bluuebunny/crossref_metadata_2025 huggingface dataset:
Sperm-specific protein kinase A catalytic subunit Cα
2
orchestrates cAMP signaling for male fertility
Authors: Nolan Michael A. , Babcock Donner F. , Wennemuth Gunther , Brown William , Burton Kimberly A. , McKnight G. Stanley
Published: September 2004

An unusual cAMP signaling system mediates many of the events that prepare spermatozoa to meet the egg. Its components include the atypical, bicarbonate-stimulated, sperm adenylyl cyclase and a cAMP-dependent protein kinase (PKA) with the unique catalytic subunit termed Cα
2
or C
s
. We generated mice that lack Cα
2
to determine its importance in the events downstream of cAMP production. Male Cα
2
null mice produce normal numbers of sperm that swim spontaneously
in vitro
. Thus, Cα
2
has no required role in formation of a functional flagellum or the initiation of motility. In contrast, we find that Cα
2
is required for bicarbonate to speed the flagellar beat and facilitate Ca
2+
entry channels. In addition, Cα
2
is needed for the protein tyrosine phosphorylation that occurs late in the sequence of sperm maturation and for a negative feedback control of cAMP production, revealed here. Consistent with these specific defects in several important sperm functions, Cα
2
null males are infertile despite normal mating behavior. These results define several crucial roles of PKA in sperm cell biology, bringing together both known and unique PKA-mediated events that are necessary for male fertility.
Attenuation of estrogen receptor α-mediated transcription through estrogen-stimulated recruitment of a negative elongation factor
Authors: Aiyar Sarah E. , Sun Jian-long , Blair Ashley L. , Moskaluk Christopher A. , Lu Yun-zhe , Ye Qi-nong , Yamaguchi Yuki , Mukherjee Amitava , Ren Da-ming , Handa Hiroshi , Li Rong
Published: September 2004

Estrogen receptor α (ERα) signaling is paramount for normal mammary gland development and function and the repression of breast cancer. ERα function in gene regulation is mediated by a number of coactivators and corepressors, most of which are known to modify chromatin structure and/or influence the assembly of the regulatory complexes at the level of transcription initiation. Here we describe a novel mechanism of attenuating the ERα activity. We show that cofactor of BRCA1 (COBRA1), an integral subunit of the human negative elongation factor (NELF), directly binds to ERα and represses ERα-mediated transcription. Reduction of the endogenous NELF proteins in breast cancer cells using small interfering RNA results in elevated ERα-mediated transcription and enhanced cell proliferation. Chromatin immunoprecipitation reveals that recruitment of COBRA1 and the other NELF subunits to endogenous ERα-responsive promoters is greatly stimulated upon estrogen treatment. Interestingly, COBRA1 does not affect the estrogen-dependent assembly of transcription regulatory complexes at the ERα-regulated promoters. Rather, it causes RNA polymerase II (RNAPII) to pause at the promoter-proximal region, which is consistent with its in vitro biochemical activity. Therefore, our in vivo work defines the first corepressor of nuclear receptors that modulates ERα-dependent gene expression by stalling RNAPII. We suggest that this new level of regulation may be important to control the duration and magnitude of a rapid and reversible hormonal response.
Segmentation in vertebrates: clock and gradient finally joined
Authors: Aulehla Alexander , Herrmann Bernhard G.
Published: September 2004

The vertebral column is derived from somites formed by segmentation of presomitic mesoderm, a fundamental process of vertebrate embryogenesis. Models on the mechanism controlling this process date back some three to four decades. Access to understanding the molecular control of somitogenesis has been gained only recently by the discovery of molecular oscillators (segmentation clock) and gradients of signaling molecules, as predicted by early models. The Notch signaling pathway is linked to the oscillator and plays a decisive role in inter- and intrasomitic boundary formation. An Fgf8 signaling gradient is involved in somite size control. And the (canonical) Wnt signaling pathway, driven by Wnt3a, appears to integrate clock and gradient in a global mechanism controlling the segmentation process. In this review, we discuss recent advances in understanding the molecular mechanism controlling somitogenesis.
Arabidopsis COP10 forms a complex with DDB1 and DET1 in vivo and enhances the activity of ubiquitin conjugating enzymes
Authors: Yanagawa Yuki , Sullivan James A. , Komatsu Setsuko , Gusmaroli Giuliana , Suzuki Genki , Yin Jianning , Ishibashi Toyotaka , Saijo Yusuke , Rubio Vicente , Kimura Seisuke , Wang Jian , Deng Xing Wang
Published: September 2004

COP10 is a ubiquitin-conjugating enzyme variant (UEV), which is thought to act together with COP1, DET1, and the COP9 signalosome (CSN) in Arabidopsis to repress photomorphogenesis. Here, we demonstrate that COP10 interacts with ubiquitin-conjugating enzymes (E2s) in vivo, and can enhance their activity in vitro, an activity distinct from previous characterized UEVs such as MMS2 and UEV1. Furthermore, we show that COP10 forms a complex with UV-damaged DNA-binding protein 1a (DDB1a) and de-etiolated 1 (DET1), and physically interacts with COP1 and the CSN. Purified CDD (COP10, DDB1, DET1) complex also shows enhancement of E2 activity (UEA) similar to that observed with COP10 itself. Our data suggests that COP10, along with COP1 and the CSN, promotes the degradation of positive regulators of photomorphogenesis, such as the transcription factor HY5, via the ubiquitin/26S proteasome system. Thus, the CDD complex may act as a ubiquitylation-promoting factor to regulate photomorphogenesis.
EGPred: Prediction of Eukaryotic Genes Using Ab Initio Methods After Combining With Sequence Similarity Approaches
Authors: Issac Biju , Raghava Gajendra Pal Singh
Published: September 2004

EGPred is a Web-based server that combines ab initio methods and similarity searches to predict genes, particularly exon regions, with high accuracy. The EGPred program proceeds in the following steps: (1) an initial BLASTX search of genomic sequence against the RefSeq database is used to identify protein hits with an E-value <1; (2) a second BLASTX search of genomic sequence against the hits from the previous run with relaxed parameters (E-values <10) helps to retrieve all probable coding exon regions; (3) a BLASTN search of genomic sequence against the intron database is then used to detect probable intron regions; (4) the probable intron and exon regions are compared to filter/remove wrong exons; (5) the NNSPLICE program is then used to reassign splicing signal site positions in the remaining probable coding exons; and (6) finally ab initio predictions are combined with exons derived from the fifth step based on the relative strength of start/stop and splice signal sites as obtained from ab initio and similarity search. The combination method increases the exon level performance of five different ab initio programs by 4%-10% when evaluated on the HMR195 data set. Similar improvement is observed when ab initio programs are evaluated on the Burset/Guigo data set. Finally, EGPred is demonstrated on an ∼95-Mbp fragment of human chromosome 13. The list of predicted genes from this analysis are available in the supplementary material. The EGPred program is computationally intensive due to multiple BLAST runs during each analysis. The EGPred server is available at http://www.imtech.res.in/raghava/egpred/.
Phylogenetic Footprint Analysis of IGF2 in Extant Mammals
Authors: Weidman Jennifer R. , Murphy Susan K. , Nolan Catherine M. , Dietrich Fred S. , Jirtle Randy L.
Published: September 2004

Genomic imprinting results in monoallelic gene transcription that is directed by cis-acting regulatory elements epigenetically marked in a parent-of-origin-dependent manner. We performed phylogenetic sequence and epigenetic comparisons of IGF2 between the nonimprinted platypus (Ornithorhynchus anatinus) and imprinted opossum (Didelphis virginiana), mouse (Mus musculus), and human (Homo sapiens) to determine if their divergent imprint status would reflect differences in the conservation of genomic elements important in the regulation of imprinting. We report herein that IGF2 imprinting does not correlate evolutionarily with differential intragenic methylation, nor is it associated with motif 13, a reported IGF2-specific “imprint signature” located in the coding region. Instead, IGF2 imprinting is strongly associated with both the lack of short interspersed transposable elements (SINEs) and an intragenic conserved inverted repeat that contains candidate CTCF-binding sites, a role not previously ascribed to this particular sequence element. Our results are the first to demonstrate that comparative footprint analysis of species from evolutionarily distant mammalian clades, and exhibiting divergent imprint status is a powerful bioinformatics-based approach for identifying cis-acting elements potentially involved not only in the origins of genomic imprinting, but also in its maintenance in humans.
An Efficient SNP System for Mouse Genome Scanning and Elucidating Strain Relationships
Authors: Petkov Petko M. , Ding Yueming , Cassell Megan A. , Zhang Weidong , Wagner Gunjan , Sargent Evelyn E. , Asquith Steven , Crew Victor , Johnson Kevin A. , Robinson Phil , Scott Valerie E. , Wiles Michael V.
Published: September 2004

A set of 1638 informative SNP markers easily assayed by the Amplifluor genotyping system were tested in 102 mouse strains, including the majority of the common and wild-derived inbred strains available from The Jackson Laboratory. Selected from publicly available databases, the markers are on average ∼1.5 Mb apart and, whenever possible, represent the rare allele in at least two strains. Amplifluor assays were developed for each marker and performed on two independent DNA samples from each strain. The mean number of polymorphisms between strains was 608±136 SD. Several tests indicate that the markers provide an effective system for performing genome scans and quantitative trait loci analyses in all but the most closely related strains. Additionally, the markers revealed several subtle differences between closely related mouse strains, including the groups of several 129, BALB, C3H, C57, and DBA strains, and a group of wild-derived inbred strains representing several Mus musculus subspecies. Applying a neighbor-joining method to the data, we constructed a mouse strain family tree, which in most cases confirmed existing genealogies.
LIDA 2004
Authors: Faletar Sanjica
Published: September 2004

conference held in Dubrovnik, May 2004, which had the dual theme of human information behaviour and competences for digital libraries.
Conference on Computers, Freedom and Privacy: Going Strong in its 14th Year
Authors: Glover Barbara , Owen Eric
Published: September 2004

Reports on the 14th Annual Conference on Computers, Freedom and Privacy, held in Berkeley, California in April 2004. Outlines the themes of the papers presented in the 12 plenary sessions.
New Public Libraries System Model and Information Society Technology in Turkey
Authors: Yalvac Mesut
Published: September 2004

This study is based on the hypothesis that in Turkey, at the beginning of 2000’s, the most important investment to be made for the future is to increase the functionality of the information network system and thereby, its subsystem, the public library system. This matter bears utmost importance and urgency for Turkey that has a young and dynamic population. The objective of the study is to outline a new public library system model integrated with information technology and to set out main conditions for its realisation. In the study, documentary analysis and systems design methods are employed. In Turkey, an insufficiency on a crisis level in all processes and levels of the public library system is observed, a fact which is caused by various factors. The three elements of the crisis are the “access” to public library system facilities, its “cost” and “quality”. The new public library system model presupposes a decrease in the state’s responsibility for public libraries by sharing this responsibility with the library users. Information society technology is suggested as the medium of the model because it will provide equal opportunities for and democratization of the public library system.
Vision to Reality: Applications of Wireless Laptops in Accessing Information from Digital Libraries: End‐Users’ Viewpoints
Authors: Khalil Mounir A.
Published: September 2004

Wireless LANs (WLAN) offer network flexibility and end‐user mobility, making them one of the hottest technologies today. They have great impact on individuals and organizations. Now people can use wireless networks in every application where recent findings indicate that growth in WLAN market continues to be driven by the corporate and educational sectors, where the desire to increase productivity and the benefit of enhanced mobility and learning outcomes continue to fuel demand. A questionnaire was developed to survey the behavior of end‐users, especially students and faculty, in using wireless laptops in accessing information from the Internet, digital libraries and many electronic sources in their education and research. The paper presents the advantages and disadvantages of using wireless network laptops as well as barriers for not using them in Higher Education. Special new update on wireless network security will be included. Guidelines for implementing wireless laptops in higher education are discussed.
E‐profile
Authors: McKiernan Gerry
Published: September 2004

The third and last in a series on Open Archives Initiative data providers. This article focuses on the social sciences and humanities, specifically on the David Rumsey Historical Map Collection ‐ a collection which includes atlases, globes, school geographies, books, maritime charts and a variety of separate maps, primarily (but not exclusively) of the Americas from the eighteenth and nineteenth centuries..
Optimal bundling of transmembrane helices using sparse distance constraints
Authors: Sale Ken , Faulon Jean‐Loup , Gray Genetha A. , Schoeniger Joseph S. , Young Malin M.
Published: September 2004

We present a two‐step approach to modeling the transmembrane spanning helical bundles of integral membrane proteins using only sparse distance constraints, such as those derived from chemical cross‐linking, dipolar EPR and FRET experiments. In Step 1, using an algorithm, we developed, the conformational space of membrane protein folds matching a set of distance constraints is explored to provide initial structures for local conformational searches. In Step 2, these structures refined against a custom penalty function that incorporates both measures derived from statistical analysis of solved membrane protein structures and distance constraints obtained from experiments. We begin by describing the statistical analysis of the solved membrane protein structures from which the theoretical portion of the penalty function was derived. We then describe the penalty function, and, using a set of six test cases, demonstrate that it is capable of distinguishing helical bundles that are close to the native bundle from those that are far from the native bundle. Finally, using a set of only 27 distance constraints extracted from the literature, we show that our method successfully recovers the structure of dark‐adapted rhodopsin to within 3.2 Å of the crystal structure.
Simulating evolution by gene duplication of protein features that require multiple amino acid residues
Authors: Behe Michael J. , Snoke David W.
Published: September 2004

Gene duplication is thought to be a major source of evolutionary innovation because it allows one copy of a gene to mutate and explore genetic space while the other copy continues to fulfill the original function. Models of the process often implicitly assume that a single mutation to the duplicated gene can confer a new selectable property. Yet some protein features, such as disulfide bonds or ligand binding sites, require the participation of two or more amino acid residues, which could require several mutations. Here we model the evolution of such protein features by what we consider to be the conceptually simplest route—point mutation in duplicated genes. We show that for very large population sizes N, where at steady state in the absence of selection the population would be expected to contain one or more duplicated alleles coding for the feature, the time to fixation in the population hovers near the inverse of the point mutation rate, and varies sluggishly with the λth root of 1/N, where λ is the number of nucleotide positions that must be mutated to produce the feature. At smaller population sizes, the time to fixation varies linearly with 1/N and exceeds the inverse of the point mutation rate. We conclude that, in general, to be fixed in 108 generations, the production of novel protein features that require the participation of two or more amino acid residues simply by multiple point mutations in duplicated genes would entail population sizes of no less than 109.
Crystallographic identification of Ca2+ and Sr2+ coordination sites in synaptotagmin I C2B domain
Authors: Cheng Yuan , Sequeira Sonia M. , Malinina Lucy , Tereshko Valentina , Söllner Thomas H. , Patel Dinshaw J.
Published: September 2004

Synaptotagmin I has two tandem Ca2+‐binding C2 domains, which are essential for fast synchronous synaptic transmission in the central nervous system. We have solved four crystal structures of the C2B domain, one of them in the cation‐free form at 1.50 Å resolution, two in the Ca2+‐bound form at 1.04 Å (two bound Ca2+ ions) and 1.65 Å (three bound Ca2+ ions) resolution and one in the Sr2+‐bound form at 1.18 Å (one bound Sr2+ ion) resolution. The side chains of four highly conserved aspartic acids (D303, D309, D363, and D365) and two main chain oxygens (M302:O and Y364:O), together with water molecules, are in direct contact with two bound Ca2+ ions (sites 1 and 2). At higher Ca2+ concentrations, the side chain of N333 rotates and cooperates with D309 to generate a third Ca2+ coordination site (site 3). Divalent cation binding sites 1 and 2 in the C2B domain were previously identified from NMR NOE patterns and titration studies, supplemented by site‐directed mutation analysis. One difference between the crystal and NMR studies involves D371, which is not involved in coordination with any of the identified Ca2+ sites in the crystal structures, while it is coordinated to Ca2+ in site 2 in the NMR structure. In the presence of Sr2+, which is also capable of triggering exocytosis, but with lower efficiency, only one cation binding site (site 1) was occupied in the crystallographic structure.
Quantification of helix–helix binding affinities in micelles and lipid bilayers
Authors: Lomize Andrei L. , Pogozheva I.D. , Mosberg H.I.
Published: September 2004

A theoretical approach for estimating association free energies of α‐helices in nonpolar media has been developed. The parameters of energy functions have been derived from ΔΔG values of mutants in water‐soluble proteins and partitioning of organic solutes between water and nonpolar solvents. The proposed approach was verified successfully against three sets of published data: (1) dissociation constants of α‐helical oligomers formed by 27 hydrophobic peptides; (2) stabilities of 22 bacteriorhodopsin mutants, and (3) protein‐ligand binding affinities in aqueous solution. It has been found that coalescence of helices is driven exclusively by van der Waals interactions and H‐bonds, whereas the principal destabilizing contributions are represented by side‐chain conformational entropy and transfer energy of atoms from a detergent or lipid to the protein interior. Electrostatic interactions of α‐helices were relatively weak but important for reproducing the experimental data. Immobilization free energy, which originates from restricting rotational and translational rigid‐body movements of molecules during their association, was found to be less than 1 kcal/mole. The energetics of amino acid substitutions in bacteriorhodopsin was complicated by specific binding of lipid and water molecules to cavities created in certain mutants.
Crystal structure of Ski8p, a WD‐repeat protein with dual roles in mRNA metabolism and meiotic recombination
Authors: Cheng Zhihong , Liu Yuying , Wang Chernhoe , Parker Roy , Song Haiwei
Published: September 2004

Ski8p is a WD‐repeat protein with an essential role for the Ski complex assembly in an exosome‐dependent 3′‐to‐5′ mRNA decay. In addition, Ski8p is involved in meiotic recombination by interacting with Spo11p protein. We have determined the crystal structure of Ski8p from Saccharomyces cerevisiae at 2.2 Å resolution. The structure reveals that Ski8p folds into a seven‐bladed β propeller. Mapping sequence conservation and hydrophobicities of amino acids on the molecular surface of Ski8p reveals a prominent site on the top surface of the β propeller, which is most likely involved in mediating interactions of Ski8p with Ski3p and Spo11p. Mutagenesis combined with yeast two‐hybrid and GST pull‐down assays identified the top surface of the β propeller as being required for Ski8p binding to Ski3p and Spo11p. The functional implications for Ski8p function in both mRNA decay and meiotic recombination are discussed.
Crystal structure of ribosomal protein L27 from Thermus thermophilus HB8
Authors: Wang Hongfei , Takemoto Chie Hori , Murayama Kazutaka , Sakai Hiroaki , Tatsuguchi Ayako , Terada Takaho , Shirouzu Mikako , Kuramitsu Seiki , Yokoyama Shigeyuki
Published: September 2004

Ribosomal protein L27 is located near the peptidyltransferase center at the interface of ribosomal subunits, and is important for ribosomal assembly and function. We report the crystal structure of ribosomal protein L27 from Thermus thermophilus HB8, which was determined by the multiwavelength anomalous dispersion method and refined to an R‐factor of 19.7% (Rfree = 23.6%) at 2.8 Å resolution. The overall fold is an all β‐sheet hybrid. It consists of two sets of four‐stranded β‐sheets formed around a well‐defined hydrophobic core, with a highly positive charge on the protein surface. The structure of ribosomal protein L27 from T. thermophilus HB8 in the RNA‐free form is investigated, and its functional roles in the ribosomal subunit are discussed.
Alanine‐scanning mutagenesis of the β‐sheet region of phage T4 lysozyme suggests that tertiary context has a dominant effect on β‐sheet formation
Authors: He Molly M. , Wood Zachary A. , Baase Walter A. , Xiao Hong , Matthews Brian W.
Published: September 2004

In general, α‐helical conformations in proteins depend in large part on the amino acid residues within the helix and their proximal interactions. For example, an alanine residue has a high propensity to adopt an α‐helical conformation, whereas that of a glycine residue is low. The sequence preferences for β‐sheet formation are less obvious. To identify the factors that influence β‐sheet conformation, a series of scanning polyalanine mutations were made within the strands and associated turns of the β‐sheet region in T4 lysozyme. For each construct the stability of the folded protein was reduced substantially, consistent with removal of native packing interactions. However, the crystal structures showed that each of the mutants retained the β‐sheet conformation. These results suggest that the structure of the β‐sheet region of T4 lysozyme is maintained to a substantial extent by tertiary interactions with the surrounding parts of the protein. Such tertiary interactions may be important in determining the structures of β‐sheets in general.
Improved stability of a protein vaccine through elimination of a partially unfolded state
Authors: McHugh Colleen A. , Tammariello Ralph F. , Millard Charles B. , Carra John H.
Published: September 2004

Ricin is a potent toxin presenting a threat as a biological weapon. The holotoxin consists of two disulfide‐linked polypeptides: an enzymatically active A chain (RTA) and a galactose/N‐acetylgalactosamine‐binding B chain. Efforts to develop an inactivated version of the A chain as a vaccine have been hampered by limitations of stability and solubility. Previously, recombinant truncated versions of the 267‐amino‐acid A chain consisting of residues 1–33/44–198 or 1–198 were designed by protein engineering to overcome these limits and were shown to be effective and nontoxic as vaccines in mice. Herein we used CD, dynamic light scattering, fluorescence, and Fourier‐transform infrared spectroscopy to examine the biophysical properties of these proteins. Although others have found that recombinant RTA (rRTA) adopts a partially unfolded, molten globule–like state at 45°C, rRTA 1–33/44–198 and 1–198 are significantly more thermostable, remaining completely folded at temperatures up to 53°C and 51°C, respectively. Deleting both an exposed loop region (amino acids 34–43) and the C‐terminal domain (199–267) contributed to increased thermostability. We found that chemically induced denaturation of rRTA, but not the truncated variants, proceeds through at least a three‐state mechanism. The intermediate state in rRTA unfolding has a hydrophobic core accessible to ANS and an unfolded C‐terminal domain. Removing the C‐terminal domain changed the mechanism of rRTA unfolding, eliminating a tendency to adopt a partially unfolded state. Our results support the conclusion that these derivatives are superior candidates for development as vaccines against ricin and suggest an approach of reduction to minimum essential domains for design of more thermostable recombinant antigens.
Circular permutation as a tool to reduce surface entropy triggers crystallization of the signal recognition particle receptor β subunit
Authors: Schwartz Thomas U. , Walczak Rudolf , Blobel Günter
Published: September 2004

The production of diffraction‐quality crystals remains a difficult obstacle on the road to high‐resolution structural characterization of proteins. This is primarily a result of the empirical nature of the process. Although crystallization is not predictable, factors inhibiting it are well established. First, crystal formation is always entropically unfavorable. Reducing the entropic cost of crystallizing a given protein is thus desirable. It is common practice to map boundaries and remove unstructured regions surrounding the folded protein domain. However, a problem arises when flexible regions are not at the boundaries but within a domain. Such regions cannot be deleted without adding new restraints to the domain. We encountered this problem during an attempt to crystallize the β subunit of the eukaryotic signal recognition particle (SRβ), bearing a long and flexible internal loop. Native SRβ did not crystallize. However, after circularly permuting the protein by connecting the spatially close N and C termini with a short heptapeptide linker GGGSGGG and removing 26 highly flexible loop residues within the domain, we obtained diffraction‐quality crystals. This protein‐engineering method is simple and should be applicable to other proteins, especially because N and C termini of protein domains are often close in space. The success of this method profits from prior knowledge of the domain fold, which is becoming increasingly common in today's postgenomic era.
Protozoan epibionts on Mysis relicta Loven, 1862 (Crustacea, Mysidacea) from Lake Lüšiai (Lithuania)
Authors: Fernandez‐Leborans Gregorio
Published: September 2004

Protozoan epibionts were found on specimens of the mysid Mysis relicta collected in Lake Lüšiai (Lithuania). These protozoans belong to three genera of ciliates: Vorticella, Dendrosoma and Tokophrya, and were located on the antennae, carapace, appendages and abdomen of the basibiont. The ciliates of the genus Vorticella had a bell‐shaped body, with concave‐type striations and a very long contractile stalk. The stalk joined the body via a truncated and overlapping zone. The macronucleus was J‐shaped, and the contractile vacuole was anterolateral. Only one ciliate species of Vorticella has been found on mysids, although on species other than M. relicta, and this is therefore the first record of Vorticella on M. relicta, and the second on the order Mysidacea. The ciliates of the genus Dendrosoma had an irregular body directly attached to the substrate. Finger‐like actinophores arose from the body, with a bundle of tentacles at their ends. The macronucleus ramified into branches that followed the actinophores. These ciliates were included in the species D. astaci. The presence of this ciliate represents the first record of this genus on Mysis relicta. The ciliates of the genus Tokophrya had a pyramidal body, the apical surface of which showed two conspicuous actinophores, with a short, longitudinally striated stalk joining to the body via a narrow unstriated band. The macronucleus was spherical or ovoid, centrally located, and there was an apical contractile vacuole. Only one previous study has referred to the presence of this genus on Mysis relicta, and the data contained in it were compared with those of the present study. The biometrical data and taxonomical position of the ciliate epibionts was considered.
Histological organization of the intestine in the crayfish Procambarus clarkii
Authors: To Terence H. , Brenner Tracy L. , Cavey Michael J. , Wilkens Jerrel L.
Published: September 2004

Six longitudinal ridges span the length of the intestine in the crayfish Procambarus clarkii. A simple columnar epithelium with tetralaminar cuticle lines the lumen. Folds of the epithelium overlie a dense irregular connective tissue packed with mixed acinar (alveolar) glands. Mucous secretions are probably involved with formation and lubrication of faecal strings; neither the nature nor the role of the serous secretions is immediately apparent. Aggregations of cells with large cytoplasmic vacuoles, called bladder cells, appear in the subepithelial connective tissue near the tops of the intestinal ridges. The bladder cells are suitably positioned to bolster the integrity of the ridges. Striated muscle of the intestine occurs in inner longitudinal and outer circular layers. The inner longitudinal layer consists of six strips, with one strip associated with the base of each intestinal ridge. The outer circular layer is essentially complete, but there are periodic apertures in this layer on the left and right sides of the intestine, providing nerves and haemolymph vessels with access to the interior of the gut. Based on histological features, and consistent with reports on other crayfish, we conclude that the intestine of P. clarkii has a proctodeal (ectodermal) origin.
Radiation‐induced brain disorders in patients with pituitary tumours
Authors: Bhansali A , Banerjee AK , Chanda A , Singh P , Sharma SC , Mathuriya SN , Dash RJ
Published: September 2004

Radiation‐induced brain disorders (RIBD) are uncommon and they are grave sequelae of conventional radiotherapy. In the present report, we describe the clinical spectrum of RIBD in 11 patients who received post‐surgery conventional megavoltage irradiation for residual pituitary tumours. Of these 11 patients (nine men, two women), seven had been treated for non‐functioning pituitary tumours and four for somatotropinomas. At the time of irradiation the age of these patients ranged from 30 to 59 years (mean, 39.4 ± 8.3; median, 36) with a follow‐up period of 6−96 months (mean, 18.3 ± 26.4; median, 11). The dose of radiation ranged from 45 to 90 Gy (mean, 51.3 ± 13.4; median, 45), which was given in 15−30 fractions (mean, 18.6 ± 5.0; median, 15) with 2.8 ± 0.3 Gy (median, 3) per fraction. The biological effective dose calculated for late complications in these patients ranged from 78.7 to 180 Gy (mean, 99.1 ± 27.5; median, 90). The lag time between tumour irradiation and the onset of symptoms ranged from 6 to 168 months (mean, 46.3 ± 57.0; median, 57). The clinical spectrum of RIBD included new‐onset visual abnormalities in five, cerebral radionecrosis in the form of altered sensorium in four, generalized seizures in four, cognitive dysfunction in five, dementia in three and motor deficits in two patients. Magnetic resonance imaging (MRI)/CT of the brain was suggestive of radionecrosis in eight, cerebral oedema in three, cerebral atrophy in two and second neoplasia in one patient. Associated hormone deficiencies at presentation were hypogonadism in eight, hypoadrenalism in six, hypothyroidism in four and diabetes insipidus in one patient. Autopsy in two patients showed primitive neuroectodermal tumour (PNET) and brainstem radionecrosis in one, and a cystic lesion in the left frontal lobe following radionecrosis in the other. We conclude that RIBD have distinctive but varying clinical and radiological presentations. Diabetes insipidus and PNET as a second neoplastic disorder in adults following pituitary irradiation have not been reported previously.
Fat necrosis in the breast: Review of the mammographic and ultrasound features, and a strategy for management
Authors: Baillie M , Mok PM
Published: September 2004

The present study reviews the mammographic and ultrasound features of fat necrosis, the degree of correlation between the two modalities, and proposes a strategy for management, especially in cases with atypical appearances.
Role of 99mTc‐glucoheptonic acid brain single photon emission computed tomography in differentiation of recurrent brain tumour and post‐radiation gliosis
Authors: Barai S , Bandopadhayaya GP , Julka PK , Naik KK , Haloi AK , Kumar R , Seith A , Malhotra A
Published: September 2004

Blood−brain barrier imaging of brain tumours is fast attracting interest now that it has been demonstrated that disruption of the blood−brain barrier is essential for uptake of all tumour‐seeking agents. The aim of the present study was to differentiate recurrent tumour from post‐radiation gliosis using 99mtechnetium‐glucoheptonate (99mTc‐GHA) as a tumour‐seeking agent. Brain single photon emission computed tomography (SPECT) with 99mTc‐GHA was performed in 73 patients with primary malignant brain tumours after radiotherapy, and the results were correlated with the clinical behaviour of the disease on follow up. The SPECT was suggestive of recurrent tumour in 55 patients. The clinical course was consistent with recurrence in 51 of the 55 patients. The clinical course was consistent with radiation necrosis in the remaining 21 patients, which included 17 patients with a negative SPECT and four patients with a positive SPECT study. Mean GHA index in recurrent tumour and post‐radiation gliosis was 7.04 ± 4.35 and 1.88 ± 1.70, respectively (P = 0.0001). Mean GHA index in high‐grade and low‐grade glioma was 7.78 ± 4.73 and 3.15 ± 2.44, respectively (P = 0.001). 99mTechnetium‐glucoheptonate brain SPECT is a sensitive and reliable diagnostic modality to differentiate recurrent tumour from post‐radiation gliosis.
Embolization for major lower gastrointestinal haemorrhage: Five‐year experience
Authors: Waugh J , Madan A , Sacharias N , Thomson K
Published: September 2004

The management of major lower gastrointestinal haemorrhage has changed dramatically in the last 15 years. Innovations in coaxial catheter technology have allowed the interventional radiologist to reach the small peripheral mesenteric arteries and perform superselective embolization with a variety of agents. The present large series represents the 5‐year experience of this technique at the Alfred Hospital, Melbourne, in a patient cohort with a high number of comorbidities. Technical success was achieved in 96% of cases. The clinical symptoms of mesenteric ischaemia developed in four patients after embolization and were managed conservatively in two. The procedure‐related mortality was low when compared with the published complication rates for emergency surgery, in this clinical setting.
Perfusion magnetic resonance imaging and magnetic resonance spectroscopy of cerebral gliomas showing imperceptible contrast enhancement on conventional magnetic resonance imaging
Authors: Batra A , Tripathi RP , Singh AK
Published: September 2004

The purpose of the present paper was to evaluate the utility of perfusion MRI in cerebral gliomas showing imperceptible contrast enhancement on conventional MRI, and to evaluate the relationships of perfusion MRI and magnetic resonance (MR) spectroscopic results in these tumours. Twenty‐two patients with histopathologically proven cerebral gliomas and showing insignificant contrast enhancement on conventional MR were included in the present study. All patients underwent perfusion MRI and MR spectroscopy on a 1.5‐T MR system. Significant differences of the relative cerebral blood volume (rCBV) values and the choline : creatine ratios were noted between low‐grade and anaplastic gliomas (P < 0.01). Good correlation was found between the rCBV values and the choline : creatine values (y = 0. 532x + 1.5643; r = 0.67). Perfusion MRI can be a useful tool in assessing the histopathological grade of non‐contrast‐enhancing cerebral gliomas. Along with MR spectroscopic imaging it can serve as an important technique for preoperative characterization of such gliomas, so that accurate targeting by stereotactic biopsies is possible.
Problem‐based learning and medical student radiology teaching
Authors: Subramaniam RM , Scally P , Gibson R
Published: September 2004

The present study describes some practical advantages and disadvantages of problem‐based learning (PBL), and makes suggestions to improve PBL radiology teaching of medical students.
All delays before radiotherapy risk progression of Merkel cell carcinoma
Authors: Tsang G , O'Brien P , Robertson R , Hamilton C , Wratten C , Denham J
Published: September 2004

Prolonged waiting times for radiotherapy have resulted in many centres assigning priorities to various patient or diagnostic groups. A high risk of progression on a waiting list is one factor that would reasonably influence the priority. The present descriptive study of 27 patients with Merkel cell carcinoma (MCC) found that a median wait of 24 days for radiotherapy is associated with a high risk of progression. Eleven (41%) of 27 patients developed progressive disease, including five (45%) of 11 patients waiting for adjuvant radiotherapy. Patients treated adjuvantly also had longer waiting times prior to their initial radiotherapy consultation (median 41 days), which may have contributed to the rate of progression. Merkel cell carcinoma is an aggressive but curable malignancy and appropriate management should include efforts to minimize all potential delays prior to the commencement of radiotherapy.
Cardiac metastasis from carcinoid tumour: Magnetic resonance imaging findings
Authors: Puvaneswary M , Thomson D , Bellamy GR
Published: September 2004

A case of myocardial metastasis from a gastrointestinal carcinoid is presented. The colon was the primary site. The patient did not manifest symptoms of carcinoid syndrome and had no echocardiographic or MRI evidence of carcinoid valvular heart disease.
Accurate localization of supernumerary mediastinal parathyroid adenomas by a combination of structural and functional imaging
Authors: Mackie GC , Schlicht SM
Published: September 2004

Reoperation for refractory or recurrent hyperparathyroidism following parathyroidectomy carries the potential for increased morbidity and the possibility of failure to localize and remove the lesion intraoperatively. Reported herein are three cases demonstrating the combined use of sestamibi scintigraphy, CT and MR for accurate localization of mediastinal parathyroid adenomas.
Cherubism: Review of four affected members in a Kuwaiti family
Authors: Petkovska L , Ramadan S , Aslam MO
Published: September 2004

Cherubism is a rare autosomal dominant fibro‐osseous disorder of childhood, mostly limited to the maxilla and mandible. Extra‐cranial skeletal involvement is rare. Post‐pubertal involution of the process and jaw remodeling occurs in adulthood. The aim of this case report is to present four cherubs, a father and his three daughters, in whom the diagnosis was made based on history, physical examination, laboratory tests and typical radiological features. The imaging characteristics are discussed and the published literature is reviewed.
Ultrasound and magnetic resonance imaging features in a patient with eosinophilic fasciitis
Authors: Chan V , Soans B , Mathers D
Published: September 2004

Eosinophilic fasciitis is a rare rheumatological disorder. We present a case of a young male patient who presented with this disease, and we describe how the findings on ultrasound and MRI correlated with the underlying pathology and assisted the diagnosis and the management of the patient.
Primary papillary serous carcinoma of the peritoneum: Four cases and review of computed tomography findings
Authors: Puvaneswary M , Proietto T
Published: September 2004

Primary papillary serous carcinoma of the peritoneum is an uncommon primary malignancy of the peritoneum and is histologically indistinguishable from papillary serous carcinoma of the ovary. The diagnosis of primary peritoneal papillary serous carcinoma should be considered in the presence of peritoneal and omental masses in the absence of an ovarian mass. Although it has been extensively documented in the pathological and gynaecological oncology literature, the CT appearance of primary papillary serous carcinoma of the peritoneum has been reported in only 51 cases in five reports. We present four patients with CT findings of pathologically proven primary papillary serous carcinoma of the peritoneum.

There were a total of 23 patients with a histopathologically proven diagnosis of primary papillary serous carcinoma of the peritoneum between 1980 and 2002 with CT imaging. However, only four of the 23 patients’ CT films were retrieved for retrospective evaluation. The rest of the films were not available as either patients had misplaced the films or patients were deceased.
Angioplasty and stenting of the superior mesenteric artery in acute mesenteric ischaemia
Authors: Lim RP , Dowling RJ , Thomson KR
Published: September 2004

Acute mesenteric ischaemia is a challenging diagnostic problem with a very high mortality. Traditionally, laparotomy is required for definitive management. We describe a successful case of angioplasty and stenting of the superior mesenteric artery in a surgically unfit patient. We recommend that stenting be considered only in situations where the diagnosis has been made prior to bowel infarction, and if the patient poses a poor operative risk.
How people with developmental disabilities navigate the Internet
Authors: Harrysson B. , Svensk A. , Johansson G. I.
Published: September 2004

We live at a time when the Internet is used increasingly for communication, for information, and for the exchange of goods and services. Questions arise about how people with learning disabilities make use of this new technology. In this article, Bjorn Harrysson, with two of his colleagues, A. Svensk and G. I. Johansson, from the Department of Design Sciences at the Lund Institute of Technology in Sweden, explores the opportunities and difficulties experienced by members of this group when navigating the Internet.

Harrysson, Svensk and Johansson observed seven people, aged between 15 and 44 and with mild to moderate developmental disabilities, as they navigated between different web pages using the general tools of Microsoft Internet Explorer Web Browser. The authors describe some of the strategies that were used for moving within and between web pages and for opening web pages, carrying out searches and finding preferred web sites.

The results of the study are partly optimistic. The people involved made good use of many of the features of the general software. They experienced greater difficulties when it became necessary to use text to navigate and explore the huge potential of the Internet. Harrysson, Svensk and Johansson close their article by making a series of recommendations for developments that would facilitate ease of access and independence in the use of the Internet for people with developmental disabilities.
Community‐based vocational rehabilitation (CBVR) for people with disabilities: experiences from a pilot project in Nigeria
Authors: Alade Eunice B.
Published: September 2004

This article discusses the community‐based vocational rehabilitation (CBVR) of persons with disabilities. In 1991, a pilot project was instituted by the International Labour Organisation and the United Nations Development Programme in conjunction with Oyo State Government in Nigeria. The aim was to facilitate the reintegration of persons with disabilities into their communities after a vocational rehabilitation programme. This project has resulted in the successful training of about 155 individuals with disabilities since its inception and a number of the trainees have benefited from a revolving loan scheme. The initial seven areas of vocational training have, over the years, expanded to 24. Recently, the project has been introduced to six other states in Nigeria. Various problem‐solving strategies have been employed in the course of the project as the need arose and the community‐based vocational rehabilitation programme has proved to be a success in Nigeria so far. In this paper, Eunice Alade, associate professor in the Department of Special Education, Kenyatta University, Kenya, provides an evaluation of an innovative alternative approach to vocational rehabilitation for people with disabilities. She discusses some of the problems experienced in Nigeria and offers suggestions about how to sustain the work. Her ideas will be of direct interest to those seeking to promote social inclusion in developing countries and elsewhere around the world.
Teaching in mainstream and special schools: are the stresses similar or different?
Authors: Williams Michelle , Gersch Irvine
Published: September 2004

Research evidence, and the direct experience of many practitioners, suggest that teaching is a stressful profession. However, a number of factors, including, for example, the age group taught, the number of pupils in the class, the hours worked and the type of school, may mediate the types and degree of stress experienced. In this article, Michelle Williams, who carried out this study as part of her degree in psychology at the University of East London and who is not a teacher, and Professor Irvine Gersch, course director of the MSc course in educational psychology at the University of East London, describe work undertaken to compare whether teaching in a mainstream or special school is perceived as more stressful and whether there are different stresses in both types of school.

The authors designed a questionnaire to measure teacher stress and collected data from 41 teachers in three mainstream and two special schools. Their results reveal no significant difference in the overall level of stress experienced between mainstream and special school teachers, but five factors do emerge indicating that different types of stress are experienced in the different school settings studied.
Feature: Geology of the bridges of the Dorset Stour
Authors: Thomas Jo
Published: September 2004

Famously, geology is on our doorstep, and an understanding of the geology of everyday things helps us communicate to those for whom it is a closed subject. The stone bridges of the River Stour from Stourhead to Christchurch in southern England are a topic worthy of study and rewarding as an example of the variety of the geology of this part of England.
Feature: The Great Whin Sill
Authors: Robinson Eric
Published: September 2004

Without question, many of the principles of geology as a science evolved as the rock outcrops of Britain were explored and discussed with an open mind. Nowhere can this be better demonstrated than in the history of opinion concerning the Whin Sill in the north of England.