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At least 235 records · Page 13Linked to original sources

Evaluation of three rhenium-188 candidates for intravascular radiation therapy with liquid-filled balloons to prevent restenosis.

BACKGROUND: Intravascular brachytherapy is an effective method for inhibiting coronary restenosis after percutaneous transluminal coronary angioplasty. A new concept for preventing restenosis is the use of a liquid-filled balloon containing a beta-ray-emitting radioisotope. Generator-produced rhenium-188 (Re-188) is a good candidate for intravascular brachytherapy. However, in the unlikely event of balloon rupture, release of Re-188 perrhenate may cause a high radiation dose to the thyroid and stomach. In this study, we compared the biodistributions of three Re-188 preparations (Re-188 perrhenate, Re-188 pentetic acid [DTPA], and Re-188 MAG3) to assess the radiation dose to organs in a rat model that mimicked balloon rupture. METHODS AND RESULTS: After injection of Re-188 preparations intravenously, rats were killed at 10 minutes, 30 minutes, 60 minutes, 2 hours, and 6 hours (n = 5/group). Tissue concentrations were calculated and expressed as percent injected dose per gram or per milliliter. In addition, urine excretion and thyroid gland uptake were evaluated in rats (n = 5/group) with a gamma camera after administration of 37 MBq (1 mCi) of each agent. Our data showed all 3 agents were excreted primarily via urine. In the Re-188 MAG3 group, 82% was excreted within 1 hour, but in the Re-188 perrhenate group, only 28% was excreted. The biodistribution data for these agents revealed that radioactivity levels in the stomach and the thyroid gland were high in the perrhenate group but low in the Re-188 DTPA and Re-188 MAG3 groups. The concentration levels in other tissues including lung, liver, testis, muscle, and blood were low throughout this study for all 3 agents. The thyroid radiation values were 0.163, 0.0167, and 0.00728 mGy/MBq for Re-188 perrhenate, Re-188 DTPA, and Re-188 MAG3, respectively. The stomach radiation values were 0.127 mGy/MBq for Re-188 perrhenate, 0.013 mGy/MBq for Re-188 DTPA, and 0.0104 mGy/MBq for Re-188 MAG3. CONCLUSIONS: In the event of balloon rupture, the release of Re-188 MAG3 or Re-188 DTPA results in lower radiation doses than release of Re-188 perrhenate, especially to the thyroid gland and the stomach.

Angioplasty, Balloon, Coronary↗

Mineral dusts as etiologic agents in pulmonary fibrosis: the diagnostic role of analytical scanning electron microscopy.

This report demonstrates the value of analytical scanning electron microscopy (SEM) in the evaluation of patients with fibrosing pulmonary disease. We describe the findings in six illustrative cases in which prebiopsy or premortem clinical and epidemiologic information did not suggest an etiologic association with exposure to fibrogenic dusts. Exogenous materials were inconstantly recognized by polarized light microscopy, but examination by SEM resulted in localization of significant inorganic deposits in the biopsy and autopsy tissues studied. Talc, mica, graphite, and mixed inorganic dusts were found in these six cases. Characterization of this material by SEM morphology and x-ray energy spectrometry provided the basis for re-appraisal of the exposure history and its potential pathogenetic importance. The technics described utilize routinely processed, paraffin-embedded tissue, and are readily applicable to problems encountered in the hospital setting.

Adult↗

The intermetallic compound Mg21Zn25.

The crystal structure of the intermetallic compound henicosamagnesium pentacosazinc, Mg(21)Zn(25), has been determined by single-crystal X-ray diffraction. It is isomorphous with Zr(21)Re(25) and deviates slightly from the rules that define the Frank-Kasper phases.

Journal Article↗

A comparison between low-volume referring regional centers and a high-volume referral center in quality of preoperative metastasis detection in esophageal carcinoma.

BACKGROUND AND AIM: An inverse correlation between hospital volume and esophageal resection mortality has been reported. In this study, we compared the quality of preoperative metastasis detection between a high-volume referral center with that of low-volume referring regional centers. METHODS: In 573 patients diagnosed with esophageal cancer (1994-2003), the results of preoperative staging investigations (CT-scan, ultrasound of abdomen and neck, and chest x-ray) performed in 61 regional centers were re-evaluated and/or repeated in one referral center. The gold standards were a radiological result with > or =6 months follow-up, fine-needle aspiration, or the postoperative TNM-stage. RESULTS: In the same group of patients, the preoperative investigations performed in regional centers detected true-positive malignant lymph nodes in 8% of patients and true-positive distant metastases in 7% of patients, whereas these percentages were 16% and 20%, respectively, in the referral center. In 72/573 (13%) patients, one or more metastases detected in the referral center had been missed in the regional centers. After allowing resectability in the presence of M1a lymph nodes, this would still have resulted in futile esophageal resections in 6% of patients. In contrast to the higher diagnostic sensitivity in the referral center, specificity was comparable between referral and regional centers. CONCLUSIONS: This study found that, in assessing the operability of esophageal cancer, the diagnostic sensitivity of metastasis detection in a high-volume referral center was higher than that in referring regional centers. This resulted from both better CT-scanning equipment and more experienced radiologists in the referral center. Should the decision to perform esophagectomy have only been based on metastasis detection in these regional centers, over 1 in 20 patients would have undergone resection in the presence of metastases.

Biopsy, Fine-Needle↗

Residual radiation damage in the mouse foot after exposure to heavy particles.

Mice receiving a first treatment with graded doses of various heavy charged particles (protons and heavy ions) to one of their hind legs were re-exposed to a fixed dose of x rays eight months later to study the "memory" of residual damage from the first treatment. No significant memory of the first radiation exposure was observed for acute skin rection. However, there is an indication of memory for foot deformity. The results do not seem to indicate any significant differences in memory after exposure to 60Co gamma rays compared with protons or heavy ions, if biological effectiveness of the doses is taken into consideration.

Animals↗

Anomalies in dual energy X-ray absorptiometry measurements of total-body bone mineral during weight change using Lunar, Hologic and Norland instruments.

A previous study showed that measurements of total-body bone mineral changes made with a Hologic QDR 1000W were unreliable when the subjects underwent weight change. The study has been extended to dual energy X-ray absorptiometry (DXA) apparatus from other manufacturers. Re-analysis of published results during weight loss using a Lunar DPX showed that they varied with the software used. Using the Extended mode, there was a 1% loss of bone mineral areal density (BMD), but no significant change in bone mineral content (BMC) or bone area (BA) following a weight loss of 16 kg, whereas the use of the Standard mode led to a larger fall of BMC and BMD. Similar findings arose from the consideration of two studies using Norland XR 26 HS absorptiometers. On the other hand, separation of two groups with similar weight changes from the population studied with a Hologic QDR 1000W confirmed that BMC changed directly with weight, but there was an inverse relationship for BMD, owing to an inappropriate change of BA. The use of Hologic Enhanced and Standard software modes led to significant differences in initial readings and measured changes. With each instrument there was a strong correlation between changes in BA and changes in BMC. When 6 kg of lard was wrapped around the limbs of volunteers or a semi-anthropomorphic phantom to simulate weight change, there were spurious increases of measured BMC and BA by about 5% with each instrument. There were no changes of BMD with Lunar, variable results with Norland, but decreases with Hologic. The results observed in vivo could be explained by the effects of fat changes, without there being any real change of bone mineral. Changes of BMD in the skeleton of the phantom were underestimated with all three brands. The anomaly observed with the Hologic QDR 1000W is less apparent with a Lunar DPX or a Norland XR 26, but there are sufficient uncertainties for all total-body measurements during weight change to be treated with suspicion.

Absorptiometry, Photon↗

[Diagnostic and therapeutic approaches to spontaneous pneumothorax].

Based on a retrospective study of 33 patients with spontaneous pneumothorax, the authors present their experience with the diagnostic and therapeutic procedure. In the majority of patients treatment was started by active suction drainage of the chest. After re-expansion of the lung another X-ray examination was made, incl. computed tomography of the chest, and endoscopic examination (bronchoscopy, thoracoscopy). On account of a relapse of pneumothorax in three patients thoracoscopy was performed and in seven patients thoracotomy. The operated patients recovered and are without signs of relapse of pneumothorax.

Adult↗

Temporal bone fractures. Vestibular and other related ear sequele.

Vertigo is a common symptom after head injuries, though often overlooked in the acute stage due to other concomitant manifestations. According to previous investigations the mechanisms of injury to the vestibular system cannot be defined as clearly as for the auditory system. Twenty patients with temporal bone fractures were reviewed and later re-examined. The results of conventional X-ray, computerized tomography, clinical, otoneurological and audiological findings were analysed. The sequelae of dizziness and auditory defects were considered and follow-ups with computerized electro-oculography were performed. Radiological evaluation revealed fractures in approximately 65%. Half complained of dizziness and positional nystagmus was the most common vestibular observation. In 25% of the patients, dizziness remained to some degree. Hearing was permanently impaired in 75%. The hearing impairment depended in 20% on fractures of the ossicular chain and in 55% on sensorineural hearing loss. In those cases where a conductive hearing loss persisted, surgery on the middle ear was indicated. The vestibular system is not so vulnerable as the auditory system. Conductive hearing loss disappeared spontaneously or could be relieved by surgery. The vestibular symptoms improved or disappeared in all cases, whereas not infrequently, a sensorineural hearing loss remained.

Adolescent↗

Tungstorhenate Heteropolyanions. 2. Synthesis and Characterization of Enneatungstorhenates(V), -(VI), and -(VII).

The tungstorhenate(V) heteropolyanion [W(9)ReO(32)](5)(-) has been isolated as guanidinium and cesium salts from reaction of [ReO(2)(PPh(3))(py)(3)](+) with sodium tungstate. Crystallographic analysis of black Cs(5)[W(9)ReO(32)].3H(2)O [triclinic, P1 or P&onemacr;; a = 10.194(1), b = 11.503(2), c = 9.682(1) Å; alpha = 100.55(1), beta = 115.81(1), gamma = 99.13(1) degrees; Z = 1], based on 3743 reflections, shows the anion to be isostructural with decatungstate, [W(10)O(32)](4)(-). Refinement in P&onemacr; led to reliability indices R = 0.084, R(w) = 0.046. Electrochemical investigation revealed the existence of Re(VI) and Re(VII) analogues, which were hydrolytically unstable in aqueous solution but which were isolated as crystalline tetra-n-butylammonium and tetra-n-heptylammonium salts, respectively, from nonaqueous solvents. The tetra-n-butylammonium salts of [W(9)Re(VI)O(32)](4)(-) and [W(10)O(32)](4)(-) were shown to be isomorphous by X-ray powder diffraction. Simulation of the Q-band ESR spectrum of [W(9)Re(VI)O(32)](4)(-) (polycrystalline solid solution in [W(10)O(32)](4)(-)) gave g(x)() = 1.69(1), g(y)() = 1.66(1), g(z)() = 1.730(2) and 10(4)A(x)()((185,187)Re, I = (5)/(2)) = (-)252(10), 10(4)A(y)() = (-)398(10), 10(4)A(z)() = (-)653(5) cm(-)(1). The orthorhombic ESR spectrum proves that the Re atom occupies one of the eight equivalent "equatorial" sites in the decatungstate structure.

Journal Article↗

fac-[Re(CO)3(dmso-O)3](CF3SO3): a new versatile and efficient Re(I) precursor for the preparation of mono and polynuclear compounds containing fac-[Re(CO)3]+ fragments.

We show here that the new complex fac-[Re(CO)3(dmso-O)3](CF3SO3) (1), efficiently prepared in one step from [ReBr(CO)5] and featuring a broad range of solubility, is, in general, a better precursor for the one-step synthesis of mono- and polynuclear inorganic compounds containing fac-[Re(CO)3]+ fragments compared to the commonly used (NEt4)2fac-[ReBr3(CO)3] and fac-[Re(CO)3(CH3CN)3](Y) (Y = PF6, BF4, ClO4) species. Compound 1 is the first example of a Re(I)-dmso complex structurally characterized and confirms the rule that dmso is always O-bonded when trans to CO. The reactivity of 1 was tested in the one-step preparation of several new and known complexes. The O-bonded sulfoxides of 1 are replaced under mild conditions by tri- (L3) and bidentate ligands (L2) to produce fac-[Re(CO)3(L3)]+ and fac-[Re(CO)3(L2)(dmso-O)]+ compounds, respectively. An excess of monodentate ligands (L) and more forcing conditions are needed to prepare fac-[Re(CO)3(L)3]+ compounds. The new compounds include fac-[Re(CO)3(bipy)(dmso-O)](CF3SO3) (4), that turned out to be an excellent precursor for binding the luminescent fac-[Re(CO)3(bipy)]+ fragment to polytopic ligands for the construction of more elaborate assemblies. One example reported here is the two-step preparation of fac-[{Re(CO)3(bipy)}(mu-4,4'-bipy){Ru(TPP)(CO)}](CF3SO3) (8) (TPP = tetraphenylporphyrin). The X-ray structures of the new compounds 1, 4, of the bis-porphyrin complex fac-[Re(CO)3Cl(4'MPyP)2] (13) (4'MPyP = 5-(4'pyridyl)-10,15,20-triphenylporphyrin), and of the rhenium-cyclophane [{(CO)3Re(mu-OH)2Re(CO)3}2(micro-4,4'-bipy)2] (15), among others, are described. Compound 1 might find useful applications in supramolecular chemistry (metal-mediated assembly of large architectures), in the in situ preparation of stable Re compounds to be used in nuclear medicine, and for the labeling of biomolecules.

Journal Article↗

Expanded Prussian blue analogues incorporating [Re6Se8(CN)6](3-/4-) clusters: adjusting porosity via charge balance.

Face-capped octahedral [Re(6)Se(8)(CN)(6)](3-/4-) clusters are used in place of octahedral [M(CN)(6)](3-/4-) complexes for the synthesis of microporous Prussian blue type solids with adjustable porosity. The reaction between [Fe(H(2)O)(6)](3+) and [Re(6)Se(8)(CN)(6)](4-) in aqueous solution yields, upon heating, Fe(4)[Re(6)Se(8)(CN)(6)](3).36H(2)O (4). A single-crystal X-ray analysis confirms the structure of 4 to be a direct expansion of Prussian blue (Fe(4)[Fe(CN)(6)](3).14H(2)O), with [Re(6)Se(8)(CN)(6)](4-) clusters connected through octahedral Fe(3+) ions in a cubic three-dimensional framework. As in Prussian blue, one out of every four hexacyanide units is missing from the structure, creating sizable, water-filled cavities within the neutral framework. Oxidation of (Bu(4)N)(4)[Re(6)Se(8)(CN)(6)] (1) with iodine in methanol produces (Bu(4)N)(3)[Re(6)Se(8)(CN)(6)] (2), which is then metathesized to give the water-soluble salt Na(3)[Re(6)Se(8)(CN)(6)] (3). Reaction of [Co(H(2)O)(6)](2+) or [Ni(H(2)O)(6)](2+) with 3 in aqueous solution affords Co(3)[Re(6)Se(8)(CN)(6)](2).25H(2)O (5) or Ni(3)[Re(6)Se(8)(CN)(6)](2).33H(2)O (6). Powder X-ray diffraction data show these compounds to adopt structures based on the same cubic framework present in 4, but with one out of every three cluster hexacyanide units missing as a consequence of charge balance. In contrast, reaction of [Ga(H(2)O)(6)](3+) with 3 gives Ga[Re(6)Se(8)(CN)(6)].6H(2)O (7), wherein charge balance dictates a fully occupied cubic framework enclosing much smaller cavities. The expanded Prussian blue analogues 4-7 can be fully dehydrated, and retain their crystallinity with extended heating at 250 degrees C. Consistent with the trend in the frequency of framework vacancies, dinitrogen sorption isotherms show porosity to increase along the series of representative compounds 7, Ga(4)[Re(6)Se(8)(CN)(6)](3).38H(2)O, and 6. Furthermore, all of these phases display a significantly higher sorption capacity and surface area than observed in dehydrated Prussian blue. Despite incorporating paramagnetic [Re(6)Se(8)(CN)(6)](3-) clusters, no evidence for magnetic ordering in compound 6 is apparent at temperatures down to 5 K. Reactions related to those employed in preparing compounds 4-6, but carried out at lower pH, produce the isostructural phases H[cis-M(H(2)O)(2)][Re(6)Se(8)(CN)(6)].2H(2)O (M = Fe (8), Co (9), Ni (10)). The crystal structure of 8 reveals a densely packed three-dimensional framework in which [Re(6)Se(8)(CN)(6)](4-) clusters are interlinked through a combination of protons and Fe(3+) ions.

Journal Article↗

The rotational spectrum and theoretical study of a dinuclear complex, MnRe(CO)(10).

The first rotational spectrum of a dinuclear complex, MnRe(CO)(10), has been obtained using a high-resolution pulsed beam microwave spectrometer. Sixty-four hyperfine components of the J=11-->J(')=12 and J=12-->J(')=13 rotational transitions were measured for two rhenium isotopomers. The B values obtained from the experiment are B=200.36871(18) MHz for the (187)Re isotopomer and B=200.5561(10) MHz for the (185)Re isotopomer. The measured rotational constants are in reasonably good agreement with the B values calculated from the x-ray diffraction structural data, and from theoretical calculations. The gas-phase Mn-Re bond distance is approximately 2.99 A, and the calculated value is only slightly longer. The experimental quadrupole coupling constant for the manganese atom is eQq(aa) ((55)Mn)=-16.52(5) MHz, and the corresponding quadrupole coupling constants for the two rhenium isotopomers are eQq(aa) ((187)Re)=370.4(4) MHz and eQq(aa) ((185)Re)=390.9(6) MHz. The quadrupole coupling constants were also determined from a variety of theoretical calculations, with very large Gaussian orbital bases. The best estimates, at a nonrelativistic level, are eQq(aa) ((55)Mn)=0.68 MHz and eQq(aa) ((187)Re)=327.6 MHz with a 874 GTO basis set, but the results are very basis set dependent, especially the sign of the Mn quadrupole coupling. Very slight bending of angles MnC(eq)O(eq) and ReC(eq)O(eq) angles is found in the calculations.

Journal Article↗

Pyrazole complexes as anion receptors.

The behavior of the receptors [Re(CO)3(Hdmpz)3]BAr'4 (Hdmpz = 3,5-dimethylpyrazole) (1) and [Re(CO)3(HtBupz)3]BAr'4 (HtBupz = 3(5)-tert-butylpyrazole) (2; Ar' = 3,5-bis(trifluoromethyl)phenyl) toward the anions fluoride, chloride, bromide, iodide, hydrogensulfate, dihydrogenphosphate, nitrate, and perrhenate was studied in CD3CN solution. In most cases, the receptors were stable. Anion exchange was fast, and binding constants were calculated from the NMR titration profiles. The structure of the adduct [Re(CO)3(HtBupz)3] x NO3 (3) was determined by X-ray diffraction. Two pyrazole moieties are hydrogen-bonded to one nitrate oxygen atom, and the third pyrazole moiety is hydrogen-bonded to an oxygen atom of an adjacent nitrate, leading to infinite chains. The structure of the adduct [Re(CO)3(Hdmpz)3]BAr'4acetone (4), also determined by X-ray diffraction, showed a similar interaction of two pyrazole N-H groups with the acetone oxygen atom. F- and H2PO4(-) deprotonate the receptors, and HSO4(-) decomposed 1. The structure of one of the decomposition products (5), determined by X-ray diffraction, is consistent with pyrazole protonation and substitution by sulfate.

Journal Article↗

Residual radiation-induced injury in dermal tissue: implications for retreatment.

The evidence for residual radiation-induced injury has been investigated in the dermal vascular/connective tissue of pig skin at intervals of 17-52 weeks after irradiation. The primary irradiation was a single dose of 18 Gy, which represents the upper limit of "tolerance" to X irradiation of pig dermal tissue. Re-irradiation was with graded single doses of X rays in order to establish dose-effect relationships for the incidence of late ischaemic dermal necrosis of the skin; dose-effect curves obtained for previously irradiated skin were compared with those obtained using previously unirradiated skin in the same group of animals. At intervals of 17, 35 and 52 weeks after the primary treatment the resulting ED50 values for dermal necrosis were not significantly different from those obtained for previously unirradiated skin. This suggests little or no effective residual injury at these time intervals after a primary full "tolerance" dose. This conclusion was supported by the findings for the latency time for the development of dermal necrosis, which were similar in re-irradiated and previously unirradiated skin. Epithelial desquamation was not induced by the doses used in these studies, either after the primary treatment or after re-irradiation; however, the early erythema reactions seen in re-irradiated skin were markedly reduced, particularly when this was carried out after 35 and 52 weeks, when compared with skin that had not previously been irradiated. This suggests that the early erythema reaction may be a particularly poor predictor of late effects after the re-irradiation of the skin. Although the present results suggest that dermal and subcutaneous tissues may safely be retreated with a full tolerance dose at relatively early times after an initial radical treatment, caution is recommended in extrapolating these results to other late-responding normal tissues. In other tissues some persistent injury may be present even at very long time intervals after the primary treatment.

Animals↗

Varus/valgus alignment of the tibial component in total knee arthroplasty.

The varus/valgus alignment of the tibial components of 350 total knee arthroplasties was assessed radiologically. All the tibial components were implanted using an extramedullary guide under the supervision of the senior author. Of components, 96.3% were implanted within 2 degrees of the perpendicular to the longitudinal axis of the tibia. In order to validate our X-ray assessment, a subgroup of 40 knees was re-assessed using a CT scanogram. Analysis of this subgroup showed a close correlation between the results using the two different methods (mean difference 0.88 degrees, S.D. 0.75). We believe that with anticipated future advances in robotic and computer assisted surgery it is important to set the benchmark for what can be achieved with current technology.

Arthroplasty, Replacement, Knee↗

Structure, reactivity and solution behaviour of [Re(ser)(7-MeG)(CO)(3)] and [Re(ser)(3-pic)(CO)(3)]: "nucleoside-mimicking" complexes based on the fac-[Re(CO)(3)](+) moiety.

The fac-[Re(CO)(3)](+) moiety was reacted with the amino acid serine (D- and L-ser) and with 7-methylguanine (7-MeG), 3-methylpyridine (3-pic) or adenine (ade) to yield novel complexes intended as nucleoside-mimicking compounds. Reaction of [Re(H(2)O)(3)(CO)(3)](+)(1) with L-ser yields the complex [Re(L-ser)(2)(CO)(3)](L-2). X-Ray structure analysis of L-2 reveals that one of the two amino acids is bound to the metal centre in a bidentate fashion while the other amino acid is bound as a zwitterion via the carboxylate oxygen only. Reaction of L-2 and of [Re(D-ser)(2)(CO)(3)](D-2) with 7-MeG yields complexes [Re(L-ser)(7-MeG)(CO)(3)](L-3) and [Re(D-ser)(7-MeG)(CO)(3)](D-3) respectively. Complexes L-3 and D-3 are received as a mixture of diastereomers. If 3-pic is used instead of 7-MeG complex [Re(L-ser)(3-pic)(CO)(3)](L-4) is obtained in good yield, while interaction of L-2 with ade gives a mixture of five distinct species. Crystallization gave one single diastereomer for L-3 and D-3 and the two forms for 4 respectively. X-Ray structure analyses reveal that in all cases the amino acid is bound in a chelate fashion with the base occupying the sixth co-ordination site. When crystals of either 2 or 3 are dissolved in a CD(3)OD/D(2)O mixture (1:1, 293 K) rapid transformation to the diastereomeric mixture is observed. While for L-2 this reorganisation is fast on the NMR time scale even at 193 K, the rate constant for the rearrangement of L-3 and D-3 is 1.36 +/- 0.24 x 10(-2) s(-1) at 293 K.

Journal Article↗