bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of an evolutionarily novel structure: Fibroblast growth factor expression in the carapacial ridge of turtle embryos
Authors: Loredo Grace A. , Brukman Alla , Harris Matthew P. , Kagle David , Leclair Elizabeth E. , Gutman Rachel , Denney Erin , Henkelman Emily , Murray B. Patrick , Fallon John F. , Tuan Rocky S. , Gilbert Scott F. 
Published: August 2002

AbstractThe turtle shell, an evolutionarily novel structure, contains a bony exoskeleton that includes a dorsal carapace and a ventral plastron. The development of the carapace is dependent on the carapacial ridge (CR), a bulge in the dorsal flank that contains an ectodermal structure analogous to the apical ectodermal ridge (AER) of the developing limb (Burke. 1989a. J Morphol 199:363–378; Burke. 1989b. Fortschr Zool 35:206–209). Although the CR is thought to mediate the initiation and outgrowth of the carapace, the mechanisms of shell development have not been studied on the molecular level. Here, we present data suggesting that carapace formation is initiated by co‐opting genes that had other functions in the ancestral embryo, specifically those of limb outgrowth. However, there is divergence in the signaling repertoire from that involved in limb initiation and outgrowth. In situ hybridizations with antisense riboprobes derived from Trionyx spiniferous fibroblast growth factor‐10 (tfgf10) and Trachemys scripta (T. scripta) fibroblast‐growth factor 8 (tfgf8) cDNAs were performed on sections of early T. scripta embryos (< 30 days). Expression of tfgf10 was localized to the mesenchyme subjacent to the ectoderm of the CR. In the chick limb bud, FGF10 is known to be expressed in the early limb‐forming mesenchyme and is capable of inducing FGF8 in the AER to initiate the outgrowth of the limb bud. Although the expression of tfgf8 was found in the AER of the developing turtle limb, it was not seen in the CR. Thus, the initiation of the carapace is in agreement with FGF10 expression in the CR, but FGF8 does not appear to have a role in mediating early carapace outgrowth. J. Exp. Zool. (Mol. Dev. Evol.) 291:274–281, 2001. © 2001 Wiley‐Liss, Inc.
Identifying genes for male sex determination in humans
Authors: Ostrer Harry 
Published: August 2002

AbstractThe convergence of genetic and molecular technologies has led to the identification of a number of genes for male sex determination. The observation of chromosomal translocations, deletions, and duplications in sex reversed individuals was instrumental for the positional cloning of SRY, SOX9, WT1, and DAX1. Cloning by protein‐DNA interaction was required for the identification of SF1. The observation of an extended phenotype for the alpha thalassemia‐mental retardation syndrome assigned a role for XH2 in the testicular determining process. Over the next several years, new sex determining genes will be identified by linkage analysis in large families with multiple sex reversed members, comparative genomic hybridization of sex reversed individuals, and database searches for genes that encode interacting proteins or paralogs of other species. Given the apparent differences in the sex determining mechanisms of even closely related species, the roles of all of these genes will require confirmation by demonstrating expression in human gonadal ridge at the critical time, and that mutations result in sex reversal. J. Exp. Zool. 290:567–573, 2001. © 2001 Wiley‐Liss, Inc.
Expression of P450arom in Malaclemys terrapin and Chelydra serpentina: A tale of two sites
Authors: Place Allen R. , Lang Jeff , Gavasso Sonja , Jeyasuria Pancharatnam 
Published: August 2002

AbstractThe formation of estrogens from androgens in all vertebrates is catalyzed by the “aromatase” complex, which consists of a membrane bound P450 enzyme, P450 aromatase (which binds the androgen substrate and inserts an oxygen into the molecule), and a flavoprotein (NADPH‐cytochrome P450 reductase). Among vertebrates, the two major sites of aromatase expression are the brain and gonads. Given the importance of estrogen in reptile sex determination, we set out to examine whether P450arom was involved in the initiation and/or stabilization of sex determination in turtles. We examined the expression of aromatase activity in the brain and gonads of two turtle species exhibiting temperature dependent sex determination (TSD), the diamondback terrapin (Malaclemys terrapin), and the common snapping turtle (Chelydra serpentina). Estradiol when applied at stage 14 of the terrapin induces expression of aromatase in the gonad of embryos incubated at male temperatures (26.5°C). The level of expression is similar to that of a normal embryonic ovary. When applied at stage 22, estradiol does not induce aromatase expression in the terrapin. The xenoestrogen, nonylphenol, sex reverses terrapin embryos at 26.5°C. Letrazole, a nonsteroidal aromatase inhibitor, suppresses aromatase activity in the brain at either incubation temperature. Ovotestes are produced by letrazole administration in the terrapin when incubated at 30.5°C.In the snapping turtle at stage 23, gonadal and brain aromatase activity in embryos incubated at female temperatures (30.5°C) is nearly half that exhibited in terrapin embryos at the same temperature. Moreover, letrazole administration suppresses aromatase expression to nearly basal levels. At male incubation temperatures (26.5°), brain aromatase expression is nearly three times higher than at female temperatures, while gonadal expression levels are nearly one third lower. However, the gonadal expression levels at male temperatures in the snapping turtle are nearly 25 times higher than that found in the terrapin. Estradiol administration elevates this level nearly three fold. These data suggest that is not merely the expression of aromatase that is important for ovarian development, but that the level of expression may be more important. J. Exp. Zool. 290:673–690, 2001. © 2001 Wiley‐Liss, Inc.
Female sperm storage in reptiles
Authors: Sever David M. , Hamlett William C. 
Published: August 2002

AbstractInternal fertilization and oviparity most likely are symplesiomorphies for modern reptiles, and viviparity has evolved independently numerous times in Sauria and Serpentes. Oviducal sperm storage is known in females of all taxa except Amphisbaenia. However, in Rhynchocephalia and Crocodilia, sperm storage is poorly studied, and specialized sperm storage tubules (Ssts) are unknown. We use the molecular phylogenetic hypothesis [(Chelonia+Archosauria) (Squamata)] to trace evolution of sperm storage characters. Ssts arose independently in Chelonia and Squamata. Turtles possess albumen‐secreting glands in the anterior half of the oviduct (the tuba or isthmus), and the most distal of these glands also serve as Ssts; in addition, some turtles possess Ssts in the adjacent segment of the oviduct, the uterus. Squamates lack albumen‐secreting glands, and the ancestral state is possession of Ssts in the posterior infundibulum (uterine tube). Secondarily, iguanids have evolved vaginal Ssts. In this paper, we present the first ultrastructural observations on vaginal Ssts in lizards, using Anolis sagrei (Polychrotidae). Proximally, the neck of these simple tubular glands continues the alternation of ciliated and secretory cells lining the lumen of the vagina. However, the epithelial cells of the distal sperm storage area are neither secretory nor ciliated. The Ssts of Anolis are more similar to those of birds more than to infundibular receptacles in snakes and lizards J. Exp. Zool. 292:187–199, 2002. © 2002 Wiley‐Liss, Inc.
Trading crossings for handles and crosscaps
Authors: Archdeacon Dan , Bonnington C. Paul , Širáň Jozef 
Published: August 2002

AbstractLet ck = crk (G) denote the minimum number of edge crossings when a graph G is drawn on an orientable surface of genus k. The (orientable) crossing sequence co, c1,c2…encodes the trade‐off between adding handles and decreasing crossings. We focus on sequences of the type co > c1 > c2 = 0; equivalently, we study the planar and toroidal crossing number of doubly‐toroidal graphs. For every ϵ > 0 we construct graphs whose orientable crossing sequence satisfies c1/co > 5/6−ϵ. In other words, we construct graphs where the addition of one handle can save roughly 1/6th of the crossings, but the addition of a second handle can save five times more crossings. We similarly define the non‐orientable crossing sequence ˜0,˜1,˜2, ··· for drawings on non‐orientable surfaces. We show that for every ˜0 > ˜1 > 0 there exists a graph with non‐orientable crossing sequence ˜0, ˜1, 0. We conjecture that every strictly‐decreasing sequence of non‐negative integers can be both an orientable crossing sequence and a non‐orientable crossing sequence (with different graphs). © 2001 John Wiley & Sons, Inc. J Graph Theory 38: 230–243, 2001
Circular flows of nearly Eulerian graphs and vertex‐splitting
Authors: Zhang Cun Quan 
Published: August 2002

AbstractThe odd edge connectivity of a graph G, denoted by λo(G), is the size of a smallest odd edge cut of the graph. Let S be any given surface and ϵ be a positive real number. We proved that there is a function fS(ϵ) (depends on the surface S and limϵ→0 fS(ϵ)=∞) such that any graph G embedded in S with the odd‐edge connectivity at least fS(ϵ) admits a nowhere‐zero circular (2+ϵ)‐flow. Another major result of the work is a new vertex splitting lemma which maintains the old edge connectivity and graph embedding. © 2002 Wiley Periodicals, Inc. J Graph Theory 40: 147–161, 2002
Cubic graphs without cut‐vertices having the same path layer matrix
Authors: Dobrynin Andrey A. 
Published: August 2002

AbstractThe path layer matrix (or path degree sequence) of a graph G contains quantitative information about all possible paths in G. The entry (i,j) of this matrix is the number of paths in G having initial vertex i and length j. It is known that there are cubic graphs on 62 vertices having the same path layer matrix (A. A. Dobrynin. J Graph Theory 17 (1993) 1–4). A new upper bound of 36 vertices for the least order of such cubic graphs is established. This bound is realized by cubic graphs without cut‐vertices. © 2001 John Wiley & Sons, Inc. J Graph Theory 38: 177–182, 2001
Ernst Mach and the episode of the monocular depth sensations
Authors: Banks Erik C. 
Published: August 2002

AbstractAlthough Ernst Mach is widely recognized in psychology for his discovery of the effects of lateral inhibition in the retina (“Mach Bands”), his contributions to the theory of depth perception are not as well known. Mach proposed that steady luminance gradients triggered sensations of depth. He also expanded on Ewald Hering's hypothesis of “monocular depth sensations,” arguing that they were subject to the same principle of lateral inhibition as light sensations were. Even after Hermann von Helmholtz's attack on Hering in 1866, Mach continued to develop theories involving the monocular depth sensations, proposing an explanation of perspective drawings in which the mutually inhibiting depth sensations scaled to a mean depth. Mach also contemplated a theory of stereopsis in which monocular depth perception played the primary role. © 2001 John Wiley & Sons, Inc.
An economic model of self‐help groups: policy implications for banks and NGO initiatives
Authors: Sivramkrishna Sashi , Panigrahi Ramakrushna 
Published: August 2002

AbstractIn India, the Self‐Help Group (SHG) has emerged as a suitable innovative institution in bringing formal financial sector credit to poor. This article constructs an economic typology of SHGs based on four important economic variables, namely, interest on members' savings paid by the SHG, sharing of SHG surpluses by members, members' claim on exit from the SHG and lending rates charged by the SHG to members. An economic analysis of each type of SHG shows these variables to be important in terms of the members' costs of borrowing and demand for credit. Based on the analysis, some leads for a set of policy guidelines for each type of SHG are presented. Copyright © 2001 John Wiley & Sons, Ltd.
Globalization, industrial development and the plastics industry in South Africa
Authors: Roberts Simon 
Published: August 2002

AbstractThrough a study of the plastics sector in South Africa, the article critically examines the globalization position that greater openness yields gains from exports and foreign direct investment. Analysis of firm‐level data reveals that the depth and extent of the internationalization of production depends on the production capabilities of firms and their position and bargaining power in the supply‐chain. It is argued that liberalization does not necessarily mean that international relationships will be deepened and that a coherent industrial policy is important in the realization of the potential gains from such internationalization. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and preliminary in vivo evaluation of 4‐[123I]iodo‐N‐{2‐[4‐(6‐trifluoromethyl‐2‐pyridinyl)‐1‐piperazinyl]ethyl}benzamide, a potential SPECT radioligand for the 5‐HT1A receptor
Authors: Vandecapelle M. , De Vos F. , Dumont F. , Audenaert K. , Leysen D. , Dierckx R. A. , Slegers G. 
Published: August 2002

Abstract4‐[123I]Iodo‐N‐{2‐[4‐(6‐trifluoromethyl‐2‐pyridinyl)‐1‐piperazinyl]ethyl}benzamide (1. 123I), a potential SPECT 5‐HT1A radioligand, was synthesized by electrophilic iododestannylation of the tributyltin derivative with n.c.a. [123I]NaI and chloramine‐T under acidic conditions (20 min, ambient temperature). Radiochemical yield averaged around 60 % (sd = 8,n = 22). After HPLC purification, chemical purity was higher than 95 % and radiochemical purity higher than 99 %. Specific activity was always higher than 222 GBq/µmol (6 Ci/µmol). The calculated log P is 4.28. Initial brain uptake in NMRI mice was 1.16 % ID (2 min) and decreased slowly afterwards (0.51 % ID (2 h)). 60 min p.i., the majority of the radioactivity in plasma and brain was present as 1. 123I, respectively 75.15 % and 96.48 %. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of Phenyl‐13C6‐ethene
Authors: Zippi Elizabeth M. 
Published: August 2002

AbstractIn an effort to prepare an improved carbon‐rich target material for the accelerator production of 13N labelled ammonia for use in positron emission tomography (PET), sulfonated poly(styrene/divinylbenzene) has been evaluated. The preparation of this target material using naturally abundant carbon‐12 compounds was investigated in an effort to optimize conditions for the preparation of the analogous carbon‐13 target material which may provide a cost‐effective method for producing nitrogen‐13 labelled ammonia via proton irradiation. As part of this study, phenyl‐13C6‐ethene was synthesized in three steps starting from benzene‐13C6. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis of multiply labelled ribonucleosides for sequence‐specific labelling of oligo‐RNA
Authors: Milecki Jan , Földesi Andras , Fischer Artur , Adamiak Ryszard W. , Chattopadhyaya Jyoti 
Published: August 2002

AbstractThe synthesis of ribonucleotide blocks multiply labelled with 2H, 13C and 15N for solid support synthesis of sequence specifically labelled RNA is described. Labels were introduced in the ribose ring (13C), C5 position of pyrimidine nucleobases (2H) and exocyclic amino groups (15N) and serve as multiple probes for studying the various physicochemical consequences of physiologically important RNA folding by high‐resolution multi‐nuclear NMR spectroscopy. Copyright © 2001 John Wiley & Sons, Ltd.
Bulbus arteriosus of the bivalve mollusc Mercenaria mercenaria: Morphology and pharmacology
Authors: Deaton Lewis E. , Felgenhauer Bruce E. , Duhon Daniel W. 
Published: August 2002

AbstractWe examined the morphology and pharmacology of the bulbus arteriosus of the marine bivalve mollusc Mercenaria mercenaria. The bulbus arteriosus is an organ of unknown function associated with the posterior aorta and the ventricle. It is composed of connective tissue interspersed with muscle bundles. In contrast to the lumen of the ventricle, which has an extensive trabecular network, the lumen of the bulbus arteriosus has no trabeculae. No valve is present in the posterior aorta connecting the lumina of the ventricle and the bulbus arteriosus. Scattered neuronal profiles are present in the wall and the axonal processes contain vesicles that may contain neurosecretory products. We did not, however, find synapses or evidence of vesicular release into the lumen of the bulbus arteriosus. The bulbus arteriosus contains acetylcholine, 5‐hydroxytryptamine (5HT), and the molluscan neuropeptides FMRFamide (phenyl‐alanyl‐methionyl‐arginyl‐phenylalaninylamide) and FLRFamide (phenylalanyl‐leucinyl‐arginyl‐phenylalanylamide). The isolated bulbus arteriosus contracts tonically in response to mechanical stress and exposure to 5HT or FMRFamide, while acetylcholine relaxes it. We surmise that the bulbus arteriosus probably functions as a mechanism for regulating the relative amounts of hemolymph pumped into the anterior and posterior aortae by the ventricle and that the bulbus arteriosus may be a neurohemal site. J. Morphol. 250:185–195, 2001. © 2001 Wiley‐Liss, Inc.
Egg of the Karner Blue butterfly (Lycaeides melissa samuelis): Morphology and elemental analysis
Authors: Nickles Elizabeth P. , Ghiradella Helen , Bakhru Hassaram , Haberl Arthur 
Published: August 2002

AbstractMost insect eggshells are ornately sculptured; that of the Karner Blue butterfly, Lycaeides melissa samuelis, exhibits a series of interwoven ridges and depressions. Scanning electron microscopic views of the shell show that the patterning resides in the outer chorion, while the inner vitelline membrane is relatively flat and featureless. We here describe the morphology of the egg and introduce a physical technique, use of a Dynamitron accelerator, to identify and localize elements in the eggshell. Most elements present are represented in the chorion, but sulfur appears restricted to the vitelline membrane. The micropyle is particularly rich in calcium and, in unhatched eggs, phosphorus as well. J. Morphol. 251:140–148, 2002. © 2002 Wiley‐Liss, Inc.
Afterload reduction in severe aortic regurgitation
Authors: Hoffmann Udo , Frank Herbert , Stefenelli Thomas , Kaiser Bernd , Klaar Ursula , Globits Sebastian 
Published: August 2002

AbstractThis study was designed to assess the effects of afterload reduction in asymptomatic patients with severe aortic regurgitation (AR) and maintained LV function by cine‐MRI. We studied 13 patients at baseline and after 0.2 mg/kg Hydralazine (I.V.). Patients were stratified according to the volumetric LV response to acute afterload reduction: Group I comprised patients with improved LV response; Group II comprised patients with unchanged or deteriorated LV response. Baseline LV function and severity of AR were not significantly different between groups. However, regurgitant fraction decreased (50 ± 12 vs. 36 ± 9%; P < 0.03) and cardiac output increased (4.9 ± 1.4 vs. 7.1 ± 1.6l/minute; P < 0,001) in Group I and remained unchanged in Group II (54 ± 10 vs. 55 ± 10%, P = n.s. and 5.5 ± 1.4 vs. 6.6 ± 0.9l/minute; P = n.s.) during maximal vasodilation. Beat‐to‐beat analysis revealed a decrease of left ventricular endsystolic volume index in group I (48 ± 13 vs. 37 ± 9 ml/beat; P < 0.05) and no change in group II (61 ± 20 vs. 62 ± 20 ml/beat; P = n.s.). In the natural history of chronic AR, the absence of improved LV performance during acute vasodilation using beat‐to‐beat analysis by MRI may identify patients with more advanced cardiac adaptation to chronic volume overload. J. Magn. Reson. Imaging 2001;14:693–697. © 2001 Wiley‐Liss, Inc.
Proton MR spectroscopy of the lumbar spine in patients with glycogen storage disease type Ib
Authors: Scherer Axel , Wittsack Hans‐Jörg , Engelbrecht Volkher , Schwarz Stefan , May Philip , Poll Ludger Wilhelm , Koch Jens Albrecht , Wendel Udo , Mödder Ulrich 
Published: August 2002

AbstractGlycogen storage disease type Ib is an autosomal recessive inherited metabolic disorder resulting from deficiency of the microsomal glucose‐6‐phosphatase enzyme system. Six patients (three of which were treated with granulocyte colony stimulating factor) suffering from this disease were examined using image guided localized proton magnetic resonance (MR) spectroscopy. The relative signal intensities of water and lipid protons of the lumbar spine were determined. Comparison was made with iliac crest biopsies in the glycogen storage disease type Ib patients and localized proton MR spectroscopic values of the lumbar spine obtained by thirteen healthy volunteers. The data demonstrate for the first time that hypercellularity and myeloid hyperplasia in subjects with glycogen storage disease type Ib due to functionally impaired leucocytes results in a strongly increased water proton signal with a very low or absent lipid signal in localized proton MR spectroscopy. Upon granulocyte colony stimulating factor treatment, the water proton signal in the lumbar spine is not further augmented. J. Magn. Reson. Imaging 2001;14:757–762. © 2001 Wiley‐Liss, Inc.
Resection of soft tissue sarcomas with intra‐operative magnetic resonance guidance
Authors: Gould Stuart William Thomas , Agarwal Tushar , Benoist Stéphane , Patel Bijen , Gedroyc Wadislaw , Darzi Ara 
Published: August 2002

AbstractPurposeTo report on a preliminary series of magnetic resonance (MR)‐guided sarcoma resections.Materials and MethodsThree patients with the skin sarcoma dermatofibrosarcoma protuberans underwent MR‐guided resection.ResultsThe extent of the tumor at MR imaging was greater in each case than suggested by clinical examination. Adequate resection margins were planned using short Tau inversion recovery (STIR) sequences and intra‐operative imaging was used to confirm complete tumor excision. Histological examination confirmed clear surgical margins of at least 1 cm in each case.ConclusionWe believe this technique may reduce the incidence of specimen margins positive for tumor following resection, and consequently reduce the need for further excisional surgery. J. Magn. Reson. Imaging 2002;15:114–119. © 2002 Wiley‐Liss, Inc.
Comparison of methods for obtaining longitudinal whole‐brain magnetization transfer measurements
Authors: Ostuni John L. , Richert Nancy , Wisniewski Ruth , Lewis Bobbi K. , Howard Thomas , Patel Jay , Frank Joseph A. 
Published: August 2002

AbstractPurposeTo investigate whether the method of applying image masks can alter quantifiable measures determined from whole‐brain MTR calculations.Materials and MethodsThirty‐five T1/MT image pairs were obtained from five normal volunteers. For each pair a mask was used to specify the regions to be analyzed. Using these regions, a histogram was used to calculate seven global MTR metrics. This process was performed three ways: 1) using a unique mask for each T1/MT pair, 2) sharing a single mask for each subject and registering all intrasubject images to the image corresponding to their mask, and 3) sharing a single mask for each subject and transforming that mask into alignment with each of their original T1/MT image pairs.ResultsWith respect to the first method, the latter two methods caused small but significant differences in several parameters.ConclusionThe method of applying image masks can affect whole‐brain MTR values. J. Magn. Reson. Imaging 2001;15:8–15. Published 2002 Wiley‐Liss, Inc.