1,4-dihydro form, resulting in the deprotonated BNA+ being coordinated to the metal complexes [Ru(tpy)(bpy)(BNA(+)-H+)]2+ (2 a) and [Re(bpy)(CO)3(BNA+-H+)]+ (2 b); "free" BNAH and the protonated adducts 1 a and 1 b cannot act in this way. X-ray crystallography was performed on the PF6- salt of 2 a, and showed that the deprotonated nitrogen atom on the carbamoyl group coordinates to the ruthenium(II) metal center with a bond length of 2.086(3) Angstroms. Infrared spectral data suggested that the deprotonated carbamoyl group on the reduced forms 3 a and 3 b is converted to the imido group, and that the oxygen atom coordinates to the metal center.
Hydrogen-Ion Concentration↗
Ornithine decarboxylase promotes catalysis by binding the carboxylate in a buried pocket containing phenylalanine 397.
Ornithine decarboxylase (ODC) is a pyridoxal 5'-phosphate (PLP) dependent enzyme that catalyzes the decarboxylation of l-Orn to putrescine, a rate-limiting step in the formation of polyamines. The X-ray crystal structures of ODC, complexed to several ligands, support a model where the substrate is oriented with the carboxyl-leaving group buried on the re face of the PLP cofactor. This binding site is composed of hydrophobic and electron-rich residues, in which Phe-397 is predicted to form a close contact. Mutation of Phe-397 to Ala reduces the steady-state rate of product formation by 150-fold. Moreover, single turnover analysis demonstrates that the rate of the decarboxylation step is decreased by 2100-fold, causing this step to replace product release as the rate-limiting step in the mutant enzyme. These data support the structural prediction that the carboxyl-leaving group is positioned to interact with Phe-397. Multiwavelength stopped-flow analysis of reaction intermediates suggests that a major product of the reaction with the mutant enzyme is pyridoximine 5'-phosphate (PMP), resulting from incorrect protonation of the decarboxylated intermediate at the C4' position. This finding was confirmed by HPLC analysis of the reaction products, demonstrating that Phe-397 also plays a role in maintaining the integrity of the reaction chemistry. The finding that the carboxylate-leaving group is oriented on the buried side of the PLP cofactor suggests that ODC facilitates decarboxylation by destabilizing the charged substrate carboxyl group in favor of an electrostatically more neutral transition state.
Alanine↗
Relativistic deuteron-nucleus scattering in the Kemmer-Duffin-Petiau formalism.
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Journal Article↗
[Relationship between Hoover sign, functional and variables, and curvature radius in patients with obstructive pulmonary disease].
The purpose of the present study was: 1) to relate the Hoover sign -SH (+)- with several functional (spirometry and lung volumes) and radiographic (AP x-ray) parameters, 2) to characterize the changes in diaphragmatic curvature radius and the efficiency and to establish some relationships with the functional and radiographic parameters. Fifteen patients with COPD (SH (+), n: 8) were studied. The radius was determined in the right hemidiaphragm after maximal inspired and expired x-ray. The SH (+) was found in more severely obstructed patients (FEV1%, p 0.005%) and with high degree of air trapping (RV/TLC %, p 0.01). The expiratory radius (Re) was higher (p 0.05), and their efficiency (1/Re), was minor (p 0.05). The FEV1% correlated with the degree of hyperinflation according to TLC % (r -0.58, p 0.022) and with air trapping according to RV % (r -0.77, p 0.0008). The patients with low FEV1% showed high Re (r -0.61, p 0.015) and decreased diaphragmatic efficiency during expiration (1/Re) according to 1/Re = 0.093 cm-1 + 0.0012 cm-1* FEV1% (r 0.688, p 0.0054). The FEV1 correlated with the diaphragmatic movement (r 0.71, p 0.003). The PaCO2 correlated with the TLC % (r 0.534, p 0.04), the RV% (r 0.62, p 0.014) and with the radiographic parameters of hyperinflation (r 0.546, p 0.035) and air trapping (r 0.528, p 0.043). The presence of Hoover sign suggest severe bronchial obstruction, diaphragmatic flattening, increase of curvature radius, decrease of mobility and efficiency.
Aged↗
[Bronchiectasis, pulmonary abcess and clubbing].
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Adult↗
[Value and limitations of scintigraphy of the hand in rheumatoid arthritis].
99mTc-polyphosphate joint imaging of the hand has been performed in 18 patients, with evidence of inflammatory joint disease, but without any significant radiographic lesions, which might be related to rheumatoid arthritis. The hand scans were compared to clinical and radiographic data. An year after, the same subjects were re-examined, with both the radionuclide imaging and radiography. Scintigraphy has been shown to be significantly more sensitive for detecting inflammatory joint disease than x-ray, especially in the early stage of rheumatoid arthritis. Although radionuclide imaging is non specific (activity is increased also in osteoarthritis, trauma, metabolic bone disease, infarction, etc.). Radiography is highly specific but relatively non sensitive.
Adult↗
[A clinical study of 5 cases of acute eosinophilic pneumonia--the relationship between beginning to smoke and acute eosinophilic pneumonia].
We encountered 5 cases of acute eosinophilic pneumonia. All cases were young men who had recently begun smoking, and they showed an acute onset hypoxemia, diffuse shadows on chest X-ray, an elevation of eosinophils in the peripheral blood and broncho-alveolar lavage fluid, and rapid recovery. One of the 5 cases showed a re-elevation of eosinophils in the peripheral blood and broncho-alveolar lavage fluid after a smoking challenge test. It appears that one of the causes of acute eosinophilic pneumonia is beginning to smoke.
Acute Disease↗
Effects of simulated space vacuum on bacterial cells.
The effect of vacuum on bacterial cells is related to water desorption. Below water vapour pressure the inactivation remains constant, independent of total pressure and exposure time. In subsequent growth, the lag-phase of the survivors is delayed. Combined treatment with vacuum and radiation (X-rays or uv of 254 nm wavelength) results in synergistic effects, whereas vacuum and heat can act antagonistically. The vacuum inactivated cells (indicated as loss of colony-forming ability) are completely damaged. They do not show cellular elongation, phage production or respiration. The cellular membrane becomes permeable by vacuum exposure: biomolecules are released from the cells when re-suspended after vacuum treatment.
Bacillus subtilis↗
Synthesis and characterization of rhenium(V) oxo complexes with N-[N-(3-diphenylphosphinopropionyl)glycyl]cysteine methyl ester. X-ray crystal structure of (ReO[Ph(2)P(CH(2))(2)C(O)-Gly-Cys-OMe(P,N,N,S)]).
The PN(2)S chelate N-[N-(3-diphenylphosphinopropionyl)glycyl]-S-tritylcysteine methyl ester [PN(2)S(Trt)-OMe] was synthesized and reacted with ReOCl(3)(PPh(3))(2) and Ph(4)P[ReOCl(4)]. The reactions of both tritylated and detritylated ligands with Re(V)O precursors gave two diastereomers, 9a and 9b, of the ReO(PN(2)S-OMe) complex. The two isomers, produced in a 1:1 molar ratio, are stable and do not interconvert. They were separated by reverse-phase HPLC and characterized by NMR, FT-IR, and UV-visible spectroscopy and electrospray mass spectrometry. X-ray analysis established for 9a the presence in the solid of the syn isomer. Compound 9a, C(21)H(23)N(2)O(5)PSRe, crystallized from warm acetonitrile in the triclinic space group Ponemacr;, a = 9.828(2) A, b = 11.163(2) A, c = 11.641(2) A, alpha = 106.48(3) degrees, beta = 109.06(3) degrees, gamma = 102.81(3) degrees, V = 1085.7(4) A(3), Z = 2. The PN(2)S coordination set is in the equatorial plane, and the complex shows a distorted square pyramidal coordination. The anti configuration assigned to 9b is consistent with all the available physicochemical data. Follow-up of the reaction of the detritylated ligand with Ph(4)P[ReOCl(4)] in ethanol or acetonitrile indicated that the phosphorus atom of the chelate binds first to the metal and that this bond acts as the driving force for coordination.
Catalysis↗
Comparison of imaging with FDG PET/CT with other imaging modalities in myeloma.
OBJECTIVE: To determine the usefulness of FDG PET/CT scanning in the management and staging of myeloma and to assess its strengths and limitations. DESIGN: FDG PET/CT scans and all other available imaging studies were reviewed retrospectively from 16 consecutive patients by two experienced musculoskeletal radiologists and two nuclear medicine physicians working in consensus. PATIENTS: The 16 patients had undergone a total of 19 FDG PET/CT scans. Radiographs were available in all cases, including 13 skeletal surveys; 25 CT scans (16 chest, three abdominal, four pelvic, one spine, one neck) and 22 MR imaging studies (17 spine, three pelvic, two extremity) also were reviewed. Patients' records were examined for relevant clinical information. All focal areas of abnormal FDG uptake were correlated with the other imaging studies to determine clinical significance. FDG PET/CT scans also were reviewed to see if small lesions shown on the other imaging studies could be identified in retrospect. RESULTS: The 12 men and four women had an average age of 58 years (range 30-69 years). All 16 patients had an established diagnosis of multiple myeloma, with average duration of disease, from time of initial diagnosis to review, of 30 months (range 6 months to 11+ years). The FDG PET/CT scans revealed a total of 104 sites (90 in bone, 14 soft tissue) that were suspicious for neoplastic activity based on a standardized uptake value (SUV) greater than 2.5. Fifty-seven of these sites (55%) were new or previously undetected. The other imaging studies (X-ray, CT, MR) and clinical information confirmed the other 47 areas but also revealed 133 other small skeletal lesions. Six of these 133 additional lesions showed mild FDG uptake on re-review of the PET/CT scans. The FDG PET/CT findings led to management changes in 9/16 patients. MR imaging revealed five cases of diffuse bone involvement (four spine, one scapula) that were not evident by FDG PET/CT. CONCLUSION: FDG PET/CT scans are useful for the management and staging of myeloma. However, if PET/CT were the sole imaging study done, it would miss many additional small lytic skeletal lesions and could miss diffuse spine involvement.
Adult↗
Thermotropic phase behaviour of long-chain alkylmaltosides.
The thermotropic phase behaviour and phase structure of crystalline and non-crystalline n-tetradecyl-beta-D-maltoside (C14G2) and n-hexadecyl-beta-D-maltoside (C16G2) have been investigated by means of differential scanning calorimetry and X-ray techniques. Upon lyophilisation, both compounds form a solid, lamellar phase comprising disordered head groups and hexagonally packed alkyl chains that are suggested to be tilted and interdigitated. This ordered lamellar phase melts into a metastable lamellar liquid crystal, which re-crystallises to a high-temperature crystalline polymorph comprising interdigitated, non-tilted alkyl chains. Remarkably, the high-temperature polymorph of C14G2 has the same melting point as that of C16G2, namely 105 degrees C for both surfactants. A low-temperature polymorph of anhydrous C14G2 crystallises from water at room temperature, whereas the hemihydrate of C14G2 crystallises at 6 degrees C from water, or from chloroform containing trace water. X-ray data suggest both these crystalline modifications to comprise interdigitated and tilted alkyl chains.
Alkanes↗