PubMed Health⌕ Search

Biomedical subjects

Paul D Smith

Publications and source records attributed to Paul D Smith.

14 recordsLinked to original sources
PubMed2006

Pi-acid/pi-base carbonyloxomolybdenum(IV) complexes and their oxomolybdenum(VI/IV) precursors.

Brown TpiPrMoO(SR)(CO) (TpiPr = hydrotris(3-isopropylpyrazol-1-yl)borate; R = Et, iPr, Ph, p-tol, Bz) are formed when TpiPrMoO(SR)(NCMe) react with CO gas in toluene. The carbonyloxomolybdenum(IV) complexes exhibit nu(CO) and nu(Mo=O) IR bands at ca. 2025 and 935 cm(-1), respectively, and NMR spectra indicative of C(1) symmetry, with delta(C)(CO) ca. 250. The crystal structure of TpiPrMoO(SiPr)(CO), the first for a mononuclear carbonyloxomolybdenum complex, revealed a distorted octahedral geometry, with d(Mo=O) = 1.683(3) A, d(Mo-C) = 2.043(5) A, and angle(O=Mo-C) = 90.87(16) degrees . The blue-green acetonitrile precursors are generated by reacting cis-TpiPrMoO2(SR) with PPh3; they are unstable, display a single nu(Mo=O) IR band at ca. 950 cm(-1), and exhibit NMR spectra consistent with C1 symmetry. Red-brown cis-TpiPrMoO2(SR) (R = as above and tBu) are formed by metathesis of TpiPrMoO2Cl and HSR/NEt3 in dichloromethane. The complexes exhibit strong nu(MoO2) IR bands at ca. 925 and 895 cm(-1), and NMR spectra indicative of Cs symmetry; the isopropyl, p-tolyl, and benzyl derivatives possess distorted octahedral geometries, with d(Mo=O)(av) = 1.698 A and angle(MoO(2))(av) = 103.5 degrees.

Journal Article↗
PubMed2006

Measuring the elasticity of clathrin-coated vesicles via atomic force microscopy.

Using a new scheme based on atomic force microscopy (AFM), we investigate mechanical properties of clathrin-coated vesicles (CCVs). CCVs are multicomponent protein and lipid complexes of approximately 100 nm diameter that are implicated in many essential cell-trafficking processes. Our AFM imaging resolves clathrin lattice polygons and provides height deformation in quantitative response to AFM-substrate compression force. We model CCVs as multilayered elastic spherical shells and, from AFM measurements, estimate their bending rigidity to be 285 +/- 30 k(B)T, i.e., approximately 20 times that of either the outer clathrin cage or inner vesicle membrane. Further analysis reveals a flexible coupling between the clathrin coat and the membrane, a structural property whose modulation may affect vesicle biogenesis and cellular function.

Clathrin-Coated Vesicles↗
PubMed2006

Models for the molybdenum hydroxylases: synthesis, characterization and reactivity of cis-oxosulfido-Mo(VI) complexes.

Atom transfer reactions have been employed to convert Tp(i)(Pr)MoO(2)(OAr) into monomeric cis-oxosulfido-Mo(VI) and dimeric mu-disulfido-Mo(V) species, [Tp(i)(Pr)MoOS(OAr)](n)() (Tp(i)(Pr) = hydrotris(3-isopropylpyrazol-1-yl)borate; OAr = phenolate or naphtholate derivative; n = 1 and 2, respectively). Dark red, monomeric Tp(i)(Pr)MoOS(OAr) complexes contain distorted octahedral cis-oxosulfido-Mo(VI) centers, with d(Mo=O) = 1.692(5) A, d(Mo=S) = 2.132(2) A, and angle(O=Mo=S) = 103.68(16) degrees for the 2-sec-butylphenolate derivative. Dark red-purple, dimeric [Tp(i)(Pr)MoOS(OAr)](2) complexes undergo S-S bond cleavage forming monomeric oxosulfido-Mo(VI) species in solution. In the solid state, the 3,5-di-tert-butylphenolate derivative exhibits a centrosymmetric structure, with distorted octahedral anti oxo-Mo(V) centers bridged by a disulfido-kappaS,kappaS' ligand. Hydrolysis of the oxosulfido-Mo(VI) complexes results in the formation of [Tp(i)(Pr)MoO](2)(mu-S(2))(mu-O). In anaerobic solutions, certain oxosulfido-Mo(VI) complexes convert to molybdenyl complexes bearing bidentate 2-mercaptophenolate or related naphtholate ligands formed via intramolecular attack of the sulfido ligand on a coligand C-H group. The oxosulfido-Mo(VI) complexes serve as precursors to biologically relevant Mo(V) and heterobimetallic MoO(mu-S)Cu species and undergo a range of biomimetic reactions.

Mixed Function Oxygenases↗
PubMed2006

Recurrent intramedullary sarcoidosis.

We present a 47-year-old man with recurrent intramedullary sarcoidosis. This condition, without any other manifestations of the disease, is rare, with less than 20 reports in the literature. Further, to our knowledge our presentation is the only reported case of intramedullary sarcoidosis recurring in a separate, distant region of the cord after a period of treatment with steroids, to which the patient had initially responded.

Humans↗
PubMed2006

Neck rejuvenation revisited.

PURPOSE: Restoration of the aesthetic neck contour is an integral component of facial rejuvenation. Multiple deformities of the neck and chin complex can make treatment of the cervical region daunting. An algorithmic approach to neck rejuvenation based on individual anatomic and clinical analysis is prudent. The authors created a simplified anatomic approach to the most common cervical deformities encountered in the patient seeking facial rejuvenation. METHODS: Retrospective analysis of the senior author's (R.J.R.) technique evolution over the last 15 years was performed. The operative techniques used in neck rejuvenation were evaluated and the long-term postoperative results were reviewed. RESULTS: Recurrent patterns of cervical deformity are present in patients presenting for facial rejuvenation. These patterns can be classified into categories based on specific anatomic deformities. CONCLUSIONS: Facial rejuvenation requires appropriate identification of deformity to effect the desired changes. Cervical deformities are classified into clinically useful categories based on careful preoperative analysis. A thorough understanding of the anatomic bases for the deformities allows the surgeon to choose the appropriate treatments to achieve consistent and reliable results.

Botulinum Toxins, Type A↗
PubMed2006

Functional dentate gyrus neurogenesis in a rapid kindling seizure model.

Neurogenesis in the adult mammalian hippocampus resulting in long-term persistence of new neurons with features of capacity for functional activation is recognized. Many stimuli are capable of increasing the rate of neurogenesis, including seizure activity. Whether these insults result in an increased number of new functionally active neurons over and above the baseline rate of neurogenesis is not known. The rapid electrical amygdala kindling (REAK) model of seizures isolates the effects of seizures alone in the absence of neuronal death and the resulting seizures induce expression of c-Fos in the vast majority of dentate gyrus (DG) granule cells. C57BL/6 mice were exposed to REAK then injected with bromodeoxyuridine (BrDU) to label dividing cells, then re-exposed to REAK after a delay period to allow detection of functional activation in new neurons by measurement c-Fos expression in response to seizures. Adult subgranular zone cells migrated into the DG granule cell layer (GCL), assumed a neuronal phenotype and demonstrated seizure-dependent responsiveness. Larger absolute numbers of new neurons demonstrating seizure-dependent activation were found in the GCL of previously kindled mice. Seizures are capable of increasing the number of new neurons with the capacity for functional activation laid down in the postseizure period and incorporated into seizure-activated circuitry.

Animals↗
PubMed2005

Development of a two-color laser fluorescence detector. On-line detection of internal standards and unknowns by capillary electrophoresis within the same sample.

A two-laser, two-color detector has been developed for the simultaneous detection of naturally occurring and recombinant (internal standards) cytokines within the same biological sample. The internal standards were labeled with Bimane and detected with a 408 nm laser while the natural cytokines were labeled with AlexaFluor633 and detected with a 633 nm laser. The two resulting electropherograms were plotted as overlaid traces and quantification of the natural materials determined by comparison with the standards. Using this system, recovery of all four cytokine standards was greater than 94% in both saline and cytokine-depleted plasma. These recoveries could be achieved with intra- and inter-assay coefficients of variance (c.v.) of less than 4.5 and 5.6, respectively. Application of this system to the examination of clinical samples demonstrated that measurement of the four pro-inflammatory cytokines could distinguish between normals, sub-clinical and clinical inflammation. An advantage of this approach is that direct calculation of unknowns by comparison to identical internal standards can shorten analytical time by eliminating the need for additional standard or calibration runs.

Color↗
PubMed2005

Oxygen atom transfer in models for molybdenum enzymes: isolation and structural, spectroscopic, and computational studies of intermediates in oxygen atom transfer from molybdenum(VI) to phosphorus(III).

Intermediates in the oxygen atom transfer from Mo(VI) to P(III), [Tp(iPr)MoOX(OPR3)] (Tp(iPr) = hydrotris(3-isopropylpyrazol-1-yl)borate; X = Cl-, phenolates, thiolates), have been isolated from the reactions of [Tp(iPr)MoO2X] with phosphines (PEt3, PMePh2, PPh3). The green, diamagnetic oxomolybdenum(IV) complexes possess local C(1) symmetry (by NMR spectroscopy) and exhibit IR bands assigned to nu(Mo==O) (approximately 950 cm(-1)) and nu(P==O) (1140-1083 cm(-1)) vibrations. The X-ray crystal structures of [Tp(iPr)MoOX(OPEt3)] (X = OC6H4-2-sBu, SnBu), [Tp(iPr)MoO(OPh)(OPMePh2)], and [Tp(iPr)MoOCl(OPPh3)] have been determined. The monomeric complexes exhibit distorted octahedral geometries, with coordination spheres composed of tridentate fac-Tp(iPr) and mutually cis monodentate terminal oxo, phosphoryl (phosphine oxide), and monoanionic X ligands. The electronic structures and stabilities of the complexes have been probed by computational methods, with the three-dimensional energy surfaces confirming the existence of a low-energy steric pocket that restricts the conformational freedom of the phosphoryl ligand and inhibits complete oxygen atom transfer. The reactivity of the complexes is also briefly described.

Borates↗
PubMed2005

A brightness-area-product-based protocol for the quantitative assessment of antigen abundance in fluorescent immunohistochemistry.

A problem frequently facing researchers examining abundance of expression of a given antigen is measurement. When the antigen is confined to the nucleus, absolute numbers of nuclei or a percentage of nuclei expressing the antigen in a given region can be estimated. When the antigen is localized to cytoplasm, cytoplasmic organelles or processes or membranes, the assessment becomes more difficult. In these settings, an observer/experimenter may assign a density score but intra- and inter-observer agreement using a three-tiered system, and finer resolution than this, is unlikely to be reproducible. Digital image analysis provides an opportunity to minimize observer bias in quantification of immunohistochemical staining. Previously, reported digital methods have mostly employed chromogen-staining methods and often report mean image brightness. We report a method for quantitatively assessing and expressing abundance of expression of an antigen in neural tissue stained with immunofluorescent methods by determining the brightness-area-product (BAP). The described protocol utilizes simple to use commercially available software and calculates BAP rather than mean brightness as a measure more representative of antigen abundance and visual interpretation. Accordingly, we propose this protocol as a useful adjunct to observer interpretation of fluorescent immunohistochemistry and its application to assessment of antigen abundance for varying patterns of antigen localization.

Animals↗
PubMed2005

Real time in vivo non-invasive optical imaging using near-infrared fluorescent quantum dots.

RATIONALE AND OBJECTIVE: Deep-tissue optical imaging is of particular interest, as the equipment costs are lower than for competing technologies such as MRI. For this purpose, the development of novel contrast agents with near-infrared (NIR) fluorescence is especially important. We report on the use of NIR semiconductor nanocrystals in deep-tissue in vivo optical imaging. MATERIALS AND METHODS: Semiconductor nanocrystals of CdMnTe/Hg were grown in aqueous solution and then coated with bovine serum albumin (BSA). The nanocrystals were approximately 5 nm in diameter and have a broad fluorescence peak in the NIR (770 nm). Nanocrystals were injected either subcutaneously or intravenously into athymic NCR NU/NU and C3H/HENCR MTV mice and then excited with a spatially broad 633 nm source; the resulting fluorescence was captured with a sensitive CCD camera. RESULTS: We have demonstrated that the nanocrystals are a useful angiographic contrast agent for vessels surrounding and penetrating a murine squamous cell carcinoma in a C3H mouse. Preliminary assessment of the depth of penetration for excitation and emission was done by imaging a beating mouse heart, both through an intact thorax and after a thoracotomy. The temporal resolution associated with imaging the nanocrystals in circulation has been addressed, and the blood clearance for this contrast agent has also been measured. CONCLUSIONS: There was no significant photobleaching or degradation of the nanocrystals after an hour of continuous excitation. The stability of the nanocrystals together with the time resolution of the optical detection makes them particularly attractive candidates for pharmacokinetic imaging studies.

Animals↗
PubMed2004

Computer interviewing in a primary care office: the patients are ready.

UNLABELLED: Computer patient interviewing has been used since 1968 and must be acceptable to a majority of patients for wide spread use to occur. Computer interviewing is still not used widely in the United States. Potential barriers have not been identified in the literature. METHODS: 150 of 164 (91.5%) eligible patients at a family medicine ambulatory practice were enrolled in a study to evaluate computer interview of cough and sore throat complaints. Subjects were given the choice to have the interview in the waiting or examination room. Telephone interviews were conducted 2-4 weeks later with 143/150 patients (95.3%). RESULTS: 102/150 (68%) of subjects chose the wait-ing room and 48/150 (32%) chose the examination room for the computer interview. 127/143 (88.8%) were willing to use the computer interview for evaluation of cough or sore throat again in the future. 116/143 (81.1%) were willing to use the computer interview for other medical complaints in the future. CONCLUSIONS: Patients are willing to use computer interview-ing and some interviews may be conducted in the waiting room.

Adolescent↗
PubMedDate not supplied

Radiographs in the office: is a second reading always needed?

BACKGROUND: We evaluated the frequency, nature, and importance of the changes in patient care that occurred as a result of differences in outpatient radiograph readings for cases in which the primary care clinician, hypothetically, would not request a second reading by a radiologist. METHODS: During 4 months, 1393 pairs of radiographic readings were collected from 9 volunteer primary care practices with 86 clinicians and a second reading by one of 42 radiologists. For 553, hypothetically, the clinician would not request a consultation from a radiologist. Review analysis of the 553 pairs revealed 100 (18.1%) radiographs in which the radiologist's reading did not agree with the clinician's reading. Data from the original visit and subsequent related care were abstracted from patient charts and reviewed. Changes in clinical care resulting from the radiologist's reading were identified. RESULTS: The radiologists' second reading of these 553 sets of radiographs resulted in 14 (2.5% of 553 and 14% of 100) cases of one or more changes in care. We found 38 documented or presumed changes in care and zero substantial changes in care. CONCLUSIONS: Primary care clinicians are able to identify radiographs for which a second reading by a radiologist will not result in substantial changes in care.

Clinical Competence↗