bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell death during germ band inversion, dorsal closure, and nervous system development in the spider Cupiennius salei
Authors: Prpic Nikola‐Michael , Damen Wim G.M.
Published: August 2005

Cell death is an important feature in the development of animals, because it is one possibility for the embryo to control cell number in developing tissues and thereby determine the form of a growing organ. In Drosophila, cell death has been shown to be involved in the shaping of many different organs of the embryo. We have used terminal deoxynucleotidyl transferase‐mediated dUTP‐digoxygenin nick end labeling (TUNEL) and an antibody against the activated form of caspase‐3 to visualize cell death in the spider Cupiennius salei. We find that similar to Drosophila, massive cell death occurs during the development of the nervous system, suggesting that this is an ancestral feature in the arthropods. We also detect cell death during leg development, most probably related to the formation of tarsal sensory organs. No cell death seems to be required for germ band segmentation. Most importantly, we find that cell death has a role in germ band inversion, a morphogenetic event unique to spiders that involves epithelial fission ventrally and tissue fusion dorsally. Our data show that germ band inversion involves cell death to facilitate the ventral splitting of the germ band, as well as the epithelial fusion during dorsal closure. Developmental Dynamics 234:222–228, 2005. © 2005 Wiley‐Liss, Inc.
Localization of Apaf1 gene expression in the early development of the mouse by means of in situ reverse transcriptase‐polymerase chain reaction
Authors: Müller Matthias , Berger Joachim , Gersdorff Nikolaus , Cecconi Francesco , Herken Rainer , Quondamatteo Fabio
Published: August 2005

Apoptosis is an essential ubiquitous process that controls the duration of the life span of cells, thus playing a crucial role in morphogenetic, histogenetic, and phylogenetic developmental processes. Apaf1 (apoptosis protease activating factor 1) is one of the central mediators of the intrinsic apoptotic pathway and a part of the apoptosome, which activates procaspase‐3 and promotes cell death. Gene knockout of Apaf1 in mice leads to late embryonic lethality with malformations such as the persistence of interdigital webs and hyperplasia of brain and retina. Therefore, Apaf1 is generally believed to play a crucial role in developmental apoptosis and have a widespread expression. However, its pattern of expression in early development remains unknown. To specify whether Apaf1 indeed plays this key role, we investigated the pattern of gene expression for Apaf1 in mouse embryos on day 7, 9, and 12 of development. Our results show, that gene expression for Apaf1 first occurs within the embryo between day 7 and 9 of development, becoming more widespread toward day 12 and then includes structures, such as yolk sac, mesenchyme, cartilage, heart anlage, otic vesicle, peridermis, and anlagen of the spinal ganglia and vertebral bodies. Our results also show that gene expression for Apaf1 is not ubiquitous in early mouse development. This finding indicates that cell death processes are independent of or less dependent on Apaf1 during this time. Of interest, an active gene expression for Apaf1 is also present in organ anlagen such as heart or intestine, in which no obvious phenotype is seen after Apaf1 deletion. This finding suggests a possible role for Apaf1 in such anlagen as a putative alternative compensatory pathway, which could be switched on in the case of defects in the mediators that are normally involved in such organs. Developmental Dynamics 234:215–221, 2005. © 2005 Wiley‐Liss, Inc.
Chromatic numbers of products of graphs: The directed and undirected versions of the Poljak‐Rödl function
Authors: Tardif Claude , Wehlau David
Published: August 2005

Let f(n) = min{χ(G × H) : G and H are n‐chromatic digraphs} and g(n) = min{χ(G × H) : G and H are n‐chromatic graphs}. We prove that f is bounded if and only if g is bounded. © 2005 Wiley Periodicals, Inc. J Graph Theory
Sperm structure and phylogeny of Astigmata
Authors: Liana Marcin , Witaliński Wojciech
Published: August 2005

The Astigmata, a large and variable group, is still a subject of taxonomic dispute. Particularly, their origin from ancestors of the lower oribatid mites (e.g., Malaconothroidea) seems well documented by many lines of evidence. The structure of spermatozoa has been successfully applied to phylogenetic investigations in many animal groups. The aim of our study was to provide new data on spermatozoon structure in Astigmata and to consider its appropriateness in phylogenetic studies. The study reveals information on spermatozoa in 17 species of Astigmata (11 species studied for the first time) extending our knowledge to 18 species (one species known only from the literature) representing 12 families and 7 superfamilies. Spermatozoa have the same basic structure in all species: cells are multiform and the chromatin forms thin threads embedded directly in the cytoplasm; the acrosome is absent. The cytoplasm in most species contains electron‐dense lamellae, varying in both number and arrangement within the cell. In Sarcoptoidea, electron‐dense tubules in contact with lamellae margins were also observed in Psoroptidae (Psoroptes equi), whereas in two representatives of Sarcoptidae (Notoedres cati and Sarcoptes scabiei), only electron‐dense tubules were found. In two species, Canestrinia sellnicki (Canestrinioidea: Canestriniidae) and Scutulanyssus obscurus (Analgoidea: Pteronyssidae), neither lamellae nor tubules were present. The mitochondria in a spermatozoon are usually gathered at the cell periphery and their structure is usually modified to form so‐called mitochondrial derivatives. The chromatin threads are an autapomorphy strongly supporting the monophyly of Astigmata. As spermatozoa vary considerably between species in Astigmata, we deduce that sperm structure may be useful for phylogenetic analyses within the group. Several conclusions concerning the affinities within Astigmata are presented. Spermatology seems to be unhelpful, however, in questions on the origin of Astigmata (particularly for Astigmata–Oribatida relationships), since their sperm do not possess synapomorphies with sperm of the remaining groups of Acariformes, i.e., Endeostigmata, Prostigmata, and Oribatida. J. Morphol. © 2005 Wiley‐Liss, Inc.
Formation of Core‐Shell‐Corona Micellar Complexes through Adsorption of Double Hydrophilic Diblock Copolymers into Core‐Shell Micelles
Authors: Zhang Wangqing , Shi Linqi , Gao Lichao , An Yingli , Wu Kai
Published: August 2005

Summary: The complexation between polystyrene‐block‐poly(acrylic acid) (PS‐b‐PAA) micelles and poly(ethylene glycol)‐block‐poly(4‐vinyl pyridine) (PEG‐b‐P4VP) is studied, and a facile strategy is proposed to prepare core‐shell‐corona micellar complexes. Micellization of PS‐b‐PAA in ethanol forms spherical core‐shell micelles with PS block as core and PAA block as shell. When PEG‐b‐P4VP is added into the core‐shell micellar solution, the P4VP block is absorbed into the core‐shell micelles to form spherical core‐shell‐corona micellar complexes with the PS block as core, the combined PAA/P4VP blocks as shell and the PEG block as corona. A model is suggested to characterize the core‐shell‐corona micellar complexes.

Schematic formation of core‐shell‐corona (CSC) micellar complexes by adsorption of PEG‐b‐P4VP into core‐shell PS‐b‐PAA micelles.

image

Schematic formation of core‐shell‐corona (CSC) micellar complexes by adsorption of PEG‐b‐P4VP into core‐shell PS‐b‐PAA micelles.
Recovery of phase inconsistencies in continuously moving table extended field of view magnetic resonance imaging acquisitions
Authors: Kruger David G. , Riederer Stephen J. , Rossman Phillip J. , Mostardi Petrice M. , Madhuranthakam Ananth J. , Hu Houchun H.
Published: August 2005

MR images formed using extended FOV continuously moving table data acquisition can have signal falloff and loss of lateral spatial resolution at localized, periodic positions along the direction of table motion. In this work we identify the origin of these artifacts and provide a means for correction. The artifacts are due to a mismatch of the phase of signals acquired from contiguous sampling fields of view and are most pronounced when the central k‐space views are being sampled. Correction can be performed using the phase information from a periodically sampled central view to adjust the phase of all other views of that view cycle, making the net phase uniform across each axial plane. Results from experimental phantom and contrast‐enhanced peripheral MRA studies show that the correction technique substantially eliminates the artifact for a variety of phase encode orders. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Continuous ASL (CASL) perfusion MRI with an array coil and parallel imaging at 3T
Authors: Wang Ze , Wang Jiongjiong , Connick Thomas J. , Wetmore Gabriel S. , Detre John A.
Published: August 2005

The purpose of this work was to assess the feasibility and efficacy of using an array coil and parallel imaging in continuous arterial spin labeling (CASL) perfusion MRI. An 8‐channel receive‐only array head coil was used in conjunction with a surrounding detunable volume transmit coil. The signal to noise ratio (SNR), temporal stability, cerebral blood flow (CBF), and perfusion image coverage were measured from steady state CASL scans using: a standard volume coil, array coil, and array coil with 2‐ and 3‐fold accelerated parallel imaging. Compared to the standard volume coil, the array coil provided 3 times the average SNR increase and higher temporal stability for the perfusion weighted images, even with threefold acceleration. Although perfusion images of the array coil were affected by the inhomogeneous coil sensitivities, this effect was invisible in the quantitative CBF images, which showed highly reproducible perfusion values compared to the standard volume coil. The unfolding distortions of parallel imaging were suppressed in the perfusion images by pairwise subtraction, though they sharply degraded the raw EPI images. Moreover, parallel imaging provided the potential of acquiring more slices due to the shortened acquisition time and improved coverage in brain regions with high static field inhomogeneity. Such results highlight the potential utility of array coils and parallel imaging in ASL perfusion MRI. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Homodyne reconstruction and IDEAL water–fat decomposition
Authors: Reeder Scott B. , Hargreaves Brian A. , Yu Huanzhou , Brittain Jean H.
Published: August 2005

Multipoint water–fat separation methods have received renewed interest because they provide uniform separation of water and fat despite the presence of B0 and B1 field inhomogeneities. Unfortunately, full‐resolution reconstruction of partial k‐space acquisitions has been incompatible with these methods. Conventional homodyne reconstruction and related algorithms are commonly used to reconstruct partial k‐space data sets by exploiting the Hermitian symmetry of k‐space in order to maximize the spatial resolution of the image. In doing so, however, all phase information of the image is lost. The phase information of complex source images used in a water–fat separation acquisition is necessary to decompose water from fat. In this work, homodyne imaging is combined with the IDEAL (iterative decomposition of water and fat with echo asymmetry and least squares estimation) method to reconstruct full resolution water and fat images free of blurring. This method is extended to multicoil steady‐state free precession and fast spin‐echo applications and examples are shown. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Achieving sufficient spectral bandwidth for volumetric 1H echo‐planar spectroscopic imaging at 4 Tesla
Authors: Ebel Andreas , Maudsley Andrew A. , Weiner Michael W. , Schuff Norbert
Published: August 2005

Complete coverage of the in vivo proton metabolite spectrum, including downfield resonances, requires a spectral bandwidth of approximately 9 ppm. Spectral bandwidth of in vivo echo‐planar spectroscopic imaging (EPSI) is primarily limited by gradient strength of the oscillating readout gradient, gradient slew rate, and limits on peripheral nerve stimulation for human subjects. Furthermore, conventional EPSI reconstruction, which utilizes even and odd readout echoes separately, makes use of only half the spectral bandwidth. In order to regain full spectral bandwidth in EPSI, it has previously been suggested to apply an interlaced Fourier transform (iFT), which uses even and odd echoes simultaneously. However, this method has not been thoroughly analyzed regarding its usefulness for in vivo 3D EPSI. In this Note, limitations of the iFT method are discussed and an alternative, cyclic spectral unwrapping, is proposed, which is based on prior knowledge of typical in vivo spectral patterns. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Whole‐body magnetic resonance imaging featuring moving table continuous data acquisition with high‐precision position feedback
Authors: Zenge Michael O. , Ladd Mark E. , Vogt Florian M. , Brauck Katja , Barkhausen Joerg , Quick Harald H.
Published: August 2005

A novel setup for whole‐body MR imaging with moving table continuous data acquisition has been developed and evaluated. The setup features a manually positioned moving table platform with integrated phased‐array surface radiofrequency coils. A high‐precision laser position sensor was integrated into the system to provide real‐time positional data that were used to compensate for nonlinear manual table translation. This setup enables continuous 2D and 3D whole‐body data acquisition during table movement with surface coil image quality. The concept has been successfully evaluated with whole‐body steady‐state free precession (TrueFISP) anatomic imaging in five healthy volunteers. Seamless coronal and sagittal slices of continually acquired whole‐body data during table movement were accurately reconstructed. The proposed strategy is potentially useful for a variety of applications, including whole‐body metastasis screening, whole‐body MR angiography, large field‐of‐view imaging in short bore systems, and for moving table applications during MR‐guided interventions. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Understanding and optimizing the amplitude modulated control for multiple‐slice continuous arterial spin labeling
Authors: Utting Jane F. , Thomas David L. , Gadian David G. , Helliar Robert W. , Lythgoe Mark F. , Ordidge Roger J.
Published: August 2005

Multiple‐slice perfusion imaging by continuous arterial spin labeling (CASL) is made possible by amplitude modulation (AM) of the labeling RF pulse, but perfusion sensitivity is reduced relative to the single‐slice technique. A computer model of the Bloch equations for velocity driven adiabatic fast passage was developed to elucidate the compromised sensitivity to perfusion of the AM control technique for CASL. Calculations were performed over ranges of RF pulse amplitude, B1; magnetic field gradient, G; phase, ϕ, and frequency, f, of the modulation function; velocity, v, and relaxation times, T1 and T2, of blood. It was found that unless f > 2πB1, ϕ determines the performance of the AM control; excessively high B1 or v reduces the efficiency of the AM control; and T1 relaxation dominates if f is too great. In vivo, in rat brain (n = 5) at 2.35 T, the sensitivity of the AM technique to perfusion was 70% of the sensitivity of single‐slice CASL. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Transverse relaxation of cells labeled with magnetic nanoparticles
Authors: Ziener C. H. , Bauer W. R. , Jakob P. M.
Published: August 2005

We describe the NMR relaxation properties of magnetically labeled cells. The cells are labeled with magnetic nanoparticles (SPIO, USPIO), which generate susceptibility contrast. The geometry of the labeled cells and the surrounding tissue is considered. We assume that the magnetic nanoparticles accumulate to form a magnetic core of radius RC inside the cell. The correlation time τ, which describes the motion of spins around this core, is analyzed. Using the strong collision approach, explicit expressions are derived for the transverse relaxation rate R for tissue containing labeled cells as a function of the core radius, the diffusion coefficient, and the concentration of the nanoparticles. The predictions of this model agree well with numerical simulations and experimental data. Magn Reson Med, 2005. © 2005 Wiley‐Liss, Inc.
Cancer in adolescents and young adults aged 15–24 years: A report from the North of England young person's malignant disease registry, UK
Authors: Pearce Mark S. , Parker Louise , Windebank Kevin P. , Cotterill Simon J. , Craft Alan W.
Published: August 2005

Background

Descriptions of population‐based data have rarely been published specifically for adolescents and young adults with cancer.

Procedure

Data on young adults (15–24 years) diagnosed with cancer in the North of England from 1968 to 1997 were obtained from the Northern Region Young Person's Malignant Disease Registry. Temporal changes in incidence and survival rates were investigated.

Results

There were 2,329 first cancers diagnosed over the study period (M:F 1.22:1). Overall age standardized incidence was 174 cases per million 15–24 years old, per year, 190 for males and 157 for females. The most common cancers in young adults were Hodgkin disease (19%), carcinomas (15%), central nervous system tumors (14%), germ cell tumors (13%), and leukemia (11%). Comparing incidence for 1968–1977 with 1988–1997 there were significant increases in the incidence of bone tumors (rate ratio 1.72, 95% CI 1.10–2.68), testicular tumors (rate ratio 1.64, 95% CI 1.16–2.32), thyroid cancer (rate ratio 2.63, 95% CI 1.37–5.02), and malignant melanoma (rate ratio 2.04, 95% CI 1.36–3.08). Survival rates improved significantly (P < 0.001) over the study period; 5‐year survival rates over the three time periods 1968–1977, 1978–1987, 1988–1997 for all cancers were 45% (95% CI 41%–49%), 62% (95% CI 58%–65%), and 74% (95% CI 71%–77%) respectively.

Conclusions

Survival rates improved and there were significant increases in incidence for specific cancers in young adults in the North of England. Further research is required to identify the reasons for changing incidence and to investigate the late effects of treatment among survivors. © 2005 Wiley‐Liss, Inc.
Childhood ITP: 12 months follow‐up data from the prospective registry I of the Intercontinental Childhood ITP Study Group (ICIS)
Authors: Imbach P. , Kühne T. , Müller D. , Berchtold W. , Zimmerman S. , Elalfy M. , Buchanan G.R.
Published: August 2005

Background

Acute and chronic idiopathic thrombocytopenic purpura (ITP) is traditionally based on the duration of thrombocytopenia at the cut‐off point of 6 months after diagnosis. Registry I evaluated the diagnosis, definition, management, and follow‐up of childhood ITP. This report focuses on children with thrombocytopenia persisting more than 6 months.

Procedure

Data were collected by questionnaires to the physicians caring for children with ITP, at diagnosis, 6, and 12 months later. Data were compared regarding initial features and follow‐up with emphasis on children with persistent thrombocytopenia, and those with ITP who recovered their platelet counts between 7 and 12 months from diagnosis.

Results

At 12 months from diagnosis, 79 of 308 (25.6%) evaluable children recovered from ITP and 229 had ongoing ITP. Children with recovered ITP were younger than children with ongoing ITP (P = 0.043) and exhibited a lower frequency of bleeding symptoms during the first 6 months after diagnosis (P = 0.018). Frequency of hospitalization, bone marrow aspiration, and drug treatment differed regionally.

Conclusions

The high rate of recovery from ITP between 7 to 12 months demonstrates, that the cut‐off point of 6 months for the definition of chronic ITP does not adequately differentiate chronic from acute ITP. The majority of children with ITP have variable time to recovery with gradual improvement of platelet counts and disappearance of bleeding signs. ITP is a heterogeneous disorder with a diverse natural history and diverse pattern of treatment response. © 2005 Wiley‐Liss, Inc.
Post‐transplant multiple myeloma in a pediatric renal transplant patient
Authors: Tcheng Wendy Y. , Said Jonathan , Hall Theodore , Al‐Akash Samhar , Malogolowkin Marcio , Feig Stephen A.
Published: August 2005

Post‐transplant lymphoproliferative disease (PTLD) is a well‐recognized complication of the intense immunosuppression required in solid organ and bone marrow transplant recipients. The clinical presentation is varied and can range from a benign infectious mononucleosis‐like syndrome to malignant lymphoma. PTLD manifesting as multiple myeloma occurs rarely. We report the unique occurrence of Epstein–Barr virus (EBV)‐associated post‐transplant multiple myeloma in a 16‐year‐old male. In contrast to previously described cases of PTLD‐myeloma type, this patient was very young, had a clear association with EBV, and an indolent clinical course. © 2005 Wiley‐Liss, Inc.
p53 pathway dysfunction in primary childhood ependymomas
Authors: Gaspar Nathalie , Grill Jacques , Geoerger Birgit , Lellouch‐Tubiana Arielle , Michalowski Mariana Bohns , Vassal Gilles
Published: August 2005

Background

Childhood ependymoma remains a major therapeutic challenge despite surgery, chemotherapy, and irradiation. We hypothesized that p53 function might be abrogated in ependymomas and implicated in their resistance to anti‐cancer therapy.

Procedure

Primary ependymomas at diagnosis or relapse from 24 children were analyzed for p53 pathway, using a functional assay in yeast, RT‐PCR, Western blot analysis, and/or immunohistochemistry for TP53 mutation, p14ARF deletion and promoter hypermethylation, MDM2 and PAX5 expression, respectively. p53‐mediated response to radiation‐induced DNA damage was evaluated using Western blot and flow cytometry analysis in two ependymoma xenograft models, IGREP37 and IGREP83, derived from primary anaplastic childhood ependymomas.

Results

No TP53, MDM2, p14ARF, PAX5 gene abnormalities were detected in the primary ependymomas tumors and xenografts tested. Interestingly, despite the lack of these abnormalities, p53 induced p21‐mediated G1 growth arrest in response to irradiation was altered in the IGREP37 xenograft tumors. Although irradiation induced necrosis and apoptotic cell death, IGREP37 tumors were moderately sensitive to radiation therapy in vivo. In contrast, irradiation yielded significant tumor growth delays and tumor regressions in the p53 functional IGREP83 xenografts.

Conclusion

Alterations in p53‐mediated growth arrest in ependymomas might be implicated in the radio‐resistance of these tumors and demand further evaluation. © 2005 Wiley‐Liss, Inc.
Textbooks and tensions that shaped physical organic chemistry in its formative years
Authors: Weininger Stephen J.
Published: August 2005

The original article to which this Erratum refers was published in J. Phys. Org. Chem. 2005; 18: 555–559; DOI 10.1002/poc.912
Barrier properties and microstructure modifications induced by liquid water for a semiaromatic polyamide
Authors: Doudou B. Ben , Dargent E. , Marais S. , Grenet J. , Hirata Y.
Published: August 2005

This work deals with the role of liquid water on the microstructure of a semiaromatic polyamide (MXD6). One side of injected plates is kept in contact with water during different durations. After immersion, microtomic cuts are performed at different depth and are analyzed by X‐ray diffraction, differential scanning calorimetry, and permeation tests. Measurements show that the water plasticizes the initially amorphous plates and induces a spherulitic crystallization, which grows from the wet side to the dry one. As a consequence, the permeation curve is unusual, and the water flux goes through a maximum before reaching a lower plateau when the front of crystallization reaches the opposite dry face. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2604–2616, 2005
Should We Deny Surgery for Malignant Hepato‐Pancreatico‐Biliary Tumors to Elderly Patients?
Authors: Petrowsky Henrik , Clavien Pierre–Alain
Published: August 2005

Malignant hepato‐pancreatico‐biliary (HPB) tumors have their highest incidence within the sixth to eighth decades of life. The aging of the world population has resulted in a dramatic increase in the number of elderly patients considered for resection of malignant HPB tumors. Because elderly patients are more likely to have more co‐morbidities, cognitive impairment, and decreased life expectancy, the benefit and appropriateness of these procedures must be scrutinized for geriatric patients. Therefore, many surgeons have compared the perioperative and long‐term outcome of hepatic and pancreatic resections for elderly and younger patients. In most series the elderly population was defined by an age of 70 years or older. The results demonstrate that hepatic resection for hepatocellular carcinoma and colorectal liver metastases can be safely performed in well‐selected elderly patients with long‐term outcome comparable to younger patients. Similar findings are also reported for pancreatic resection in elderly patients with either ampullary or pancreatic cancer. Although the survival benefit of pancreatico‐duodenectomy is limited in all age groups, the absence of competitive therapy justifies this procedure as the sole curative option in younger as well as older patients. Data on resection of gallbladder cancer and hilar bile duct cancer in the elderly are sparse, but there is evidence from large series on resection of these types of tumors that advanced age per se is not a risk factor for reduced outcome. Therefore, surgical options should not be denied to elderly patients with a malignant HPB tumor, and the evaluation should include surgeons expert in HPB surgery.
Ex Vivo Sentinel Lymph Node Study For Rectal Adenocarcinoma: Preliminary Study
Authors: Baton Olivier , Lasser Philippe , Sabourin Jean‐Christophe , Boige Valérie , Duvillard Pierre , Elias Dominique , Malka David , Ducreux Michel , Pocard Marc
Published: August 2005

Intraoperative sentinel lymph node (SLN) detection has been reported for colon cancer, but no study has focused on rectal cancer. Only an ex vivo technique can be performed easily in this location. We evaluated SLN detection using blue dye injection in patients with rectal adenocarcinoma. This prospective study included 31 patients. Preoperative radiotherapy (45 Gy) was done in 15 cases. After proctectomy the surgical specimen was examined in the operating room. Submucosal peritumoral injections were done. One to three SLNs were retrieved. The SLNs were sectioned at three levels and examined histologically and then, if negative by hematoxylin‐eosin (H&E) staining and immunohistochemistry (IHC). There were 7 abdominoperineal resections, 12 colorectal anastomoses, 11 coloanal anastomoses, and 1 Hartmann procedure. The median number of lymph nodes harvested was 21 (7–38). A SLN was identified in 30 cases (feasibility 97%). The mean number of SLNs was 2 (0–3). A micrometastasis was discovered in 3 of 23 pNO cases when H&E was used on multisection levels, thus changing the stage to pN1. Each time the only positive lymph node was the SLN. IHC evaluation did not change the result, as only isolated tumor cells were discovered in one case. Only four of seven N+ patients had a positive SLN, resulting in a false‐negative rate of 43%. Ex vivo detection of SLNs is possible for rectal cancer and is a simple technique. Classic analysis using H&E remains the gold standard. However, SLNs detection can change the tumor stage by upstaging nearly 15% of the tumors from T2‐3N0 to T2‐3 N+.
The integration of investigative toxicology in the drug discovery process
Authors: Dean Jack H , Olson Harry M
Published: August 2005

Summary— Integrating toxicology early in the drug discovery process adds value by providing the earliest possible identification of a compound's potential for toxicological and pathological effects relevant to intended clinical use. With this approach true ‘lead’ candidates, with a high probability of clinical success, are identified and advanced while reducing effort and resources expended on compounds without the requisite therapeutic index. Resources are focussed on the speed of getting a discovery ‘lead’ into early clinical development, defining the mechanisms of observed preclinical toxicity and their relevance to human use, and developing early safety data with in vitro test systems ahead of in vivo systems where possible, thus reducing animal use.
Regio‐ and stereo‐selectivity in the induction of peroxisome proliferation by substituted hexanoic acids
Authors: Macherey Anne‐Christine , Leguy Isabelle , Gregoire Stephane , Tainturier Gerard , Lhuguenot Jean‐Claude
Published: August 2005

Summary— Quantitative structure‐activity relationship is an effective tool in order to predict drug potency. A similar approach is actually developed for peroxisome proliferation induced by substituted carboxylic acids issued from plasticizer metabolism in rats. The study is focused on acids found in rat urine after adipic diester dosings. Size, location of the substituted group and length of the chain have been studied. 3‐D structure has also been taken in account for 2‐ethyl hexanoic acids. The results obtained so far demonstrate that peroxisome proliferation potencies of the considered acids are modified according structure changes. At this time location of the group along the chain appears to be a predominant factor.
Peroxisome proliferators as inducers and substrates of UDP‐glucuronosyltransferases
Authors: Magdalou Jacques , Fournel‐Gigleux Sylvie , Pritchard Michael , Siest Gérard
Published: August 2005

Summary— Peroxisome proliferators, despite their chemically unrelated structures, share the common property of being able to stimulate the glucuronidation of bilirubin in rodents and, probably, also in man. The aryloxycarboxylic acids (clofibric acid, fenofibrate, bezafibrate, ciprofibrate), tiadenol and probucol, all of which have hypolipidemic properties, as well as the fatty acid‐like perfluorodecanoic acid all enhanced the expression of the UDP‐glucuronosyltransferase (UGT) form involved in the conjugation of the pigment. This induction is manifested by an increase in the mRNA species encoding the protein with a subsequent increase in the neosynthesis of the corresponding protein in the endoplasmic reticulum. The induction process is concomitant with that of cytochrome P‐450‐IVA1 and cytosolic epoxide hydrolase, which, like bilirubin UGT, are mainly involved in the metabolism of endogenous substrates. With a series of carboxylic acids related to clofibric acid, it was possible to demonstrate that induction was mediated via specific interactions based on the physicochemical properties of the inducers. Until now, the molecular basis of induction of bilirubin UGT is not known. The peroxisome proliferators that possess a carboxyl group are good substrates of UGT, especially in man. The acylglucuronides formed are known for their instability and reactivity which could contribute to the toxicity encountered in some patients treated with the drugs. There is convincing evidence that UGT bilirubin does not catalyze the glucuronidation of these substances even if the two types of substrate form acylglucuronides.
Preliminary studies about novel strategies to reverse chemoresistance to adriamycin regarding glutathione metabolism, peroxisomal and extraperoxisomal hydroperoxide and valproic acid metabolic pathways
Authors: Vamecq Joseph , Vallée Louis , Fontaine Monique , Nuyts Jean‐Pierre , Lambert Didier , Poupaert Jacques
Published: August 2005

Summary— The present work was aimed at defining novel strategies to reverse chemoresistance to anticancer drugs, especially by interfering with cellular glutathione metabolism, peroxisomal and/or extraperoxisomal hydroperoxide metabolic pathways. Preliminary results are presented about molecules we demonstrated to be capable of interfering with hydrogen peroxide metabolism in cells. Prior to describing these molecules, a short overview of glutathione and free radical metabolic pathways is presented as well as a rapid presentation of the characteristics of chemo‐sensitivity and ‐resistance towards the anticancer drug adriamycin, with special emphasis on hydrogen peroxide metabolism. The strategies currently developed to reverse chemoresistance are further presented. in subsequent sections, our own strategy to achieve inhibition of hydrogen peroxide breakdown and stimulation of peroxisomal hydrogen peroxide production is illustrated on the basis of molecular modelling studies and biochemical investigations on extraperoxisomal and peroxisomal metabolic pathways. Preliminary studies on cultured cells have been initiated. The perspective for future studies is presented as well as other possible models of chemoresistance as target for the design of hydrogen peroxide metabolism‐interfering pharmacomolecules.
Response of genetically obese Zucker rats to ciprofibrate, a hypolipidemic agent, with peroxisome proliferation activity as compared to Zucker lean and Sprague‐Dawley rats
Authors: Pacot Corinne , Petit Michel , Caira Françoise , Rollin Michel , Behechti Niloufar , Grégoire Stéphane , Malki Mustapha Cherkaoui , Cavatz Chantal , Moisant Maryvonne , Moreau Christine , Thomas Corinne , Descotes Gérard , Gallas Jean‐François , Deslex Paul , Althoff Jürgen , Zahnd Jean‐Pierre , Lhuguenot Jean‐Claude , Latruffe Norbert
Published: August 2005

Summary— Genetically obese Zucker (fa/fa) rats were used as an experimental model to study the effects of hypolipidemic agents on peroxisome proliferation; comparison was made with Zucker lean phenotype (Fa/−) and Sprague‐Dawley strain/phenotype. The pharmacokinetics of a single administration of ciprofibrate (1 or 3 mg/kg), appeared to be similar in all strains/phenotypes. After a 2‐week oral administration at the same dosages, there were dosage‐related increases in hepatocellular peroxisomal yield and in the hepatic enzymes' cyanide‐insensitive acyl‐CoA oxidase and catalase. The peroxisomal yield was less increased in Zucker than in Sprague‐Dawley rats, while the enzyme activities were similarly increased. Although the absolute specific activity of microsomal ω‐lauryl hydroxylase (cytochrome P4504A1) was lower in Zucker rats, it was increased more in this strain than in Sprague‐Dawley rats in response to drug exposure. The hypolipidemic effect (cholesterol and triglyceride reduction) was more pronounced in Zucker obese rats. Based on biochemical and morphological results, no major differences between strains/phenotypes in terms of peroxisome proliferation were observed following a 2‐week administration of ciprofibrate.
Stimulation of peroxisomal palmitoyl‐CoA oxidase activity by ciprofibrate in hepatic cell lines: Comparative studies in Fao, MH1C1 and HepG2 cells
Authors: Brocard Cécile , Es‐Souni Malika , Ramirez Leyla C , Latruffe Norbert , Bournot Paulette
Published: August 2005

Summary— The response of two rat cell lines, Fao and MH1C1, and one human cell line, HepG2, to the peroxisome proliferator ciprofibrate, was studied. Using a fluorometric assay for palmitoyl‐CoA oxidase, the dose‐ and time‐dependent increase of this enzymatic activity was determined. From the lowest concentration (100 μM) stimulation is evident in the two rat cell lines. In the Fao line, the activity was stimulated reaching a seven‐fold increase over the control level at 250 μM after 72 h of treatment. In the MH1C1 line, the maximum stimulation, four‐ to five‐fold, was obtained at 250 and 500 μM after 72 h. In the HepG2 cell line, activity increased two‐fold at 250 μM after 72 h reaching a three‐fold increase at 1000 μM after 48 h. Ciprofibrate was more toxic to Fao cells than to MH1C1 and HepG2 cells which is also the order of the acyl‐CoA oxidase stimulation by ciprofibrate. These preliminary results suggest that the two rat cell lines are appropriate for investigating the induction of peroxisomal β‐oxidation enzymes and the expression of their genes. The HepG2 cell line is a complementary model for the study of interspecies differences in the response to peroxisomal proliferators and of the peroxisomal functions implied in the lipid metabolism of human liver.
Peroxisome proliferators and cellular signaling pathways. A review
Authors: Bieri Françoise
Published: August 2005

Summary— In a variety of biological systems, the cellular response to an extracellular stimulus is mediated by a complex cascade of biochemical signals transduced from the cellular membrane to the specific part(s) of the cell where the response(s) occur(s). The signal transduction pathways do form a matrix of several reactions involving increased intracellular free Ca2+ levels, activation of Na+/H+ exchange, stimulation of phosphatidylinositol turnover, activation of protein kinase C and increased transcription of several cellular proto‐oncogenes. Each of them is subject to modulation at many levels, and is also susceptible to deregulation during chemically‐induced carcinogenesis. It is the aim of this short review to give an insight into the complexity of this system which may mediate the effects induced in hepatocytes by peroxisome proliferators or may, upon chronic exposure, be altered by some of them.
Transferrin gene as a model for liver‐specific gene expression
Authors: Petropoulos Isabelle , Zakin Mario M
Published: August 2005

Summary— The results obtained in the recent years have led to an understanding of the mechanisms controlling liver‐specific gene expression. They indicate that this expression needs an appropriate combination of hepatocyte and ubiquitous transcriptional factors, interacting with cis‐acting DNA elements, in a characteristic manner for each gene. However, a number of important questions about liver organogenesis and specific cell differentiation remain to be answered.
Positive regulation of the peroxisomal β‐oxidation pathway by fatty acids through activation of peroxisome proliferator‐activated receptors (PPAR)
Authors: Dreyer Christine , Keller Hansjög , Mahfoudi Abderrahim , Laudet Vincent , Krey Grigorios , Wahli Walter
Published: August 2005

Summary— Peroxisome proliferators regulate the transcription of genes by activating ligand‐dependent transcription factors, which, due to their structure and function, can be assigned to the superfamily of nuclear hormone receptors. Three such peroxisome proliferator‐activated receptors (PPARα, β, and γ) have been cloned in Xenopus laevis. Their mRNAs are expressed differentially; xPPARα and β but not xPPARγ are expressed in oocytes and embryos. In the adult, expression of xPPARα and β appears to be ubiquitous, and xPPARγ is mainly observed in adipose tissue and kidney. Immunocytochemical analysis revealed that PPARs are nuclear proteins, and that their cytoplasmic‐nuclear translocation is independent of exogenous activators. A target gene of PPARs is the gene encoding acyl‐CoA oxidase (ACO), which catalyzes the rate‐limiting step in the peroxisomal β‐oxidation of fatty acids. A peroxisome proliferator response element (PPRE), to which PPARs bind, has been identified within the promoter of the ACO gene. Besides the known xenobiotic activators of PPARs, such as hypolipidemic drugs, natural activators have been identified. Polyunsaturated fatty acids at physiological concentrations are efficient activators of PPARs, and 5,8,11,14‐eicosatetraynoic acid (ETYA), which is the alkyne homolog of arachidonic acid, is the most potent activator of xPPARα described to date. Taken together, our data suggest that PPARs have an important role in lipid metabolism.
Peroxisome through cell differentiation and neoplasia
Authors: Keller Jean‐Marie , Cablé Sylvie , El Bouhtoury Fatima , Heusser Sandrine , Scotto Christian , Armbruster Lysiane , Ciolek Eric , Colin Suzanne , Schilt Joseph , Dauça Michel
Published: August 2005

Summary— Peroxisomes are essential in cellular metabolism as their dysgenesis or defects in single enzymes or impairment of multiple peroxisomal enzymatic functions have been found in several inherited metabolic diseases with serious clinical sequelae. The assembly and formation of these cytoplasmic organelles constitute a major and intringuing research topic. In the present study the biogenesis of peroxisomes and the developmental patterns of their enzymes have been reviewed during embryonic and/or post‐embryonic ontogenesis of lower (amphibians) and higher (avians, mammals) vertebrates. In developing vertebrates, epithelial cell differentiation is accompanied by increases in frequency and size of peroxisomes. The tissue‐specific expression of peroxisomal enzymes contributes substantially to the biochemical maturation of epithelial cells. The relationship between biogenesis of peroxisomes, expression of peroxisomal enzymes and structural and functional cellular phenotype has also been investigated in differentiating epithelial cells along the crypt‐villus axis of the adult rat intestine. Cytochemical studies at the ultrastructural level have provided evidence that peroxisomes are already present in proliferating cells of the intestinal crypt region before they begin to differentiate. Migration and differentiation of intestinal epithelial cells from crypt to villus compartments are marked by significant increases in number and size of catalase‐positive structures. Increasing activity gradients from crypt to surface areas are found for the peroxisomal oxidases examined (enzymes of the peroxisomal β‐oxidation system, d‐amino acid oxidase and polyamine oxidase). Thus, peroxisomes are more and more involved in oxidative metabolic pathways as intestinal epithelial cells differentiate. Finally, we have analyzed the peroxisomal behaviour in human neoplastic epithelial cells. The presence of peroxisomes has been cytochemically revealed in human breast and colon carcinomas. Peroxisomal enzyme specific activities are significantly lower in human breast and colon carcinomas than in the adjacent healthy mucosa. Furthermore, a relationship is found between the specific activities of some peroxisomal enzymes and the histological tumour grades.
Sequence of the novel joints present in the amplified DNA of N‐phosphonacetyl‐L‐aspartate resistant Drosophila cells: Implication on the mechanisms of amplification in these cells
Authors: Azou Yannick , Laval Monique
Published: August 2005

Summary— We have previously shown the presence, in the amplified DNA of a Drosophila cell line resistant to N‐phosphonacetyl‐L‐aspartate (PALA), of two units of 150 kb and 120 kb respectively duplicated and amplified. The two joints (J1 and J2) linking these units as well as their respective wild‐type counterparts have been sequenced. Sequence analysis indicates that a region of the Drosophila genome which corresponds to the proximal boundary of the 150 kb unit is common to both joints. In addition to this common region, the J1 junction possesses a 26‐nucleotide sequence belonging to the J2 junction. This indicates that the J2 junction was the first formed, and that J1, therefore, results from recombination between J2 and a region of the wild‐type genome 120 kb distal to J2. Sequence analysis also reveals that the joints result from illegitimate recombination between unrelated regions. AT‐rich sequences, strand bias composition and putative topoisomerase I and II sites were found in at least one of the two parental sequences involved in the formation of the joints. On the basis of these results we can hypothesize that after two illegitimate recombinations between sister chromatids, leading first to J2 and then to J1, the amplification may have arisen by a series of homologous (unequal crossing‐over) or illegitimate recombinations, or by an intrachromosomal rolling circle.
Ultrastructural cytochemistry of the nucleus and nucleolus in growing rabbit oocytes
Authors: Šutovsky Peter , Jelínková Ladislava , Antalíková Libuše , Motlík Jan
Published: August 2005

Summary— Ultrastructural changes of the germinal vesicle during the growth of rabbit oocytes were studied by means of light and electron microscopy, 3H‐uridine autoradiography, Ag‐NOR staining and E‐PTA staining. Particular interest was paid to the nucleologenesis and condensation of chromatin. In contrast to other mammalian species, chromosome condensation in rabbit oocytes occurred concomitantly with rRNA synthesis‐dependent nucleolar compaction and preceded nuclear envelope breakdown and resumption of meiosis.
Culture of human preovulatory granulosa cells: Effect of extracellular matrix on steroidogenesis
Authors: Bussenot Isabelle , Ferre Guy , Azoulay‐Barjonet Catherine , Murgo Christine , Vieitez Gérard , Parinaud Jean
Published: August 2005

Summary— Human luteal granulosa cells, harvested from preovulatory follicles during in vitro fertilization attempts, were cultured in a serum‐precoated substratum (‘serum cells’) or on a collagen matrix (‘collagen cells’). Concerning the ‘serum cell’ model, E2 secretion was very low in the absence of androgen; when androstenedione was added to the culture medium, cells secreted 180 ± 52 pmol/ml/24 h of estradiol, 440 ± 78 pmol/ml/24 h of testosterone and lower quantities of estrone and estriol. Follicle stimulating hormone induced a significant increase in estradiol and estriol, while the secretion of the other steroids was not altered. The secretion of progesterone was 3.15 ± 1 nmol/ml/24 h and significantly enhanced by luteinizing hormone (+ 95%; P < 0.01). The secretions of 17α‐hydroxyprogesterone and 20α‐dihydroprogesterone were low and not modified by luteinizing hormone. ‘Collagen cells’, in basal conditions, showed an increased secretion of estradiol (+ 50%, P < 0.05), became rounded and were less responsive to gonadotropins when compared with ‘serum cells’. Thus, the use of a collagen matrix, similarly to gonadotropins, stimulated granulosa cell steroidogenesis in relation to modifications of cell shape. The higher responsiveness of serum cells to gonadotropins makes this model more suitable for physiological and pharmacological studies than the collagen one.
Endocytosis of α1‐acid glycoprotein variants by human monocytic lineage cells
Authors: Carpentier Valérie , Midoux Patrick , Monsigny Michel , Roche Annie‐Claude
Published: August 2005

Summary— Human α1‐acid glycoprotein (AGP or orosomucoid) is a major glycoprotein of plasma. AGP can be separated on immobilized concanavalin A into three variants bearing none (AGP A), one (AGP B) or two (AGP C) biantennary glycans. In this paper, we show, using flow cytometry and confocal microscopy, that AGP C which is eluted from concanavalin A with mannose, binds to human monocytes, monocyte‐derived macrophages as well as human promonocytic cell lines such as THP1 or U937. Conversely HL60, a promyelocytic cell line, does not express the surface AGP C binding protein. AGP C is internalized and degraded with an efficiency depending on the state of differentiation of these cells. In contrast, AGP A which is not recognized by concanavalin A, does not bind to any of these cells.