bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis and Crystal Structures of Palladium(II) Complexes of Macrobicyclic Azathiaether Ligands
Authors: Siedle Gabriel , Kersting Berthold
Published: December 2003

The macrobicyclic azathioether ligands L1 and L2 were investigated regarding their capability to form complexes with divalent palladium. L1 represents a cyclophane‐like ligand system comprising two 4‐tert‐butyl‐2, 6‐bis(aminomethyl)thiophenolate units, which are linked by an ethylene and two 3‐aza‐1, 5‐pentylene units to give two seventeen‐membered dithia‐triaza crowns fused at the common ArSCH2CH2SAr fragment. L2 is the hexa‐N‐methylated derivative of L1. Treatment of L1 and L2 with two equivalents of [PdCl2(CH3CN)2] gave the new complexes [(L1)Pd2Cl]+ (1) and [(L2)Pd2Cl2]2+ (2), respectively, which were isolated as perchlorate salts and characterized by elemental analysis, IR and NMR spectroscopy and by X‐ray crystallography. In 1, L1 acts as a septadentate ligand to give two distorted square‐planar PdN3S and PdN3Cl units, respectively. The structure of 2 shows L2 to be hexacoordinate, yielding two distorted square‐planar PdN2SCl units leaving two NMe groups dangling. NMR spectroscopic studies reveal that both complexes retain their solid‐state structures in solution. The reaction of L2 with one equivalent of [PdCl2(CH3CN)2] is accompanied by a bond cleavage reaction of one of the two aliphatic thioether bonds to afford the dinuclear complex [(L3)Pd2Cl2]Cl (3·Cl) of the ring‐opened 24‐membered hexaaza‐vinylthioether/thiophenolate derivative (L3)‐. The crystal structure determination of 3·Cl reveals two distorted‐square planar PdN2ClS units which are bridged by the thiophenolate sulfur atom of (L3)‐. The vinyl‐thioether moiety and the two remaining amine donors of (L3)‐ do not interact with the two palladium ions. The X‐ray structure analysis of the free macrocycle L2 demonstrates that the C‐S bond lengths become elongated upon coordination to the palladium(II) ions.
Diaza Crown Ethers and Cryptants as Bridging Ligands in Lamellar Copper(I) Coordination Polymers
Authors: Mühle Jörg , Sheldrick William S.
Published: December 2003

CuX‐based coordination polymers (X = I, CN, SCN) with diazacrown ethers or cryptands as bridging ligands have been prepared by reaction of CuX with appropriate macrocycle in acetonnitrile/hexane solution at 100 °C. Whereas [CuI (1, 7‐DA12C4)] (1) and [CuI(1, 10‐DA18C6)] (2) (1, 7‐DA12C4 = 1, 7‐diaza‐12‐crown‐4, 1, 10‐DA18C6 = 1, 10‐diaza‐18‐crown‐6) are both monomeric, [(CuI)2(1, 10‐DA18C6)] (3) contains infinite chains in which (CuI)2 rings are linked in a μ‐N1, N10 manner by thiacrown ether moieties. The distorted tetrahedral coordination of the CuI atoms in 3 is completed by a weak Cu…O interaction (2.393(7)Å) to a 1, 10‐DA18C6 oxygen atom. [(Cu4I4)(1, 10‐DAcrypt)2] (4), (1, 10DAcrypt = 1, 10‐diaza‐cryptand [2.2.2]), [{(CuCN)6(1, 7‐DA12C4)4]·2CH3CN (5) and [(CuSCN)2 (1, 10‐DA18C6] (6) all exhibit lamellar networks with respectively Cu4I4 cubes, (CuCN)6 hexagons and [(CuSCN)2] double chains as their CuX substructures. 4 can imbibe up to 0.64 mol KNO3/mol cryptand and 6 up to 0.35 mol KNO3/mol 1, 10‐DA18C6 as a guest lattice. Crystal structures are reported for 1‐6, thermal analysis data (TG/DTA) for complexes 2, 3 and 5.
Über das Hydratisomer Gd3(H2ClCCOO)9(H2O)5
Authors: Rohde Alexander , Urland Werner
Published: December 2003

On the Hydrate Isomer Gd3(H2ClCCOO)9(H2O)5

Single crystals of Gd3(H2ClCCOO)9(H2O)5 have been obtained by reaction of Gd2O3 with an aqueous solution of H2ClCCOOH. The compound crystallizes in the monoclinic space group P 21/a (Z = 4, a = 1438.2(3), b = 1870.2(4), c = 1475.9(3) pm, β = 95.37(2)°). There are three kinds of crystallographically independent Gd3+ ions. All of them are ninefold coordinated, two of them are each coordinated by a tricapped trigonal prism, whereas the third one is coordinated by a monocapped square antiprism. The compound represents an hydrate isomer of the known Gd3(H2ClCCOO)9(H2O)4 ·H2O.
Synthesis, Crystal Structures and Thermal Properties of the New Copper(I) Pseudohalide Coordination Polymers Catena[(μ2‐thiocyanato‐N, S)‐(1‐ethyl‐2‐methylpyrazine‐N)]copper(I) and Poly[(di‐μ2‐thiocyanato‐N, S)‐(μ2‐1‐ethyl‐2‐methylpyrazine‐N, N′)]dicopper(I)
Authors: Näther Christian , Jeß Inke , Kowallik Petra
Published: December 2003

Reaction of copper(I) thiocyanate with 1‐ethyl‐2‐methyl‐pyrazine in acetonitrile yields the two new coordination polymers catena[(μ2‐thiocyanato‐N, S)‐(1‐ethyl‐2‐methylpyrazine‐N)] copper(I)(I) and poly[(di‐μ2‐thiocyanato‐N, S)‐(μ2‐1‐ethyl‐2‐methylpyrazine‐N, N′)] di‐copper(I) (II). The crystal structure of I is composed of CuSCN double chains in which each copper atom is connected to two thiocyanate anions and two 1‐ethyl‐2‐methyl‐pyrazine ligands. In this compound only one nitrogen atom of the 1‐ethyl‐2‐methyl‐pyrazine ligand is involved in copper coordination. The crystal structure of II is composed of CuSCN layers that are connected by the N‐donor ligands via μ‐N, N′ coordination into a three‐dimensional coordination network. On heating the amine rich compound I loses half of the ligands and transforms into the amine‐poorer compound II which occurs as an intermediate. Compound II decomposes on further heating to CuSCN. This reaction was investigated using simultaneous differential thermoanalysis and thermogravimetry coupled with mass spectroscopy and temperature dependent X‐ray powder diffraction.
Co[(C6H10)(NH3)2][C6H2(COO)4] · 2H2O und Zn[(C6H12)(NH3)2][C6H2(COO)4] · 1/2H2O ‐ Zwei zeolithartige dreidimensionale Koordinationspolymere
Authors: Köferstein Roberto , Robl Christian
Published: December 2003

Monokline Einkristalle von Co[(C6H10)(NH3)2][C6H2(COO)4]·2H2O (1) wurden in wässeriger Lösung bei 80 °C erhalten. Raumgruppe C2/c (Nr. 15), a = 1065.92(8), b = 1568.97(9), c = 1140.88(9) pm, β = 90.101(6)°, V = 1.9080(2) nm3, Z = 4. Co2+ besetzt eine zweizählige kristallographische Achse und ist verzerrt tetraedrisch durch vier Sauerstoffatome der Pyromellitatanionen koordiniert (Co‐O 197.87(12) und 200.64(12) pm). Aus der Verbindung von Co2+ mit C6H2(COO)44‐ resultiert ein dreidimensionales Koordinationspolymer mit kanalartigen Hohlräumen, die von Wassermolekülen und (C6H10)(NH3)22+‐Kationen belegt sind, welche die negative Überschußladung des Gerüstes kompensieren. Bei der thermogravimetrischen Untersuchung an Luft erwies sich das Anhydrid der Verbindung zwischen 198 und 361 °C als stabil. Die weitere Zersetzung führte zu CoO. Zn[(C6H12)(NH3)2][C6H2(COO)4] · 1/2H2O (2) wurde analog zu 1 unter Verwendung von 1, 6‐Diaminohexan hergestellt. Raumgruppe P21/n (Nr. 14), a = 1087.78(8), b = 1515.18(11), c = 1162.21(10) pm, β = 96.249(7)°, V = 1.9042(3) nm3, Z = 4. Zn2+ ist ebenfalls wie Co2+ tetraedrisch von vier Sauerstoffatomen der Pyromellitatanionen koordiniert (Zn—O 195.0(4) ‐ 197.8(4)). Aus der Verknüpfung von Zn2+ mit den Pyromellitatanionen resultiert ein dreidimensionales Gerüst, das sehr große Ähnlichkeiten mit der Struktur von 1 aufweist und in seinen Hohlräumen (C6H12)(NH3)22+‐Kationen und Wassermoleküle beherbergt. 2 war in wasserfreier Form zwischen ca. 120 und 340 °C stabil, anschließend erfolgte die Zersetzung zu ZnO, die bei 700 °C abgeschlossen war.
Photochemische Reaktionen von Cyclopentadienylbis(ethen)rhodium mit 2‐ und 4‐Vinylpyridin
Authors: Müller Jörn , Hirsch Cordula , Ha Kwang
Published: December 2003

Bei der UV‐Bestrahlung von [CpRh(C2H4)2] (1) (Cp = η5‐C5H5) in Hexan in Gegenwart von 2‐Vinylpyridin erfolgt einerseits schrittweise Substitution der Ethenliganden durch die Vinylgruppe unter Bildung der einkernigen Komplexe [CpRh(C2H4)(η2‐C2H3C5H4N)] (2) und [CpRh(η2‐C2H3C5H4N)2] (3). In zwei weiteren zweikernigen Reaktionsprodukten tritt andererseits zusätzlich N‐Koordination auf, nämlich in [{CpRh(μ‐η1:η2‐2‐vinylpyridin)}2] (4) und in [(μ‐H)(μ‐η1:η1:η2‐2‐vinylidenpyridin)(CpR h)2] (5). DieVerbindung 5 enthält neben einer unsymmetrischen Hydridobrücke einen durch C‐H‐Aktivierung des Vinylsubstituenten in der β‐Position entstandenen Aza‐rhoda‐cyclopentadien‐Ring. Die Photoreaktion von 1 mit 4‐Vinylpyridin liefert dagegen neben Oligomeren des Liganden ausschließlich den zu 2 analogen Komplex 6. Die neuen Verbindungen wurden analytisch und spektroskopisch charakterisiert, im Falle von 5 auch durch Röntgenstrukturanalyse.
Self‐assembly of a Novel trans‐Oxamidato‐bridged Copper(II) Compound with a Neutral Oxamidate‐Ester Ligand as a Spacer. Crystal Structure, Spectroscopy, and Magnetism of a Chain of Dinuclear Units
Authors: van Albada Gerard A. , Mohamadou Aminou , Reedijk Jan , Kooijman Huub , Spek Anthony L.
Published: December 2003

The structural, spectroscopic and magnetic properties of a new dinuclear‐based polymeric oxamidato‐bridged CuII compound, [Cu2(H2oxen)(oxen)(H2O)(ClO4)2]n(C2H6O)2n (in which H2oxen = N, N′‐bis(2‐aminoethyl)oxamide) is reported. The X‐ray structure analysis reveals the triclinic space group P1¯ with a = 7.0857(10) , b = 10.333(2), c = 11.285(2)Å, α = 71.599(7), β = 83.047(7), γ = 83.238(8)°, Z = 2. The coordination around the CuII ion is distorted octahedral, the basal plane is formed by two N atoms and one O atom of the deprotonated ligand (distances in the range 1.919(2), 2.028(2)Å) and one N‐atom of the second ligand, which acts as the “spacer” ligand (Cu‐N distance 1.971(2)Å). The apical positions are occupied by a water molecule (Cu‐O1 distance 2.445(2)Å) and an O atom of a perchlorate anion at a semi‐coordination distance of 2.912(2)Å. The dinuclear units are connected with a H2oxen ligand forming an indefinite 2‐D polymeric array. The Cu‐Cu separation through trans‐oxen ligand within de dinuclear entity is 5.2548(11)Å and the Cu‐Cu‐ separation through the H2 oxen‐spacer ligand is 11.458(2)Å. Magnetic susceptibility measurements have been performed over a temperature range of 5‐350 K and resulted in an antiferromagnetic behaviour with a singlet‐triplet energy gap J = ‐558.1 cm‐1.
Synthesis and Structural Characterization of a New Tetranuclear Macrocyclic Copper(I) Complex
Authors: Utz Diana , Heinemann Frank W. , Mukherjee Jhumpa , Mukherjee Rabindranath , Schindler Siegfried
Published: December 2003

A tetranuclear copper(I) complex [Cu4(L2)Cl4] with a new macrocyclic ligand derived from the [4+4] condensation of ethylenediamine and isophthalaldehyde was synthesized and structurally characterized. The copper(I) ions are coordinated in a distorted tetrahedral manner by two imine nitrogen and two chloro donor atoms. The copper copper separation is 3.056(2)Å.
Synthesis, Structure, and Spectroscopic Properties of a Dinuclear FeIII(μ2‐O)FeIII Complex Using a Strongly Electron‐Donating Ligand: Implications for the Generation of New High‐Valent Species
Authors: Glaser Thorsten , Pawelke Roland H. , Heidemeier Maik
Published: December 2003

The dinuclear complex [LFeIII(μ2‐O)FeIIIL] (1) (H2L = ‐N, N′‐dimethyl‐N, N′‐bis(3, 5‐di‐tert‐butyl‐2‐hydroxybenzyl)‐1, 2diaminoethane) has been synthesized and structurally characterized by elemental analysis, MALDI‐TOF MS, FTIR, and single crystal X‐ray diffraction. The electronic structure has been investigated by means of electronic absorption, electrochemistry, Mössbauer spectroscopy, and variable‐temperature magnetic susceptibility measurements. The iron atoms are five‐coordinated in an idealized square‐pyramidal coordination environment. The N2O2 donor set of L2— forms the equatorial plane while the bridging oxo‐ligand is in the axial position forming a linear Fe—O—Fe unit. The Mössbauer spectrum at 80 K consists of one quadrupole doublet with an isomer shift of 0.45 mm s—1 and a quadrupole splitting of 1.22 mm s—1. The low isomer shift is indicative of highly covalent metal‐ligand bonds resulting in electron‐rich FeIII high spin centers (Si = 5/2). Variable‐temperature magnetic susceptibility measurement reveals an intramolecular antiferromagnetic coupling (J = —96 cm—1). Strong LMCT transitions in the vis‐region of the absorption spectrum are in accordance to the highly covalent nature of the FeIII sites. The electrochemical analysis reveals two oxidative electron‐transfer waves at E1/2 = +0.28 V and E1/2 = +0.45 V vs Fc+/Fc. These experimental data provide insight into the electronic structure of the dinuclear complex and into the ability of the strongly electron‐donating ligand L2— to stabilize high‐valent dinuclear iron species.
Growth of Calcite Single Crystals Underneath Monolayers of 5, 11, 17, 23‐Tetra‐t‐butyl‐25, 26, 27, 28‐tetrakis(carboxymethoxy)calix[4]arene
Authors: Volkmer Dirk , Fricke Marc
Published: December 2003

The amphiphilic 5, 11, 17, 23‐tetra‐t‐butyl‐25, 26, 27, 28‐tetrakis(carboxymethoxy)calix[4]arene (1) forms stable monolayers at the air‐water interface which serve as template to induce growth of CaCO3(calcite) single crystals. The nucleation density and the preferred orientation(s) of calcite single crystals depend on the surface pressure applied to the monolayer. Models of the pressure‐dependant aggregation of amphiphiles at the air‐water interface are derived from the crystal structures of the novel Ca coordination compounds [(Ca(C52H60O12))2Ca(H2O)2(CH3OH)3Ca(H2O)2(CH3OH)2]·12CH3OH·4H2O (2) and [Ca(C52H60O12)Ca(H2O)2.5(MeOH)0.5]·7H2O·CH3OH (3). Structural data are analyzed in terms of supramolecular packing arrangements and Ca coordination motifs of the constituting amphiphilic macrocycles.
Synthesis and Characterization of a Siderophore‐based Luminescent Sensor for Molybdate
Authors: Jedner Stephanie B. , Perutz Robin N. , Duhme‐Klair Anne‐K.
Published: December 2003

By connecting a bidentate siderophore to a luminescent tris(2, 2′‐bipyridyl)ruthenium(II) unit, a modular sensor reagent has been synthesised and characterised which selectively signals the presence of molybdate in solution through a decrease in emission intensity.
Bis[acetylacetonato(1—)‐O, O]di(cyanato‐N)silicon(IV): A Neutral Hexacoordinate Silicon Complex with Two Cyanato‐N Ligands
Authors: Tacke Reinhold , Bertermann Rüdiger , Penka Martin , Seiler Oliver
Published: December 2003

The neutral hexacoordinate silicon(IV) complex cis‐[(acac)2Si(NCO)2] (cis‐8; acac = acetylacetonato‐O, O) was synthesized, starting from Si(NCO)4. Compound cis‐8 was structurally characterized in the solid state (13C, 15N, and 29Si MAS NMR; crystal structure analysis) and in solution (1H, 13C, and 29Si NMR). The experimental investigations were complemented by computational studies (RI‐MP2 geometry optimizations of cis‐8 and trans‐8 and of the corresponding cyanato‐O isomers cis‐[(acac)2Si (OCN)2] (cis‐9) and trans‐[(acac)2Si(OCN)2] (trans‐9); calculations of the 29Si NMR chemical shifts of cis‐8, trans‐8, cis‐9 and trans‐9 using the optimized structures).
Halogen‐Halogen‐Wechselwirkungen im Kristall von 2 ImIBr · Br‐CF2CF2‐I (Im = 1, 3‐Diisopropyl‐4, 5‐dimethylimidazoly [1]
Authors: Kuhn Norbert , Abu‐Rayyan Ahmed , Steimann Manfred
Published: December 2003

Interactions between Halogen Atoms in the Crystal of 2 ImIBr · Br‐CF2CF2‐I (Im = 1, 3‐Diisopropyl‐4, 5‐dimethylimidazoly[1]

2, 3‐Dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐ylidene (3, Im) reacts with Br‐CF2CF2‐I to give the adduct 2 Im‐I‐Br · Br‐CF2CF2‐I (5). The crystal structure analysis of 5 exhibits near linear C‐I‐Br interactions in addition to short Br‐Br and Br‐I contacts to the Br‐CF2CF2‐I fragment.
Biometallorganische Koordinationsverbindungen: Synthese und Strukturen von Übergangsmetallkomplexen mit Tropidinyl‐ und Tropidin‐Liganden
Authors: Tamm Matthias , Kunst Andreas , Hahn F. Ekkehardt , Pape Tania , Fröhlich Roland
Published: December 2003

Die Deprotonierung des Alkens Tropidin bzw. 8‐Methyl‐8‐azabicyclo[3.2.1]oct‐2‐en (1) mit n‐Butylnatrium führt in guten Ausbeuten zum Natriumsalz des Tropidinyl‐Anions (2). Die Reaktion mit Me3SnCl liefert 4‐Trimethylstannyltropidin (3), welches als Ausgangsmaterial für den Aufbau von Tropidinyl‐Übergangsmetallkomplexen dient. Die Komplexe [(2)M(CO)3] (M = Mn, 4a; M = Re, 4b) können durch Umsetzung von 3 mit den Bromiden [M(CO)5Br] synthetisiert werden, während [(2)Ru(PPh3)2Cl] (5) durch Reaktion mit [Ru(PPh3)3Cl2] erhalten wird. Der Tropidinyl‐Ligand 2 koordiniert in den Komplexen 4 und 5 sowohl über das verbrückende Stickstoffatom als auch über die drei allylischen Kohlenstoffatome und kann mit seinen getrennten 2σ‐ und 4π‐Elektronen‐Donorzentren als Cp‐analoger Ligand aufgefaßt werden. Die Reaktion des Chloro‐Komplexes 5 mit Superhydrid, Li[BEt3H], ergibt das Hydrid [(2)Ru(PPh3)2H] (6). Bei der Kristallisation von 6 wird der Peroxo‐Komplex [(1)Ru(PPh3)2(O2)] (7) isoliert, der den Tropidin‐Liganden 1 enthält. Die Komplexe 4a, 5·CH2Cl2 und 7 konnten durch Einkristall‐Röntgenstrukturanalysen charakterisiert werden.
Stability of new implicit iteration procedures for a class of nonlinear set‐valued mixed variational inequalities
Authors: Fang Y.‐p. , Deng C.‐x.
Published: December 2003

In this paper, we develop some new implicit iteration procedures for solving a class of nonlinear set‐valued mixed variational inequalities. We also introduce a concept of stability of implicit iteration procedures and discuss the convergence and stability of the iterative sequences generated by the algorithms. The results presented in this paper extend and improve the corresponding results of Huang [11].
Solution of the Lyapunov matrix equation for a system with a time‐dependent stiffness matrix
Authors: Pommer C. , Kliem W.
Published: December 2003

The stability of the linearized model of a rotor system with non‐symmetric strain and axial loads is investigated. Since we are using a fixed reference system, the differential equations have the advantage to be free of Coriolis and centrifugal forces. A disadvantage is nevertheless the occurrence of time‐dependent periodic terms in the stiffness matrix. However, by solving the Lyapunov matrix equation we can formulate several stability conditions for the rotor system. Hereby the positive definiteness of a certain averaged stiffness matrix plays a crucial role.
Elliptic integral solutions of variable‐arc‐length elastica under an inclined follower force
Authors: Chucheepsakul S. , Phungpaigram B.
Published: December 2003

This paper presents exact closed‐formed solutions using elliptic integrals for large deflection analysis of elastica of a beam with variable arc‐length subjected to an inclined follower force. The beam is hinged at end but slides freely over the support at the other end. In the undeformed state, the inclined follower force applied at any distance from the hinged end making an angle γ with respect to vertical axis while in the deformed state its direction remains at an angle γ from the normal to the beam axis. The set of nonlinear equations is obtained from the boundary conditions, and solved iteratively for the solutions. The effect of the direction and the position of the follower force on the beam bending behaviour is demonstrated. Comparisons of equilibrium configurations of the beam under non‐follower force and follower force are also given.
Lymphoid–Epithelial Secretory Immune System in Human Fetuses in the Second Trimester of Gestation
Authors: Gurevich Pavel , Ben-Hur Herzl , Szvalb Sergio , Moldavsky Moisey , Zusman Itshak
Published: December 2003

The development of the secretory immune system (SIS) in the respiratory, digestive, and urogenital tracts and other organs of fetuses in the second trimester of gestation is described. Tissues of all internal organs of human fetuses ( n = 36) that had died between 13 and 25 weeks of gestation were studied immunohistochemically for the presence of secretory component (SC), J chain, IgA, IgM, IgG, macrophages, and different subsets of lymphocytes. We found protein elements of the SIS in fetuses during the entire second trimester in the epithelium of the digestive, respiratory, and urinary tracts; in hepatocytes; in the epithelium of the bile duct, renal tubules, and all the urinary tract; in the salivary glands, pancreas, and thyroid; in the epithelium of the Fallopian tubes and uterus; in the epididymis and the rete testes; in the skin; and in other organs. Immunocompetent cells, including IgA- and IgM-secreting cells, were located in these organs under the epithelium and sometimes between epithelial cells. In fetuses with acute infection, the number of immunocompetent cells was higher, reflecting a whole–immune system reaction, including the SIS. We conclude that the fetal SIS is a ramified, defensive immune system that is distributed throughout most organs of epithelial origin in second-trimester fetuses, and that it reacts against intrafetal infiltration by foreign antigens.
Demonstration of Placental Vascular Anatomy in Monochorionic Twin Gestations
Authors: De Paepe Monique E. , Burke Sarah , Luks Francois I. , Pinar Halit , Singer Don B.
Published: December 2003

Invasive treatment modalities for severe chronic twin-to-twin transfusion syndrome (TTTS), such as fetoscopic laser coagulation of communicating vessels, have revived the need for detailed studies of placental angioar-chitecture. We describe a practical placental vascular injection technique using alcohol-resistant tissue-staining dyes. Injection of color-coded gelatin-dye mixtures effectively delineated the intertwin vasculature, and allowed unequivocal macroscopic classification of vascular communications as artery-to-artery, vein-to-vein, or deep artery–to-vein anastomoses. The existence of deep artery–to-vein anastomoses was further confirmed by light microscopic demonstration of venous dye of one twin and arterial dye of the opposite twin within the same stem villus. Furthermore, the injection technique allowed determination of the caliber of the anastomoses, the direction of the artery-to-vein anastomoses, and the relative vascular territory of each twin. Documenting the vascular communications in monochorionic twin placentas with and without TTTS may enhance our understanding of the pathogenesis of chronic TTTS. Correlating the anastomotic patterns and location of the laser coagulation scars with post-ablation outcome will aid in the design of rational therapeutic methods for this often lethal condition.
Agenesis of the Mesencephalon and Metencephalon with Cerebellar Hypoplasia: Putative Mutation in the EN2 Gene—Report of 2 Cases in Early Infancy
Authors: Sarnat Harvey B. , Benjamin Denis R. , Siebert Joseph R. , Kletter Gad B. , Cheyette Sarah R.
Published: December 2003

Congenital absence of the midbrain and upper pons is a rare human malformation. We describe two unrelated infants with this anomaly and cerebellar hypoplasia who were born at term but died in early infancy from lack of central respiratory drive. MRI in both cases disclosed the lesions during life. Neuropathological examination, performed in one, included immunocytochemical studies of NeuN, synaptophysin, vimentin, and glial fibrillary acidic protein (GFAP). Autopsy revealed a thin midline cord passing through the clivus, in place of the mid-brain; it corresponded to hypoplastic and fused corticospinal tracts with ectopic neural tissue in the surrounding leptomeninges. Some ectopia were immunoreactive for synaptophysin and NeuN and others were nonreactive. The neural surfaces facing the subarachnoid fluid-filled space left by the absent midbrain and upper pons were lined by an abnormal villous ependyma. The architecture of the cerebellar cortex was imperfect but generally normal, and Bergmann glial cells had normal radial processes shown by vimentin and GFAP. Structures of the telencephalon, diencephalon, lower brainstem, and spinal cord were generally well formed, but inferior olivary and dentate nuclei were rudimentary and the spinal central canal was dilated at lumbar levels. The cerebral cortex was normally laminated, but pyramidal neurons of layer 5 were sparse in the frontal lobes. The hippocampus, olfactory system, and corpus callosum were formed. An ectopic lingual thyroid was found and had been associated with hypothyroidism during life. A murine model resembling this dysgenesis is demonstrated by homozygous mutations of the organizer genes Wnt1 or En1, also resulting in cerebellar aplasia, and En2, associated with cerebellar hypoplasia. These genes are essential to the formation of the mesencephalic neuromere and rhombomere 1 (metencephalon or upper pons and cerebellum). Pax8 has binding sites in the promoter for En2 and is essential for thyroid development. We speculate that in the human, the failure to form a mesencephalon and metencephalon, with cerebellar hypoplasia, results from a mutation or deletion in the EN2 ( Engrailed-2) gene.
Chromosome Rearrangement with No Apparent Gene Mutation in Familial Adenomatous Polyposis and Hepatocellular Neoplasia
Authors: de Chadarévian Jean-Pierre , Dunn Stephen , Malatack J. Jeffrey , Ganguly Arupa , Blecker Uwe , Punnett Hope H.
Published: December 2003

We have identified a constitutional inversion in chromosome 5 associated with familial adenomatous polyposis in three generations of a Mexican family. Two of three siblings developed hepatic neoplasia in infancy. The gene truncation assay failed to demonstrate a truncated protein in the segment harboring the adenomatous polyposis coli (APC) genes. Polymerase chain reaction (PCR) amplification of APC gene coding exons and sequencing of PCR products did not reveal any significant mutation. The data suggest that in this family, the phenotype may be the result of a “position effect.”
Enteric Nervous System: Development and Developmental Disturbances—Part 1
Authors: Newgreen Donald , Young Heather M.
Published: December 2003

This review, which is presented in two parts, summarizes and synthesizes current views on the genetic, molecular, and cell biological underpinnings of the early embryonic phases of enteric nervous system (ENS) formation and its defects. In the first part, we describe the critical features of two principal abnormalities of ENS development: Hirschsprung's disease (HSCR) and intestinal neuronal dysplasia type B (INDB) in humans, and the similar abnormalities in animals. These represent the extremes of the diagnostic spectrum: HSCR has agreed and unequivocal diagnostic criteria, whereas the diagnosis and even existence of INDB as a clinical entity is highly controversial. The difficulties in diagnosis and treatment of both these conditions are discussed. We then review the genes now known which, when mutated or deleted, may cause defects of ENS development. Many of these genetic abnormalities in animal models give a phenotype similar or identical to HSCR, and were discovered by studies of humans and of mouse mutants with similar defects. The most important of these genes are those coding for molecules in the GDNF intercellular signaling system, and those coding for molecules in the ET-3 signaling system. However, a range of other genes for different signaling systems and for transcription factors also disturb ENS formation when they are deleted or mutated. In addition, a large proportion of HSCR cases have not been ascribed to the currently known genes, suggesting that additional genes for ENS development await discovery.
Pulmonary Hemangiomas of Infancy and Childhood: Report of Two Cases and Review of the Literature
Authors: Abrahams Neil A. , Colby Thomas V. , Pearl Richard H. , Chipps Bradley E. , Juris Andrew , Leslie Kevin O.
Published: December 2003

Pulmonary hemangiomas are exceptionally rare in childhood and more so in infancy. They may involve the airways or the parenchyma, and may be localized or multifocal. We present two cases of pulmonary capillary hemangiomas. The first case is a localized form of capillary hemangioma that was resected from an 8-week-old infant with signs of respiratory distress. A computed tomography scan showed a cystic mass initially thought to be an intrapulmonary bronchogenic cyst. A segmental resection was performed and examination revealed a localized capillary hemangioma without cystic or cavernous features. The second case is an example of a multifocal capillary hemangioma from a 9-year-old child who presented clinically with clubbing of fingers and toes and radiologically had multiple discrete nodules localized to the right lung. The clinical and pathological features of the cases are discussed together with a review of the literature. The distinction from other vascular neoplasms of childhood is briefly described. Although rare, pulmonary hemangiomas should be entertained in the diagnosis of both solid and cystic intrapulmonary lesions of childhood and infancy.
Intralobar Sequestration of the Lung is a Congenital Anomaly: Anatomopathological Analysis of Four Cases Diagnosed in Fetal Life
Authors: Walford Norman , Htun Kyaw , Chen Jeanette , Liu Yan Ying , Teo Harvey , Yeo George S.H.
Published: December 2003

The origin of intralobar sequestration of the lung (ILS)— whether congenital or acquired—has often been controversial, since firm anatomical evidence of prenatal origin has been sparse. We describe four cases in which anomalous arterial supply from the aorta to abnormally echogenic lower lung lobes was demonstrated on routine antenatal ultrasound examination, and the diagnosis of ILS was subsequently confirmed by postmortem examination including bronchography of the fetuses at between 20 and 23 wk. One right-sided lesion was supplied from a branch of the coeliac axis, and three left-sided lesions were supplied from the thoracic aorta. In two cases, the arterial supply was shown to be multiple. All lesions were situated in the lower lobes. They showed a cystic transformation of the affected lung tissue which was histologically indistinguishable from cases diagnosed as congenital cystic adenomatoid lesion (CCAM) at the same gestational age, but clearly different from that seen in bronchial obstruction due to laryngeal stenosis at that age. Similar vascular lesions have been reported in otherwise normal lungs. The character of the anomalous arterial vessels is consistent with origin from the embryonic splanchnic plexus. The precise sequence of pathogenetic events is unclear but there appears to be a close relationship of this condition not only with CCAM but also with the condition of anomalous arterial supply to the lower lobe.
Immunohistochemical Localization of Endothelin-1 in Human Placenta from Normal and Growth-Restricted Pregnancies
Authors: Erdem Mehmet , Erdem Ahmet , Erdem Ozlem , Yildirim Gizem , Memis Leyla , Himmetoğlu Ozdemir
Published: December 2003

The purpose of this study was to investigate whether the localization of endothelin-1 (ET-1) immunoreactivity differs in human placental tissues from third-trimester normal and intrauterine growth restricted (IUGR) pregnancies. Immunohistochemistry for ET-1 was performed on human placentas from 30 IUGR and 30 uncomplicated pregnancies matched for gestational age. The distribution and intensity of ET-1 immunoreactivity was assessed by a semiquantitative scoring system. Doppler flow velocity waveform analysis of the umbilical artery was performed in each patient before delivery. ET-1 was localized diffusely in placental specimens from normal and IUGR pregnancies. The localization of ET-1 immunoreactivity was significantly higher in the capillary endothelial cells of villi as well as in the endothelial, decidual, and trophoblastic cells of the basal plate in placentas from normal pregnancies than from IUGR pregnancies. There was no significant difference in placental ET-1 immunoreactivity between IUGR pregnancies with normal and abnormal umbilical artery Doppler flow velocity waveforms. Placental ET-1 immunoreactivity was significantly higher in the decidual and trophoblastic cells of the basal plate and the capillary endothelial cells of villi in normal pregnancies than in IUGR pregnancies with normal umbilical artery Doppler flow velocity waveforms. However, only the decidual and trophoblastic cells of the basal plate demonstrated significantly higher abundant localization of ET-1 immunoreactivity in normal pregnancies than in IUGR pregnancies with abnormal umbilical artery Doppler flow velocity waveforms. In conclusion, our findings suggest that the lower expression of ET-1 in placental tissues from IUGR pregnancies might be secondary to an adaptive mechanism to reduce the vasoconstrictor effect of ET-1.
Gastrointestinal Polyposis in Childhood: Clinicopathologic and Genetic Features
Authors: Lowichik Amy , Jackson W. Daniel , Coffin Cheryl M.
Published: December 2003

Gastrointestinal polyps and certain extraintestinal lesions in children may herald a hereditary polyposis syndrome, with an increased risk of neoplasia and other health problems for both children and their relatives. The availability of molecular/genetic screening tests has increased early diagnosis of younger members of known polyposis families. This article reviews the gross and microscopic features of polyposis syndromes of childhood and summarizes the molecular/genetic advances in this field. Clinical management is also briefly discussed.
Molecular Insights into Congenital Disorders of the Digestive System
Authors: Bates Michael D. , Deutsch Gail H.
Published: December 2003

Recent work is providing new insights into molecular mechanisms of digestive system development and their alteration in clinically significant disorders. An understanding of these mechanisms has largely been gained through the use of animal models, because many of the basic processes required in embryogenesis are functionally conserved among species. Such conserved factors include cell–cell signaling pathways and the regulation of gene expression. Disruption of these pathways have been implicated in several congenital disorders of the digestive system, including Hirschsprung disease, malrotation, altered sphincter development, Meckel diverticulum, biliary atresia, Alagille syndrome, pancreatic heterotopias, and pancreatic agenesis. In this review, we highlight recent studies in digestive system development, which elucidate mechanisms underlying congenital disorders of the human digestive system.
Expression of Angiogenesis-Related Factors in Lungs of Patients with Congenital Diaphragmatic Hernia and Pulmonary Hypoplasia of Other Causes
Authors: de Rooij Jessica D. , Hösgör Münnever , Ijzendoorn Ynske , Rottier Robbert , Groenman Frederick A. , Tibboel Dick , de Krijger Ronald R.
Published: December 2003

Congenital diaphragmatic hernia (CDH) is a congenital disorder, complicated by pulmonary hypoplasia (PH) and pulmonary hypertension. Hypoplastic lungs have fewer and smaller airspaces than normal, with thicker interalveolar septa; the adventitia and media of pulmonary arteries are thickened, and the total size of the pulmonary vascular bed is decreased compared to normal. Although histological abnormalities in PH have been described, less is known about the underlying molecular mechanisms. Therefore, we have investigated a series of proteins, known to be involved in angiogenesis, including von Hippel-Lindau protein (pVHL), hypoxia-inducible factor-1a (HIF-1a), vascular endothelial growth factor (VEGF), fetal liver kinase 1 (Flk-1), and endothelial and inducible nitric oxide synthase (eNOS, iNOS) by immunohistochemistry on paraffin-embedded lung tissue of CDH patients (n = 13), patients with lung hypoplasia due to other causes (n = 20), and normal controls (n = 33). pVHL was expressed more frequently in the arterial smooth muscle cells of CDH lungs compared with both other groups. Furthermore, HIF-1a was expressed less frequently in the endothelium of arteries, veins, and capillaries of CDH lungs as compared with both other groups. No differences were observed in the expression patterns of VEGF, Flk-1, eNOS, and iNOS between the different groups. Our data suggest a role for pVHL and HIF-1a in normal and abnormal pulmonary angiogenesis. The differential expression of these proteins may provide a molecular basis for the histological differences observed in the lung vessels of patients with CDH.
Primary Ocular Adnexal Lymphoma in Pediatric Patients: Report of Two Cases and Review of the Literature
Authors: Liang Xiayuan , Stork Linda C. , Albano Edythe A.
Published: December 2003

Primary ocular adnexal lymphoma (POAL) is a rare extranodal lymphoma. The mucosa-associated lymphoid tissue (MALT) subtype predominates and primarily occurs after the sixth decade of life. Most studies of ocular adnexal lymphoma are from the adult population. The data and experience in pediatric patients with POAL are limited to a few cases reported in the literature. Here we describe two pediatric cases of POAL and review the literature to further help characterize the clinical features and histopathologic appearance of this uncommon lymphoma.
Beckwith-Wiedemann Syndrome-associated Hepatoblastoma: Wnt Signal Activation Occurs Later in Tumorigenesis in Patients with 11p15.5 Uniparental Disomy
Authors: Fukuzawa Ryuji , Hata Jun-ichi , Hayashi Yutaka , Ikeda Hitoshi , Reeve Anthony E.
Published: December 2003

Beckwith-Wiedemann syndrome (BWS) patients with chromosome 11p15.5 uniparental isodisomy (UPD) have an increased risk for developing embryonal tumors. UPD in these patients involves maternal loss of heterozygosity (LOH) and paternal duplication, which leads to tissue overgrowth and tumor development. Although 11p15.5 UPD predisposes to tumorigenesis, the events leading to tumorigenesis in UPD patients remains unknown. We have examined two hepatoblastomas in the BWS patients with UPD to determine the sequence of genetic events. Constitutional 11p15.5 LOH was detected in the blood or nonneoplastic liver of the BWS patients with hepatoblastoma. Mutation of β-catenin gene (CTNNB1) was found in one hepatoblastoma. Although mutations in CTNNB1 were not found in the second hepatoblastoma, nuclear accumulation of β-catenin was detected. However, mutation of CTNNB1 or nuclear accumulation of β-catenin was not detected in the tissue with hepatomegaly which contains UPD cells. These data indicate that Wnt signal activation can be involved as a later event in BWS-associated hepatoblastoma involving 11p15.5 UPD.
Basal Cells of Second Trimester Fetal Breasts: Immunohistochemical Study of Myoepithelial Precursors
Authors: Jolicoeur Francine , Gaboury Louis A. , Oligny Luc L.
Published: December 2003

The molecular characterization of human mammary myoepithelial cells is incomplete, hindering our understanding of its importance in breast physiology and pathology. Because data on the precursors of this cell lineage remain scarce and often contradictory, basal epithelial cells of second trimester fetal breasts were studied by light microscopy (LM) and immunohistochemistry (IHC). Up to 20 wk of gestational age, the mammary rudiments only comprised roundish primary outgrowths, “primary buds,” more likely to represent immature nipples than true mammary tissue. At 21 wk secondary outgrowths, “projections,” extended from enlarged primary buds into well-vascularized layers of dense mesenchyme. Basal projection cells had a partial myoepithelial-like phenotype: they reacted with CD29, CD49f, CD104, keratin 14, vimentin, S100β protein, and p63; furthermore, many became positive for keratin 17, α-smooth muscle actin, and CD10 (but not for keratin 19) between wk 21 and 25. The continuous basement membrane associated with the fetal mammary rudiments was strongly positive for collagens type IV and VII, and for laminin 5. Consistently strong and basally polarized staining for hemidesmosomal components suggested that although incompletely differentiated, most second trimester myoepithelial precursors might already mediate local epithelial-mesenchymal interactions, i.e., complex signaling pathways which are crucial for both orderly growth during development and maintenance of homeostasis during adult life. Because they are likely implicated in the phenomenon of menstrual cycle-related growth spurts in the adult resting breast, the strategically positioned cells of the myoepithelial lineage might constitute critical protagonists in defective epithelial-mesenchymal signaling associated with cancer progression.
Developmentally Regulated Expression of Survivin in Human Pancreatic Islets
Authors: Liggins C. , Orlicky D.J. , Bloomquist L.A. , Gianani Roberto
Published: December 2003

Islet cell apoptosis plays a role in both normal development of the endocrine pancreas and in the pathogenesis of Type I and Type II diabetes. The molecular mechanisms regulating islet cell death and survival in both normal and pathological situations are still not completely elucidated. The inhibitor of apoptosis protein (IAP) Survivin has an anti-apoptotic function mediated by several mechanisms; these include inhibiting caspase 3 and caspase 7. Survivin expression has been reported in human fetal islets and it may play a role in pancreatic remodeling and islet homeostasis. However, there are no data concerning either its expression in neonate or adult islets or its expression in any specific subtype of islet cells. We identified Survivin expression by immunohistochemistry in alpha cells and beta islet cells of 5/5 fetal pancreases. In contrast, fetal delta cells failed to demonstrate any detectable level of Survivin expression. Survivin expression was subsequently lost in the beta cells but not the alpha cells of 5/5 newborns and 5/5 adult subjects. Neonatal and adult delta cells maintained the lack of Survivin expression seen in fetal islets. These data show that different subtypes of islet cells differ in their pattern of Survivin expression. Furthermore, expression of Survivin in the beta cells is developmentally regulated.
Unusual Hepatic Tumor with Features of Mesenchymal Hamartoma and Congenital Solitary Nonparasitic Cyst
Authors: Azar Georgia M. , Kutin N. , Kahn Ellen
Published: December 2003

We report a hepatic tumor in an adolescent that does not fit into any of the described categories of liver tumors. The patient presented with hepatomegaly, abdominal pain, and normal liver function test; the tumor was cystic in imaging studies. The resected specimen, result of a partial hepatectomy, measured 21 cm and was multicystic with solid areas. Microscopically, the cysts were lined by a mucous-producing or intestinal-type epithelium, associated with smooth muscle and small mucous-producing glands. The solid component contained fibrous and adipose tissue, smooth muscle and thick-walled vessels. Aneuploidy was demonstrated by flow cytometry. We interpreted the tumor as having features of a mesenchymal hamartoma and congenital solitary nonparasitic cyst. It is conceivable that the lesions originated with small peribiliary glands with dilatation and intestinal metaplasia.
Estimation of Time of Fetal Death in the Second Trimester by Placental Histopathological Examination
Authors: Jacques Suzanne M. , Qureshi Faisal , Johnson Anthony , Alkatib Aziz A. , Kmak David C.
Published: December 2003

It has been suggested that certain placental histopathological changes may be useful in predicting the time of death in stillborn fetuses. We retrospectively evaluated 36 placentas from therapeutic terminations in which the time interval between fetal death and delivery was relatively short and well-documented to determine the earliest stillbirth-associated changes and the utility of placental examination in timing death in the second trimester. In each case, termination had been initiated by creating fetal asystole with intracardiac KCl injections. The gestational age ranged from 18–23 wk. The time from asystole to placental delivery range was 2.8–52.0 h. Placental groups were categorized by time intervals from asystole to delivery: I,<12h[ n = 4(11%)]; II, 12–24 h [ n = 15 (42%)]; III, 24–36 h [ n = 14 (39%)]; IV, > 36 h [ n = 3 (8%)]. Among eight histopathologic changes involving the umbilical cord or chorionic villi evaluated, only three were present in a significant number of cases and also appeared to be the result of stillbirth. Degeneration of cord vascular smooth muscle was present in 33% of umbilical cords in group I, but was seen in 100% of cords in groups II–IV; the extent of these changes increased significantly with increasing time intervals. Intravascular karyorrhexis was present in villous blood vessels in 75, 73, 64, and 100%, respectively, for groups I–IV. Villous blood vessel luminal abnormalities were seen in 25, 7, 21, and 67%, respectively, for groups I–IV. These findings indicate that these are the earliest morphological changes in stillbirth in second trimester placentas, but they cannot be used to accurately predict time of death in the relatively short time intervals evaluated in this study.
Adolescent religiosity and sexuality: an investigation of reciprocal influences
Authors: Hardy Sam A , Raffaelli Marcela
Published: December 2003

The present study examined potential bi‐directional associations between religiosity and first sexual intercourse. The sample, drawn from the National Longitudinal Survey of Youth, included 303 teens (22% Hispanic, 35% Black, 43% White; 53% male) aged 15–16 in 1996 and 17–18 in 1998. All teens included in the sample were virgins at Time 1. In the longitudinal analyses, higher Time 1 religiosity (a composite of importance of religion and frequency of church attendance) was associated with a lower likelihood of first sexual intercourse between Time 1 and Time 2. However, transition to sexual activity between Time 1 and Time 2 was not significantly related to Time 2 religiosity. Thus, results do not support a bi‐directional association; instead, it appears that teens with higher levels of religiosity tend to delay sexual involvement more than those with lower levels of religiosity.
Newly identified exons encoding novel variants of p94/calpain 3 are expressed ubiquitously and overlap the α‐glucosidase C gene
Authors: Kawabata Yukiko , Hata Shoji , Ono Yasuko , Ito Yoshimasa , Suzuki Koichi , Abe Keiko , Sorimachi Hiroyuki
Published: December 2003

There are two classes of an intracellular ‘modulator protease’, calpain: ubiquitous and tissue‐specific. p94/calpain 3 is an example of the latter, predominantly expressed in muscle. A defect in the p94 gene causes muscular dystrophy. Here we report that human and mouse p94 genes have a possible novel alternative promoter expressing p94 variants in all tissues examined including human lens epithelial cells. The possible promoter region and the following novel exons overlap the 3′ region of the neutral α‐glucosidase C gene. Unlike p94, the novel p94 variants expressed in COS7 cells do not undergo rapid autolysis, suggesting basic functions different from p94.
Identification of a new expanding family of genes characterized by atypical LRR domains. Localization of a cluster preferentially expressed in oocyte
Authors: Dadé Sébastien , Callebaut Isabelle , Mermillod Pascal , Monget Philippe
Published: December 2003

In the present work, we have used the in silico subtraction methodology to identify novel oocyte‐specific genes in the mouse. By this way, we have identified in silico a new family of genes composed of more than 80 members. Sequence analysis showed that these genes belong to the superfamily of leucine‐rich repeat (LRR) proteins. However, LRRs of this family display some variability in length and in amino acids composition within the β‐strands region, as more leucine residues are substituted by other hydrophobic amino acids as compared to canonical LRRs. Interestingly, for nine of these genes, the ESTs were represented almost exclusively in mouse egg libraries. Three of them were selected for experimental study. By RT‐PCR and in situ hybridization, we confirmed their specific expression in the mouse oocyte from primary to preovulatory follicles. These three genes are localized in a cluster on mouse chromosome 4, in the vicinity of another recently discovered oocyte specific gene called oogenesin, that we also found to belong to the same family. We thus re‐named this latter gene ‘oogenesin‐1’, and the three genes identified here were named oogenesin‐2, ‐3 and ‐4.