A Co2N2 diamond-core resting state of cobalt(I): a three-coordinate CoI synthon invoking an unusual pincer-type rearrangement.
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Chelating Agents↗
Biomedical subjects
John Tomaszewski
Publications and source records attributed to John Tomaszewski.
Tl(I), Fe(II), and Co(II) complexes supported by a monoanionic N,N,N'-heteroscorpionate ligand bis(3,5-di-tertbutylpyrazol-1-yl)-1-CH2NAr (Ar = 2,6-iPr2C6H3).
The lithium salt (L)Li(THF) (L- = bis(3,5-di-tertbutylpyrazol-1-yl)-1-CH2NAr, Ar = 2,6-iPr2C6H3) can be readily prepared from lithium bis(3,5-di-tertbutylpyrazol-1-yl)methide and the N-methyleneaniline H2C=NAr. This N,N,N'-heteroscorpionate lithium reagent can be transmetalated with Tl(OTf), FeCl2(THF)(1.5), and CoCl2 to yield the (L)Tl, (L)FeCl, and (L)CoCl complexes, respectively. Single crystal structural data for compounds (L)Li(THF), (L)Tl, (L)FeCl, and (L)CoCl reveal in each case the hapticity of the sterically demanding, monoanionic L- ligand to be kappa3-N3.
Journal Article↗
Three-coordinate Co(I) provides access to unsaturated dihydrido-Co(III) and seven-coordinate Co(V).
The three-coordinate, T-shaped Co(I) complex, PNPCo (PNP = [(tBu2PCH2SiMe2)2N-], is readily synthesized by magnesium reduction of divalent PNPCoCl. Triplet (S = 1) PNPCo is coordinatively and electronically unsaturated and undergoes a thermally reversible oxidative addition reaction with H2, producing trivalent PNPCo(H)2. In contrast, the reaction with excess primary silane PhSiH3 quantitatively generates the base-stabilized silylene Co(V) compound {kappa2-tBu2PCH2Me2SiNSiMe2CH2tBu2P(H)Si=}Co(H)3(SiH2Ph)2.
Journal Article↗
Preoperative parameters, including percent positive biopsy, in predicting seminal vesicle involvement in patients with prostate cancer.
PURPOSE: Complete dissection of the SVs during RP can contribute to increased morbidity including erectile dysfunction and incontinence. Therefore we evaluated the clinical parameters associated with a positive SV finding on final pathology and identified those patients with a minimal risk of SV involvement for potential SV sparing surgery. MATERIALS AND METHODS: We retrospectively reviewed our RP database from 1991 to 1999 to evaluate the incidence and clinical correlates of SV invasion. Variables studied included preoperative total serum PSA, percent positive biopsy cores, DRE and biopsy Gleason score. Statistical analysis included univariate, multivariate regression analysis and ROC curves. RESULTS: Of our 1,056 patients 79 (7.4%) had SV involvement. Of the 356 patients with less than 17% positive biopsies, only 2 (0.5%) had SV involvement on final pathology. Preoperative PSA, biopsy Gleason score and percent positive biopsies were all highly predictive of SV invasion on multivariate analysis. Percent positive biopsy was found to be the single best predictor of seminal vesicle invasion (p <0.0001). CONCLUSIONS: In our series percent positive biopsy was the single best predictor of SV invasion at the time of RP. An analysis of preoperative parameters including percent positive biopsy, biopsy Gleason score and preoperative PSA may define a subset of patients in which prospective studies could be used to determine the value and safety of SV sparing surgery.
Biopsy↗
A facile approach to a d4 RuN: moiety.
Replacement of chloride in (PNP)RuCl, PNP = (tBu2PCH2SiMe2)2N, by Me3SiN3 gives a pre-redox adduct that, already at -30 degrees C, releases N2 to produce the mononuclear nonplanar Ru(IV) nitride (PNP)RuN, characterized by spectroscopic and X-ray methods. DFT calculations show the planar structure to be only 1.6 kcal/mol less stable, which explains the time-averaged simplicity of the 1H NMR spectrum, as well as the large vibrational amplitude of the nitride ligand.
Journal Article↗
Core-shell nanostructures from single poly(N-vinylcaprolactam) macromolecules: stabilization and visualization.
Formation of core-shell poly(N-vinylcaprolactam) (PVCL) single-molecule nanostructures due to interaction of PVCL with metal ions was studied using transmission electron microscopy, 13C NMR, and light scattering. This study demonstrates that addition of CoCl2 to PVCL in its globular conformation yields unimolecular core-shell polymer particles with the core decorated with Co(II) ions. The crucial condition for formation of well-defined unimolecular nanostructures is the presence of stable globular aggregates in aqueous solution. Moreover, the metal ions should have a sufficiently high coordination number (higher than 2) to provide a cross-linking and stabilization of the core.
Caprolactam↗
Impact of multiple biopsy cores on predicting final tumor volume in prostate cancer detected by a single microscopic focus of cancer on biopsy.
OBJECTIVES: To compare the impact that the number of biopsy cores have on final pathologic findings when minimal disease is detected at biopsy. Discordance has been noted between transrectal ultrasound-guided biopsy results and tumor volume even when minimal amounts of tumor are found on biopsy. METHODS: We identified patients who had undergone radical retropubic prostatectomy for a single microscopic focus of adenocarcinoma from a prospectively maintained surgical database. Patients were stratified into two groups: those with six biopsies or less and those with seven or more. The Gleason score, margin status, presence of extracapsular extension, and percentage of tumor volume were compared. RESULTS: A total of 102 patients in our database had a single microscopic focus of adenocarcinoma detected by needle biopsy. Of these patients, 65 underwent six or fewer biopsies and 37 underwent seven or more at transrectal ultrasonography. Of the 37 patients in group 2, 27 (73%) had a final tumor volume of less than 5% compared with 24 (37%) of 65 patients in group 1 (P = 0.002). Of the group 2 patients, 15 (75%) with Stage T1c had an estimated tumor volume of less than 5% compared with only 11 (34%) in group 1 (P = 0.01). No statistically significant difference was noted between the two groups for margin status, presence of extracapsular extension, or Gleason score. CONCLUSIONS: A single microscopic focus of cancer obtained after multiple cores predicts for a significantly lower tumor volume on final pathologic examination across clinical stages. In the context of greater tissue sampling, the minimal disease designation may carry more predictive value and be a useful parameter in stratifying patients with Stage T1c and other good-risk factors with regard to surgical outcome.
Adenocarcinoma↗
Terminal vanadium-neopentylidyne complexes and intramolecular cross-metathesis reactions to generate azametalacyclohexatrienes.
Four-coordinate vanadium complexes containing a terminal neopentylidyne functionality have been prepared by two consecutive alpha-hydrogen abstraction reactions both of which were induced by one-electron oxidations. Among these vanadium-alkylidyne complexes are the neutral and the cation (Nacnac)VCtBu(OTf) and [(Nacnac)VCtBu(THF)]+, respectively (Nacnac- = [Ar]NC(CH3)CHC(CH3)N[Ar], Ar = 2,6-(CHMe2)2C6H3). The vanadium-alkylidynes have been characterized by 1H, 13C, 51V NMR spectroscopy and single-crystal X-ray diffraction and are consistent with a short VC bond. These alkylidynes were found to transform to azametalacyclohexatriene systems via an intramolecular cross-metathesis reaction. Kinetic studies of the transformation of (Nacnac)VCtBu(OTf) in C7D8 reveal the formation of the azametalacyclohexatriene to be independent of solvent (toluene vs THF) and the reaction to be first order in vanadium (k = 3.30(5) x 10-5 s-1 at 80 degrees C, with activation parameters DeltaH= 25.4(3) kcal/mol, DeltaS = -6(3) cal/molK). High-level DFT calculations on the full model suggest an intramolecular mechanism invoking only one transition state. The overall thermodynamic driving force for the reaction (DeltaG) in solution phase was estimated to be -21.3 kcal/mol.
Journal Article↗
Multifunctional behavior by a Bis-(phosphinimino)methanide ligand: eta 2- vs eta 3-coordination vs Bronsted basicity.
The reaction of [(Cymene)RuCl2]2 with the chelate LiHC(PPh2NPh)2 occurs to remove both chloride ligands, to furnish a cationic Ru(II) complex with the monoanionic ligand bound eta3, through two N and an sp3 carbon. This cation is also produced from the conjugate acid of the ligand H2C(PPh2NPh)2 because this molecule can serve as a Brønsted base, to deprotonate the acidic carbon of another molecule of H2C(PPh2NPh)2. DFT calculations show an energy surface where (Cymene)RuHC(PPh2NPh)2L is more stable with a Ru-CH(PPh2NPh)2 bond and with L = Cl- or MeCN not coordinated to Ru, than to an eta2-HC(PPh2NPh)2 structure with coordinated L; this is tested experimentally. The greater tendency for this ligand to be coordinated eta3 vs analogous diketiminates is discussed. The nucleophilicity of Cgamma in structure 1, vs that of donors L = Cl- or MeCN, is evaluated to understand the preference of the bis(phosphinimino)methanide to be bidentate or tridentate.
Journal Article↗
Functional polymer colloids with ordered interior.
Polymer colloids with internal ordering were synthesized using hydrolytic condensation of octadecyl-dimethyl(3-trimethoxysilylpropyl)ammonium chloride (ODMACl) and a mixture of ODMACl and the trisodium salt of the triacetic acid N-(trimethoxysilylpropyl)ethylenediamine (TANED). The structure and morphology of these colloids were studied with small-angle X-ray scattering, transmission electron microscopy, nuclear magnetic resonance, sedimentation in ultracentrifuge; and other methods. When polymer colloids are obtained from a single precursor (ODMACl), their local structure, molecular weight characteristics, and morphology strongly depend on the reaction conditions, while lamellar ordering remains nearly unaffected. Use of a mixture of cationic and anionic silanes (ODMACl and TANED) as precursors in hydrolytic condensation results in novel zwitterionic copolymer colloids with two-dimensional hexagonal packing. Interaction of the ODMACl quaternary ammonium groups with the three carboxy groups of TANED leads to replacement of sodium and chloride ions and formation of gegenions, resulting in a molar ratio ODMACl:TANED = 3:1 (each TANED molecule contains three carboxy groups). Due to their ordered interior, polyODMACl (PODMACl) and PODMACl-TANED colloids can be used as templates for controlled positioning of nanoparticles within these colloids. For example, lamellar ordering controls Pt nanoparticle formation within PODMACl colloids providing Pt nanoparticle alignment within the lamellar structure. Loading of PODMACl-TANED colloids with iron salts followed by pH increase results in the formation of iron oxide nanoparticles located within PODMACl-TANED cylinders.
Journal Article↗
Quantitative analysis of immunohistologic features of very early rheumatoid synovitis in disease modifying antirheumatic drug- and corticosteroid-naïve patients.
OBJECTIVE: To describe the immunohistochemical features of very early rheumatoid synovitis in disease modifying antirheumatic drug- and corticosteroid-naïve patients. METHODS: Eight patients presenting with oligoarthritis or polyarthritis, who later met American Rheumatism Association criteria for rheumatoid arthritis (RA), underwent needle synovial biopsies of a knee joint within the first 6 weeks after onset of disease symptoms. Using antibodies to CD3, CD8, L26, CD68, and von Willebrand factor, a detailed quantitative immunohistochemical analysis was done. RESULTS: CD3+ T lymphocytes, CD8+ T lymphocytes, L26+ B lymphocytes, and CD68+ macrophages were seen in 8/8 (100%), 7/8 (87%), 4/8 (50%), and 6/6 (100%) of synovial biopsies stained with the respective marker. There was a wide variation in number of positive cells between patients. CD3+ and CD8+ T cells were seen predominantly in perivascular areas, less often in a diffuse distribution, and not in aggregates. L26+ B lymphocytes were found in much smaller numbers compared with T lymphocytes. A mean of 67 vessels/mm2 was noted. No lymphoid aggregates were seen. In all cases, infiltration of macrophages and lymphocytes was limited mainly to relatively superficial parts of synovium, i.e., within 1 to 2 high power fields of the surface. CONCLUSION: An absence of lymphoid aggregates or dramatic vascularity and a predominantly superficial infiltrate consisting mainly of perivascular T cells with few B cells characterized our patients with very early RA of < 6 weeks' duration. Thus, there appear to be some potentially important differences from findings reported in well established disease.
Adrenal Cortex Hormones↗
Four-coordinate phosphinidene complexes of titanium prepared by alpha-H-migration: phospha-Staudinger and phosphaalkene-insertion reactions.
alpha-Hydrogen migration in the phosphide (Nacnac)Ti=CHtBu(PHR) (Nacnac- = [Ar]NC(Me)CHC(Me)N[Ar], Ar = 2,6-iPr2C6H3, R = C6H11, 2,4,6-iPr3C6H2, 2,4,6-tBuC6H2), prepared from salt metathesis of (Nacnac)Ti=CHtBu(PHR) with LiPHR, generates terminal and four-coordinate phosphinidene complexes (Nacnac)Ti=PR(CH2tBu), one of which was structurally characterized (R = 2,4,6-tBu3C6H2). Phosphinidene intermediate (Nacnac)Ti=PR(CH2tBu) (R = C6H11, 2,4,6-iPr3C6H2) transform to ([Ar]NC(Me)CHC(Me)P[R][CH2tBu])Ti=NAr(OEt2) through "phospha-Staudinger" and subsequent phosphaalkene-insertion reactions.
Journal Article↗
A terminal and four-coordinate titanium alkylidene prepared by oxidatively induced alpha-hydrogen abstraction.
One-electron oxidation of the beta-diketiminate titanium(III) bis-neopentyl complex (Nacnac)Ti(CH2tBu)2 (Nacnac = [Ar]NC(Me)CHC(Me)N[Ar], Ar = 2,6-(CHMe2)2C6H3) promotes alpha-abstraction to afford the rare and terminal four-coordinate neopentylidene (Nacnac)Ti=CHtBu(OTf), which was structurally characterized. Alkylidene (Nacnac)Ti=CHtBu(OTf) reacts cleanly with benzophenone and the imine functionality of the Nacnac ligand to afford the corresponding Wittig-type products.
Journal Article↗
Expression of SHP-1 phosphatase indicates post-germinal center cell derivation of B-cell posttransplant lymphoproliferative disorders.
SHP-1 tyrosine phosphatase acts as a negative regulator of signaling by receptors for growth factors, cytokines, and chemokines and by receptors involved in immune response. Our recent study showed that SHP-1 is tightly regulated at various stages of B-cell differentiation and is expressed in the mantle and marginal zones, interfollicular B cells, and plasma cells, whereas it is nondetectable in germinal center cells. In this study we evaluated expression of SHP-1 in vitro and in vivo in nine cell lines representing three different types of EBV+ B-cell populations closely resembling or derived from posttransplant lymphoproliferative disorders (PTLDs). Furthermore, we examined tissue samples from 58 patients with B-cell PTLDs, both EBV+ (85% of the cases analyzed) and EBV- (15%). SHP-1 protein was strongly expressed in all cell lines and PTLD cases. In addition, the PTLD cases were essentially negative for germinal center B-cell markers: none expressed CD10 and only one expressed BCL-6. More than 40% expressed a late post-germinal B-cell marker, CD138. The universal expression of SHP-1, lack of expression of CD10 and BCL-6, and frequent expression of CD138 suggest that PTLDs are derived from post-germinal center B cells regardless of the EBV cell infection status. Based on the immunophenotype, B-cell PTLDs could be divided into two broad categories corresponding to the early (CD10-/BCL-6-/SHP-1+/CD138-) and late (CD10-/BCL-6-/SHP-1+/CD138+) post-germinal center cells. By being expressed earlier, SHP-1 is a more sensitive marker of post-germinal center B cells than CD138, which is seen on the terminally differentiated immunoblasts and plasma cells.
B-Lymphocytes↗
Ultra-sensitive immunoassays using multi-photon-detection in diagnostic proteomics of blood.
Multiphoton-detection methods that detect as little as 1000 atoms of (125)I-streptavidin increase the sensitivity of immunoassays by 200- to 1000-fold (1 femtogram/mL). Improved background suppression allows 20- to 100-fold improvements in sensitivity for conventional immunoassays (10-50 femtogram/mL). Quantitation of low abundance biomarkers in blood (PSA, TNFalpha, VEGF, IL-1beta, IL-6, and IL-8), for the first time for complete patient cohorts, indicates that very high analytical sensitivity and new statistical methods are crucial for serum-based diagnostic proteomics.
Adult↗