bluuebunny/crossref_metadata_2025 huggingface dataset:
Preserved α-Adrenergic Tone in the Leg Vascular Bed of Spinal Cord–Injured Individuals
Authors: Kooijman Miriam , Rongen Gerard A. , Smits Paul , Hopman Maria T.E.
Published: October 2003

Background—

Supraspinal sympathetic control of leg vascular tone is lost in spinal cord–injured individuals, but this does not result in a reduced leg vascular tone: Leg vascular resistance is even increased. The aim of this study was to assess the α-adrenergic contribution to the increased vascular tone in the lower extremity in patients without central sympathetic control of leg circulation.

Methods and Results—

Upper-leg vascular resistance responses to local infusion of incremental doses of phentolamine (a competitive antagonist of the α-adrenoceptor) into the femoral artery were determined in 10 spinal cord–injured individuals (SCI) and 8 healthy age-matched control subjects during local β-adrenergic receptor blockade with propranolol. Basal leg vascular resistance was higher in SCI than in control subjects (41±6 arbitrary units [AU] versus 24±4 AU;
P
=0.034). The same accounts for minimal leg vascular resistance, assessed during reactive hyperemia, which was higher in SCI compared with control subjects (6.9±1.0 AU versus 2.5±0.2 AU;
P
<0.01). The maximal phentolamine-induced reduction in leg vascular resistance normalized to each individual’s minimal resistance did not differ between the groups (68±17% and 51±4% for SCI and control subjects, respectively;
P
>0.1). A decline in mean arterial pressure was observed in both groups with increasing dosage of phentolamine. In response, baroreceptor-mediated vasoconstriction was observed in the noninfused leg of the control subjects, whereas in SCI individuals this reaction was absent.

Conclusions—

These results indicate that the α-adrenoceptor–mediated vascular tone in the leg is preserved in spinal cord–injured individuals without sympathetic supraspinal control.
Effect of Hypertension and Hypertension-Glucose Intolerance on Myocardial Ischemic Injury
Authors: Mozaffari Mahmood S. , Schaffer Stephen W.
Published: October 2003

Systemic hypertension and type 2 diabetes mellitus are major risk factors for myocardial infarction. Yet, glucose intolerance, a prelude stage to type 2 diabetes, is associated with reduced infarct size. Since chronic hypertension adversely affects the myocardium, we tested the hypothesis that the coexistence of systemic hypertension and glucose intolerance reverses the cardioprotection associated with impaired glucose tolerance. Hearts from 9-month-old animals were subjected to a 40-minute occlusion of the left coronary artery followed by 2 hours of reperfusion. Before ischemia, similar values for the four experimental groups were observed for the coronary flow, heart rate, and maximum ventricular pressure. During the course of the ischemia-reperfusion insult, the two hypertensive groups displayed greater reductions in contractility than their normotensive counterparts. Infarct size was lower in the normotensive glucose-intolerant rat than in the normotensive control rat. Surprisingly, the hypertrophied hearts of the hypertensive and hypertensive glucose-intolerant rats displayed reduced infarct size (
P
<0.05). However, raising the afterload pressure from 100 to 160 cm H
2
O increased infarct size in the two hypertensive groups. This narrowed the differential between the hypertensive glucose-intolerant (160 cm H
2
O) and the normotensive control (100 cm H
2
O) rats. Nonetheless, at the higher afterload pressure, infarct size was less in the hypertensive glucose-intolerant rats than in their hypertensive counterparts. In conclusion, the impairment in contractile function despite the reduction in infarct size underscores the increased susceptibility of the hypertrophied, hypertensive heart to ischemic injury. Furthermore, exacerbation of cell death at elevated afterload pressure indicates the potential benefit of aggressive antihypertensive therapy.
Contrasting Roles of NADPH Oxidase Isoforms in Pressure-Overload Versus Angiotensin II–Induced Cardiac Hypertrophy
Authors: Byrne,* Jonathan A. , Grieve David J. , Bendall Jennifer K. , Li Jian-Mei , Gove Christopher , Lambeth J. David , Cave Alison C. , Shah Ajay M.
Published: October 2003

Increased production of reactive oxygen species (ROS) is implicated in the development of left ventricular hypertrophy (LVH). Phagocyte-type NADPH oxidases are major cardiovascular sources of ROS, and recent data indicate a pivotal role of a gp91
phox
-containing NADPH oxidase in angiotensin II (Ang II)–induced LVH. We investigated the role of this oxidase in pressure-overload LVH. gp91
phox−/−
mice and matched controls underwent chronic Ang II infusion or aortic constriction. Ang II–induced increases in NADPH oxidase activity, atrial natriuretic factor (ANF) expression, and cardiac mass were inhibited in gp91
phox−/−
mice, whereas aortic constriction-induced increases in cardiac mass and ANF expression were not inhibited. However, aortic constriction increased cardiac NADPH oxidase activity in both gp91
phox−/−
and wild-type mice. Myocardial expression of an alternative gp91
phox
isoform, Nox4, was upregulated after aortic constriction in gp91
phox−/−
mice. The antioxidant,
N
-acetyl-cysteine, inhibited pressure-overload–induced LVH in both gp91
phox−/−
and wild-type mice. These data suggest a differential response of the cardiac Nox isoforms, gp91
phox
and Nox4, to Ang II versus pressure overload.
Rape Prevention With College Males
Authors: O’Donohue William , Yeater Elizabeth A. , Fanetti Matthew
Published: October 2003

This study investigated the immediate impact of a video-based prevention program developed to decrease undergraduate men’s potential to commit rape. Three video segments (rape myth acceptance, victim empathy, and outcome expectancies) were developed through expert consultation and focus groups. Evidence for the construct validity of each component was evaluated by examining change scores in a pilot study of 101 male undergraduates on measures of rape myth acceptance, victim empathy, and outcome expectancies. In the main study, 102 male undergraduates were randomly assigned to either the experimental program consisting of the video-based intervention or an equivalently long, alternate video-based program judged to contain none of the experimental elements. The experimental video produced greater immediate changes on measures of rape myth acceptance, attitudes toward interpersonal violence, adversarial sexual beliefs, attraction to sexual aggression, rape empathy, and self-efficacy ratings. Limitations of this study and directions for future research with college men are discussed.
Protein 4.2 is critical to CD47-membrane skeleton attachment in human red cells
Authors: Dahl Kris Noel , Parthasarathy Ranganath , Westhoff Connie M. , Layton D. Mark , Discher Dennis E.
Published: October 2003

The reduction in expression of the integral membrane protein CD47 in human red blood cells (RBCs) deficient in protein 4.2 suggests that protein 4.2 may mediate a linkage of CD47 to the membrane skeleton. We compared the fractions of membrane skeleton-attached CD47, Rh-associated glycoprotein (RhAG), Rh, and band 3 in normal and protein 4.2-deficient cells using fluorescence-imaged microdeformation. We found that CD47 attachment decreases from 55% in normal cells to 25% to 35% in 4.2-deficient cells. RhAG, which has been shown to have no significant variation in expression among the cells studied, shows a significant decrease in membrane skeleton attachment in 4.2-deficient cells from 60% to 40%. Both Rh and band 3, which have also been shown to have no change in expression, show a smaller decrease from 75% attached in normal RBCs to 55% attached in 4.2-deficient cells. In normal cells, Rh phenotype influences CD47 expression but not the level of membrane skeleton attachment of CD47. In contrast, the results indicate that protein 4.2 strongly influences CD47 levels as well as the extent of membrane skeleton attachment in the RBC, whereas protein 4.2 affects membrane skeletal attachment of RhAG, Rh, and band 3 to a lesser extent. (Blood. 2004;103:1131-1136)
5-Hydroxytryptamine-induced vasodilator responses in the hindquarters of the anaesthetized rat, involve β2-adrenoceptors
Authors: Calama E , García M , Jarque M J , Morán A , Martín M L , Román L San
Published: October 2003

These studies were conducted to examine the role of the vasoactive mediators nitric oxide (NO) and adrenaline (epinephrine) in the serotonin (5-hydroxytryptamine; 5-HT)-induced vasodilator response in the hindquarter vascular bed of anaesthetized rats. Intra-arterial administration of doses of 5-HT in the range 0.12–25 ng kg−1 produced a dose-independent vasodilator effect in the hindquarters. The selective 5-HT1D/1B receptor agonist, L-694,247 at intra-arterial doses of 0.0012–1000 ng kg−1, as well as adrenaline (at doses of 0.05–50 ng kg−1 i.a.), mimicked the dose-independent vasodilator effect induced by intra-arterial administration of 5-HT. Intravenous pre-treatment with the selective β2-receptor antagonist ICI 118,551 (0.5 mg kg−1) blocked the vasodilator effect of 5-HT, adrenaline and L-694,247. Additionally, the inhibitor of NO synthase NG-nitro-L-arginine (L-NAME) (at a dose of 10 mg kg−1 i.v.) blocked the vasodilator action of acetylcholine 300–3000 ng kg−1) but did not modify 5-HT-induced vasodilatation. The vasodilator effect produced by intra-arterial administration of 5-HT in the hindquarters was significantly inhibited both 30 min after denervation of the lumbar sympathetic chains and 1 h after bilateral adrenalectomy. Our data suggest that in the in-situ autoperfused hindquarters of the rat 5-HT-induced vasodilatation is mediated by a local 5-HT1D or 5-HT1D/1B activation, which in turn mediates the adrenal release of adrenaline, which then produces β2-activation and vasodilatation.
Single oral dose study of two isosorbide-based aspirin prodrugs in the dog
Authors: Gilmer John F , Murphy Michael A , Shannon Jean A , Breen Colm G , Ryder Sheila A , Clancy John M
Published: October 2003

The objective of this study was to compare two aspirin prodrugs, isosorbide diaspirinate (ISDA) and a nitroaspirin (ISMNA), with aspirin in terms of effects on dog platelet function after administration of a single oral dose. Groups of six dogs were administered ISDA (2 mg kg−1), ISMNA (4 mg kg−1) or aspirin (2 mg kg−1). Blood was sampled at 1, 2, 4, 8, 12 and 24 h post-dosing and evaluated for capacity to generate post-clotting thromboxane (TX)B2. The aggregation response to arachidonic acid (AA) (100 μM), ADP (30 μM) or collagen (10 μg mL−1) was estimated at each time-point using the whole blood impedance method. Plasma ISMN following oral administration of ISMNA was also measured and compared with plasma ISMN following administration of a physical mixture of ISMN and aspirin. ISDA administration (2 mg kg−1) was associated with a significant reduction (P< 0.05) in serum TXB2 at 12 and 24 h (>90%) post-dosing and persistent inhibition of AA-induced platelet aggregation. ISDA administration caused a more marked depression of post-clotting TXB2 levels than aspirin in this study, although its ability to inhibit platelet aggregation was less consistent than that of aspirin. The nitroaspirin ISMNA was least effective at inhibiting platelet aggregation response or TXB2 production. The ISMN AUC0–24h for the ISMNA-treated dogs was 77% of that for the physical mix-treated dogs and the tmax was delayed. This study indicates that the two aspirin esters cause aspirin-like effects on platelet function, probably through aspirin release, when administered orally to dogs.
LET-99 opposes Gα/GPR signaling to generate asymmetry for spindle positioning in response to PAR and MES-1/SRC-1 signaling
Authors: Tsou Meng-Fu Bryan , Hayashi Adam , Rose Lesilee S.
Published: October 2003

G-protein signaling plays important roles in asymmetric cell division. In C. elegans embryos, homologs of receptor-independent G protein activators, GPR-1 and GPR-2 (GPR-1/2), function together with Gα (GOA-1 and GPA-16) to generate asymmetric spindle pole elongation during divisions in the P lineage. Although Gα is uniformly localized at the cell cortex,the cortical localization of GPR-1/2 is asymmetric in dividing P cells. In this report, we show that the asymmetry of GPR-1/2 localization depends on PAR-3 and its downstream intermediate LET-99. Furthermore, in addition to its involvement in spindle elongation, Gα is required for the intrinsically programmed nuclear rotation event that orients the spindle in the one-cell. LET-99 functions antagonistically to the Gα/GPR-1/2 signaling pathway,providing an explanation for how Gα-dependent force is regulated asymmetrically by PAR polarity cues during both nuclear rotation and anaphase spindle elongation. In addition, Gα and LET-99 are required for spindle orientation during the extrinsically polarized division of EMS cells. In this cell, both GPR-1/2 and LET-99 are asymmetrically localized in response to the MES-1/SRC-1 signaling pathway. Their localization patterns at the EMS/P2 cell boundary are complementary, suggesting that LET-99 and Gα/GPR-1/2 signaling function in opposite ways during this cell division as well. These results provide insight into how polarity cues are transmitted into specific spindle positions in both extrinsic and intrinsic pathways of asymmetric cell division.
Wavelet thresholding in partially linear models: a computation and simulation
Authors: Qu Leming
Published: October 2003

Partially linear models have a linear part as in the linear regression and a non‐linear part similar to that in the non‐parametric regression. The estimates in Partially Linear Models have been studied previously using traditional smoothing methods such as smoothing spline, kernel and piecewise polynomial smoothers. In this paper, a wavelet thresholding method for estimating the corresponding parameters in Partially Linear Models is presented. Extensive simulation results shows that wavelet smoothing approach is comparable to traditional smoothing methods when their assumptions are satisfied. But wavelet smoothing is often superior when assumptions about the smoothness of the underlying function of non‐parametric part are not satisfied. The computational complexity is linear on the sample size. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of mandibular landmarks from computed tomography and 3D digitizer data
Authors: Williams Frank L'Engle , Richtsmeier Joan T.
Published: October 2003

We recorded 3D coordinates for 28 mandibular landmarks from three‐dimensional reconstructions of CT axial slices using the image analysis program eTDIPS. The images were acquired from a pediatric series of human mandibles (neonate to 13 years of age) from the Bosma collection (Shapiro and Richtsmeier, 1997, Am. J. Phys. Anthropol. 103:415–416). To test the accuracy of these coordinate data, we recorded the same 28 landmarks directly on the Bosma mandibles using a Polhemus 3Space digitizer. The directly digitized landmarks serve as a gold standard upon which to evaluate the eTDIPS data. Standard deviations of landmark placement using eTDIPS show a greater degree of variation compared to the data gathered using the digitizer, although this error is more heavily concentrated in certain types of landmarks. All possible linear distances between unique pairs of landmarks were calculated, and like linear distances were compared between the two data collection methods. The absolute difference for all like linear distances ranged from 0.001–3.9 mm (mean = 0.377 mm; SD = 1.136), with the eTDIPS data being consistently larger than the digitizer coordinates. This study demonstrates that landmark coordinate data can be reliably collected from digital CT images of the human mandible. We define a set of mandibular landmarks useful in evaluating the effects of craniofacial disorders, growth and other biological processes. Clin. Anat. 16:494–500, 2003. © 2003 Wiley‐Liss, Inc.
Clinical anatomy of ligamentum nuchae
Authors: Mercer Susan R. , Bogduk Nikolai
Published: October 2003

In view of the disparities in the anatomical, clinical, and biomechanical literature this study was undertaken to reappraise the gross anatomy of ligamentum nuchae with the objective of providing an accurate anatomical basis for biomechanical studies and for clinical theories and practices. Ligamentum nuchae was studied by gross dissection in ten embalmed human adult cadavers and was found to be comprised of two structures: a dorsal raphe and a midline fascial septum. The dorsal raphe was formed by the interweaving of the right and left upper trapezius, splenius capitis, and rhomboid minor. It spanned the cervical spine and was firmly attached to the external occipital protuberance and to the spinous process of C7. The fascial septum consisted of dense connective tissue and ran ventrally from the midline raphe to be confluent with the interspinous ligaments and atlanto‐axial and atlanto‐occipital membranes. These findings agree with those anatomical descriptions that portray ligamentum nuchae as a two‐part structure but not with those studies in which it is characterized as a strong ligament attaching to all cervical spinous processes. Importantly, the findings of this study emphasize the need for clinical and biomechanical literature to portray the gross anatomy of ligamentum nuchae accurately. Clin. Anat. 16:484–493, 2003. © 2003 Wiley‐Liss, Inc.
Axillary arch: Potential cause of neurovascular compression syndrome
Authors: Mérida‐Velasco J.R. , Rodríguez Vázquez J.F. , Mérida Velasco J.A. , Sobrado Pérez J. , Jiménez Collado J.
Published: October 2003

During routine bilateral dissection of 64 upper limbs in 32 adult human cadavers, four cases of an axillary arch, a muscular anomaly, were found. In one case, the axillary arch presented on both sides and in two cases it presented unilaterally on the right side. The innervation and relationships of the axillary arches are reported and the surgical significance of the anomaly is discussed. Clin. Anat. 16:514–519, 2003. © 2003 Wiley‐Liss, Inc.
The spinoglenoid ligament: An anatomic study
Authors: Demirkan Ahmet Fahir , Sargon Mustafa F. , Erkula Gurkan , Kiter Esat
Published: October 2003

The spinoglenoid ligament and its anatomic variations are described in 27 shoulders from 15 cadavers. In each shoulder one or two distinct spinoglenoid ligaments originated from the base of the spine of the scapula; they inserted on the neck of the scapula or the shoulder joint capsule. In the 19 shoulders in which only one spinoglenoid ligament was present, it inserted into the neck of the scapula in 14 cases and into the shoulder joint capsule in five instances. In the eight shoulders in which there were two ligaments, one inserted into the neck of the scapula and the other into the shoulder joint capsule. We did not observe any hypertrophic spinoglenoid ligaments that may have compressed the suprascapular nerve. Clin. Anat. 16:511–513, 2003. © 2003 Wiley‐Liss, Inc.
Prevalence of osteophytes associated with the acromion and acromioclavicular joint
Authors: Mahakkanukrauh Pasuk , Surin Patcharin
Published: October 2003

Osteophytes as a stigma for shoulder impingement syndrome and osteoarthritis of the acromioclavicular (AC) joint were studied on the acromions and AC joints in 346 skeletons (230 males; 116 females), ranging in age from 15–100 years. Osteophytes were found on 28.9% (200/692) of the acromions, mostly on the anteroinferior aspect (54%; 108/200). Of these 28.9%, 87% (174/200) were of the traction type and 13% (26/200) of the claw type. Regarding the clavicles, 11.6% (80/692) had osteophytes on the articular facets of their lateral ends; all were of the traction type. There were statistically more osteophytes on the right than on the left side of both acromion and clavicle (P < 0.05). The occurrence of osteophytes and increasing age were significantly correlated (r = 0.65, P < 0.001). No gender differences were noted in the frequency of osteophytes on acromions or clavicles. These data should prove beneficial to clinicians in planning a proper course of treatment for patients suffering from painful conditions of the shoulder. Clin. Anat. 16:506–510, 2003. © 2003 Wiley‐Liss, Inc.
Evidence for the Formation of Singly Bonded Dimers During the Reductive Electrochemistry of Methanofullerenes
Authors: Oçafrain Maïténa , Herranz M. Ángeles , Marx Lucien , Thilgen Carlo , Diederich François , Echegoyen Luis
Published: October 2003

Four methanofullerene derivatives, with phosphonate or sulfone groups attached to a C60 core through a Bingel procedure, were synthesized to probe their stability upon electrolytic reduction. Derivatives 1 and 2 are the most stable upon electroreduction and do not exhibit retro‐cyclopropanation reactions until more than three electrons per C60 derivative are transferred. The cyclopropane ring is then removed and C60(>CH2)n (n=1–3) products result from reactions of the trianion of C60 with the solvent, CH2Cl2. The situation with diphosphonate 3 or phosphonatecarboxylate 4 is dramatically different. For 3, quantitative retro‐cyclopropanation occurs when 2.8 e− per molecule are transferred. In the case of 4, when more than two electrons per molecule are transferred, there is evidence of the reversible formation of a very stable intermediate, which is oxidized at a potential 500 mV more positive than the first fullerene‐based reduction of the parent compound. Electrolysis of a simple C70‐Bingel monoadduct (5) also exhibits the formation of a similar intermediate. On the basis of cyclic voltammetry, ESR spectroscopy, and MALDI analysis of products, the intermediate observed during the electrolysis of compounds 4 and 5 is assigned to a dimeric structure.
Absolute Asymmetric Synthesis of “Chiral‐at‐Metal” Grignard Reagents and Transfer of the Chirality to Carbon
Authors: Vestergren Marcus , Eriksson Johan , Håkansson Mikael
Published: October 2003

Two new six‐coordinate Grignard reagents, cis‐[(p‐CH3C6H4)MgBr(dme)2] (1) and cis‐[MgCH3(thf)(dme)2]I (2), have been synthesized and their crystal structures have been determined. Both reagents are cis‐octahedral and therefore chiral. They crystallize as conglomerates and racemize rapidly in solution. By utilizing these properties, the absolute asymmetric synthesis of specifically the Δ or the Λ enantiomer was achieved for both Grignard reagents. Enantiopure 1 and 2 were then reacted with butyraldehyde or benzaldehyde to give the corresponding alcohol in up to 22 % enantiomeric excess. At −60 °C, the Grignard reagents crystallize as racemic phases instead of conglomerates. Consequently, the crystal structures of rac‐cis‐[(p‐CH3C6H4)MgBr(dme)2]⋅DME (3) and rac‐cis‐[MgCH3(thf)(dme)2]I (4) could be determined.
Synthesis, Structure, and Spectroscopy of Phenylacetylenylene Rods Incorporating meso‐Substituted Dipyrrin Ligands
Authors: Halper Sara R. , Cohen Seth M.
Published: October 2003

The synthesis, structure, and spectroscopic characterization of a series of phenylacetylenylene rodlike molecules containing dipyrromethene (dipyrrin) ligands are described. The combination of the phenylacetylenylene groups with the porphyrinogenic dipyrrin moieties results in a rich absorption spectroscopy for these compounds, although the fluorescence of the phenylacetylenylene moiety is quenched by presence of the dipyrrin chelator. The Cu2+ and Fe3+ complexes of these ligands have been prepared and three of these compounds have been structurally characterized by using single‐crystal X‐ray diffraction. Unlike other octahedral metal‐dipyrrin complexes described to date, one of the iron complexes demonstrates ideal threefold symmetry in the solid‐state. The elongated structure and high symmetry of these complexes suggests the use of these meso‐substituted phenylacetylenylene ligands as an interesting class of extended, branched molecules for the construction of supramolecular architectures.
GA and AG Sequences of DNA React with Cisplatin at Comparable Rates
Authors: Monjardet‐Bas Véronique , Bombard Sophie , Chottard Jean‐Claude , Kozelka Jiří
Published: October 2003

The sequence selectivity of the antitumor drug cisplatin (cis‐[PtCl2(NH3)2] (1)) between the 5′‐AG‐3′ and 5′‐GA‐3′ sites of DNA has been a matter of discussion for more than twenty years. In this work, we compared the reactivity of GA and AG sequences of DNA towards the aquated forms of cisplatin (cis‐[PtCl(NH3)2(H2O)]+ (2), cis‐[Pt(NH3)2(H2O)2]2+ (3), and cis‐[Pt(OH)(NH3)2(H2O)]+ (4)) using two sets of experiments. In the first, we investigated a DNA hairpin, whose duplex stem contained a TGAT sequence as the single reactive site, and determined the individual rate constants of platination with 2 and 3 for G and A in acidic solution. The rate constants at 20 °C in 0.1 M NaClO4 at pH 4.5±0.1 were 0.09(4) M−1 s−1 (G) and 0.11(3) M−1 s−1 (A) for 2, and 9.6(1) M−1 s−1 (G) and 1.7(1) M−1 s−1 (A) for 3. These values are similar to those obtained previously for an analogous hairpin that contained a TAGT sequence. The monoadducts formed with 2 by both GA purines are extremely long‐lived, partly as a result of the slow hydrolysis of the chloro monoadduct at A, and partly because of the very low chelation rate (1.4×10−5 s−1 at 20 °C) of the aqua monoadduct on the guanine. In the second set of experiments, we incubated pure or enriched samples of 1, 2, 3, or 4 for 18–64 h at 25 °C with a 19 base pair (bp) DNA duplex, whose radiolabeled top strand contained one GA and one AG sequence as the only reactive sites. Quantification of the number of GA and AG cross‐links afforded a ratio of about two in favor of AG, irrespective of the nature of the leaving ligands. These results disagree with a previous NMR spectroscopy study, and indicate that GA sequences of DNA are substantially more susceptible to attack by cisplatin than previously thought.
α–γ Hybrid Peptides that Contain the Conformationally Constrained Gabapentin Residue: Characterization of Mimetics of Chain Reversals
Authors: Aravinda Subrayashastry , Ananda Kuppanna , Shamala Narayanaswamy , Balaram Padmanabhan
Published: October 2003

The crystal structures of four dipeptides that contain the stereochemically constrained γ‐amino acid residue gabapentin (1‐(aminomethyl)cyclohexaneacetic acid Gpn) are described. The molecular conformation of Piv‐Pro‐Gpn‐OH (1), reveals a β‐turn mimetic conformation, stabilized by a ten atom CH⋅⋅⋅O hydrogen bond between the Piv CO group and the pro S hydrogen of the Gpn CH2CO group. The peptides Boc‐Gly‐Gpn‐OH (2), Boc‐Aib‐Gpn‐OH (3), and Boc‐Aib‐Gpn‐OMe (4) form compact, folded structures, in which a distinct reversal of polypeptide chain direction is observed. In all cases, the Gpn residue adopts a gauche,gauche (g,g) conformation about the CγCβ (θ1) and CβCα (θ2) bonds. Two distinct Gpn conformational families are observed. In peptides 1 and 3, the average backbone torsion angle values for the Gpn residue are ϕ=98°, θ1=−62°, θ2=−73°, and ψ=79°, while in peptide 2 and 4 the average values are ϕ=−103°, θ1=−46°, θ2=−49°, and ψ=−92°. In the case of 1 and 3, an intramolecular nine‐membered OH⋅⋅⋅O hydrogen bond is formed between the CO of the preceding residue and the terminal carboxylic acid OH group. All four α–γ dipeptide sequences yield compact folded backbone conformations; this suggests that the Gpn residue may be employed successfully in the design of novel folded structures.
Discrete and Infinite Cage‐Like Frameworks with Inclusion of Anionic and Neutral Species and with Interpenetration Phenomena
Authors: Fan Jian , Zhu Hui‐Fang , Okamura Taka‐aki , Sun Wei‐Yin , Tang† Wen‐Xia , Ueyama Norikazu
Published: October 2003

Complex [Ag(tpba)N3] (1) was obtained by reaction of novel tripodal ligand N,N′,N″‐tris(pyrid‐3‐ylmethyl)‐1,3,5‐benzenetricarboxamide (TPBA) with [Ag(NH3)2]N3. While the reactions between 1,3,5‐tris(imidazol‐1‐ylmethyl)‐2,4,6‐trimethylbenzene (TITMB) and silver(I) salts with different anions and solvent systems give six complexes: [Ag3(titmb)2](N3)3⋅CH3OH⋅4 H2O (2), [Ag3(titmb)2](CF3SO3)2(OH)⋅5 H2O (3), [Ag3(titmb)2][Ag(NO3)3]NO3⋅H2O (4), [Ag3(titmb)2(py)](NO3)3⋅H2O (py=pyridine) (5), [Ag3(titmb)2(py)](ClO4)3 (6), and [Ag3(titmb)2](ClO4)3⋅CHCl3 (7). The structures of these complexes were determined by X‐ray crystallography. The results of structural analysis of complexes 1 and 2, with the same azide anion but different ligands, revealed that 1 is a twofold interpenetrated 3D framework with interlocked cage‐like moieties, while 2 is a M3L2 type cage‐like complex with a methanol molecule inside the cage. Entirely different structure and topology between 1 and 2 indicates that the nature of organic ligands affected the structures of assemblies greatly. While in the cases of complexes 2–7 with flexible tripodal ligand TITMB, they are all discrete M3L2 type cages. The results indicate that the framework of these complexes is predominated by the nature of the organic ligand and geometric need of the metal ions, but not influenced greatly by the anions and solvents. It is interesting that there is a divalent anion [Ag(NO3)3]2− inside the cage 4 and an anion of ClO4− or NO3− spontaneously encapsulated within the cage of complexes 5, 6 and 7.
Wie entstand das Leben auf der Erde?: Ammoniak aus Stickstoff unter präbiotischen Bedingungen
Authors: Kreisel Günter , Wolf Claudia , Weigand Wolfgang , Dörr Mark
Published: October 2003

Der Artikel befasst sich mit der Stickstoff‐Fixierung sowohl auf natürlichem, als auch auf technischem Wege. Zudem wird ein mögliches Szenario der Stickstoff‐Fixierung in präbiotischer Zeit vorgestellt. Das dabei entstehende Ammoniak ist Grundlage für die Bildung erster Aminosäuren, den Grundbausteinen aller stickstoffhaltigen Biomoleküle.
Stable Platinum(0) Catalysts for Catalytic Hydrosilylation of Styrene and Synthesis of [Pt(Ar‐bian)(η2‐alkene)] Complexes
Authors: Sprengers Jeroen W. , de Greef Michiel , Duin Marcel A. , Elsevier Cornelis J.
Published: October 2003

The use of alkenes and bidentate N‐ligands in the platinum(0)‐catalyzed hydrosilylation of styrene with triethylsilane has been evaluated. A number of bidentate N‐ligands, phen, bpy, dafo, and phenyl‐bian, were tested at various reaction temperatures using in situ formed catalysts with [Pt(nbe)3] as a precursor. The main conclusions are: (i) ligands, such as phen, which form stable platinum(0) complexes, give lower catalytic activities compared to the ligands which form less stable complexes; (ii) a small ligand effect is observed with dafo and phenyl‐bian compared to [Pt(nbe)3], the precursor complex, displaying the lability of these ligands. The complex [Pt(nbe)3], that only has labile alkene ligands, is an active catalyst at low temperatures. At higher temperatures, the catalyst is no longer stable and a decrease in yield is observed. Several novel complexes have been synthesized: [Pt(m,m‐(CF3)2‐C6H3‐bian)(tcne)], [Pt(m,m‐(CF3)2‐C6H3‐bian)(ma)], [Pt(p‐MeO‐C6H4‐bian)(ma)], [Pt(p‐MeO‐C6H4‐bian)(dmfu)] and [Pt(phenyl‐bian)(dmfu)]. Whereas the two [Pt(Ar‐bian)(ma)] complexes are intrinsically more active than the two [Pt(Ar‐bian)(dmfu)] complexes, the latter are much more stable, i.e. the nature of the alkene in these complexes is an important factor in determining their catalytic behavior. Compared to [Pt(Me‐nq)(nbe)2], the two [Pt(Ar‐bian)(dmfu)] complexes are much more stable resulting in significantly higher overall yields. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Long‐Lived MLCT Excited States‐RuII Complexes with a Helical Bis‐Phen Ligand
Authors: Goze Christine , Chambron Jean‐Claude , Heitz Valérie , Pomeranc Didier , Salom‐Roig Xavier J. , Sauvage Jean‐Pierre , Morales Angeles Farrán , Barigelletti Francesco
Published: October 2003

The synthesis of a new RuII complex [Ru(L1)(4,7‐dpphen)]2+, bearing a tetradentate bis‐1,10‐phenanthroline ligand L1, is described. X‐ray crystal structure analysis shows that the tetradentate ligand L1 coils around the metal and occupies both axial and two of the equatorial positions of the complex. 1H NMR studies clearly indicate that the complex has C2 symmetry in solution. The room temperature luminescence properties of [Ru(L1)(4,7‐dpphen)]2+ have been studied, as have those of the related complex [Ru(L2)(4,4′‐dmbp)]2+. For both complexes, the luminescence quantum yields and lifetimes are three to ten times higher than those of [Ru(bpy)3]2+. These unusual results are explained by the geometrical constraints imposed by the tetradentate ligands L1 and L2 in their respective complexes, resulting in an effective decoupling between the 3MLCT and 3MC excited states. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Coenzyme B12 Model Studies − Kinetics of Axial Ligation of Alkylcobalt Complexes Containing a Tridentate Amino‐Oximate Ligand
Authors: Alzoubi Basam M. , Hamza Mohamed S. A. , Felluga Alessandro , Randaccio Lucio , Tauzher Giovanni , van Eldik Rudi
Published: October 2003

The ligand‐substitution reaction of [RCo(LNHpy)(HLNHpy)]+ by cyanide was studied in methanol as a solvent, where R = Et (1), Me (2), CF3CH2 (3), and bridging CH2 (4), HLNHpy = 2‐(2‐pyridylethyl)amino‐3‐butanone oxime and LNHpy− is its conjugate base. The second‐order rate constants for the substitution of the 2‐pyridylethyl moiety in [RCo(LNHpy)(HLNHpy)]+ by cyanide were found to be 19.1, 0.25, 2.2·10−2, and 1.7·10−2 M−1·s−1 for R = Et, Me, CF3CH2, and bridging CH2, respectively. From the temperature‐ and pressure‐dependence studies of the substitution reaction, the activation parameters (ΔH‡, ΔS‡, ΔV‡) for the reaction of [RCo(LNHpy)(HLNHpy)]+ with cyanide in methanol were found to be, for R = Et: 69±2 kJ·mol−1, +11±7 J·K−1 mol−1, +9.6±0.3 cm3·mol−1; R = Me: 86±4 kJ·mol−1, +31±15 J·K−1·mol−1, +4.3±0.2 cm3·mol−1; R = CF3CH2: 73±3 kJ·mol−1, −33±10 J·K−1·mol−1, +8.7±0.2 cm3·mol−1; R = bridging CH2: 80±1 kJ·mol−1, −13±3 J·K−1·mol−1, +5.4±0.1 cm3·mol−1, respectively. Based on the reported rate and activation parameters, the mechanism of the ligand‐substitution reaction varies between a limiting dissociative and a dissociative interchange type of mechanism depending on the σ‐donor and steric effects of the alkyl group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
P8O12·2BH3 − The Borane Adduct of a New Molecular Phosphorus Oxide
Authors: Tellenbach Akbar , Jansen Martin
Published: October 2003

P4O6·BH3, which readily forms from P4O6 and Me2S·BH3 in a stoichiometric reaction, dimerizes spontaneously at −30 °C in a concentrated toluene solution resulting in the crystallization of P8O12·2BH3 (1). The synthesis of 1 represents the first selective interconnection of molecular phosphorus chalcogenides leading to the formation of a new, flexible P8O12 cage. The thermodynamic driving force for the dimerization reaction results from a gain of enthalpy due to enhanced P−O double‐bond contributions and a relief of angular strain. In terms of kinetics, the behavior of P4O6·BH3, differing from that of other P4O6 derivatives, is caused by the low π‐donor ability of BH3 provoking a Michaelis−Arbuzov‐like reactivity at the adjacent phosphorus atom and thus inducing cage opening. 1 was characterized by means of X‐ray diffractometry (powder, single crystal), NMR spectroscopy (solution, solid), IR spectroscopy, Raman spectroscopy, and mass spectrometry. Mass spectrometric investigations suggest considerable BH3 abstraction as well as an enhanced stability of P8O12·BH3 and P8O12, compared to 1. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Synthesis, Structure and Magnetic Properties of a New Iron Arsenate, [C10N4H28][{FeF(OH)(HAsO4)}4], with a Layer Structure
Authors: Chakrabarti Sandip , Pati Swapan K. , Green Mark A. , Natarajan Srinivasan
Published: October 2003

The reaction of FeCl3·6H2O, H3AsO4, HF and 1,4‐bis(3‐aminopropyl)piperazine under solvothermal conditions gives rise to a new iron arsenate, [C10N4H28][{FeF(OH)(HAsO4)}4] (I) with a layered structure. The cell parameters are monoclinic, space group = P21/n (no.14), M = 1143.08, a = 9.6320(3), b = 8.3598(3), c = 10.7794(1) Å, β = 115.036(1)°, V = 786.42(4) Å3, Z = 4, R1 = 0.0492, wR2 = 0.1227 [1114 observed reflections with I > 2σ(I)]. The connectivity between FeO3F2(OH) octahedra and HAsO4 tetrahedra forms a secondary building unit (SBU) of the type SBU‐4. The SBU‐4 units are linked together to form a layer structure with apertures formed by 8‐T atoms (T = Fe, As). The amine molecules are disordered and occupy the inter‐lamellar region. To the best of our knowledge, I is the first example of an iron arsenate structure formed from only one type of secondary building unit, SBU‐4. A dimer model has been used to describe the magnetic behavior. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Clinical application of the gender role strain paradigm: Group treatment for adolescent boys
Authors: Richmond Katherine , Levant Ronald
Published: October 2003

The aim of this article is to demonstrate the clinical application of the gender role strain paradigm with a group of adolescent boys. Adolescent boys experience overwhelming pressure to adhere to gender norms. As they attempt to conform to the expectations associated with the male role, boys suffer from gender role strain. We illustrate how the protective environment of the group enables boys to engage and discuss problems with male role norms. The shift in the boys' adherence to traditional notions of masculinity supports the utility of the gender role strain paradigm in clinical work. © 2003 Wiley Periodicals, Inc. J Clin Psychol/In Session.
Butyrate‐treated colonic Caco‐2 cells exhibit defective integrin‐mediated signaling together with increased apoptosis and differentiation
Authors: Lévy Peggy , Robin Hélène , Bertrand France , Kornprobst Michel , Capeau Jacqueline
Published: October 2003

We previously reported that the enterocytic differentiation of human colonic Caco‐2 cells correlated with alterations in integrin signaling. We now investigated whether differentiation and apoptosis of Caco‐2 cells induced by the short‐chain fatty acid butyrate (NaBT) was associated with alterations in the integrin‐mediated signaling pathway with special interest in the expression and activity of focal adhesion kinase (FAK), of the downstream phosphatidylinositol 3′‐kinase (PI 3‐kinase)–Akt pathway and in the role of the nuclear factor κB (NF‐κB). NaBT increased the level of sucrase. It induced apoptosis as shown by: (1) decreased Bcl‐2 and Bcl‐XL proteins and increased Bax protein; (2) activation of caspase‐3; and (3) increased shedding of apoptotic cells in the medium. This effect was associated with defective integrin‐mediated signaling as shown by: (1) down‐regulation of β1 integrin expression; 2) decreased FAK expression and tyrosine phosphorylation; (3) concerted alterations in cytoskeletal and structural focal adhesions proteins (talin, ezrin); and (4) decreased FAK ability to associate with PI 3‐kinase. However, in Caco‐2 cells, β1‐mediated signaling failed to be activated downstream of FAK and PI 3‐kinase at the level of Akt. Transfection studies show that NaBT treatment of Caco‐2 cells promoted a significant activation of the NF‐κB which was probably involved in the NaBT‐induced apoptosis. Our results indicate that the prodifferentiating agent NaBT induced apoptosis of Caco‐2 cells probably through NF‐κB activation together with a defective β1 integrin‐FAK‐PI 3‐kinase pathways signaling. J. Cell. Physiol. 197: 336–347, 2003© 2003 Wiley‐Liss, Inc.
Role of Rho in rabbit parietal cell
Authors: Tashiro Keiichiro , Nagao Taku , Kurose Hitoshi , Ichijo Hidenori , Urushidani Tetsuro
Published: October 2003

Rho is known as an important regulator of actin microfilament formation. We were led to study it because a dynamic rearrangement of actin filaments occurs during activation of gastric acid secretion. In order to use specific probes, the rabbit gastric gland culture system was employed and the various genes were expressed using adenovirus vector. When the constitutive active mutant of Rho (RhoAV14) was expressed, histamine‐ or carbachol‐stimulated acid secretion monitored by 14C‐aminopyrine accumulation was inhibited. Conversely, expression of C3 toxin, the specific inhibitor of Rho, and expression of G12/13‐specific regulator of G‐protein signaling domain, the specific inhibitor of G12/13 which is considered to be an upstream mediator of Rho, both potentiated acid secretion stimulated by the agonists. F‐actin staining of parietal cell expressing RhoAV14 revealed that the microfilament supporting the intracellular canaliculi (not on the basolateral membrane) almost disappeared. No clear changes in the intracellular localization of Rho were observed during stimulation of parietal cell. In resting glands, the endogenous active form of Rho was relatively high, and it decreased during histamine stimulation. The finding that any treatment which inhibit Rho augment acid secretion whereas those that activate Rho inhibit secretion strongly suggests that the Rho‐pathway conducts a negatively regulating signal in parietal cell activation, possibly via site‐specific regulation of actin microfilaments. J. Cell. Physiol. 197: 409–417, 2003© 2003 Wiley‐Liss, Inc.
JS‐K, a novel non‐ionic diazeniumdiolate derivative, inhibits Hep 3B hepatoma cell growth and induces c‐Jun phosphorylation via multiple MAP kinase pathways
Authors: Ren Zhenggang , Kar Siddhartha , Wang Ziqiu , Wang Meifang , Saavedra Joseph E. , Carr Brian I.
Published: October 2003

JS‐K, a non‐ionic diazeniumdiolate derivative, is capable of arylating nucleophiles and spontaneously generating nitric oxide (NO) at physiological pH. This recently synthesized low molecular weight compound is shown here to be an inhibitor of cell growth with concomitant activation of mitogen‐activated protein kinase (MAPK) members ERK, JNK, and p38 and their downstream effectors c‐Jun and AP‐1. Inhibitors of these MAPK pathways abrogated the growth inhibitory actions of JS‐K. In addition to the well‐described actions of JNK as a kinase for c‐Jun, we show that c‐Jun is also an ERK target. Furthermore, JS‐K generated NO in culture and NO inhibitors antagonized both MAPK induction and the growth inhibitory effects of JS‐K. These results suggest two possible mechanisms for the mediation of JS‐K growth inhibitory actions, namely NO‐induction of MAPK pathway constituents as well as possible arylation reactions. The data support the idea that prolonged MAPK activation by JS‐K action is important in mediating its growth‐inhibitory actions. JS‐K thus represents a promising platform for novel growth inhibitory analog synthesis. J. Cell. Physiol. 197: 426–434, 2003© 2003 Wiley‐Liss, Inc.
Water storage, surface, and structural properties of sandy forest humus horizons
Authors: Hajnos Mieczyslaw , Jozefaciuk Grzegorz , Sokołowska Zofia , Greiffenhagen Andreas , Wessolek Gerd
Published: October 2003

In this paper, we tried to find interrelations between water retention properties, surface characteristics, and structural features of sandy soils rich in organic matter. Raw humic, epihumic, and endohumic horizons of four acidic sandy forest soils were selected for this study. Specific areas and water adsorption energies were estimated from water vapor adsorption isotherms, micropore (nanometer range) parameters from desorption isotherms, mesopore (micrometer range) parameters from mercury intrusion porosimetry, and macropore (millimeter range) parameters from water retention curves measured using combined suction plate and pressure chamber methods. In the studied soils, pore volumes in all pore ranges were proportional to soil organic matter content. Thin column wicking technique was used to determine migration velocity vs. time dependence in the samples beds for a range of liquids of various surface tensions. From these dependencies the surface free energy and its components were estimated that were used for calculation of water contact angles and forces of interparticle interaction via a water meniscus. The dominant interactions in the studied soils were dispersive Lifshitz‐Van der Waals forces. In the two upper horizons polar acid‐base interactions were absent, however in the deepest horizons, high input of polar interactions occurred, due practically to electron‐donor component of the surface free energy. The electron‐acceptor contribution was low. The wettability of the soils was low in upper horizons as indicated by high water contact angles.
Raman spectroscopic study of the vivianite arsenate minerals
Authors: Frost Ray L. , Martens Wayde , Williams Peter A. , Kloprogge J. Theo
Published: October 2003

The molecular structures of the vivianite‐type arsenate minerals were studied using a combination of Raman and infrared spectroscopy. The Raman spectra of the hydroxyl‐stretching regions are complex with overlapping bands at 3419, 3209, 3185 and 3010 cm−1. This complexity is reflected in the water HOH bending modes with strong infrared bands in the 1660–1685 cm−1 region indicating strong hydrogen bonding to arsenate anions in adjacent layers. The Raman arsenate AsO stretching region shows strong similarity between the vivianite arsenate minerals. In the infrared spectra complexity exists with multiple antisymmetric stretching vibrations observed, indicating a reduction of symmetry. Strong infrared bands around 700 and 560 cm−1 are attributed to librational modes of water. Vibrational spectra enable the structure of the minerals to be determined and, whilst similarities exist in the spectral patterns, sufficient differences exist to determine the identification of the minerals. In particular, Raman spectroscopy assists in the identification of the complex isomorphous substitution in these vivianite arsenate minerals. Copyright © 2003 John Wiley & Sons, Ltd.
Raman spectroscopy of natural oxalates at 298 and 77 K
Authors: Frost Ray L. , Weier Matt L.
Published: October 2003

A comparative study of a suite of natural oxalates including weddellite, whewellite, moolooite, humboldtine, glushinskite, natroxalate and oxammite was undertaken using Raman spectroscopy at 298 and 77 K. Oxalates are found as films on host rocks as a result of heavy metal expulsion by primitive plants such as lichens and fungi. The minerals are characterized by the Raman position of the CO stretching vibration, which is cation sensitive. The band is observed at 1468 cm−1 for weddellite, 1464 cm−1 for whewellite, 1489 cm−1 for moolooite, 1489 cm−1 for humboldtine, 1471 cm−1 for glushinskite, 1456 cm−1 for natroxalate and 1473 cm−1 for oxammite. Except for oxammite, the infrared and Raman spectra are mutually exclusive, indicating that the minerals are bidentate and planar. Significant differences are observed in the CC stretching region and in the OCO bending region centred upon 910 and 860 cm−1, respectively. The significance of this work rests with the ability of Raman spectroscopy to identify oxalates which often occur as a film on a host rock. As such, Raman spectroscopy has the potential to identify the existence or pre‐existence of life forms on planets such as Mars. Copyright © 2003 John Wiley & Sons, Ltd.
Pressure effect at room temperature on the low‐energy Raman spectra of nitromethane‐h3 and ‐d3 up to 45 GPa
Authors: Pinan‐Lucarré J.‐P. , Ouillon R. , Canny B. , Pruzan Ph. , Ranson P.
Published: October 2003

The effect of pressure on the lattice dynamics in solid nitromethane, a prototype energetic material, was studied at room temperature using Raman scattering. Experiments were performed on the hydrogenated and perdeuterated compounds in a diamond anvil cell. An assignment of the main peaks of the low‐energy Raman bandshape into groups of modes is proposed. Apart from the splitting of some groups of lattice modes above 7 Gpa, no relevant effects indicating the occurrence of phase transformations were observed. In other words, the solid phase maintains the orthorhombic P212121 symmetry in the pressure range of its chemical stability at room temperature (0.3–30 GPa in nitromethane‐h3 and 0.3–45 GPa in nitromethane‐d3). In contrast with earlier interpretation, the present work suggests that the modifications that were observed on the vibron Raman bandshapes in similar conditions result only from different molecular conformations, without involving a change in the space group symmetry. These conclusions are consistent with recent theoretical simulations of the effects of a uniform or uniaxial strain on solid nitromethane. Copyright © 2003 John Wiley & Sons, Ltd.