bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractSki8p 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

AbstractRibosomal 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

AbstractIn 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

AbstractRicin 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

AbstractThe 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

AbstractProtozoan 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

AbstractSix 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

SummaryRadiation‐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.
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

SummaryBlood−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

SummaryThe 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

SummaryThe 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.
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

SummaryProlonged 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

SummaryA 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

SummaryReoperation 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

SummaryCherubism 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

SummaryEosinophilic 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

SummaryPrimary 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

SummaryAcute 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.