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PubMed1987

Evaluation of renal parenchyma in children by DMSA scintigraphy, X-ray computed tomography and intravenous urography.

The demonstration of diminished or scarred renal parenchyma in children is often the decisive factor in determining the future management of children with urinary tract malformations. Renal scintigraphy using technetium 99m-labelled dimercaptosuccinic acid (DMSA), computed tomography (CT) and intravenous urography (IU) were used to evaluate the renal parenchyma prior to ureter re-implantation in a series of 13 children. Their ages ranged from 5 months to 3 years 8 months. The indication for operation was ureteric reflux in 8 children and distal ureteric stenosis in 5. CT was performed on a Toshiba TCT-80 scanner. Renal scintigraphy was performed 3 hours after intravenous injection of DMSA. Compared with IU, DMSA imaging gave more information about the renal parenchyma in 6 children, gave equal information in 6 and less in 1. Compared with CT, DMSA imaging gave more information in 2 children, was equally informative in 8 and less so in 3. Accordingly, DMSA imaging was judged to be more sensitive than IU and as sensitive as CT. DMSA imaging can be used both for the initial evaluation and for follow-up assessment of renal parenchymal damage.

Child, Preschool↗
PubMed1975

Comparative mutagenic effects of ethyl methane-sulfonate, n-methyl-n'-nitro-n-nitrosoguanidine, ultraviolet radiation and caffeine on Dictyostelium discoideum.

A high frequency of morphogenetic mutants of Dictyostelium discoideum can be induced by treatment with MNNG under conditions which result in relatively low cell killing. Six temperature-sensitive growth mutants induced by this treatment were isolated by replica plating. Among these, five showed spontaneous reversion rates of 10(-4) to 10(-5). The mutagenic activity of ems, measured for the induction of both morphogenetic and temperature-sensitive mutants, was weaker than that of MNNG and UV radiation. High frequencies of morphogenetic mutants were obtained only with doses of UV irradiation that resulted in high killing of cells or spores. Caffeine, at concentrations that slightly decreased the growth rate of amoebae in axenic medium, induced morphogenetic defects and also enhanced the mutagenic effect of UV irradiation. However, all the aggregateless clones derived from caffeine treatment that were studied reverted to the wild-type phenotype after a variable number of clonal re-isolations.

Caffeine↗
PubMed2000

Standardisation and decay data of 186Re

A solution of 186Re was standardised using the 4pi(PC)-gamma-coincidence technique. Two gamma channels were employed to provide separate detection efficiency data arising from the two decay modes (beta and electron capture): the resulting data were analysed using a two-dimensional extrapolation. Calibration factors for a high pressure re-entrant ionisation chamber as well as for the NPL secondary standard radionuclide calibrator were also determined. An efficiency-calibrated germanium spectrometer was used to measure the emission probabilities of the X- and gamma-rays.

Journal Article↗
PubMed2000

Chemistry of the rhenium-azopyridine family: an oxo parent and derivatives thereof including a novel oxo-imido dimer.

The concerned azo ligands are 2-(phenylazo)pyridine (HL) and 2-((p-chlorophenyl)azo)pyridine (ClL). The reaction of KReO4 with HL in hot concentrated HCl is attended with metal reduction and ligand chlorination affording the oxo complex ReVOCl3(ClL), 2, which furnishes ReIII(OPPh3)Cl3(ClL), 3, upon treatment with PPh3. Aromatic amines, ArNH2, convert 2 to the imido complex ReV(NAr)Cl3(ClL), 5, and the unusual oxo-imido dimer (ClL)-Cl2(O)ReVOReV(NAr)Cl2(ClL), 7. The complex ReIII(OPPh3)Cl3(HL), 4, has been generated from ReVOCl3(PPh3)2 and HL. Reaction of 4 with HL has yielded ReV(NPh)Cl3(HL), 6, via azo splitting. The complexes have been characterized with the help spectral, magnetic, and X-ray structural data (2, 3, 5c (Ar = pClC6H4) and 7.CH2Cl2 (Ar = pMeC6H4)). In 2, 3, and 5c the ReCl3 fragment is meridionally disposed, and in 7 the ReCl2 fragments have a trans configuration. The Re-O(oxo) bond, 1.663(6) A, in 2 and Re-N(imido) bond, 1.719(5) A, in 5c are triple bonds. The corresponding bonds are slightly longer in 7 wherein the (O)Re(1)-O(2)-Re(2)(NAr) bridge is angular (151.0(5) degrees) and unsymmetrical, the Re(1)-O(2) bond, 1.849(7) A, having a large double-bond character (Re(2)-O(2), 1.954(7) A). In effect, cis-ReVO2 acts as a monodentate oxygen ligand toward ReVNAr in 7. In all cases the pyridine nitrogen binds trans to the oxo, OPPh3, or NAr donor. Bond length data are consistent with the presence of substantial d(Re)-pi*(azo) back-bonding. In acetonitrile solution the complexes display electrochemical one-electron metal (ReVI/ReV or ReIV/ReIII) and azo redox. The imido ligand in 5 stabilizes the ReVI state (E1/2 approximately 1.4 V) better than the oxo ligand in 2 (approximately 1.9 V). Parallely it is more difficult to reduce the azo group in 5 (approximately -0.4 V) than in 2 (approximately 0.0 V). In 7 the metal (approximately 1.0 V) and azo (approximately -0.4 V) couples correspond to the imido and oxo halves, respectively. The significantly higher (by 0.2-0.6 V) metal reduction potentials of the azopyridine compared to pyridine-2-aldimine complexes is ascribed to the superior pi-acidity and electron-withdrawing character of the azo function relative to the aldimine function. This also makes the transfer of the ReVO oxygen function much more facile under azopyridine chelation as in 2. For the same reason, ReOCl3(PPh3)2 reacts with HL affording only 4 while it reacts with pyridine-2-aldimines furnishing oxo species. Crystal data for the complexes are as follows: 2, empirical formula C11H8Cl4N3ORe, crystal system triclinic, space group P1, a = 7.118(4) A, b = 8.537(4) A, c = 13.231(9) A, alpha = 79.16(5) degrees, beta = 78.03(5) degrees, gamma = 70.96(4) degrees, V = 737.2(7) A3, Z = 2; 3, empirical formula C29H23Cl4N3OPRe, crystal system monoclinic, space group P2(1)/n, a = 11.264(2) A, b = 15.221(3) A, c = 17.628(4) A, beta = 94.21(3) degrees, V = 3014(1) A3, Z = 4; 5c, empirical formula C17H12Cl5N4Re, crystal system triclinic, space group P1, a = 9.683(3) A, b = 10.898(3) A, c = 11.522(3) A, alpha = 63.67(2) degrees, beta = 71.24(2) degrees, gamma = 86.79(2) degrees, V = 1026(1) A3, Z = 2; 7.CH2Cl2, empirical formula C30H25Cl8N7O2Re2, crystal system triclinic, space group P1, a = 12.522(6) A, b = 12.857(8) A, c = 13.182(7) A, alpha = 67.75(4) degrees, beta = 88.30(4) degrees, gamma = 82.09(4) degrees, V = 1945(2) A3, Z = 2.

Journal Article↗
PubMed2002

Ligand-modulated stereo- and regioselective tandem addition reactions of rhenium-bound naphthalene.

A series of complexes of the form TpRe(CO)(L)(eta(2)-naphthalene) (Tp = hydridotris(pyrazolyl)borate) undergoes tandem electrophile/nucleophile addition reactions with a high degree of regiocontrol depending on the auxiliary ligand, L. When L = PMe(3), the reaction of the eta(2)-naphthalene complex with triflic acid followed by a silyl ketene acetal favors the 1,4-addition product, whereas when L = pyridine, N,N-dimethylaminopyridine, N-methylimidazole, or NH(3) the 1,2-addition product is favored. These reactions proceed with excellent stereocontrol: both electrophile (H(+), D(+)) and nucleophile (silyl ketene acetal) add anti to the face of metal coordination, and a single coordination diastereomer can be isolated for each reaction. One-electron oxidation of the Re complex affords the corresponding free dihydronaphthalene in good yield.

Crystallography, X-Ray↗
PubMed2006

Comparison of dose calculation algorithms for treatment planning in external photon beam therapy for clinical situations.

A study of the performance of five commercial radiotherapy treatment planning systems (TPSs) for common treatment sites regarding their ability to model heterogeneities and scattered photons has been performed. The comparison was based on CT information for prostate, head and neck, breast and lung cancer cases. The TPSs were installed locally at different institutions and commissioned for clinical use based on local procedures. For the evaluation, beam qualities as identical as possible were used: low energy (6 MV) and high energy (15 or 18 MV) x-rays. All relevant anatomical structures were outlined and simple treatment plans were set up. Images, structures and plans were exported, anonymized and distributed to the participating institutions using the DICOM protocol. The plans were then re-calculated locally and exported back for evaluation. The TPSs cover dose calculation techniques from correction-based equivalent path length algorithms to model-based algorithms. These were divided into two groups based on how changes in electron transport are accounted for ((a) not considered and (b) considered). Increasing the complexity from the relatively homogeneous pelvic region to the very inhomogeneous lung region resulted in less accurate dose distributions. Improvements in the calculated dose have been shown when models consider volume scatter and changes in electron transport, especially when the extension of the irradiated volume was limited and when low densities were present in or adjacent to the fields. A Monte Carlo calculated algorithm input data set and a benchmark set for a virtual linear accelerator have been produced which have facilitated the analysis and interpretation of the results. The more sophisticated models in the type b group exhibit changes in both absorbed dose and its distribution which are congruent with the simulations performed by Monte Carlo-based virtual accelerator.

Algorithms↗
PubMed1993

Early evacuation of clotted blood in hemothorax using thoracoscopy: case reports.

Hemothorax complicated by clotting of the blood is traditionally treated with thoracotomy. Successful treatment using early thoracoscopy in two patients is described. A third patient, in whom thoracoscopic evacuation failed, is also discussed. Early timing of the procedure appears to enhance the opportunity for adequate drainage of the thorax with lung re-expansion.

Adult↗
PubMed2004

Thoracic complications during urological laparoscopy.

PURPOSE: We documented thoracic related complications during urological laparoscopic surgery. MATERIALS AND METHODS: A total of 1129 patients underwent major urological laparoscopic procedures in a 5-year period. Operative reports and postoperative radiographic reports were retrospectively reviewed to identify patients with thoracic related medical and surgical sequelae. Of the patients 619 (55%) underwent at least 1 chest x-ray in the immediate or early postoperative period. In the remaining 510 patients (45%) there was no clinical indication to perform chest x-ray. RESULTS: Of 619 patients undergoing chest x-ray 438 (71%) were completely normal. Medical pulmonary complications, surgical thoracic complications and subclinical, incidentally detected gas collections in the chest were identified in 12.6%, 0.5% and 5.5% of patients, respectively. Medical complications in 12.6% of cases included pulmonary infiltrate/atelectasis in 9.7%, pleural effusion in 4.8% and pulmonary embolus in 0.3%. Surgical complications included symptomatic pneumothorax in 4 patients (0.35%), hemothorax in 1 (0.08%) and chylothorax in 1 (0.08%). Subclinical abnormal thoracic gas collections were radiographically noted in 34 of the 619 patients (5.5%) on chest x-ray, including pneumomediastinum in 19 (3.1%), pneumothorax in 10 (1.6%) and pneumopericardium in 5 (0.8%). Overall 36 of 40 (90%) thoracic surgical complications (3) and subclinical, incidentally detected gas collections (33) occurred during retroperitoneal laparoscopy. Re-intervention was necessary in 6 patients (0.5%), namely pulmonary embolus requiring vena caval filter placement in 3 (0.3%), pneumothorax requiring a chest tube in 2 (0.17%) and hemothorax requiring emergency open thoracotomy in 1 (0.08%). No patient underwent open conversion to complete the initial proposed operation. CONCLUSIONS: Due to its high solubility the expectant management of incidental CO2 pneumothorax, pneumopericardium and pneumomediastinum is recommended initially in the clinically stable patient. Inadvertent diaphragmatic entry can be satisfactorily repaired laparoscopically without open conversion. Although it is rare, surgical thoracic complications are potentially life threatening, requiring prompt identification and management.

Adult↗
PubMed2005

Supercooled liquid-like solvent in trypsin crystals: implications for crystal annealing and temperature-controlled X-ray radiation damage studies.

The study of temperature-dependent physical changes in flash-cooled macromolecular crystals is pertinent to cryocrystallography and related issues such as crystal annealing, X-ray radiation damage and kinetic crystallography. In this context, the unit-cell volume of flash-cooled trigonal and orthorhombic trypsin crystals has been monitored upon warming from 100 to 200 K and subsequent re-cooling to 100 K. Crystals of both forms were obtained under the same crystallization conditions, yet they differ in solvent content and channel size. An abrupt non-reversible unit-cell volume decrease is observed at 185 K in orthorhombic and at 195 K in trigonal crystals as the temperature is increased; this result is consistent with ultra-viscous solvent leaving the crystals. Concomitant appearance of ice rings in the diffraction patterns suggests that the transported solvent forms crystalline ice. These results demonstrate that solvent in flash-cooled protein crystals is liquid-like near its crystallization temperature, as has been proposed, yet controversially discussed, for the case of pure water. The use of mineral oil prevents the unit-cell volume decrease in trigonal but not in orthorhombic crystals. The observation of liquid-like solvent has implications in the development of annealing protocols and points a way to the rational design of temperature-controlled crystallographic studies that aim either at studying specific radiation damage or at trapping enzymatic intermediate states.

Animals↗
PubMed2001

Posterior C1-C2 transarticular screw fixation for Atlanto-axial instability.

The objective of this study was to reveal that the treatment of C1-C2 instability by transarticular C1-C2 screw fixation with bone graft has a better result than conventional sublaminar wiring with bone graft by Gallie's technique. This technique, proposed by Magerl and Semann in 1987, produces a rigid three points fixation resulting in maximal bone fusion rate and does not require an orthosis post-operatively. This technique is performed in patients with fractured lamina of C1 or in patients who need a laminectomy of C1 for spinal cord decompression. This study revealed 10 patients having C1-C2 instability who were operated on by transarticular C1-C2 screw fixation with bone graft. No complication was encountered. No screw and bone graft slipping were noted. The patients were improved clinically and the average follow-up period was 7.7 months. There were 2 cases which had previously been operated on for sublaminar wiring but the operation was unsuccessful because there was a fractured lamina of C1. Both patients were sent to Prasat Neurological Institute & Hospital for transarticular C1-C2 screw fixation. Another 2 cases were operated on for sublaminar wiring with bone graft. The follow-up X-ray of both cases disclosed a displacement of C1-C2. Lost of C1 lamina was found in one case and there was slipping of wire in another case, because of this the patients were re-explored for transarticular C1-C2 screw fixation with bone graft. The conclusion is, this technique of transarticular C1-C2 screw fixation, is the best surgical treatment for C1-C2 instability, in the hands of experienced surgeons with an excellent knowledge of anatomy.

Adult↗