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P Braunstein

Publications and source records attributed to P Braunstein.

At least 19 recordsLinked to original sources
PubMed2000

Strategies for the anchoring of metal complexes, clusters, and colloids inside nanoporous alumina membranes.

Two complementary strategies are presented for the anchoring of molecular palladium complexes, of cobalt or platinum clusters or of gold colloids inside the nanopores of alumina membranes. The first consists in the one step condensation of an alkoxysilyl functional group carried by the metal complex with the hydroxy groups covering the surface of the membrane pores. Thus, using the short-bite alkoxysilyl-functionalized diphosphane ligands (Ph2P)2N(CH2)3Si(OMe)3 (1) and (Ph2P)2N(CH2)4SiMe2(OMe)] (2) derived from (Ph2P)2NH (dppa) (dppa bis(diphenylphosphanyl)amine), the palladium complexes [Pd(dmba)(kappa2-P,P-(Ph2P)2N(CH2)3Si(OMe)3)] Cl (3) and [Pd(dmba)[kappa2-P,P-(Ph2P)2N(CH2)4SiMe2(OMe)]]Cl (4) (dmba-H = dimethylbenzylamine). respectively, were tethered to the pore walls. After controlled thermal treatment. confined and highly dispersed palladium nanoparticles were formed and characterized by transmission electron microscopy (TEM). This method could not be applied to the cobalt cluster [Co4(CO)8(mu-dppa)[mu-P,P-(Ph2P)2N(CH2)4SiMe2(OMe)]] (7) owing to its too limited solubility. However, its anchoring was achieved by using the second method which consisted of first derivatizing the pore walls with 1 or 2. The covalent attachment of the diphosphane ligands provides a molecular anchor that allows subsequent reaction with the cluster [Co4(CO)10(mu-dppa)] 6 to generate anchored 7 and this step was monitored by UV/Vis spectroscopy. In addition, the presence of carbonyl ligands in the cluster provides for the first time a very sensitive spectroscopic probe in the IR region which confirms both cluster incorporation and the retaining of its molecular nature inside the membrane. The presence of the bridging dppa ligand in 6 provides additional stabilization and accounts for the selectivity of the procedure. Using this method, platinum clusters (diameter ca. 2 nm) and gold colloids (diameter ca. 13 nm) were immobilized after passing their solution through the functionalized membrane pores. The resulting membranes were characterized by TEM which demonstrated the efficiency of the complexation and showed the high dispersion of the metal loading. The successful application of these methods has demonstrated that nanoporous alumina membranes are not only unique supports to incorporate metal complexes, clusters, or colloids but can also be regarded as functional matrices or microreactors, thus opening new fields for applications.

Journal Article↗
PubMed2000

Novel metal-to-metal silyl-migration reactions in heterometallic complexes.

An unprecedented, intramolecular metal-to-metal silyl ligand migration reaction has been discovered in a series of phosphido-bridged iron-platinum complexes and which may be triggered by an external nucleophile. Thus, reaction of solutions of [(OC)3-(R1/3Si)Fe(mu-PR2R3)Pt(1,5-COD) (1a R1 = OMe, R2 = 3 = Ph; 1b R1 = OMe, R2 = R3 = Cy; 1c R1 = Ph, R2 = R3 = Ph; 1d R1 = Ph, R2 = R3 = Cy; 1e R1 = Ph, R1 = H, R3 = Ph) in CH2Cl2 with CO rapidly afforded the corresponding complexes [(OC)4Fe(mu-PR2R3)Pt(SiR1/3)-(CO)] (2a-e) in which the silyl ligand has migrated from Fe to Pt, while two CO ligands have been ligated, one on each metal. When 1a or 1c was slowly treated with two equivalents of tBuNC at low temperature, quantitative displacement of the COD ligand was accompagnied by silyl migration from Fe to Pt and coordination of an isonitrile ligand to Fe and to Pt to give [(OC)3-(tBuNC)Fe(mu-PPh2)Pt[Si(OMe)3](CNtBu)] (3a) and [(OC)3(tBuNC)-Fe(mu-PPh2)Pt[SiPh3](CNtBu)] (3c). Reaction of 2a with one equivalent of tBuNC selectively led to substitution of the Pt-bound CO to give [(OC)4-Fe(mu-PCy2)Pt[Si(OMe)3](CNtBu)] (4b), which reacted with a second equivalent of tBuNC to give [(OC)4Fe(mu-PCy2)-Pt[Si(OMe)3](CNtBu)2] (5b) in which the metal-metal bond has been cleaved. Opening of the Fe-Pt bond was also observed upon reaction of 3a with tBuNC to give [(OC)3(tBuNC)-Fe(mu-PPh2)Pt[Si(OMe)3](CNtBu)2] (6). The silyl ligand migrates from Fe, in which it is trans to mu-PR2R3 in all the metal-metal-bonded complexes, to a position cis to the phosphido bridge on Pt. However, in 5a,b and 6 with no metal-metal bond, the Pt-bound silyl ligand is trans to the phosphido bridge. The intramolecular nature of the silyl migration, which may be formally viewed as a redox reaction, was established by a cross-over experiment consisting of the reaction of 1a and 1d with CO; this yielded exclusively 2a and 2d. The course of the silyl-migration reaction was found to depend a) on the steric properties of the -SiR1/3 ligand, and for a given mu-PR2R3 bridge (R2 = R3 = Ph), the migration rate decreases in the sequence Si(OMe)3> SiMe2Ph> SiMePh2>>SiPh3; b) on the phosphido bridge and for a given silyl ligand (R1 = OMe), the migration rate decreases in the order mu-PPh2 >> mu-PHCy; c) on the external nucleophile since reaction of 1c with two equivalents of P(OMe)3, P(OPh)3 or Ph2PCH2C(O)Ph led solely to displacement of the COD ligand with formation of 11a-c, respectively, whereas reaction with two equivalents of tBuNC gave the product of silyl migration 3c. Reaction of [(OC)3-[(MeO)3Si]Fe(mu-PPh2)Pt(PPh3)2] (7a) with tBuNC (even in slight excess) occurred stereoselectively with replacement of the PPh3 ligand trans to mu-PPh2, whereas reaction with CO led first to [(OC)3((MeO)3Si)Fe(mu-PPh2)Pt(CO)-(PPh3)] (8a), which then isomerized to the migration product [(OC)4Fe(mu-PPh2)Pt[Si(OMe)3](PPh3)] (9a). Most complexes were characterized by elemental analysis, IR and 1H, 31P, 13C, and 29Si NMR spectroscopy, and in five cases by X-ray diffraction.

Journal Article↗
PubMed2000

Stepwise Ethene and/or Methyl Acrylate/CO Insertions into the Pd-C Bond of Cationic Palladium(II) Complexes Stabilized by a (P,O) Chelate This work was supported by the Centre National de la Recherche Scientifique, the Ministère de l'Education Nationale, de l'Enseignement et de la Recherche (Grant to C.F. and Action Incitative), Elf Atochem, and Elf Aquitaine. Special thanks are due to Ms. N. Kyritsakis, Dr. A. DeCian, and Prof. J. Fischer for the X-ray structure determination of 3. We also thank Dr. R. Graff (Service Commun RMN, Université Louis Pasteur) and Mr. R. Hubert (Laboratoire de Spectrométrie de Masse, Université Louis Pasteur).

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Journal Article↗
PubMed2000

Theoretical study of two-dimensional COSY experiments for S = 7/2 spins: application to (59)Co in the tetrahedral cluster HFeCo(3)(CO)(11)PPh(2)H.

The first investigation and analysis of (59)Co 2D NMR homonuclear chemical shift correlation spectra are reported for the tetrahedral mixed-metal cluster HFeCo(3)(CO)(11)PPh(2)H. For this cluster in solution, the (59)Co 2D COSY and DQF COSY NMR spectra prove the existence of a scalar coupling between (59)Co nuclei. In order to obtain a value of this coupling, the 2D COSY and DQF COSY NMR spectra for a three-spin 7/2 AX(2) system have been simulated by numerical density matrix calculations. The comparison between experimental and theoretical 2D NMR spectra gives a spin-coupling constant |(1)J((59)Co - (59)Co)| = (115 +/- 20) Hz for this cluster. Experimental measurements of T(1) and of the line widths for cobalt 59 as well as theoretical (59)Co 1D NMR spectra are reported and support our findings.

Cobalt Isotopes↗
PubMed1995

Perfused Kupffer cell mass. Correlation with histology and severity of chronic liver disease.

The perfused Kupffer cell mass determines sulfur colloid distribution by liver spleen scan (LSS) and is proportional to the perfused hepatocyte mass. This accounts for the correlation of sulfur colloid distribution with tests of hepatic function and raises the question of whether the LSS can be used as a quantitative test of hepatic function. The recent ability to precisely measure sulfur colloid distribution by single-photon-emission computerized tomography (SPECT) prompted us to evaluate the clinical value in 329 consecutive patients with adequate LSS and clinical information, of which 27 apparent normals and 220 patients with chronic liver disease (CLD) were included in this study. The liver-bone marrow index (LBI) indicated the distribution of counts between the liver and bone marrow. The liver-spleen index (LSI) indicated the distribution between liver and spleen adjusted for spleen size. The LBI and LSI correlated with each other (r = 0.753; P < 0.001). The arithmetic mean of LBI and LSI was defined as the severity score. Detailed clinical evaluation was available in these patients and included 109 who had liver biopsy. A severity score in 27 normals was 102 +/- 5 (mean +/- SD) with all values > 85. The severity score correlated with hepatic fibrosis (r = -0.694; P < 0.001) in 109 patients with benign liver disease who had recent biopsies and with the Child-Pugh classification (r = 0.78; P < 0.001) in 220 patients with CLD.(ABSTRACT TRUNCATED AT 250 WORDS)

Biopsy↗
PubMed1995

The liver-spleen scan as a quantitative liver function test: correlation with liver severity at peritoneoscopy.

Sulfur colloid distribution on liver-spleen scan is determined by the perfused Kupffer cell mass. The perfused Kupffer cell mass is proportional to the perfused hepatocyte mass, but is less affected by acute changes in hepatocyte function. Thus, sulfur colloid distribution parameters (precisely measured by quantitative liver-spleen scan [QLSS]) may be an excellent test of the perfused hepatic mass. Although no gold standard exists for confirmation, a close correlation should exist between liver disease severity assessed at peritoneoscopy and sulfur colloid distribution. Peritoneoscopy severity (scored as total peritoneoscopy score [PS]; range, 0-5) was assessed in 76 patients who also had QLSS. Multivariate equation were generated to estimate liver disease severity from the QLSS. These were then applied prospectively in 20 consecutive patients to validate these equations. In 76 patients, 62 were evaluated because of chronic liver disease (CLD) and included those with micronodular (20) and macronodular (20) cirrhosis with various degrees of severity (Child's A, 16; B, 29; C, 17). Multivariate analysis yielded a number of combinations of QLSS parameters that correlated with peritoneoscopic severity. These equations were used to estimate liver disease severity. Estimates of liver disease severity (estimated PS [EPS]) correlated well with the PS in these 76 patients (r = .9064; r2 = .8216; P < .0001). Adding histological fibrosis to the QLSS parameters yields an equation for estimating PS that was even more effective (r = .9462; r2 = .8953; P < .001). However, validation of multivariate equations requires confirmation of their value in a second population.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Radioimmunodetection of Hodgkin's disease and non-Hodgkin's lymphomas with monoclonal antibody to eosinophil peroxidase.

The purpose of this study was to determine if a radiolabeled murine monoclonal antibody (EOS) directed against eosinophil peroxidase would localize specifically to tumor sites in patients with lymphomas infiltrated by eosinophils. Ten patients with Hodgkin's disease and eosinophilia, three patients with non-Hodgkin's lymphomas and eosinophilia and five control patients received an intravenous injection of 3-10 mg of EOS antibody radiolabeled with 74-155 MBq (2.0-4.2 mCi) of 111In. At intervals of 24, 48 and 72 hr after injection, gamma camera images were obtained along with blood and urine specimens and the imaging results were correlated with the results of other staging modalities. As early as 24 hr after antibody injection, there was clear visualization of identifiable sites of lymphoma with eosinophilia greater than 1 cm in size, including the spleen, bone marrow and lymph nodes. Although EOS also localized nonspecifically to the liver and, in some patients, to the nasopharynx, there was no appreciable uptake in normal bone marrow, spleen, uninvolved lymph nodes, lymphomas without eosinophilia or various other pathologic conditions without eosinophilia. Except for transient pain at tumor sites in three patients, no adverse reactions were noted. We conclude that a radiolabeled monoclonal antibody directed against eosinophil peroxidase localizes to lymphoma sites infiltrated by eosinophils.

Adult↗
PubMed1992

Diagnosis of myocardial contusion. Quantitative analysis of single photon emission computed tomographic scans.

Prior studies from our institution have shown that single photon emission computed tomography is sensitive (100%) in predicting patients at risk for serious arrhythmias. However, the positive predictive value is low (15% to 20%). The purpose of this study was to determine if quantitative analysis of single photon emission computed tomographic defects could improve predictive value. One hundred seventy-five patients with positive single photon emission computed tomographic scans were studied. One hundred two patients developed arrhythmias, 42 of which were ventricular. Arrhythmias were associated with all defect loci and all defect sizes. The incidence of arrhythmias did increase with increasing size. Patients were at risk for arrhythmias up to 72 hours after trauma. The value of single photon emission computed tomography is its ability to predict patients at risk for arrhythmias. This study shows that any single photon emission computed tomographic defect, regardless of location or size, is a significant predictor of arrhythmias.

Adolescent↗
PubMed1991

[Elimination half life of the opiate etorphine].

In the capacity of an initial study both, the pharmacocinetics as well as the metabolism of etorphine were investigated. In a self-trial a bolus of 8 micrograms tritium-marked etorphine as administered intravenously and subsequently the half-lives in serum and urine were determined. To achieve this, etorphine and etorphineclucuronide were separated via HPLC and then quantified by measuring the radioactivity. The development of the concentrations was devided into 3 phases. Within the first phase half-lives of etorphine and etorphineglucuronide were found in the range of 0.3-1 hour in serum and, likewise, in urine. During the second phase the estimated half-life of etorphineglucuronide was 160-260 hours in serum as well as in urine. Within the last phase half-lives in urine were 47 hours for etorphine and 41 hours for etorphineglucuronide while the calculation of the half-lives in serum was not sufficiently feasible.

Adult↗
PubMed1989

Radionuclide detection of duodenal ulcer perforation.

An elderly obese male with a lengthy history of melanotic stools was admitted and was shown to have a posterior duodenal ulcer by endoscopy. He became obtunded and developed infected ascites. Because of his obesity, ascites, and inability to cooperate, the GI radiologist felt that a Gastrografin upper GI series would not be helpful. We therefore gave the patient 99mTc-labeled sulfur colloid and tap water through his nasogastric tube. We were able to clearly image a site of perforation at the duodenal bulb communicating with the lesser sac.

Aged↗
PubMed1987

Diagnosing iliofemoral vein occlusion from radionuclide blood pool venography.

There have been reports regarding the efficacy of Tc-99m labeled RBC venograms. The authors have found that potentially dangerous iliac vein occlusions can be missed unless especially careful attention is paid in looking for any asymmetry of the iliac vessels with respect to intensity, thickness, and/or definition, along the whole or at least 50% of one of the vessel's length, and the presence or absence of blood pool activity in the most proximal portion of the left common iliac vein, i.e., whether the activity arises from the IVC or the aorta. Eight (21%) of 38 consecutive labeled RBC venograms performed at this institution over six months produced findings that met criteria and/or. Iliofemoral vein occlusion was confirmed in six of the eight patients (16% of all patients). Thus, while the above criteria are not pathognomonic for iliofemoral vein occlusion, their rigid application has enabled the authors to detect a significant proportion of patients with iliofemoral occlusions which would otherwise have gone undetected. All eight cases were confirmed by further workup with direct injection radionuclide venography or contrast venography.

Erythrocytes↗
PubMed1986

Diagnosis of traumatic cardiac contusion.

Cardiac contusion following blunt chest trauma remains a diagnostic problem because of a lack of sensitive diagnostic tests. This study evaluated thallous chloride Tl 201 single-photon-emission computed tomography in a series of 48 patients following blunt chest trauma. Of the 48 patients, 23 had normal scans. None of these patients proved to have serious arrhythmias during three days of continuous monitoring. Of 25 patients with abnormal or ambiguous studies, five (20%) developed serious arrhythmias requiring therapy. Single-photon-emission computed tomography scanning thus was sensitive in indicating that group of patients at risk of serious arrhythmias, and may therefore prove to be a useful screening test to determine the need for hospitalization and arrhythmia monitoring following blunt chest trauma.

Accidents, Traffic↗
PubMed1985

Radionuclide evaluation of tubal function.

The tubal capacity to transport radioactively labeled human albumin microspheres deposited in the vaginal fornix and cervical canal and to concentrate them on the ovarian surface was evaluated in a group of 34 patient-volunteers. One millicurie of technetium-99 was used to label human albumin microspheres of 20 mu in diameter, suspended in 1 ml of saline. The distribution of the radioactive material was imaged on a gamma camera at different intervals between 15 and 240 minutes. The radiation dose to the ovaries was estimated to be similar to that of a hysterosalpingogram. The results of the radionuclide evaluation were compared with the surgical findings at the time of laparoscopy or laparotomy performed for diagnostic or therapeutic reasons. The overall correlation was 87.1%. It would appear that as opposed to the traditional hysterosalpingogram, a radionuclide test may give a better understanding of the functional capacity of the tube and may also prove a useful method in the evaluation of the results of tubal microsurgical procedures.

Adult↗
PubMed1985

Radionuclide hysterosalpingography for evaluation of fallopian tube patency.

A prospective study was undertaken to evaluate the efficacy of radionuclide hysterosalpingography (RNHSG) using a technique with some modifications, that was described by Iturralde and Ventner (1). As these investigators demonstrated, technetium-labeled human albumin microspheres (HAM) will normally migrate spontaneously from the vagina to the ovaries. This study confirms that in the presence of fallopian tube obstruction, fibrosis and/or lack of motility, this migration does not take place, and that the presence or absence of migration of HAM can be imaged with a gamma camera. In the evaluation of 52 tubes we found that the efficiency of RNHSG for evaluation of fallopian tube patency when compared with contrast hysterosalpingography and/or direct observation of surgical pathology was over 94%. RNHSG is an essentially innocuous technique for assessing functional and mechanical fallopian tube obstruction that can be performed with conventional nuclear imaging equipment.

Evaluation Studies as Topic↗
PubMed1984

Comparison of ultrasound and hepatobiliary imaging in the early detection of acute total common bile duct obstruction.

We retrospectively reviewed the clinical data of 17 selected patients who underwent hepatobiliary imaging studies using technetium Tc 99m iprofenin that demonstrated acute complete common bile duct obstruction, and who also had a temporally related ultrasonographic study of the hepatobiliary tree. We compared the accuracy of the two methods in the detection of common duct obstruction. The average duration of symptoms was 2.9 days. Serum bilirubin levels averaged 3.3 mg/dL and the average alkaline phosphatase level was 336 mg/dL. The serum amylase level was elevated in only three patients. Ultrasonographic dilatation of the ductal structures was present in seven (41%) of 17 patients; 88% of the patients had other manifestations of gallbladder disease on ultrasonography--either cholelithiasis, dilatation of the gallbladder, or wall thickening. Of 15 patients who were operated on, 11 had stones impacted at the ampulla of Vater. There was a poor correlation of ultrasonographic ductal dilatation and operative findings of ductal dilatation. This study shows the superiority of nuclear imaging over ultrasonography in the early detection of acute, common bile duct obstruction.

Adult↗
PubMed1983

Total bile duct obstruction. Prompt diagnosis by hepatobiliary imaging.

The value of hepatobiliary imaging for the early diagnosis of total bile duct obstruction is not well known. Four hundred eighteen technetium Tc 99m iprofenin (Pipida) hepatobiliary scans were reviewed, and the anatomic diagnosis was established by postmortem examination, laparotomy, endoscopic retrograde cholangiopancreatography, transhepatic cholangiography, or ultrasound. Sixty cases demonstrated the technetium Tc 99m iprofenin pattern of total bile duct obstruction. Of these, 41 had total bile duct obstruction, 14 had advanced hepatocellular disease, four had massive liver metastasis, and one had portal vein thrombosis. The test was 100% sensitive for the detection of total bile duct obstruction. When the bilirubin level was less than 10 mg/dL, the predictive value was 100%. As the bilirubin level rose to 15 and 20 mg/dL, the predictive value fell to 92% and 88%, respectively. If performed early, hepatobiliary scanning is the preferred test for suspected total bile duct obstruction.

Bilirubin↗
PubMed1983

Radionuclide enemas for localization of gastrointestinal bleeding sites.

The anatomical site of gastrointestinal bleeding may not be determined accurately with a scintigraphic bleeding scan. A case in which a radionuclide enema following a positive scintigraphic bleeding scan helped to guide the surgeon to the appropriate bleeding site, is presented. The radionuclide enema also obviates the need for barium examinations that would interfere with subsequent angiography.

Aged↗