bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tetrahedral intermediates in reactions of carboxylic acid derivatives with nucleophiles
Authors: Adler Martin , Adler Sandra , Boche Gernot 
Published: October 2004

AbstractTransacylation reactions of carboxylic acids, carboxylic acid esters, carboxylic acid amides and other carboxylic acid derivatives are among the most widespread and most important reactions in chemistry and biochemistry. Already in 1887, Claisen suggested a tetrahedral intermediate in transformations of carboxylic acid derivatives with nucleophiles. A historical overview gives insight into the studies to detect possible tetrahedral intermediates in such reactions. However, only in recent years has detailed information concerning the structures of such species become available. In this review, neutral, cationic and anionic tetrahedral intermediates are described which serve as models for transacylations under neutral, acid‐catalysed or basic conditions. The characteristically different structures correspond nicely with experimental experience with reactions of carboxylic acid derivatives and with quantum chemical model calculations on tetrahedral intermediates. Finally, by means of model calculations, an explanation is given for the fast reactions of Weinreb amides, RC(O)N(CH3)OCH3, with organolithium and even with Grignard reagents: the reactions are determined by comparatively stable chelate transition states. Copyright © 2004 John Wiley & Sons, Ltd.
Tailored noise waveform/collision‐induced dissociation of ions stored in a linear ion trap combined with liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry
Authors: Vilkov Andrey N. , Bogdanov Bogdan , Paša‐Tolić Ljiljana , Prior Dave C. , Anderson Gordon A. , Masselon Christophe D. , Moore Ronald J. , Smith Richard D. 
Published: October 2004

AbstractA new collision‐induced dissociation (CID) technique based on broadband tailored noise waveform (TNW) excitation of ions stored in a linear ion trap has been developed. In comparison with the conventional sustained off‐resonance irradiation (SORI) CID method commonly used in Fourier transform ion cyclotron resonance mass spectrometry (FTICR‐MS), this MS/MS technique increases throughput by eliminating the long pump‐down delay associated with gas introduction into the high vacuum ICR cell region. In addition, the TNW‐CID method speeds spectrum acquisition since it does not require Fourier transformation, calculation of resonant frequencies and generation of the excitation waveforms. We demonstrate TNW‐CID coupled with on‐line capillary reverse‐phase liquid chromatography separations for the identification of peptides. The experimental results are compared with data obtained using conventional quadrupole ion trap MS/MS and SORI‐CID MS/MS in an ICR cell. Copyright © 2004 John Wiley & Sons, Ltd.
Derivatization of phosphorylated peptides with S‐ and N‐nucleophiles for enhanced ionization efficiency in matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Klemm Clementine , Schröder Stephan , Glückmann Matthias , Beyermann Michael , Krause Eberhard 
Published: October 2004

AbstractThe identification of phosphorylation sites is essential for a full understanding of the cellular functions of proteins. However, mass spectrometric analysis is often hampered by the low abundance of phosphoproteins, the difficulty of obtaining full sequence coverage by specific proteolysis reactions, and the low ionization efficiency of phosphopeptides compared with their non‐phosphorylated analogs. In the present work a beta‐elimination/Michael addition was used to replace the phosphate groups of pSer or pThr by a group which gives rise to an enhanced ionization efficiency. In order to find optimum reaction conditions, beta‐elimination/Michael addition was examined using phosphorylated model peptides. Whereas complete elimination of phosphate could be achieved by treatment with barium hydroxide in organic solvents such as ethanol or acetonitrile, the yield of the Michael adduct strongly depended on the nucleophile and the peptide sequence. Reaction with 2‐phenylethanethiol, p‐bromophenethylamine and ethylenediamine clearly resulted in products showing higher matrix‐assisted laser desorption/ionization (MALDI) signal intensities compared with those of the corresponding phosphorylated precursors. The method was successfully used to identify phosphorylated sequences of ovalbumin and human Stat1 by in‐gel derivatization with 2‐phenylethanethiol and subsequent peptide mass fingerprint analysis of the trypsin digests. Copyright © 2004 John Wiley & Sons, Ltd.
Identification of intact long‐chain p‐hydroxycinnamate esters in leaf fibers of abaca (Musa textilis) using gas chromatography/mass spectrometry
Authors: del Río José C. , Rodríguez Isabel M. , Gutiérrez Ana 
Published: October 2004

AbstractThe study of acetone‐extractable components from the leaf fibers of the non‐wood plant abaca (Musa textilis) resulted in the isolation and identification of series of intact hydroxycinnamate esters consisting of ferulic and p‐coumaric acids esterified to long‐chain fatty alcohols (C20 to C28) and ω‐hydroxyfatty acids (C22 to C28). These series of compounds were characterized by high‐temperature gas chromatography/mass spectrometry (GC/MS) using capillary columns (12 m length) with thin films that allowed the analysis of intact (i.e., without prior saponification) hydroxycinnamate esters. Characterization of intact individual compounds was achieved based on the mass spectra obtained by GC/MS of the underivatized compounds and their methyl and/or trimethylsilyl ether derivatives. Copyright © 2004 John Wiley & Sons, Ltd.
Proximal B cell receptor signaling pathways
Authors: Skaggs Brian J. , Clark Marcus R. 
Published: October 2004

AbstractEngagement of the B cell antigen receptor by antigen initiates a complex and interconnected cascade of signaling pathways that determine whether a B cell will divide, differentiate, or die. Both biochemical and genetic studies have defined the principal molecules, including the BCR components Igσ and Igβ, Src kinases, Syk, and Btk. Linker proteins such as BLNK have recently been shown to play a vital role in organizing proximal signaling molecules and coupling the BCR to distal signaling pathways. In this review, we will pay particular attention to how BCR‐proximal kinases coordinate the activation of PLCγ2, leading to the initiation and amplification of BCR‐mediated calcium flux and the activation of PI‐3 kinase.
Extrusion of Starch Acetate with Mixed Blowing Agents
Authors: Zhou Jiahua , Hanna Milford A. 
Published: October 2004

AbstractThere are three consecutive processes involved in extrusion foaming: extrusion (mixing and melting), cell initiation and cell growth, and cooling. Extrusion of polysaccharide‐based polymers with a single blowing agent is limited by cost, safety, and the various physicochemical requirements of the three processes in extrusion. Balancing or comprising between requirements of various processes should be maintained in the optimization process. Secondary blowing agents such as pentane, ethyl acetate, and sodium bicarbonate were used in water and ethanol‐based foaming processes. The introduction of secondary blowing agents of low surface tension or, in other words, of high evaporation rate, such as pentane and ethyl acetate, increased cell density while the addition of high surface tension secondary blowing agents reduced cell density. The specific volume of foams can be increased by secondary blowing agents by increasing nuclei density, increasing solvency, and increasing the amount of vaporized blowing agent.
EPR Studies of Thermally Treated Oxidized Corn Starch
Authors: Bidzińska Ewa , Dyrek Krystyna , Fortuna Teresa , Łabanowska Maria , Pietrzyk Sławomir 
Published: October 2004

AbstractThe formation of radicals in oxidized corn starch at 20–250°C in air was investigated by quantitative EPR spectroscopy. It was found that the presence of carboxyl groups in the oxidized starch increases the starch's ability to generate radical species. Introducing Cu2+ ions into the starch, as a catalyst or as an EPR probe, leads to the formation of copper‐carboxyl complexes containing two carboxyl ligands. Drastic increase in the number of radical species at about 250°C is accompanied by a decrease in the intensity of EPR signal of Cu2+‐carboxyl complexes, indicating that the thermal degradation of oxidized corn starch occurs with the formation of radicals, probably via breaking the chemical bonds in the carboxyl groups.
Resistant Starch Made from Banana Starch by Autoclaving and Debranching
Authors: González‐Soto Rosalia A. , Agama‐Acevedo Edith , Solorza‐Feria Javier , Rendón‐Villalobos Rodolfo , Bello‐Pérez Luis Arturo 
Published: October 2004

AbstractResistant starches (RS) were prepared from banana starch by debranching with pullulanase for different times and after autoclaving treatment. The different treatments produced seven RS products, which were tested with respect to available starch (AS), RS and in vitro hydrolysis rate. The control sample (without debranching) had the highest AS (80.5%) and the lowest RS content (9.1%). The samples debranched for 5 h and longer did not show significant differences (α = 0.05) in AS (approximately 72%) and RS (approximately 18%). The RS values obtained in the samples prepared were twice as high as that of the control sample. However, the sample debranched for the longest time had the highest hydrolysis rate, demonstrating that this product has a high digestion rate. Banana starch is a good source for RS preparation by autoclaving due to its high RS content and can be an alternative source in developing countries for obtaining a nutraceutic ingredient for functional food preparation.
In vitro Digestibility of Cross‐Linked Starches – RS4
Authors: Shin Malshick , Song Jiyoung , Seib Paul A. 
Published: October 2004

AbstractIn vitro digestibility of cross‐linked starches (RS4 type), which were prepared from wheat, corn, rice, potato, and high‐amylose corn starches, was determined by Prosky AOAC and pancreatin gravimetric (P/G) methods. The RS levels of RS4 starches obtained by the AOAC method were higher than those by the P/G method. Pronase treatment before digestion with heat‐stable α‐amylase (AOAC method) gave similar RS levels as those by P/G method. The shapes of residues after digestion by the AOAC method were not different from untreated ones, but those after digestion by the P/G method showed irregular and fluffy forms. It was found that the P/G method provided more exhaustive digestion of RS4 starches than the AOAC method.
Recurrent Laryngeal Nerve Palsy in Well‐differentiated Thyroid Carcinoma: Clinicopathologic Features and Outcome Study
Authors: Chan Wai‐Fan , Lo Chung‐Yau , Lam King‐Yin , Wan Koon‐Yat 
Published: October 2004

AbstractInvolvement of the recurrent laryngeal nerve (RLN) by well‐differentiated thyroid carcinoma may not invariably lead to unilateral cord palsy, although the presence of RLN palsy is associated with locally advanced disease. The present study evaluates the clinicopathologic features and outcomes of patients surgically treated for well‐differentiated thyroid carcinoma with documented nonfunctioning RLN at presentation. From 1970 to 2002, 20 of 709 patients undergoing surgical treatment for well‐differentiated thyroid carcinoma were found to have ipsilateral unilateral cord palsy by routine preoperative laryngoscopy. There were 5 men and 15 women with a median age of 70 years. Nine patients (45%) did not have a clinically palpable thyroid mass, and hoarseness was the primary presenting symptom. All patients had histologically confirmed pT4 papillary thyroid carcinoma with a median size of 4 cm. Cervical nodal and pulmonary metastases were detected in 14 (70%) and 2 (10%) patients, respectively. The ipsilateral recurrent nerve was transected in all patients because of gross tumor involvement, and 19 patients underwent total or completion total thyroidectomy. Resection was incomplete in 15 patients, including 2 who underwent a debulking procedure and required reoperation for local control. Postoperative radioactive iodine ablation and external‐beam irradiation were administered to 18 and 13 patients, respectively. Over a median follow‐up of 4.5 years, 10 patients survived without evidence of recurrence, 5 died of disease recurrence, and 5 died of unrelated causes. The 5‐year and 10‐year cause‐specific mortality was 17% and 42%, respectively. Patients developing distant metastasis at presentation or during follow‐up had a significantly increased cause‐specific mortality (p = 0.002). Preoperative RLN palsy can be the first symptom in patients with locally advanced papillary thyroid carcinoma. Despite the adoption of a relatively conservative surgical treatment, long‐term survival can be achieved in selected patients.
Focused Cervical Exploration for Primary Hyperparathyroidism without Intraoperative Parathyroid Hormone Monitoring or Use of the Gamma Probe
Authors: Jacobson Steven R. , van Heerden Jon A. , Farley David R. , Grant Clive S. , Thompson Geoffrey B. , Mullan Brian P. , Curlee Kathleen J. 
Published: October 2004

AbstractSelected patients with primary hyperparathyroidism (pHPT) who have a positive preoperative sestamibi scan can be managed safely and successfully with a focused cervical exploration without either adjuvant intraoperative parathyroid hormone (PTH) monitoring or use of a gamma probe. This article reports a retrospective analysis of a consecutive series of patients surgically treated at a tertiary referral center. From August 1998 to August 2002, 100 patients (68 women, 32 men; mean age 63 years [range: 29–89 years]) underwent a focused cervical approach without intraoperative PTH monitoring or use of the gamma probe after perioperative sestamibi injection. The study group comprised 9% of all patients (n = 1063) undergoing cervical exploration for pHPT during the study period. Ninety patients underwent an initial exploration, and 10 others underwent repeat cervical exploration following prior parathyroid (n = 7) or thyroid (n = 3) operation. Sestamibi scanning correlated with one enlarged parathyroid gland in all patients. Other enlarged glands were, however, not demonstrated in three patients (true positive = 97%; false negative = 3%). The single enlarged glands excised in all patients had a mean weight of 795 mg (range: 90–3640) and were histologically compatible with an adenoma. Postoperatively, 97% of patients were eucalcemic. Three patients remained hypercalcemic (3%). Of the three patients with persistent hypercalcemia, one underwent successful re‐exploration with excision of a 500 mg second adenoma, whereas the other two patients (with confirmed familial HPT) remained hypercalcemic. Mean hospitalization was 0.5 days (range: 0–3 days). There was no operative mortality. No patients had permanent hypocalcemia. Postoperative morbidity occurred in three patients: two self‐limiting cervical hematomas and one permanent vocal cord paralysis. Selected patients with pHPT due to single‐gland disease and an unequivocally positive preoperative sestamibi scan can safely and successfully be managed with a focused unilateral cervical exploration without either intraoperative PTH monitoring or use of the gamma probe. Further experience with this surgical approach seems warranted to determine the overall cure rate, operative morbidity, and the sensitivity and specificity of preoperative localization studies.
Sestamibi Scan–directed Parathyroid Surgery: Potentially High Failure Rate without Measurement of Intraoperative Parathyroid Hormone
Authors: Westerdahl Johan , Bergenfelz Anders 
Published: October 2004

AbstractThe present study evaluated sestamibi scan–directed parathyroidectomy with intraoperative parathyroid hormone (PTH) assessment (ioPTH). The preoperative sestamibi scintigraphies were compared with the intraoperative findings for 103 patients undergoing first exploration for sporadic primary hyperparathyroidism (pHPT). Data were collected prospectively. Ninety‐nine patients (96%) were cured. Patients with persistent pHPT (n = 4) all had an incorrect scintigram as well as an insufficient decline of ioPTH. At operation, 90 patients (87%) had solitary parathyroid adenoma; 12 patients had multiglandular disease. In one patient no enlarged parathyroid gland was found. Overall 77 of 118 abnormal glands (65%) were correctly identified by sestamibi scintigraphy. The sensitivity for localizing a single parathyroid adenoma was 80%. Patients with incorrect scintigrams had a higher proportion of upper pole adenomas than patients with correct scans. High glandular weight and high level of serum PTH were important factors for detectability. Sestamibi scintigraphy did not predict multiglandular disease. However, the use of ioPTH identified 8 of the 9 patients with a positive scan (a solitary focus) and multiglandular disease. In contrast, false‐negative ioPTH led to four unnecessary bilateral explorations in the 63 patients with a scan‐identified adenoma. With the help of ioPTH, a focused parathyroidectomy was accomplished in 43% of scan‐negative patients with a solitary adenoma. In conclusion, sestamibi scintigraphy is an acceptable method for localizing a solitary parathyroid adenoma. However, the technique alone does not reliably predict multiglandular disease. Potentially the failure rate in scan‐directed parathyroidectomy could increase, with up to 10% of patients without ioPTH.
Accuracy of Surgeon‐performed Ultrasound in Parathyroid Localization
Authors: Van Husen Russell , Kim Lawrence T. 
Published: October 2004

AbstractUltrasound is one of the preferred modalities for localization of abnormal parathyroids. Accuracy of ultrasound is technician‐dependent. This study was undertaken to determine the accuracy of surgeon‐performed ultrasound (SPU) for the localization of parathyroid tumors in comparison to radiology‐performed ultrasound (RPU) and nuclear scintigraphy (NS). In this series 74 consecutive patients with untreated primary hyperparathyroidism underwent SPU at the initial clinic visit; 21 of these patients did not undergo surgery and are excluded from the analysis. Of the 53 patients remaining, RPU was obtained in 26, and 52 patients underwent NS. Directed parathyroidectomy was performed with use of the intraoperative parathyroid hormone assay (IOPTH). In all, 46 patients had a single adenoma as indicated by IOPTH and final pathology. Two patients had double gland disease, and 5 patients had multi‐gland hyperplasia. The sensitivity of SPU was 82% and the specificity was 90% in detecting the diseased glands on the correct side (right versus left). The sensitivity for RPU was 42% and the specificity was 92% (n = 26). The sensitivity of NS was 44% and the specificity was 98% (n = 52). In only one case did RPU or NS detect a gland not found by SPU. SPU can be done with accuracy comparable to other ultrasound series in the literature, and it may be superior to RPU or NS in some institutions. It is important for surgeons to be aware of local institutional expertise when relying on RPU and NS during preoperative evaluation prior to directed parathyroidectomy.
Does Robotic Adrenalectomy Improve Patient Quality of Life When Compared to Laparoscopic Adrenalectomy?
Authors: Brunaud Laurent , Bresler Laurent , Zarnegar Rasa , Ayav Ahmet , Cormier Luc , Tretou Sebastien , Boissel Patrick 
Published: October 2004

AbstractThe purpose of this study was to evaluate and compare perioperative quality of life in patients after laparoscopic versus robotic adrenalectomy. From November 2000 through August 2003, 33 consecutive patients underwent laparoscopic (n = 14) and robotic (n = 19) adrenalectomy. Data were obtained prospectively during management and by patient questionnaire (SF36, State‐Trait Anxiety Inventory) preoperatively and postoperatively, at day 4 and at 6 weeks. Physical functioning, role limitations due to physical health problems, and bodily pain (Physical SF36 scores) were decreased at day 4 (p = 0.004) in all patients when compared to preoperative levels; and became similar to preoperative levels after 6 weeks. Patients who underwent robotic adrenalectomy had an increased score at 6 weeks of role limitations due to emotional problems (Mental SF36 score) (p = 0.03). No other significant difference was observed between patients after laparoscopic or robotic adrenalectomy. Although state anxiety was decreased postoperatively at day 4 and at 6 weeks (p = 0.01) in all patients, there was no significant difference between laparoscopic and robotic adrenalectomy. Postoperative pain was similar in both groups but had a tendency to be higher when patients underwent a left adrenalectomy (p = 0.07). Similarly, state anxiety had a tendency to be higher postoperatively at day 4 in patients after left adrenalectomies (p = 0.06). This study provides an evaluation of perioperative quality of life in patients after minimally invasive (laparoscopic and/or robotic) adrenalectomy. We observed no major difference between patients who underwent laparoscopic or robotic adrenalectomy. Thus, patients’ perioperative quality of life is not a justifiable parameter on which to base promotion of robotic adrenalectomies.
Multiple Endocrine Neoplasia Type 1 Parathyroid Adenoma Development over Time
Authors: Doherty Gerard M. , Lairmore Terry C. , DeBenedetti Mary K. 
Published: October 2004

AbstractMultiple gland parathyroid disease is one of the hallmarks of multiple endocrine neoplasia (MEN) type 1. Often mislabeled parathyroid hyperplasia, the process is actually the development of multiple adenomas. Some clinicians have reported results of selective parathyroidectomy in this group, removing only grossly enlarged glands. We argue that all the glands are at risk and should be addressed at any planned parathyroid intervention. Our hypothesis is that, given sufficient time, patients would all develop adenomas in each of the parathyroid glands. Our available data to address this issue are the parathyroidectomy results from a single institution series. Patients who had initial parathyroid exploration for hyperparathyroidism in the setting of MEN‐1 were reviewed. This study includes those patients who had the weights of the resected glands documented; 23 men and 21 women met the criteria. The total weight of the parathyroid glands did not vary with the age of the patient at operation. However, the number of normal glands identified did vary significantly with age (p < 0.02), with older patients being less likely to have any normal parathyroid glands. Although total parathyroid weight may correlate with development of hypercalcemia and indications for operation, the involvement of multiple parathyroid glands in MEN‐1 is a function of time, as independent events in each gland must occur. Given time, MEN‐1 patients all develop multiple gland disease, and this reality must be used in planning operative management for patients with this syndrome.