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Kinds of C4 Terms modified by C4 Selected AbstractsSynthesis and crystal structure determination of 6,7-dihydro-2-methoxy-4-(substituted)-5H -benzo[6,7]cyclohepta[1,2- b ]pyridine-3-carbonitrileCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2007A. M. Moustafa Abstract The compounds 6,7-dihydro-2-methoxy-4-(4-methylphenyl)-5H -benzo[6.7]cyclohepta[1,2 -b ]pyridine-3-carbonitrile (compound IIIa) and 4-(4-chlorophenyl)-6,7-dihydro-2-methoxy-5H -benzo[6,7]cyclohepta[1,2- b ]pyridine-3-carbonitrile (compound IIIb) were synthesized and their structures have been determined from three dimensional X-ray data using direct method and refined by full matrix least squares with anisotropic thermal parameters for non-hydrogen atoms to conventional R(gt) of 0.036 and 0.038 for the two compounds respectively. For compound (IIIa) the crystals are monoclinic, space group Cc, with a=11.2909 (5) Å, b=17.7755(8) Å, c=9.1437(4) Å and ,=95.428(3)°, while the crystals of the second compound (IIIb) are triclinic, space group P1, with a=8.7465(3)Å, b=10.3958(3)Å, c=10.9011(4)Å, ,= 108.3870(10)°, ,=101.3741(12)°, ,=97.9594(12)°. The molecular structure of the two compounds have nearly the same configuration, where the cyclohepta ring takes the boat shape and the methoxy and the carbonitrile groups are attached at the same position C2 and C8. The difference occurs only at the position C4, where the substituent is methylphenyl for compound (IIIa) and chlorophenyl for the other. The bond lengths, valency angles and the hydrogen bonding were calculated and fully discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] An audit of the accuracy of fine needle aspiration using a liquid-based cytology system in the setting of a rapid access breast clinicCYTOPATHOLOGY, Issue 6 2002L. Joseph We have assessed the effectiveness and accuracy of reporting fine needle aspirates of the breast (FNAB) using a liquid-based cytology (LBC) system (the Cytospin® method) in the pressure situation of a rapid access clinic (RAC). We have reviewed every case from the RAC from June 1997 to February 2001 inclusive. There were 1322 cases, which accounted for 26% of the total FNAB received in our department over the period. There were 323 cancers and 999 benign cases in the group. The inadequate/nondiagnostic rate (C1) was 18%. The absolute sensitivity, including C1 cases, was 73% with the complete sensitivity being 90%. The groups of ,atypical, probably benign' (C3) and ,suspicious, probably malignant' (C4) accounted for a total of 6.2%. There were 28 false negative cases and 1 false positive case (a borderline phyllodes tumour). Comparing our results with the standards recommended by the NHSBSP has shown that the diagnosis of FNAB using this LBC method is feasible, accurate and reliable even in the pressure situation of a RAC. [source] An audit of ,equivocal' (C3) and ,suspicious' (C4) categories in fine needle aspiration cytology of the breastCYTOPATHOLOGY, Issue 4 2001R. A. Deb An audit of ,equivocal' (C3) and ,suspicious' (C4) categories in fine needle aspiration cytology of the breast We have audited the frequency of use and outcome of the ,equivocal/atypia probably benign' (C3) and ,suspicious of malignancy' (C4) category for breast cytology in our Unit. A total of 14 935 cytological specimens were reported by at least one of the three pathologists with a special interest in breast pathology, according to five categories of the NHSBSP guidelines for cytology reporting, 1992; 3.7% (555 cases) and 3.9% (587 cases) of cases were classified as equivocal (C3) and suspicious (C4), respectively, giving a total rate (C3 + C4) of 7.6%. Of the C3 cases, 68% were subsequently benign and 32% were malignant. Of the C4 cases, 19% were subsequently benign and 81% malignant. The commonest benign lesions in both categories were fibroadenomas (7.6% of C3 and 19.8% of C4), fibrocystic change (14.3% of C3 and 12.5% of C4), radial scars (6.2% of C3 and 10.4% of C4) and papillomas (6.2% of C3 and 6.3% of C4). Of the malignant lesions (particularly those classified as C3), a high proportion were low grade or special type cancers. The categories of atypia probably benign (C3) and suspicious of malignancy (C4) in breast cytology provide a strategy for classification of problematic or uncertain cases; this maintains the predictive value of the benign (C2) and malignant (C5) categories, and allows separation of these difficult cases into clinically useful groups with differing probabilities of malignancy. [source] Serum Iron and Matrix Metalloproteinase-9 Variations in Limbs Affected by Chronic Venous Disease and Venous Leg UlcersDERMATOLOGIC SURGERY, Issue 6 2005Paolo Zamboni MD Background. Severe chronic venous disease (CVD) is characterized by both dermal hemosiderin accumulation and matrix metalloproteinase (MMP) hyperactivation. The iron-driven pathway is one of the recognized mechanisms of MMP hyperactivation. Objective. To investigate the potential consequences of leg hemosiderin deposits on both iron metabolism and activation of MMPs. Methods. We contemporaneously assessed the following in the serum of the arm and ankle veins of 30 patients (C4,6) with CVD and 14 normal subjects: ferritin, transferrin, iron, percentage of transferrin iron binding capacity (%TIBC), and MMP-9. Optical microscopy examinations with Perls' staining of chronic wounds were also performed. Results. Histology consistently revealed iron deposits. Serum ferritin, iron, and %TIBC were significantly increased in the legs affected by severe CVD compared with the arm of the same subjects or the controls. In addition, iron and %TIBC were significantly elevated in the legs of ulcer patients. The rate of activation of MMP-9 was significantly elevated in CVD. Conclusions. The increased iron deposition in legs affected by CVD seems to be more instable in ulcer patients, leading to iron release in the serum of the affected leg. Our data suggest the iron-driven pathway as a further mechanism for MMP hyperexpression leading to tissue lesion. [source] Endovenous Laser Treatment of the Lesser Saphenous Vein With a 940-nm Diode Laser: Early ResultsDERMATOLOGIC SURGERY, Issue 4 2003Thomas M. Proebstle MD BACKGROUND Until now, endovenous laser treatment (ELT) of the lesser saphenous vein (LSV) has not been reported. OBJECTIVE To evaluate efficacy and side effects for ELT of the LSV. METHODS Otherwise unselected patients with an incompetent LSV were included. After perivenous infiltration of tumescent local anesthesia, laser energy (940 nm) was administered endovenously, either in a pulsed fashion or continuously during constant backpull of the laser fiber. Patients were scheduled for duplex follow-up at Day 1 and also at 1, 3, 6 and 12 months, postoperatively. RESULTS Forty-one LSVs were targeted in 33 patients with a median age of 66 years (range, 35 to 93). Seventy-three percent of patients had skin changes (C4). Thirty-six percent had an open or healed venous ulcer (C5,6) and 15% a postthrombotic syndrome (ES AS,D PR). Thirty-nine LSVs (95%) completed ELT successfully. During a median follow-up interval of 6 months (range, 3 to 12 months), no recanalization event could be observed. Apart from one thrombosis of the popliteal vein in a patient with polycythemia vera, only minor side effects, particularly no permanent paresthesia, could be observed. CONCLUSION ELT of the LSV under tumescent local anesthesia is feasible and effective. Caution is warranted with ELT of thrombophilic patients. [source] Cervical spinal cord injury following cephalic presentation and delivery by Caesarean sectionDEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 4 2001C Morgan MD MRCP MRCPCH We describe a term infant with an acute spinal cord injury following emergency Caesarean section. Foetal movements were normal on the day that the mother was admitted for postterm induction of labour. Caesarean section was performed because of foetal distress and failure to progress during labour. The initial clinical picture suggested acute birth asphyxia. The presence of a high cervical spine injury became more obvious as the clinical picture evolved over the next 7 days. A discontinuity of the cervical spinal cord at C4,5 was confirmed on MRI. Spontaneous respiration failed to develop and intensive care was withdrawn on day 15. No evidence of trauma, or a vascular, neurological, or congenital anomaly of the cervical spinal cord was found at post mortem. The absence of a similar case following cephalic presentation and Caesarean section made bereavement couselling of the parents especially difficult. [source] Fire and the Miocene expansion of C4 grasslandsECOLOGY LETTERS, Issue 7 2005Jon E. Keeley Abstract C4 photosynthesis had a mid-Tertiary origin that was tied to declining atmospheric CO2, but C4 -dominated grasslands did not appear until late Tertiary. According to the ,CO2 -threshold' model, these C4 grasslands owe their origin to a further late Miocene decline in CO2 that gave C4 grasses a photosynthetic advantage. This model is most appropriate for explaining replacement of C3 grasslands by C4 grasslands, however, fossil evidence shows C4 grasslands replaced woodlands. An additional weakness in the threshold model is that recent estimates do not support a late Miocene drop in pCO2. We hypothesize that late Miocene climate changes created a fire climate capable of replacing woodlands with C4 grasslands. Critical elements were seasonality that sustained high biomass production part of year, followed by a dry season that greatly reduced fuel moisture, coupled with a monsoon climate that generated abundant lightning-igniting fires. As woodlands became more open from burning, the high light conditions favoured C4 grasses over C3 grasses, and in a feedback process, the elevated productivity of C4 grasses increased highly combustible fuel loads that further increased fire activity. This hypothesis is supported by paleosol data that indicate the late Miocene expansion of C4 grasslands was the result of grassland expansion into more mesic environments and by charcoal sediment profiles that parallel the late Miocene expansion of C4 grasslands. Many contemporary C4 grasslands are fire dependent and are invaded by woodlands upon cessation of burning. Thus, we maintain that the factors driving the late Miocene expansion of C4 were the same as those responsible for maintenance of C4 grasslands today. [source] Autoinducers extracted from microbial mats reveal a surprising diversity of N -acylhomoserine lactones (AHLs) and abundance changes that may relate to diel pHENVIRONMENTAL MICROBIOLOGY, Issue 2 2009Alan W. Decho Summary Microbial mats are highly structured and diverse communities, and one of the earliest-known life assemblages. Mat bacteria interact within an environment marked by strong geochemical gradients and fluctuations. We examined natural mat systems for the presence of autoinducers involved in quorum sensing, a form of cell,cell communication. Our results revealed that a diverse array of N -acylhomoserine lactones (AHLs) including C4 - to C14 -AHLs, were identified from mat extracts using mass spectrometry (MS), with further confirmation by MS/MS-collision-induced dissociation (CID), and additions of external standards. Microelectrode measurements showed that mats exhibited diel pH fluctuations, ranging from alkaline (pH 9.4) during daytime (net photosynthesis) to acidic (pH 6.8) during darkness (net respiration/fermentation). Under laboratory conditions, AHLs having shorter acyl-chains were degraded within the time frame that daily alkaline pH (> 8.2) conditions exist in mats. Intensive sampling of mats after full day- or night-time incubations revealed that accumulations of extractable shorter-chain AHLs (e.g. C8 - and C10 -AHLs) were significantly (P < 0.001) diminished during daytime. Our study offers evidence that stabilities of AHLs under natural conditions may be influenced by the proximal extracellular environment. We further propose that the ancient periodicity of photosynthesis/respiration in mats may potentially drive a mechanism for diel differences in activities of certain autoinducers, and hence bacterial activities mediated through quorum sensing. [source] Language-Related Potentials in Temporal Lobe Epilepsy Before and After Surgical TreatmentEPILEPSIA, Issue 2000Toshihiko Ito Purpose: Temporal lobectomy has contributed to treatment for medically intractable epilepsies. However, influence of the surgical treatment on cognitive function is not still clear, especially from the electrophysiological viewpoint. N400, an event related potential (ERP) named for its negative polarity and peak latency of 400 ms, is reported to be an electrophysiological sign of neural activities associated with semantic priming in language perception. In the present study, ERPs are applied to evaluate the cognitive function of temporal lobe epilepsy before and after temporal lobectomy. Methods: Two patients with intractable temporal lobe epilepsy participated in this study. Fifteen normal subjects served as controls. The incongruous sentence task (Kutas and Hillyard 1980) was used to record N400 components in an auditory modality. Two types of sentences (40 Japanese sentences for each type) were prepared, in which the terminal words were either semantically congruent or incongruent. The scntences were randomly presented at approximately 65 dB SPL peak intensity. ERPs were recorded according to the international 10,20 system, with a balanced non-cephalic electrode reference and 2 1 channels. The band-pass filter was set from 0.5 to 30 Hz, and the ERPs were sampled at 500 Hz from 200 ms before the onset of terminal words to 824 ms post-stimulus. Waves were calculated by subtracting ERPs in the congruent condition from those in the incongruent condition. N400 was scored as the most negative point between 250 and 450 ms in the subtraction waves. Amplitudes were measured from the baseline of 100 ms before the terminal words. Motor responses were also measured with a right index finger, to estimate the accuracy of understanding sentences. Results: Case I was a 22-year-old male who had intractable epilepsy for 7 years. Magnetic resonance imaging (MRI) showed high-intensity signals in the right amygdalo-hippocampal region. The epileptic seizures were confirmed to originate from the region hy electroencephalography/closed-circuit television monitoring, and single-photon-emission computed tomography. ERPs were recorded I month before and after the right anterior temporal lobectomy. Before the surgery, the rate of correct responses showed no difference between the patient (96 %) and the controls (96 %). The amplitudes of N400 for the patient reduced in the right frontal and central areas (F4, C4), comparing to 99 % confidence limit for control subjects. After the surgery, the rate of correct responses was 97 %, and the amplitudes reduced in the right central, parietal, and posterior temporal areas (C4, P4, 0 2, T6). Case 2 (37-year-old female) had intractable epilepsy for 30 years. MRI showed brain atrophy in the right hippocampal region. The epileptic seizures were confirmed to originate from the region. N400 was recorded 3 months after the resection. The rate of correct responses was 95 %. The amplitudes of N400 were lower in the right frontal, parietal, and temporal areas (electrodes Fp2, F4, P4, T6, Pz), comparing to 99 % confidence limit of controls. Conclusions: Before the lpbectomy, the reduction of amplitudes of N400 indicated that the pathogenesis of intractable temporal lobe epilepsy would influence the process of semantic priming in language perception. After the resection, it was suggested that the right temporal lobectomy might affect the cognitive function in the brain from electrophysiological aspects. We could benefit from further study including analysis of the discrepancy between the amplitudes of N400 and behavioral responses. [source] Radiographic anatomy of the articular process joints of the caudal cervical vertebrae in the horse on lateral and oblique projectionsEQUINE VETERINARY JOURNAL, Issue 9 2009J. M. WITHERS Summary Reasons for performing study: Plain radiography is the standard imaging technique for investigation of diseases associated with the articular process joints (APJ) of the caudal neck; however, the radiographic anatomy of these structures on both lateral and oblique radiographic projections has not previously been described in detail. Objectives: To determine the optimal technique for obtaining oblique radiographs of the APJ of the caudal cervical vertebrae (C4-5, C5-6 and C6-7) and to provide a detailed description of their normal radiographic appearance, on both lateral and oblique radiographic projections. Methods: Radiopaque markers were used to highlight the contours of the APJ on both lateral and oblique radiographs. A novel cineradiographic technique was employed to determine the optimal oblique projection to permit both left and right APJ to be assessed on the same radiograph. Lateral and oblique radiographs of the caudal neck were obtained in 6 live horses under standing sedation to assess the feasibility of the technique. Results: The radiopaque markers facilitated identification of the APJ by clearly outlining the margins of the cranial and caudal articular processes on lateral and oblique radiographs. The optimal range of angles for obtaining oblique radiographs was 50,55° for C4- 5, 45,55° for C5-6 and 45,55° for C6-7. Obtaining oblique radiographs within the specified range of angles resulted in a consistent radiographic image of the APJ in the caudal cervical region in the live individual. Conclusions and potential relevance: The description of the normal radiographic anatomy of the cervical APJ of the caudal neck region in horses provides a valuable reference for the interpretation of cervical radiographs. Using the standardised technique to obtain oblique radiographs of the equine cervical vertebrae may provide additional diagnostic information about the APJ. [source] Formation of an Olfactory Search Image for Explosives Odours in Sniffer Dogs,ETHOLOGY, Issue 7 2005Irit Gazit The term ,search image' refers to an animal's heightened ability to detect a specific cryptic prey, after experience with that prey. Formulated in 1960 by Tinbergen (Archives Neerlandaises de zoologie, vol. 13, pp. 265,343), the search image concept has been the subject of much research, albeit almost entirely based on visual search cues in birds of prey. Given the theoretical and practical importance of this concept for foraging or searching in general, we set out to investigate whether dogs could form olfactory search images for explosive odours. Seven experienced explosives detector dogs were first tested for their ability to detect 30 g of the explosives 2,4,6-trinitrotoluene (TNT), RDX + polyisobutylene + di(2-ethylhexyl)sebacate + fuel oil (C4) or pentaerythritol tetranitrate (PETN) placed in various containers randomly distributed along a 300-m limestone track. In consecutive stages of the experiment, we altered the relative percentages of the three explosives. The results showed that the percentage of TNT containers detected by the dogs increased in trials that followed placing of a high percentage of TNT relative to other explosives and decreased in trials that follwed placing of a relatively low percentage of TNT containers. The percentage detection of C4 and PETN was not influenced by their relative abundance at any stage. Overall, these results suggest that dogs can form an olfactory search image that might aid in prey/target detection. [source] Fluoride-Free Hiyama and Copper- and Amine-Free Sonogashira Coupling in Air in a Mixed Aqueous Medium by a Series of PEPPSI-Themed Precatalysts,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2009Chandrakanta Dash Abstract A new series of robust, user-friendly, and highly active PEPPSI-themed (pyridine-enhanced precatalyst preparation, stabilization and initiation) (NHC)PdX2(pyridine)-type (X = Cl, Br) precatalysts of C4,C5 saturated imidazole- (1,4) and triazole-based (5 and 6) N-heterocyclic carbenes for the Hiyama and Sonogashira couplings under amenable conditions are reported. Specifically 1,6 efficiently catalyze the fluoride-free Hiyama coupling of aryl halides with PhSi(OMe)3 and CH2=CHSi(OMe)3 in air in the presence of NaOH as a base in a mixed aqueous medium (dioxane/H2O, 2:1 v/v). Along the same lines, these 1,6 precatalysts also promote the Cu-free and amine-free Sonogashira coupling of aryl bromides and iodides with phenylacetylene in air and in a mixed aqueous medium (DMF/H2O, 3/1 v/v). The complexes 1,6 were synthesized by the direct reaction of the respective imidazolinium and triazolium halide salts with PdCl2 in pyridine in the presence of K2CO3 as a base. DFT studies on the catalytically relevant palladium(0) (NHC)Pd(pyridine) precursors 1a,6a reveal significant donation from the N-heterocyclic carbene lone pair onto the unfilled ,* orbital of the trans Pd,pyridine bond. This weakens the Pd-bound "throwaway" pyridine ligand, and its dissociation marks the initiation of the catalytic cycle.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Quantum Chemical Analysis of the Enantiomerisation Mechanism of Complexes of the Type [MII(XU)4]F+ (M = Pt, Pd, Ni; X = S, Se, Te;U = urea)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 20 2006Ralph Puchta Abstract The enantiomerisation pathway for {[Pt(thiourea)4]}F+ [a model for the C4 -symmetric [Pt(SU)4]SiF6 (SU = thiourea) complex] and derivatives is explored by density functional theory (B3LYP/LANL2DZp) und the activation barrier for the one-step process from C4 to C4, via a C4 transition state is computed. The substitution of Pt2+ by Pd2+ and Ni2+ and the exchange of selenourea and tellurourea increase the barrier. ({[Pt(thiourea)4]}F+: 4.2 kcal/mol, {[Pd(thiourea)4]}F+: 4.5 kcal/mol, {[Ni(thiourea)4]}F+: 7.6 kcal/mol, {[Pt(selenourea)4]}F+: 5.3 kcal/mol, {[Pt(tellurourea)4]}F+: 8.8 kcal/mol). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Ring Closure of Alkoxycarbonyl(tetracarbonyl)pyruvoyliron Complexes into Metallalactones Induced by Nucleophilic Attack of CarbanionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2006Patrice Cabon Abstract The reaction of carbanions with the pyruvoyl-substituted iron complex [(CO)4Fe(CO2CH3){C(O)C(O)CH3}] (1) affords the anionic trifunctionalized metallalactones [(CO)3Fe{C(O)C(CH3)(CRR,R,)OC4(O)(Fe,C4)}(CO2CH3)], (3), whose formation results from the addition of the nucleophile to the , carbonyl of the pyruvoyl moiety, followed by attack of the oxygen of this , carbonyl on a terminal carbonyl ligand. These anionic lactones react, at low temperature, with HCl to give rise to the neutral lactones [(CO)4Fe{C(O)C(CH3)(CRR,R,)OC4(O)(Fe,C4)}] (2), which were previously obtained by addition of NuH nucleophiles to 1. Complex 3(3), whose lactonic ring formation has been performed using the diethyl malonate anion (R = R, = CO2C2H5; R, = H), and the dimethyl-substituted neutral lactone 2(1) (R = R, = R, = H) have been characterized by X-ray diffraction studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] 3-D Water-Soluble Reversible Neodymium(III) and Lanthanum(III) Coordination PolymersEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 14 2004Tina Vermonden Abstract The formation of soluble supramolecular 3-D coordination polymers with Nd3+ and La3+ in aqueous solution has been studied for two bifunctional ligands consisting of two pyridine-2,6-dicarboxylate groups connected at the 4-position by O(CH2CH2O)4 and O(CH2CH2O)6 spacers (C4 and C6, respectively). Viscosity measurements were used to monitor the network formation as a function of the ligand concentration, and the ratio between metal ions and ligands. For corresponding conditions C4 solutions with Nd3+ always gave much higher viscosities than C6 solutions with Nd3+. C6 is long, and flexible enough to bind with both chelating groups to only one metal ion (ring formation). This causes the polymers to stop growing, resulting in smaller average sizes of the 3-D polymers. The ring-structures could be demonstrated by 1H NMR spectroscopy using C6 and La3+ at low concentrations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Transcranial direct current stimulation disrupts tactile perceptionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2004Andreas Rogalewski Abstract The excitability of the cerebral cortex can be modulated by various transcranial stimulation techniques. Transcranial direct current stimulation (tDCS) offers the advantage of portable equipment and could, therefore, be used for ambulatory modulation of brain excitability. However, modulation of cortical excitability by tDCS has so far mostly been shown by indirect measures. Therefore, we examined whether tDCS has a direct behavioral/perceptional effect. We compared tactile discrimination of vibratory stimuli to the left ring finger prior to, during and after tDCS applied for 7 min at 1-mA current intensity in 13 subjects. Stimulation was pseudorandomized into cathodal, anodal and sham conditions in a within-subject design. The active electrode was placed over the corresponding somatosensory cortex at C4 according to the 10,20 EEG system and the reference electrode at the forehead above the contralateral orbita. Cathodal stimulation compared with sham induced a prolonged decrease of tactile discrimination, while anodal and sham stimulation did not. Thus, cortical processing can be modulated in a behaviorally/perceptually meaningful way by weak transcranial current stimulation applied through portable technology. This finding offers a new perspective for the treatment of conditions characterized by alterations of cortical excitability. [source] Somatic and visceral afferents to the ,vasodepressor region' of the caudal midline medulla in the ratEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2003Jason R. Potas Abstract Previous research has found that the integrity of a restricted region of the caudal midline medulla (including caudal portions of nucleus raphé obscurus and nucleus raphé pallidus) was critical for vasodepression (hypotension, bradycardia, decreased cardiac contractility) evoked either by haemorrhage or deep pain. In this anatomical tracing study we found that the vasodepressor part of the caudal midline medulla (CMM) receives inputs arising from spinal cord, spinal trigeminal nucleus (SpV) and nucleus of the solitary tract (NTS). Specifically: (i) a spinal,CMM projection arises from neurons of the deep dorsal horn, medial ventral horn and lamina X at all spinal segmental levels, with approximately 60% of the projection originating from the upper cervical spinal cord (C1,C4); (ii) a SpV,CMM projection arises primarily from neurons at the transition between subnucleus caudalis and subnucleus interpolaris; (iii) a NTS,CMM projection arises primarily from neurons in ventrolateral and medial subnuclei. In combination, the specific spinal, SpV and NTS regions which project to the CMM receive the complete range of somatic and visceral afferents known to trigger vasodepression. The role(s) of each specific projection is discussed. [source] An Improved Synthesis of Procyanidin Dimers: Regio- and Stereocontrol of the Interflavan BondEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2006Isabelle Tarascou Abstract A direct and general synthesis of procyanidin dimers B1, B2, B3 and B4 (10a,d) is presented. The approach is based on the stoichiometric coupling of two protected monomeric units (the nucleophilic 2a,b and electrophilic 4a,b partners) and deals with the regio- and stereocontrol of the C4,C8 interflavan bond as well as the control of the degree of oligomerization. The synthesis involves a five-step pathway starting from the native catechin (1a) or epicatechin (1b) to the fully deprotected dimers 10a,d. Furthermore, the process appears to be iterative as the coupling intermediates 9a,d themselves can be readily used in further selective syntheses of trimers or higher oligomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Identification of Chiral cis- and trans- 2-Stannyloxazolidines by Their NMR Spectra and Solid-State StructuresEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2004Jean-Christophe Cintrat Abstract The assignment of cis and trans configurations in N -protected 4-substituted 2-tributylstannyl-1,3-oxazolidines by NMR has been achieved through the use of extrapolations of Karplus,Kitching-type relationships for 3J(119Sn,C,Z,13C) to establish the shape of the oxazolidine ring. Examination of 3J(H,H) allowed the determination of torsion angles for the substituents on C4 and C5, discrimination being completed by comparison of the H2 chemical shifts, together with the 2J(Sn,C,H2) values. The validity of the method was subsequently corroborated by comparison of the results obtained for the liquid phase with those obtained from radiocrystallographic structures of triphenylstannyl analogues or DFT calculations on trimethylstannyl analogues. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Total Synthesis without Protection: Three-Step Synthesis of Optically Active Clavicipitic Acids by a Biomimetic RouteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2004Yuusaku Yokoyama Abstract A three-step synthesis of a mixture of optically active cis - and trans -clavicipitic acids 6, which are ergot alkaloids, was achieved, starting from 4-bromoindole (7) and dl -serine (dl - 2). This short synthesis was made possible by omitting the protection and deprotection steps from the synthetic route. The key step was the spontaneous cyclization of 4-vinyltryptophan (10) formed from the Heck reaction of 4-bromotryptophan (8) with 2-methyl-3-buten-2-ol (9) in aqueous media. During this investigation, we also found that the palladium-catalyzed reaction of 8 with 9 showed an interesting pH dependence; under strongly basic conditions, the Heck reaction occurred to give a C4 -vinylated product 10, whereas an N -allylated product 19b was formed under neutral or weakly basic conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Structural and thermodynamic insights into the binding mode of five novel inhibitors of lumazine synthase from Mycobacterium tuberculosisFEBS JOURNAL, Issue 20 2006Ekaterina Morgunova Recently published genomic investigations of the human pathogen Mycobacterium tuberculosis have revealed that genes coding the proteins involved in riboflavin biosynthesis are essential for the growth of the organism. Because the enzymes involved in cofactor biosynthesis pathways are not present in humans, they appear to be promising candidates for the development of therapeutic drugs. The substituted purinetrione compounds have demonstrated high affinity and specificity to lumazine synthase, which catalyzes the penultimate step of riboflavin biosynthesis in bacteria and plants. The structure of M. tuberculosis lumazine synthase in complex with five different inhibitor compounds is presented, together with studies of the binding reactions by isothermal titration calorimetry. The inhibitors showed the association constants in the micromolar range. The analysis of the structures demonstrated the specific features of the binding of different inhibitors. The comparison of the structures and binding modes of five different inhibitors allows us to propose the ribitylpurinetrione compounds with C4,C5 alkylphosphate chains as most promising leads for further development of therapeutic drugs against M. tuberculosis. [source] The metabolic role and evolution of l -arabinitol 4-dehydrogenase of Hypocrea jecorinaFEBS JOURNAL, Issue 10 2004Manuela Pail l -Arabinitol 4-dehydrogenase (Lad1) of the cellulolytic and hemicellulolytic fungus Hypocrea jecorina (anamorph: Trichoderma reesei) has been implicated in the catabolism of l -arabinose, and genetic evidence also shows that it is involved in the catabolism of d -xylose in xylitol dehydrogenase (xdh1) mutants and of d -galactose in galactokinase (gal1) mutants of H. jecorina. In order to identify the substrate specificity of Lad1, we have recombinantly produced the enzyme in Escherichia coli and purified it to physical homogeneity. The resulting enzyme preparation catalyzed the oxidation of pentitols (l -arabinitol) and hexitols (d -allitol, d -sorbitol, l -iditol, l -mannitol) to the same corresponding ketoses as mammalian sorbitol dehydrogenase (SDH), albeit with different catalytic efficacies, showing highest kcat/Km for l -arabinitol. However, it oxidized galactitol and d -talitol at C4 exclusively, yielding l -xylo-3-hexulose and d -arabino-3-hexulose, respectively. Phylogenetic analysis of Lad1 showed that it is a member of a terminal clade of putative fungal arabinitol dehydrogenase orthologues which separated during evolution of SDHs. Juxtapositioning of the Lad1 3D structure over that of SDH revealed major amino acid exchanges at topologies flanking the binding pocket for d -sorbitol. A lad1 gene disruptant was almost unable to grow on l -arabinose, grew extremely weakly on l -arabinitol, d -talitol and galactitol, showed reduced growth on d -sorbitol and d -galactose and a slightly reduced growth on d -glucose. The weak growth on l -arabinitol was completely eliminated in a mutant in which the xdh1 gene had also been disrupted. These data show not only that Lad1 is indeed essential for the catabolism of l -arabinose, but also that it constitutes an essential step in the catabolism of several hexoses; this emphasizes the importance of such reductive pathways of catabolism in fungi. [source] BJ46a, a snake venom metalloproteinase inhibitorFEBS JOURNAL, Issue 10 2001Isolation, characterization, cloning, insights into its mechanism of action Fractionation of the serum of the venomous snake Bothrops jararaca with (NH4)2SO4, followed by phenyl-Sepharose and C4 -reversed phase chromatographies, resulted in the isolation of the anti-hemorrhagic factor BJ46a. BJ46a is a potent inhibitor of the SVMPs atrolysin C (class P-I) and jararhagin (P-III) proteolytic activities and B. jararaca venom hemorrhagic activity. The single-chain, acidic (pI 4.55) glycoprotein has a molecular mass of 46 101 atomic mass units determined by MALDI-TOF MS and 79 kDa by gel filtration and dynamic laser light scattering, suggesting a homodimeric structure. mRNA was isolated from the liver of one specimen and transcribed into cDNA. The cDNA pool was amplified by PCR, cloned into a specific vector and used to transform competent cells. Clones containing the complete coding sequence for BJ46a were isolated. The deduced protein sequence was in complete agreement with peptide sequences obtained by Edman degradation. BJ46a is a 322-amino-acid protein containing four putative N-glycosylation sites. It is homologous to the proteinase inhibitor HSF (member of the fetuin family, cystatin superfamily) isolated from the serum of the snake Trimeresurus flavoviridis, having 85% sequence identity. This is the first report of a complete cDNA sequence for an endogenous inhibitor of snake venom metalloproteinases (SVMPs). The sequence reveals that the only proteolytic processing required to obtain the mature protein is the cleavage of the signal peptide. Gel filtration analyses of the inhibitory complexes indicate that inhibition occurs by formation of a noncovalent complex between BJ46a and the proteinases at their metalloproteinase domains. Furthermore, the data shows that the stoichiometry involved in this interaction is of one inhibitor monomer to two enzyme molecules, suggesting an interesting mechanism of metalloproteinase inhibition. [source] Carbon sources of Amazonian fisheriesFISHERIES MANAGEMENT & ECOLOGY, Issue 4 2000E. Benedito-Cecilio Variation in the seasonal and spatial isotopic composition of plant C4 (aquatic macrophytes) and C3 (forest, C3 aquatic macrophytes and algae), and that of fish [Prochilodus nigricans Agassiz, Mylossoma duriventre (Cuvier), Colossoma macropomum (Cuvier), Semaprochilodus insignis (Schomburgk) and S. taeniurus Steindachner in the Amazon floodplain were analysed to test whether the fisheries deliver plant carbon to the population of Manaus in the same proportion as it is available in the floodplain. The contribution of C4 plants was significantly lower in 13C during the season of high water levels and increased toward the west of the basin. Mylossoma duriventre and C. macropomum changed ,13C levels, while the ,13C of P. nigricans and C. macropomum shifted spatially. The contribution of C4 to the fisheries yield was small. C3 plants (excluding phytoplankton) also contributed less than expected. This was explained by the importance of detritivores to the yield of the fisheries and the dependence of these species on algal carbon. [source] Life histories of Eucalanus bungii and Neocalanus cristatus (Copepoda: Calanoida) in the western subarctic Pacific OceanFISHERIES OCEANOGRAPHY, Issue 2004ATSUSHI TSUDA Abstract Life cycles of the large suspension-feeding copepods, Eucalanus bungii and Neocalanus cristatus were investigated by seasonal sampling in the western subarctic Pacific. Eucalanus bungii has a diapause from August to March at copepodite stages between copepodite 3 (C3) and C6 female. We propose that individuals with early birth dates are young of overwintering C5 and C6-females that develop to C4 in their birth year, while individuals with late birth dates are young of overwintering C4 that develop to C3 in their birth year. Thus, a majority of the population has annual generations alternating with biennial generations. Neocalanus cristatus showed life history almost identical to the population in the Alaskan gyre. Timing of the life cycle in N. cristatus is very close to that in the eastern subarctic gyre, but that of E. bungii is 2 months earlier than in the eastern subarctic. This difference is probably caused by the timing difference in the maximum primary production in the two areas and the plasticity of the life cycle strategy in E. bungii. [source] Distribution of piperitone oxide stereoisomers in Mentha and Micromeria species and their chemical synthesesFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2007Olga Larkov Abstract Chiral GC,MS analyses of natural and synthetic trans- and cis- piperitone oxide were performed on an Rt- ,DEX-sm capillary column in order to clarify the stereochemistry of their enantiomeric forms. Only enantiomerically pure laevo-rotatory piperitone oxides, (1S,2S,4S)- trans- piperitone oxide and (1S,2S,4R)- cis- piperitone oxide, were detected by chiral analyses of Micromeria fruticosa (L.) Druce and Mentha longifolia L. The occurrence of the cis - and trans -piperitone oxides was dependent on the population of the species. In all cases (1S,2S,4S)- trans- piperitone oxide was detected together with (4S)-piperitone, while (1S,2S,4R)- cis- piperitone oxide was detected together with (4R)-piperitone in the plants analysed. The four stereoisomers of trans - and cis -piperitone oxide were obtained by alkaline epoxidation of both (4R)- and (4S)-piperitone. The formation of the 1,2-epoxide can take place on either side of the 1,4-substituted six-membered ring. Racemization at C4 was observed under alkaline epoxidation reaction conditions due to keto-enol tautomerism. Copyright © 2007 John Wiley & Sons, Ltd. [source] Can C4 plants contribute to aquatic food webs of subtropical streams?FRESHWATER BIOLOGY, Issue 6 2003Joanne E. Clapcott Summary 1. Recent stable isotope studies have revealed that C4 plants play a minor role in aquatic food webs, despite their often widespread distribution and production. We compared the breakdown of C3 (Eucalyptus) and C4 (Saccharum and Urochloa) plant litter in a small rain forest stream and used laboratory feeding experiments to determine their potential contribution to the aquatic food web. 2. All species of litter broke down at a fast rate in the stream, although Urochloa was significantly faster than Eucalyptus and Saccharum. This was consistent with the observed higher total organic nitrogen of Urochloa compared with the other two species. 3. The breakdown of Urochloa and Saccharum was, however, not associated with shredding invertebrates, which were poorly represented in leaf packs compared with the native Eucalyptus. The composition of the invertebrate fauna in packs of Urochloa quickly diverged from that of the other two species. 4. Feeding experiments using a common shredding aquatic insect Anisocentropus kirramus showed a distinct preference for Eucalyptus over both C4 species. Anisocentropus was observed to ingest C4 plant litter, particularly in the absence of other choices, and faecal material collected was clearly of C4 origin, as determined by stable isotope analysis. However, the stable carbon isotope values of the larvae did not shift away from their C3 signature in any of the feeding trials. 5. These data suggest that shredders avoid the consumption of C4 plants, in favour of native C3 species that appear to be of lower food quality (based on C : N ratios). Lower rates of consumption and lack of assimilation of C4 carbon also suggest that shredders may have a limited ability to process this material, even in the absence of alternative litter sources. Large scale clearing of forest and vegetation for C4 crops such as sugarcane will undoubtedly have important consequences for stream ecosystem function. [source] C3,C4 composition and prior carbon dioxide treatment regulate the response of grassland carbon and water fluxes to carbon dioxideFUNCTIONAL ECOLOGY, Issue 1 2007H. W. POLLEY Summary 1Plants usually respond to carbon dioxide (CO2) enrichment by increasing photosynthesis and reducing transpiration, but these initial responses to CO2 may not be sustained. 2During May, July and October 2000, we measured the effects of temporarily increasing or decreasing CO2 concentration by 150,200 µmol mol,1 on daytime net ecosystem CO2 exchange (NEE) and water flux (evapotranspiration, ET) of C3,C4 grassland in central Texas, USA that had been exposed for three growing seasons to a CO2 gradient from 200 to 560 µmol mol,1. Grassland grown at subambient CO2 (< 365 µmol mol,1) was exposed for 2 days to an elevated CO2 gradient (> 365 µmol mol,1). Grassland grown at elevated CO2 was exposed for 2 days to a subambient gradient. Our objective was to determine whether growth CO2 affected the amount by which grassland NEE and ET responded to CO2 switching (sensitivity to CO2). 3The NEE per unit of leaf area was greater (16,20%) and ET was smaller (9,20%), on average, at the higher CO2 concentration during CO2 switching in May and July. The amount by which NEE increased at the higher CO2 level was smaller at elevated than subambient growth concentrations on both dates, but relationships between NEE response and growth CO2 were weak. Conversely, the effect of temporary CO2 change on ET did not depend on growth CO2. 4The ratio of NEE at high CO2 to NEE at low CO2 during CO2 change in July increased from 1·0 to 1·26 as the contribution of C3 cover to total cover increased from 26% to 96%. Conversely, in May, temporary CO2 enrichment reduced ET more in C4 - than C3 -dominated grassland. 5For this mesic grassland, sensitivity of NEE and ET to brief change in CO2 depended as much on the C3,C4 composition of vegetation as on physiological adjustments related to prior CO2 exposure. [source] A QSAR analysis of toxicity of Aconitum alkaloidsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2004Angélica M. Bello-Ramírez Abstract Biological activity of Aconitum alkaloids may be related to their toxicity rather than to a specific pharmacological action. A Quantitative structure-activity relationships (QSAR) analysis was performed on the following two groups of alkaloids: compounds with an aroyl/aroyloxy group at R14 position (yunaconitine, bulleyaconitine, aconitine, beiwutine, nagarine, 3-acetyl aconitine, and penduline), and compounds with the aroyloxy group at R4 position (N -deacetyllappaconitine, lappaconitine, ranaconitine, N -deacetylfinaconitine, N -deacetylranaconitine). The LD50 (,mol/kg) of the 12 alkaloids were obtained from the literature. LD50 was significantly lower in group 1 than in group 2. The steric and core,core repulsion energies were significantly higher in group 1. The total energy and heat of formation and electronic energies were significantly lower in group 1. The reactivity index of N, C1,, C4, and C6, were similar between groups. The reactivity index of C2, was significantly higher and the reactivity index of C3, and C5, were significantly lower in group 1. Log P and pKa were similar between groups. Molecular weight was significantly higher in group 1. A significant linear relationship was observed between log LD50 and either analgesic log ED50 or local anesthetic log ED50. The LD50/analgesic ED50 obtained from average values was 5.9 for group 1 and 5.0 for group 2. However, the LD50/local anesthetic ED50 was 40.4 and 318, respectively. The study supports that the analgesic effects of these alkaloids are secondary to their toxic effects whereas alkaloids from group 2 are susceptible to be further studied as local anesthetic agents. [source] Where temperate meets tropical: multi-factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove-salt marsh communityGLOBAL CHANGE BIOLOGY, Issue 5 2008KAREN L. McKEE Abstract Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2 - and N-enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above- and belowground production of existing mangrove stands, particularly in combination with higher soil N. [source] | ||||||||||||||||||||||||||||||||||||||||