bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Short and Concise Asymmetric Synthesis of Hamigeran B
Authors: Trost Barry M. , Pissot‐Soldermann Carole , Chen Irwin 
Published: December 2004

AbstractThe interesting biological properties of the hamigerans wherein hamigeran B is a potent antiviral agent with low cytotoxicity to host cells make these deceptively simple looking structures challenging synthetic targets. A strategy to hamigeran B evolved wherein the three contiguous stereocenters are established ultimately from a Pd catalyzed asymmetric allylic alkylation (AAA). The latter involves an asymmetric allylation of a non‐stabilized ketone enolate in 77 % yield and 93 % ee. By using this process, (S)‐5‐allyl‐2‐isopropyl‐5‐methyl‐1‐trifluoromethanesulfonyloxycyclopentene becomes available in four steps from 2‐methylcyclopentanone. Introduction of the aryl unit by cross‐coupling proceeded intermolecularly but failed intramolecularly. On the other hand, reductive removal of the triflate permitted a Heck reaction to effect intramolecular introduction of the aryl ring. The unusual conformational properties of this molecular architecture are revealed by the regioselectivity of the β‐hydrogen elimination in the Heck reaction and the diastereoselectivity of the reduction establishing the stereochemistry of the carbon bearing the isopropyl group. The successful route consists of 15 steps from 2‐methylcyclopentanone and dimethylorcinol illustrating the efficiency of the route based upon the Pd AAA.
A Phase I trial of fixed dose rate gemcitabine and capecitabine in metastatic renal cell carcinoma
Authors: Rini Brian I. , Weinberg Vivian , Small Eric J. 
Published: December 2004

AbstractBACKGROUNDMetastatic renal cell carcinoma (RCC) has modest response rates to chemotherapy with gemcitabine and 5‐fluorouracil (5‐FU). Fixed dose rate gemcitabine infusion leads to enhanced intracellular accumulation of drug and possible augmented clinical effect. To determine the toxicity of this combination therapy in metastatic RCC, a Phase I trial was conducted.METHODSPatients with metastatic RCC were enrolled in a Phase I dose escalation trial. Patients received fixed dose rate gemcitabine on Days 1, 8, and 15 in combination with capecitabine, an oral 5‐FU analog, given on Days 1–21 of a 28‐day cycle.RESULTSNine patients were enrolled at one of two dose levels. The initial dose level produced dose‐limiting toxicity (DLT), including prominent palmar‐plantar erythrodysesthesia (hand‐foot syndrome). A modified second dose level also resulted in DLT, precluding further study. No central nervous system (CNS) toxicity was observed in three patients with CNS metastases. Two patients demonstrated an objective partial response.CONCLUSIONSFixed dose rate gemcitabine in combination with capecitabine produced unacceptable toxicity in patients with advanced RCC. Further development of this schedule in RCC cannot be recommended. Cancer 2005. © 2004 American Cancer Society.
Predicting the status of axillary sentinel lymph nodes in 4351 patients with invasive breast carcinoma treated in a single institution
Authors: Viale Giuseppe , Zurrida Stefano , Maiorano Eugenio , Mazzarol Giovanni , Pruneri Giancarlo , Paganelli Giovanni , Maisonneuve Patrick , Veronesi Umberto 
Published: December 2004

AbstractBACKGROUNDReliable predictors of metastatic involvement would enable a better selection of candidate patients for sentinel lymph node biopsy (SLNB) and possibly allow identification of patients with such a low risk of axillary sentinel lymph node (SLN) involvement to be even spared SLNB.METHODSThe authors evaluated 4351 consecutive patients surgically treated for breast carcinoma who also underwent SLNB. Clinicopathologic features significantly associated with SLN metastases by univariate analysis were included in a multivariate model.RESULTSBy multivariate analysis, the prevalence of SLN metastases was associated directly with tumor size, multifocality, and with the occurrence of peritumoral vascular invasion (PVI; all P < 0.0001), and was associated inversely with a favorable histotype (P = 0.0007) and lack of progesterone receptors (P = 0.004). A predictive model based on the features more closely associated with SLN status documented that the patients with a favorable tumor type ≤ 1 cm in size and without PVI (n = 178 [4% of the population]) had the lowest risk of SLN metastases (9.5%) whereas patients with tumors > 2 cm and with PVI (n = 250 [5.7% of the population]) had the highest risk (77.2%) of SLN involvement.CONCLUSIONSTumor size and PVI emerged as the most powerful independent predictors of SLN metastases. Although no combination of features identified patients with a < 9.5% risk of SLN metastases, the current data may be used to tailor the management of patients with breast carcinoma with the aim of minimizing as much as possible the diagnostic and therapeutic procedures, thus improving the quality of life of the patients without any adverse effect on their survival rates. Cancer 2005 © 2004 American Cancer Society
Cyto‐ and chemoarchitecture of the cerebral cortex of an echidna (Tachyglossus aculeatus). II. Laminar organization and synaptic density
Authors: Hassiotis Maria , Paxinos George , Ashwell Ken W.S. 
Published: December 2004

AbstractWe have examined the distribution and morphology of neurons immunoreactive for nonphosphorylated neurofilament protein (SMI‐32 antibody), calcium‐binding proteins (parvalbumin, calbindin, calretinin), and neuropeptide Y as well as neurons reactive for NADPH diaphorase in the cerebral cortex of the Australian short‐beaked echidna (Tachyglossus aculeatus). We have also studied synaptic morphology and density in S1 somatosensory cortex and assessed parameters associated with metabolic activity of the cerebral cortex (vessel volume density, mitochondrial volume density, and mitochondrial numerical density) in semi‐ and ultrathin sections. SMI‐32 immunoreactivity was found mostly in layer V pyramidal neurons in selected cortical regions (S1, PV, V1, A). These neurons often showed atypical morphology compared with therian cortex. Neurons immunoreactive for calcium‐binding proteins were broadly similar in both morphology and distribution to those seen in therian cortex, although calretinin‐immunoreactive neurons were rare. Both Gray type I and Gray type II synapses could be identified in echidna S1 cortex and were similar to those seen in therian cortex. Peak synaptic density was in upper layer IV, followed by layer I, lower layer II, and upper layer III. Most synapses were of type I (72%), although types I and II were encountered with similar frequency in lower layer II and upper layer III. The capillary volume fraction values obtained for the echidna (from 1.18% in V1 to 1.34% in S1 cortex) fall within the values for rodent cortex. Similarly, values for mitochondrial volume fraction in echidna somatosensory cortex (4.68% ± 1.76%) were comparable to those in eutherian cortex. J. Comp. Neurol. 482:94–122, 2005. © 2004 Wiley‐Liss, Inc.
Taste bud development in the channel catfish
Authors: Northcutt R. Glenn 
Published: December 2004

AbstractTaste bud formation in channel catfish is first seen to occur in stage 39 embryos, when taste bud primordia (stage 1), consisting of three to five cells, including a single calretinin‐positive cell, can be recognized within the oropharyngeal cavity and maxillary barbels. Within a short time (stage 40), stage 2 taste bud primordia are apparent and include two or three calretinin‐positive cells. The number of calretinin‐positive cells continues to increase (stage 3), and the primordia begin to erupt as mature taste buds (stage 4) by embryonic stage 48. This same pattern of taste bud development characterizes other regions of the head, with calretinin‐positive cells first detected around the mouth and on the other barbels by stage 41 and on the rest of the head by stage 48. The development of trunk taste buds lags far behind that of the head, with the first calretinin‐positive cells occurring on the lobes of the caudal fin by stage 48 and on the remaining fins by stage 50. Taste bud primordia on the trunk proper do not begin to appear until stage 53, when the larvae begin to feed, and these receptors begin to erupt only in 1‐week‐old larvae. Fibers of the facial nerve, which innervate all external taste buds, ramify within the ectoderm prior to the first appearance of taste bud primordia or their precursors. J. Comp. Neurol. 482:1–16, 2005. © 2004 Wiley‐Liss, Inc.
Connectivity and cytoarchitecture of the ventral telencephalon in the salamander Plethodon shermani
Authors: Laberge Frédéric , Roth Gerhard 
Published: December 2004

AbstractThe cytoarchitecture and axonal connection pattern of centers in the ventral telencephalon of the salamander Plethodon shermani were studied using biocytin for anterograde and retrograde labeling of cell groups, as well as by intracellular injections. Application of biocytin to the main and accessory olfactory bulbs identified the olfactory pallial regions and the vomeronasal portion of the amygdala, respectively. According to our results, the amygdala of Plethodon is divided into (1) a rostral part projecting to visceral and limbic centers and receiving afferents from the dorsal thalamus, and (2) a caudal part receiving accessory olfactory input. The striatopallial transition area (SPTA) lies rostrodorsally to the caudal (vomeronasal) amygdala and is similar in connections and possibly in function. The rostral striatum has few descending projections to the medulla, whereas the intermediate striatum sends strong projections to the tegmentum and medulla. The caudal striatum has strong ascending projections to the striatum and descending projections to the ventral hypothalamus. The dendritic trees of neurons labeled below the striatum and in the SPTA spread laterally from the soma, whereas dendrites of striatal neurons converge into the laterally situated striatal neuropil. In the caudal amygdala, three distinct types of neurons are found differing in dendritic arborization. It is concluded that, hodologically, the rostral part of the urodele amygdala corresponds to the central and basolateral amygdala and the caudal part to the cortical/medial amygdala of mammals. The urodele striatum is divided into a rostral striatum proper, an intermediate dorsal pallidum, and a caudal part, with distinct connections described here for the first time in a vertebrate. J. Comp. Neurol. 482:176–200, 2005. © 2004 Wiley‐Liss, Inc.
The development of heparan sulfate sugars as therapeutics: Versatility that couples stem cells, tissue engineering, and wound repair
Authors: Nurcombe Victor , Kumarasuriyar Arjuna , Cool Simon M. 
Published: December 2004

AbstractThe extracellular matrix (ECM) is a dynamically complex component of all tissues, especially during phases of growth and development. Although historically thought of as “ground substance” or “glycocalyx,” it actually functions as a scaffold for tissue morphogenesis, provides cues for cell proliferation and differentiation, promotes the maintenance of differentiated tissues, and both triggers and enhances the repair response after injury. Although various types of collagens, adhesion glycoproteins, growth factors, and chemokines are present in the extracellular matrices in tissue‐ and temporal‐specific manners, a large fraction of the bioactivity is carried by its sugar component, and especially the heparan sulfate glycosaminoglycans. Because tissue morphogenesis is mediated by multiple ECM influences and by multiple active sites on these components, it is now becoming clear that heparan sulfates play major roles in orchestrating these complex arrangements, particularly during growth and repair processes. Because of their extractability, robustness, and resistance to chemical treatment, biologically active, ECM‐derived sugars seem to be well placed for use in tissue repair, regeneration, and engineering. They also seem to have a promising future in “programming” stem cells for tissue replacement. Drug Dev. Res. 62:303–316, 2004. © 2004 Wiley‐Liss, Inc.
The Biosynthesis of 3‐(trans‐2‐Nitrocyclopropyl)alanine, a Constituent of the Signal Metabolite Hormaomycin
Authors: Brandl Melanie , Kozhushkov Sergei I. , Zlatopolskiy Boris D. , Alvermann Petra , Geers Bernadette , Zeeck Axel , de Meijere Armin 
Published: December 2004

AbstractFeeding experiments with Streptomyces griseoflavus using deuterium‐labeled racemic 3,3‐[D2]‐ (6b), 4,4‐[D2]‐ (6c), 5,5‐[D2]‐ (6d), and 6,6‐[D2]‐lysine (6e), and 3‐amino‐5‐(2‐amino‐1,1‐dideuterioethyl)‐4,5‐dihydrofuran‐2‐one dihydrochloride (34·2HCl) were carried out in order to obtain detailed information about the hitherto unknown biosynthetic pathway from lysine to the unusual amino acid 3‐(trans‐2′‐nitrocyclopropyl)alanine [(3‐Ncp)Ala] (2), which is a building block of hormaomycin 1a. The corresponding lysine dihydrochlorides were prepared in 33, 24, 19, and 30% overall yield, respectively, along a new efficient general synthetic route applying an alkylation of the lithium enolate of O′Donnel’s glycine equivalent 7 as a key step. In the attempted preparation of 5,5‐[D2]‐4‐hydroxylysine (29), the respective γ‐lactone (34·2 HCl) was obtained in five steps with 10% overall yield. The distribution of isotope labels in hormaomycins 1b−d led to the formulation of a reasonable cyclization mechanism of 2‐amino‐4‐hydroxy‐6‐(hydroxyimino)hexanoic acid, an ψ‐oxime analogue of 4‐hydroxylysine. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Decomposition of N′‐Benzoyl‐N‐nitrosoureas in Aqueous Media
Authors: Faustino Celia , García‐Río Luis , Leis José Ramón , Norberto Fátima 
Published: December 2004

AbstractThe decomposition of N′‐benzoyl‐N‐methyl‐N‐nitrosourea (BMNU) in aqueous media over the 0−14 pH range has been studied. In basic and neutral media (6 < pH < 14) the reaction proceeds through abstraction of the acidic proton of BMNU (pKa = 7.8) and subsequent decomposition of the conjugate base of the thus formed nitrosourea, via an intermediate benzoyl isocyanate. Support for this mechanism is provided by the presence of N,N′‐dibenzoylurea in the final reaction mixtures, as the result of the trapping of benzoyl isocyanate with benzamide generated from hydrolysis of the former. The hydrolysis of BMNU takes place through three competitive pathways: spontaneous decomposition of the conjugate base of BMNU, and buffer‐catalyzed and hydroxide ion catalyzed water addition to the carbonyl group of the deprotonated nitrosourea. N′‐Benzoyl‐N,N′‐dimethyl‐N‐nitrosourea (BDMNU), a benzoyl nitrosourea lacking the acidic proton of BMNU, is hydrolyzed in basic media by attack of hydroxide ion on the carbonyl group of the urea. In acid media (0 < pH < 6), BMNU gives only deamination products, differing from the reported behavior of other N‐nitroso compounds and of the isoster nitrosoguanidine, in which denitrosation is almost quantitative. The reaction is acid‐catalyzed in the 0−2.5 pH range and pH‐independent in the 3−5 pH range. The presence of general acid catalysis (α = 0.60), the absence of nucleophilic catalysis, and the thermodynamic activation parameters for the reaction support the mechanism proposed in the literature for the deamination of N‐nitrosoureas in acidic media. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthesis of Cyclopeptidic Analogues of Triostin A with Quinoxalines or Nucleobases as Chromophores
Authors: Dietrich Björn , Diederichsen Ulf 
Published: December 2004

AbstractThe natural antibiotic triostin A (1) is based on a conformationally rigid disulfide‐bridged cyclo‐octadepsipeptide scaffold. This bicyclic core structure provides a perfect preorganization of two covalently attached quinoxalines resulting in sequence‐specific bis(intercalation) of the chromophores in double‐stranded DNA. Herein for the first time the corresponding cyclopeptide has been synthesized as a scaffold instead of the cyclodepsipeptide of triostin A by solid‐phase peptide synthesis followed by bis(cyclization) in solution. Furthermore, when in contact with DNA the bicyclic peptide provides additional hydrogen‐bonding possibilities and greater conformational rigidity in comparison to triostin A. These modifications to the backbone of triostin A might be especially valuable in combination with the use of nucleobases instead of quinoxalines for additional DNA recognition next to bis(intercalation) like major groove binding or detection of abasic DNA damages. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Cover Picture: Chalcogenide−Lewis Acid Mediated Tandem Michael Aldol Reaction − an Alternative to the Morita−Baylis−Hillman Reaction and a New Development (Eur. J. Org. Chem. 1/2005)
Authors: Kataoka Tadashi , Kinoshita Hironori 
Published: December 2004

AbstractThe cover picture shows cormorant fishing “Ukai” (the ancient techniques of fishing) on the Nagara River, Gifu, Japan, where the research reported in the Microreview by T. Kataoka and H. Kinoshita on p. 45 ff. was performed. You can imagine a fisherman “Usho”, who controls ten to twelve birds by handling the leash ropes, as a Lewis acid. His skilled use of leashes effects a fish catch just as the ability of a Lewis acid to chelate reactants has a great influence on the reaction. You enjoy a wonderful spectacle from May 11 to October 15 every year and the research throughout the year in Gifu, Japan.
High Dispersion and Electrocatalytic Properties of Platinum on Functional Multi‐Walled Carbon Nanotubes
Authors: Guo Dao‐Jun , Li Hu‐Lin 
Published: December 2004

AbstractPlatinum (Pt) nanoparticles were electrochemically dispersed on 4‐aminobenzene monolayer‐grafted multi‐walled carbon nanotubes (MWNTs) by a potential‐step method. The structure and nature of the resulting Pt‐MWNT composites were characterized by transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The electrocatalytic properties of Pt‐MWNT composites for methanol oxidation have been investigated by cyclic voltammetry (CV) and high electrocatalytic activity can be observed. This may be attributed to the small particle size, high dispersion of platinum particles and the particular properties of MWNT supports. The results imply that the Pt‐MWNT composites have good potential applications in direct methanol fuel cell (DMFC). Additionally, the long‐term cycling stability of platinum catalysts was also investigated.
Multifractal characterization of Hong Kong air quality data
Authors: Anh V. V. , Leung Y. , Lam K. C. , Yu Z. G. 
Published: December 2004

AbstractThis article develops a theory for characterization of air quality data based on their measure representation. The measures are shown to be random cascades generated by an infinitely divisible distribution. This probability distribution is uniquely determined by the exponent K (q), q≥0, in the multifractal analysis of the cascade. The theory is applied to the SO2, NO and NO2 time series at seven locations of the Hong Kong Electric Co. monitoring network. The Gamma density function is demonstrated to give an excellent fit to the K (q) curve of each time series. This precise characterization therefore provides a needed tool for modelling pollution episodes as well as classification of the monitoring network. Copyright © 2004 John Wiley & Sons, Ltd.
The micro‐topography of the wetlands of the Okavango Delta, Botswana
Authors: Gumbricht T. , McCarthy T. S. , Bauer P. 
Published: December 2004

AbstractThe surface of the 40 000 km2 Okavango alluvial fan is remarkably smooth, and almost everywhere lies within two to three metres of a perfectly smooth theoretical surface. Deviations from this perfect surface give rise to islands in the Okavango wetlands. This micro‐topography was mapped by assigning empirical elevations to remotely sensed vegetation community classes, based on the observation that vegetation is very sensitive to small, local differences in elevation. Even though empirical, the method produces fairly accurate results. The technique allows estimation of depths of inundation and therefore will be applicable even when high resolution radar altimetry becomes available. The micro‐topography has arisen as a result of clastic sedimentation in distributary channels, which produces local relief of less than two metres, and more importantly as a result of chemical precipitation in island soils, which produces similar local relief. The micro‐topography is, therefore, an expression of the non‐random sedimentation taking place on the fan. Volume calculations of islands extracted from the micro‐topography, combined with estimates of current sediment inﬂux, suggest that the land surface of the wetland may only be a few tens of thousands of years old. Constant switching of water distribution, driven by local aggradation, has distributed sediment widely. Mass balance calculations suggest that over a period of c. 150 000 years all of the fan would at one time or other have been inundated, and thus subject to sedimentation. Coalescing of islands over time results in net aggradation of the fan surface. The amount of vertical aggradation on islands and in channels is restricted by the water depth. Restricted vertical relief, in turn, maximizes the distribution of water, limiting its average depth. Aggradation in the permanent swamps occurs predominantly by clastic sedimentation. Rates of aggradation here are very similar to those in the seasonal swamps, maintaining the overall gradient, possibly because of the operation of a feedback loop between the two. The limited amount of local aggradation arising from both clastic and chemical sedimentation, combined with constant changes in water distribution, has resulted in a near‐perfect conical surface over the fan. In addition to providing information on sedimentary processes, the micro‐topography has several useful hydrological applications. Copyright © 2004 John Wiley & Sons, Ltd.
Dust production and the release of iron oxides resulting from the aeolian abrasion of natural dune sands
Authors: Bullard Joanna E. , White Kevin 
Published: December 2004

AbstractGlobal dust trajectories indicate that signiﬁcant quantities of aeolian‐transported iron oxides originate in contemporary dryland areas. One potential source is the iron‐rich clay coatings that characterize many sand‐sized particles in desert duneﬁelds. This paper uses laboratory experiments to determine the rate at which these coatings can be removed from dune sands by aeolian abrasion. The coatings impart a red colour to the grains to which previous researchers have assigned variable geomorphological signiﬁcance. The quantities of iron removed during a 120 hour abrasion experiment are small (99 mg kg−1) and difﬁcult to detect by eye; however, high resolution spectroscopy clearly indicates that ferric oxides are released during abrasion and the reﬂectance of the particles alters. One of the products of aeolian abrasion is ﬁne particles (<10 µm diameter) with the potential for long distance transport. Copyright © 2004 John Wiley & Sons, Ltd.
Water distillation kinetic study of spearmint essential oil and of its major components
Authors: Benyoussef El‐Hadi , Yahiaoui Nabila , Khelfaoui Assia , Aid Fatiha 
Published: December 2004

AbstractAlgerian Mentha spicata L. essential oil yield evolution during water distillation has been investigated as a function of time. GC analysis helped to determine the extraction kinetics of the major components of this essential oil. The results show that there are two kinetic types. We have tried to correlate this kinetic type with the essential oil location in the vegetable material. The microscopic observations show that most of the essential oil is localized in exogenous deposits in the leaves but there are some endogenous sites in the stem. Each kinetic type corresponds to the considered compound being localized in either endogenous or in exogenous deposits. Copyright © 2004 John Wiley & Sons, Ltd.