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PubMed2001

Mixed-metal assemblies containing multiply bonded dirhenium species linked through thiocyanate- and cyanide-containing bridging units.

The lability of the terminal Re-Cl bond that is cis to the bridging CO ligand in the edge-sharing bioctahedral complexes Re(2)(mu-Cl)(mu-CO)(mu-PP)(2)Cl(3)(L), where PP = Ph(2)PC(=CH(2))PPh(2) (dppE) when L = CO (1) and PP = Ph(2)PCH(2)PPh(2) (dppm) when L = CO (2) or XyINC (3), has been exploited in the preparation of mixed-metal Re(4)Pd(2), Re(2)Ag, Re(2)W, Re(2)Pt, and Re(2)Rh assemblies, in which the dirhenium units are bound to the other metals through NCS or CN bridges. These complexes, which retain the Re=Re bonds of the parent dirhenium complexes, comprise the novel centrosymmetric complex [Re(2)Cl(3)(mu-dppE)(2)(CO)(2)(mu-NCS)](2)Pd(2)(mu-SCN)(mu-NCS)Cl(2) (9), and the trimetallic complexes Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-NC)Ag(CN)] (10), Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-NC)W(CO)(5)] (11), [Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-NC)Pt(CN)(CN-t-Bu)(2)]]PF(6) (12), [Re(2)Cl(3)(mu-dppE)(2)(CO)(2)[(mu-N(CN)(2))Rh(CO)(PPh(3))(2)]]O(3)SCF(3) (13), and Re(2)Cl(3)(mu-dppm)(2)(CO)(2)[(mu-NC)W(CO)(5)] (16). The identities of 9 and 16 have been established by X-ray crystallography, and all complexes characterized by IR and NMR spectroscopy and cyclic voltammetry. The reactions of the dicarbonyl complex 1, and the isomeric pair of complexes Re(2)Cl(4)(mu-dppm)(2)(CO)(CNXyl), which have edge-sharing bioctahedral (ESBO) (3) and open bioctahedral (OBO) (4) geometries, with Na[N(CN)(2)] and K[C(CN)(3)] have been used to prepare complexes in which the uncoordinated CN groups have the potential to coordinate other mono- or dimetal units to form extended arrays. The complexes which have been prepared and characterized are the monosubstituted species Re(2)Cl(3)(X)(mu-dppE)(2)(CO)(2) (X = N(CN)(2) (14) or C(CN)(3) (15)) and Re(2)Cl(3)(X)(mu-dppm)(2)(CO)(CNXyl) (X = N(CN)(2) (17) or C(CN)(3) (18) with ESBO structures; X = N(CN)(2) (19) or C(CN)(3) (20) with OBO structures), of which 15, 18, and 20 have been characterized by single-crystal X-ray structure determinations. The substitutional labilities of the Re-Cl bonds in the complexes Re(2)Cl(4)(mu-dppm)(2)(CO) (5), Re(2)Cl(4)(mu-dppm)(2)(CNXyl) (6), and Re(2)Cl(4)(mu-dppm)(2) (7) toward Na[N(CN)(2)] and K[C(CN)(3)] have also been explored and the complexes Re(2)Cl(3)(X)(mu-dppm)(2)(CO) (X = N(CN)(2) (21) or C(CN)(3) (22)), Re(2)Cl(3)(X)(mu-dppm)(2)(CNXyl) (X = N(CN)(2) (23) or C(CN)(3) (24)), Re(2)Cl(2)(X)(2)(mu-dppm)(2)(CNXyl) (X = N(CN)(2) (25) or C(CN)(3) (26)), Re(2)[N(CN)(2)](4)(mu-dppm)(2) (27), and Re(2)[C(CN)(3)](4)(mu-dppm)(2) (28) isolated in good yield. Single-crystal X-ray structure determinations of 24, 26, and 27 have shown that the Re-Re triple bonds present in the starting materials 5-7 are retained in these products.

Journal Article↗
PubMed1992

[Analysis of the difference between the results of complex mammography and histology-- a contribution to the sensitivity and specificity of mammography].

Of a total of 18,500 mammographic examinations of our own patients, 1393 diagnosis had been confirmed by histology. In 89 cases (6.39%) where x-ray diagnosis did not agree with histological findings, we re-assessed the mammographies retrospectively. 29% of the false negative diagnosis proved retrospectively to be due to errors on the part of the examiner, whereas in the remaining 24 patients the carcinoma of the breast could be visualized by mammography (3.8% of all histologically confirmed malignomas). In the 41 false positive findings the x-ray symptoms "focus with radial ramifications" and "microcalcifications" were the most frequent causes of performing a diagnostic extirpation. Sensitivity of the mammographic method in identifying a carcinoma was 94.8% and the specificity 94.6%. The causes of erroneous assessment are discussed and the need for performing complex diagnosis of the breast is underlined.

Adult↗
PubMed1987

Re-refinement of the B-dodecamer d(CGCGAATTCGCG) with a comparative analysis of the solvent in it and in the Z-hexamer d(5BrCG5BrCG5BrCG).

The effects of X-ray refinement algorithm on parameters characterising nucleic acid structure are analysed following the re-refinement of the B-dodecamer d(CGCGAATTCGCG). The main conclusions are the following. Mean deviations of main chain torsion angles between the two refinements average 12.6 degrees. Phase angle of pseudorotation for sugar puckers vary between 100 degrees and 180 degrees in the present refinement with amplitude of pucker around 30 degrees. On the other hand, the helical parameters have mean deviations less than 2 degrees. At most half of the assigned solvent positions are within 2 A in both refinements. In the second part of the work, plots of temperature factors (B's) versus occupancies (Q's) for solvent peaks have been analysed in the B-dodecamer and in the Z-hexamer d(5BrCG5BrCG5BrCG). Owing to the poor statistics, some of those conclusions should be regarded as tentative. Occupancy appears to depend on the number of contacts made by the solvent peak with the nucleic acid while temperature factor does not. Except when engaged in particular interaction sites, solvent molecules bound to phosphates have a tendency for high B's and variable Q's. Water molecules bound to polar atoms of the bases occupy various positions in the B-Q diagram. Particularly striking is the behavior of the water molecules belonging to the B-spine and to the Z-spine: the spread in occupancy of water molecules in the hydration spine of the Z-oligomer is larger than in the hydration spine of the B-oligomer. An opposite tendency is observed for the temperature factors. The first observation might reflect the special mobility of the water molecules building up the spine hydration in the Z-form where it continues without interruption from one hexamer to the next. In the B-form, on the contrary, the spine is restricted to the center part of the dodecamer. The second observation might reflect the sharpness of the local attractive potential in the Z-form and its broadness in the B-form. In both cases, dipole reorientations would occur, leading to a high local dielectric constant: in the Z-form, through water molecules hopping from one site to another and, in the B-form, because of rotational freedom.

Magnetic Resonance Spectroscopy↗
PubMed1999

Synthesis and Structures of Solvated Monoclusters and Bridged Di- and Triclusters Based on the Cubic Building Block [Re(6)(&mgr;(3)-Se)(8)](2+).

The cluster formulated as [Re(6)Se(7)(SeH)I(6)](3)(-) has been previously shown to undergo ligand substitution reactions to generate the family [Re(6)Se(8)(PEt(3))(n)()I(6)(-)(n)()](()(n)()(-)(4)+) (n = 3-6), several members of which form solvate clusters upon treatment with Ag(I) in acetonitrile. Here it is demonstrated that additional de-iodination reactions afford solvate clusters useful in building up bridged cluster arrays. In dichloromethane/solv (5:1 v/v) in the presence of 2 equiv of AgSbF(6) at room temperature, trans-[Re(6)Se(8)(PEt(3))(4)I(2)] forms trans-[Re(6)Se(8)(PEt(3))(4)(solv)(2)](2+) (solv = MeCN (5), DMF (6), Me(2)SO (7)). The hexaiodo cluster with 6 equiv of AgSbF(6) gives the fully solvated clusters [Re(6)Se(8)(solv)(6)](2+) (solv = DMF (9), Me(2)SO (10), py (11)). In refluxing chlorobenzene for 3 days, [Re(6)Se(8)(PEt(3))(5)(MeCN)](2+) (1) and 4,4'-bipyridine (4,4'-bpy) yield [Re(6)Se(8)(PEt(3))(5)(4,4'-bpy)](2+) (12); similarly, cis- and trans-[Re(6)Se(8)(PEt(3))(4)(MeCN)(2)](2+) afford the cis- and trans-14 isomers, respectively, of [Re(6)Se(8)(PEt(3))(4)(4,4'-bpy)(2)](2+). Clusters 1 and 12 (or 1 and 1/2 equiv of 4,4-bpy) under the same conditions afford the bridged dicluster {[Re(6)Se(8)(PEt(3))(5)](2)(4,4'-bpy)}(4+) (15). The related diclusters {[Re(6)Se(8)(PEt(3))(5)](2)(L-L)}(4+) (L-L = 4,4'-py(2)C(2)H(2) (16), 4,4'-py(2)C(2)H(4) (17) (4,4'-py(2)C(2)H(2) = trans-1,2-bis(4-pyridyl)ethylene, 4,4'-py(2)C(2)H(4) = trans-1,2-bis(4-pyridyl)ethane)) are obtained by analogous methods. Reaction of 14 and 2 equiv of 1 in refluxing dichloromethane produces the linear tricluster {[Re(18)Se(24)(PEt(3))(14)(4,4'-bpy)(2)}(6+). All clusters were isolated as SbF(6)(-) salts in yields of ca. 60-90% and were characterized by their (1)H and (31)P NMR spectra and by mass spectrometry. In addition, the structures of 10 clusters (5-7, 9-12, 14-16) were confirmed by X-ray structure determinations. All clusters are based on the cubic [Re(6)(&mgr;(3)-Se)(8)](2+) core whose dimensions are insensitive to the nature and substitution pattern of the ligands. All substitution reactions, as indicated, proceed with retention of stereochemistry. Appropriate choice of solvate cluster leads to the unambiguous formation of 14-17, and should allow the construction of these and other cluster array shapes with variable bridging ligands. On the basis of voltammetric and EPR properties, clusters originally described as the monoprotonated species [Re(6)Se(7)(SeH)I(6)](3)(-) and [Re(6)S(7)(SH)Br(6)](3)(-) are reformulated as the oxidized 23-electron clusters [Re(6)Se(8)I(6)](3)(-) and [Re(6)S(8)Br(6)](3)(-).

Journal Article↗
PubMed1984

DNA repair kinetics after low doses of X-rays. A comparison of results obtained by the unwinding and nucleoid sedimentation methods.

A re-examination of some of our previously published and our more recent data has led us to reconsider the interpretation of the kinetics of the repair of DNA single-strand breaks in mammalian cells. We investigated the detailed kinetics of this repair after low doses of X-rays in mouse Ehrlich ascites tumour cells grown in suspension cultures, using two different methods that measure strand breaks in DNA: the unwinding method and the 'nucleoid' sedimentation method. The results thus obtained, either under weak alkaline conditions (unwinding method) or under neutral conditions ('nucleoid' sedimentation method) both showed an initial fast repair component, with a half time, t1/2 of 5-6 min, followed by a component between 10 and 30 min after irradiation, in which the kinetic curves levelled off or turned upwards, indicating the possibility of the introduction of new breaks into the DNA. We propose that these additional DNA strand breaks may arise by incision of the DNA by endonucleases at base-damaged sites, and we therefore suggest that the previous interpretation of the kinetics of DNA single-strand break repair in terms of two or more first-order repair components may have been an approximation. The measured kinetics of strand break repair after X-irradiation probably represent a mixture of break ligation and incision, and therefore correspondingly deviate from first order, especially 10-30 min after exposure to X-rays.

Animals↗
PubMed2003

Syntheses of a Cp'Re=S derivative and more complex products.

The reaction of Cp'ReCl(2)S(3) (Cp' = Me(4)EtC(5)) with slightly less than 2 equiv of a phosphine reagent results in the formation of [Cp'Re(Cl)(2)(mu-S)](2), 2, which has been characterized by an X-ray diffraction study. Reactions of 2 with nucleophiles did not lead to monomeric derivatives of the type Cp'ReS(Cl)(2)(Nuc). The reaction of Cp'ReCl(2)(SC(2)H(4)S) with (Me(3)Si)(2)S resulted in the formation of three new products: Cp'ReS(SC(2)H(4)S), 4; Cp'Re(S(3))(SC(2)H(4)S), 5; and a tetranuclear derivative, [(Cp'Re)(2)(mu-S)(mu,eta(2)-SC(2)H(4)S)(mu,eta(1)-SC(2)H(4)S](2)Cl(2), 6. Complexes 4 and 6 have been characterized by X-ray diffraction studies. The electrochemical properties of the mononuclear Re=S derivative, 4, are compared with those of Re=O and Re=NR analogues.

Journal Article↗
PubMed2006

Enhanced biological effectiveness of low energy X-rays and implications for the UK breast screening programme.

Recent radiobiological studies have provided compelling evidence that the low energy X-rays as used in mammography are approximately four times--but possibly as much as six times--more effective in causing mutational damage than higher energy X-rays. Since current radiation risk estimates are based on the effects of high energy gamma radiation, this implies that the risks of radiation-induced breast cancers for mammography X-rays are underestimated by the same factor. The balance of risk and benefit for breast screening have been re-analysed for relative biological effectiveness (RBE) values between 1 and 6 for mammography X-rays. Also considered in the analysis is a change in the dose and dose-rate effectiveness factor (DDREF) from 2 to 1, women with larger than average breasts and implications for women with a family history of breast cancer. A potential increase in RBE to 6 and the adoption of a DDREF of unity does not have any impact on the breast screening programme for women aged 50-70 years screened on a 3 yearly basis. Situations for which breast screening is not justified due to the potential cancers induced relative to those detected (the detection-to-induction ratio (DIR)) are given for a range of RBE and DDREF values. It is concluded that great caution is needed if a programme of early regular screening with X-rays is to be used for women with a family history of breast cancer since DIR values are below 10 (the lowest value considered acceptable for women below 40 years) even for modest increases in the RBE for mammography X-rays.

Adult↗
PubMed2002

Synthesis, crystal structure, and photoelectric properties of Re(CO)(3)ClL (L = 2-(1-ethylbenzimidazol-2-yl)pyridine).

A novel Re(I) complex, Re(CO)(3)ClL (L = 2-(1-ethylbenzimidazol-2-yl)pyridine), has been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. Crystal data for C(17)H(13)ClN(3)O(3)Re: space group, orthorhombic, Pbca; a = 12.713(6) A; b = 15.103(7) A; c = 18.253(8) A; Z = 8. Stable vacuum vapor deposition of the Re complex has been verified by UV-vis and infrared spectroscopy. A two-layer electroluminescent device with configuration of ITO/TPD/Re(CO)(3)ClL/Mg(0.9)Ag(0.1)/Ag has been fabricated, which gave a turn-on voltage of as low as 3 V and a maximum luminance of 113 cd/m(2) at a bias voltage of 10.5 V, and confirmed that the Re complex can function as a bright orange-red emitter and an electron transport material in an electroluminescent device.

Journal Article↗
PubMed2001

Location of Zn within the Mg12(LaxCe1-x) lattice by X-ray incoherent channelling patterns.

Systematic electron diffraction studies on intermetallic precipitates formed within a lightweight Mg-RE-Zn alloy (RE = La or Ce) identify these to be of structural type Mn(12)Th (space group I4/mmm). Analytical electron microscopy yields an overall composition of Mg(12)(La(x)Ce(1-x)) with x ~ 0.43, with 1 at.% Zn incorporated within the lattice. Variations in characteristic X-ray emission rates, as an electron beam is rocked near zone-axis orientations, are used to form two-dimensional channelling patterns, termed X-ray incoherent channelling patterns. This channelling contrast enables a specific sublattice site that is occupied by Zn to be unambiguously identified within the Mg(12)RE lattice. The particular sublattice site is denoted by the Wyckoff letter f, and is one of the three different Mg sublattice sites f, i and j. Of these three sites, the Wigner-Seitz cell that is centred on the f sublattice site has the largest Mg-RE interatomic distance, and therefore the f site is expected to be favoured for accommodating the substitution of a larger Zn atom.

Journal Article↗
PubMed2001

Layered rare-earth gallium antimonides REGaSb(2) (RE = La--Nd, Sm).

The ternary rare-earth gallium antimonides, REGaSb(2) (RE = La--Nd, Sm), have been synthesized through reaction of the elements. The structures of SmGaSb(2) (orthorhombic, space group D(5)(2)-C222(1), Z = 4, a = 4.3087(5) A, b = 22.093(4) A, c = 4.3319(4) A) and NdGaSb(2) (tetragonal, space group D(19)(4h)-I4(1)/amd, Z = 8, a = 4.3486(3) A, c = 44.579(8) A) have been determined by single-crystal X-ray diffraction. The SmGaSb(2)-type structure is adopted for RE = La and Sm, whereas the NdGaSb(2)-type structure is adopted for RE = Ce--Nd. The layered SmGaSb(2) and NdGaSb(2) structures are stacking variants of each other. In both structures, two-dimensional layers of composition (2)(infinity)[GaSb] are separated from square nets of Sb atoms [Sb] by RE atoms. Alternatively, the structures may be considered as resulting from the insertion of zigzag Ga chains between (2)(infinity)[RE Sb(2)] slabs. In SmGaSb(2), all of the Ga chains are parallel and the (2)(infinity)[SmSb(2)] layers are stacked in a ZrSi(2)-type arrangement. In NdGaSb(2), the Ga chains alternate in direction, resulting in a doubling of the long axis relative to SmGaSb(2), and the (2)(infinity)[NdSb(2)] layers are stacked in a Zr(3)Al(4)Si(5)-type arrangement. Extended Hückel band structure calculations are used to explain the bonding in the [GaSb(2)](3-) substructure.

Journal Article↗
PubMed2005

[Limits of chest X-ray investigation in the diagnosis of recurrent pulmonary tuberculosis].

PURPOSE: To investigate the usefulness of chest X-ray investigation for early diagnosis of recurrent pulmonary tuberculosis. OBJECT: Patients who start re-treatment at Fukujuji Hospital from 1993 to 2003 due to the recurrence of lung tuberculosis after the completion of standard chemotherapy. METHOD: Chart review. RESULT: Deterioration of chest X-ray was not observed in 19.5% (8/41) of recurrent pulmonary tuberculosis, and in 4 cases even improvement of chest X-ray finding was observed. Sensitivity of chest X-ray in all recurrent cases was around 80 %, and this figure did not increase in smear positive recurrent cases. Sensitivity of chest X-ray for symptomatic recurrent cases was 92.3%, and that for non-symptomatic recurrent cases 60.0%, which is significantly lower than that for symptomatic cases. CONCLUSION: Sensitivity of chest X-ray for early diagnosis of recurrent pulmonary tuberculosis is not very high, and bacteriological examinations are more important irrespective of chest X-ray finding. Especially in non-symptomatic recurrent cases, usefulness of chest X-ray is considerably limited. Method and necessity of regular follow-up in non-symptomatic persons after successful tuberculosis chemotherapy should be re-considered.

Adult↗
PubMed2005

Reactivity of rhenium(V) oxo Schiff base complexes with phosphine ligands: rearrangement and reduction reactions.

The symmetric rhenium(V) oxo Schiff base complexes trans-[ReO(OH2)(acac2en)]Cl and trans-[ReOCl(acac2pn)], where acac2en and acac2pn are the tetradentate Schiff base ligands N,N'-ethylenebis(acetylacetone) diimine and N,N'-propylenebis(acetylacetone) diimine, respectively, were reacted with monodentate phosphine ligands to yield one of two unique cationic phosphine complexes depending on the ligand backbone length (en vs pn) and the identity of the phosphine ligand. Reduction of the Re(V) oxo core to Re(III) resulted on reaction of trans-[ReO(OH2)(acac2en)]Cl with triphenylphosphine or diethylphenylphosphine to yield a single reduced, disubstituted product of the general type trans-[Re(III)(PR3)2(acac2en)]+. Rather unexpectedly, a similar reaction with the stronger reducing agent triethylphosphine yielded the intramolecularly rearranged, asymmetric cis-[Re(V)O(PEt3)(acac2en)]+ complex. Reactions of trans-[Re(V)O(acac2pn)Cl] with the same phosphine ligands yielded only the rearranged asymmetric cis-[Re(V)O(PR3)(acac2pn)]+ complexes in quantitative yield. The compounds were characterized using standard spectroscopic methods, elemental analyses, cyclic voltammetry, and single-crystal X-ray diffraction. The crystallographic data for the structures reported are as follows: trans-[Re(III)(PPh3)2(acac2en)]PF6 (H48C48N2O2P2Re.PF6), 1, triclinic (P), a = 18.8261(12) A, b = 16.2517(10) A, c = 15.4556(10) A, alpha = 95.522(1) degrees , beta = 97.130(1) degrees , gamma = 91.350(1) degrees , V = 4667.4(5) A(3), Z = 4; trans-[Re(III)(PEt2Ph)2(acac2en)]PF6 (H48C32N2O2P2Re.PF6), 2, orthorhombic (Pccn), a = 10.4753(6) A, b =18.4315(10) A, c = 18.9245(11) A, V = 3653.9(4) A3, Z = 4; cis-[Re(V)O(PEt3)(acac2en)]PF6 (H33C18N2O3PRe.1.25PF6, 3, monoclinic (C2/c), a = 39.8194(15) A, b = 13.6187(5) A, c = 20.1777(8) A, beta = 107.7730(10) degrees , V = 10419.9(7) A3, Z = 16; cis-[Re(V)O(PPh3)(acac2pn)]PF6 (H35C31N2O3PRe.PF6), 4, triclinic (P), a = 10.3094(10) A, b =12.1196(12) A, c = 14.8146(15) A, alpha = 105.939(2) degrees , beta = 105.383(2) degrees , gamma = 93.525(2) degrees , V = 1698.0(3) A3, Z = 2; cis-[Re(V)O(PEt2Ph)(acac2pn)]PF6 (H35C23N2O3PRe.PF6), 5, monoclinic (P2(1)/n), a = 18.1183(18) A, b = 11.580(1) A, c = 28.519(3) A, beta = 101.861(2) degrees , V = 5855.9(10) A(3), Z = 4.

Journal Article↗
PubMed2001

[Is chronic, untreated scapho-trapezoid arthrosis after resection arthroplasty of the carpometacarpal joint clinically relevant?].

Basal joint arthrosis and scapho-trapezio-trapezoid arthrosis (triscaphe-arthrosis) are common degenerative diseases with proven surgical treatment. Besides the extirpation of the trapezium during the resection-suspension arthroplasty, we have performed additional fusion of the scaphoid and the trapezoid (ST arthrodesis) in patients with heavy arthrotic changes in both locations. But the combination of these two surgical procedures results in a prolonged rehabilitation and may lead to more complications, e.g. nonunion. Thus the question arises, whether there is any clinical relevance to an untreated scapho-trapezoid arthrosis after resection-suspension arthroplasty of the carpometacarpal joint of the thumb. From 1992 to 1998, we performed resection-suspension arthroplasty of the carpometacarpal joint of the thumb without additional intervention at the scapho-trapezoid joint in 229 patients. In reviewing the perioperative X-rays of these patients, we found 55 cases with untreated arthrosis of the scapho-trapezoid joint. 36 of these patients were reviewed and re-examined. We used the wrist-score as well as new X-rays for our retrospective examination. The untreated arthrosis of the scapho-trapezoid joint does not lead to any reduction of wrist movement and only in some cases to a slight decrease of grip strength (compared with the other side). 23 of the 36 patients were free of pain. Two thirds of the reviewed patients (24 of 36) did not feel any loss of usability of the hand. Only four in 36 cases suffered a significant loss of function. The X-rays for this follow-up showed an increase in arthrotic changes of the scapho-trapezoid joint in comparison to the X-rays after the resection-suspension arthroplasty of the carpometacarpal joint of the thumb in one-third of the patients. In conclusion, in the majority of the patients there are no clinical symptoms of an untreated scapho-trapezoid arthrosis after resection-suspension arthroplasty of the carpometacarpal joint of the thumb. Individual subjective symptoms did exist, even with increased radio-morphologic changes, only in a few cases. We cannot recommend combining of the resection-suspension arthroplasty of the carpometacarpal joint of the thumb with the risky, uncomfortable fusion of the scaphoid and the trapezoid. Presently, we treat very severe arthrotic changes in both joints with a double-resection arthroplasty. These are very rare cases. If there are any advantages in this procedure, those will need to be proven in another follow-up study.

Aged↗
PubMed2002

Nasopharyngectomy for recurrent nasopharyngeal cancer: a 2- to 17-year follow-up.

OBJECTIVE: To review the 2- to 17-year outcome of nasopharyngectomy following local recurrence of nasopharyngeal carcinoma. DESIGN: Retrospective review. SETTING: University medical center. PATIENTS: Thirty-seven patients with biopsy-proven recurrent nasopharyngeal cancer followed up for a minimum of 2 years after transpalatal, transmaxillary, and/or transcervical resection with and without neck dissection. OUTCOME: Clinical examination, magnetic resonance imaging, chest x-ray examination, and liver function tests to determine re-recurrence; unlimited follow-up. RESULTS: With a mean follow-up of 5.4 years, the crude, 5-year, overall, free-of-disease survival rate was 52%, local control at 5 years was 67%, and the 5-year actuarial survival rate was 60%. Survival by recurrent T stage (rT) was as follows: rT1, 73%; rT2, 40%; rT3, 14%; and rT4, 0%. Complications occurred in 54% and included 1 death from carotid artery injury and 1 patient with permanent pharyngeal plexus paralysis with resultant dysphagia. The remaining patients had transitory complications that spontaneously resolved, required further surgery (closure of palate fistula, debridement, and reapplication of skin graft), or required further medical therapy. CONCLUSIONS: The results of this study are better than most published reports of additional irradiation for rT1 and rT2 lesions. More recent radiation studies that use radiosurgery or implants suggest promising early results. A randomized prospective study comparing surgery with additional irradiation for recurrent disease at the primary site is warranted.

Adult↗
PubMed2005

Revision of the absolute configuration of plumericin and isoplumericin from Plumeria rubra.

The absolute configurations of plumericin (1) and isoplumericin (2), isolated from Plumeria rubra, were re-assigned based on a combination of X-ray crystal-structure determination and quantum-mechanical calculations of their circular dichroism (CD) spectra. The experimental CD spectra showed an excellent match with those calculated for the (1S,5R,8R,9R,10R) absolute configuration (corresponding to ent-1 and ent-2, resp.), opposite to that generally accepted and published in the literature. Since the (false) plumericin configuration has been often used to derive the absolute configuration of related iridoids by chemical correlation, their absolute configurations also have to be reconsidered.

Apocynaceae↗
PubMed1992

Excavations into the active-site gorge of cholinesterases.

Acetyl- and butyrylcholinesterase (ACHE, BCHE) from evolutionarily distant species display a high degree of primary sequence homology and have biochemically similar catalytic properties, yet they differ in substrate specificity and affinity for various inhibitors. The biochemical information derived from analyses of ACHE and BCHE from human, Torpedo, mouse, and Drosophila, as well as that from the recombinant forms of their natural variants and site-directed mutants, can currently be re-examined in view of the recent X-ray crystallography data revealing the three-dimensional structure of Torpedo ACHE. The picture that emerges deepens the insight into the biochemical basis for choline ester catalysis and the complex mechanism of interaction between cholinesterases and their numerous ligands.

Acetylcholinesterase↗
PubMed2000

Fast re-rendering of volume and surface graphics by depth, color, and opacity buffering.

A method for quickly re-rendering volume data consisting of several distinct materials and intermixed with moving geometry is presented. The technique works by storing depth, color and opacity information, to a given approximation, which facilitates accelerated rendering of fixed views at moderate storage overhead without re-scanning the entire volume. Storage information in the ray direction (what we have called super-r depth buffering), allows rapid transparency and color changes of materials, position changes of sub-objects, dealing explicitly with regions of overlap, and the intermixing or separately rendered geometry. The rendering quality can be traded-off against the relative storage cost and we present an empirical analysis of output error together with typical figures for its storage complexity. The method has been applied to the visualization of medical image data for surgical planning and guidance, and presented results include typical clinical data. We discuss the implications of our method for haptic (or tactile) rendering systems, such as for surgical simulation, and present preliminary results of rendering polygonal objects in the volume rendered scene.

Algorithms↗