bluuebunny/crossref_metadata_2025 huggingface dataset:
Octaploid mouse embryos produced by electrofusion polarize and cavitate at the same time as normal embryos
Authors: Winkel Glen K. , Nuccitelli Richard
Published: February 2005

We created enlarged octaploid mouse blastomeres by subjecting four‐cell embryos to a large (>2.000 V/cm) dc field of brief duration (10 μsec). This electrofusion pulse caused three to four of the blastomcres to fuse in 60% of the embryos tested. Modifications of fusion chamber and medium enabled fusion of up to 20 embryos per pulse, greatly increasing the yield for this fusion method. The effectiveness of the electrofusion pulse depended upon such parameters as embryonic cell cycle time and the pH and temperature of the electrofusion medium. There was no discernable lag in the onset of the third cleavage division or the time of cavitation in fused blastomeres. These fused blastomeres also underwent polarization of their apical surfaces at the same time as controls in spite of their increased cell size. These results suggest that octaploid mouse blastomeres created via electrofusion divide normally through the blastocyst stage and polarize at the same time and in the same sequence as smaller control blastomeres. This suggests that the mechanisms underlying cell division, cavitation, and cortical polarization are not affected by changes in cellular size or ploidy.
Growth and development of rat oocytes in vitro
Authors: Daniel Susan A. J. , Armstrong David T. , Gore‐Langton Robet E.
Published: February 2005

Rat oocytes from preantral follicles have been shown to grow and acquire meiotic competence in vitro. Follicles were isolated by enzymatic digestion of ovaries from infant (10‐ or 11‐day‐old) Wistar rats. Follicles were cultured for up to 20 days in Minimum Essential Medium (MEM) supplemented with 2 mM hypoxanthine to maintain meiotic arrest. When cultures were begun, oocytes were in midgrowth phase (40–45 μm diameter), and were incapable of undergoing meiotic maturation when placed in hypoxanthine‐free MEM. Oocytes grew and acquired meiotic competence during culture for 20 days attaining mean diameters of 62. 6 ± 0.6 μm and 61.1 ± 0.6 μm in two experiments. Germinal vesicle breakdown (GVB) occurred in 60–70% of oocytes when transferred to MEM without hypoxanthine. Concomitant with oocyte growth and maturation were spontaneous increases in follicular production of progestins, androgens and estrogens. When oocytes grown and matured in this system were inseminated in vitro with epididymal sperm, 36.1% and 25.8% were penetrated by one or more sperm in two experiments. However, fertilization was not generally normal with multiple penetrations and abnormal numbers of pronuclei (one or three) being common, suggesting that in these oocytes cytoplasmic maturation was incomplete or abnormal. In the two experiments, normal fertilization (two pronuclei and one sperm tail in the vitellus) occurred in 34.6% and 47 1% of penetrated oocytes with development of these apparently normal zygotes to two‐cell embryos being 66.7% and 62.5%, respectively.
Effects of protein kinase C stimulation and free Ca2+ rise in mammalian egg activation
Authors: Colonna R. , Tatone C. , Malgaroli A. , Eusebi F. , Mangia F.
Published: February 2005

Protein phosphorylation activity, chromosome segregation, and cortical granule exocytosis (CGE) have been studied in mouse eggs activated parthenogeneticaliy by specific PKC stimulators such as 4β‐phorbol 12‐myristate 13‐acetate (PMA) and l‐oleyl‐2‐acetylglycerol (OAG), or by agents inducing an immediate increase in cytosolic calcium concentration ([Ca2+]i) such as ethanol and Ca‐ionophore A23187. When protein phosphorylation activity of mouse eggs was analyzed 10 min after different activation treatments, the phosphorylation of a 32 kDa polypeptide was a feature common to all different parthenogenetic agents used. The appearance of such labeling was independent of an increasing [Ca2+]i, as indicated by direct measurements of i) cytosolic Ca2+ concentration with fura‐2 and 2) exogenous Ca2+ entrance into activated eggs. Emission of the second polar body was blocked in PMA‐elicited partheno‐genones, whereas it was apparently normal in OAG‐treated eggs, unless the eggs were continuously exposed to OAG. CGE was almost immediate in ethanol‐activated eggs, but in PMA‐treated cells, it occurred significantly later, with a timing corresponding to that found for the appearance of sustained Ca2+ oscillations in this system. Here, we propose that in mammalian eggs 1) PKC stimulation represents an early regulatory step in egg activation; 2) this kinase activity is turned off before the second meiotic cleavage; and 3) cytosolic free Ca2+ rise is essential for CGE occurrence.
Role of spermatozeugmata in the spawning ecology of the brooding oyster Ostrea edulis
Authors: Foighil Diarmaid Ó
Published: February 2005

Ostrea edulis spawns spermatozeugmata, each composed of radially arrayed sperm cells attached by an extracellular matrix (ECM) to a core of acellular vesicles. The acellular vesicles arc formed from excess nuclear and plasma membranes produced during spermatid condensation, and the ECM is topologically restricted to the interstices between acellular vesicles and sperm heads, being absent from the flagellar surface. When released into seawater, spermatozeugmata retain their structural integrity for varying periods (up to 24 hours) and become demersally distributed in still water. The flagella activate, initially beating in a non‐synchronized, languid manner; however, both the tempo and amplitude of the flagellar action gradually increase to resemble that of typical ‘primitive’ sperm once the cells are released from the spermatozeugma. This increase in flagellar activity and subsequent gamete release coincide with an erosion of the ECM and suggest that the ECM may modulate sperm motility in addition to adhering the cells to the spermatozeugma. Sperm are capable of fertilizing eggs only after dissociating from the spermatozeugma. The net effect of spermatozeugma formation in Ostrea edulis may be the retention of viable sperm in high concentrations at the benthic/ water column interface for prolonged periods after spawning, at least in low current regimes. Unfertilized O. edulis eggs are also concentrated at this location, in the inhalent chambers of female oysters. Spermatozeugmata are entrained by the inhalent current of females and carried into the brood chamber where fertilization occurs. The Ostrea edulis spermatozeugma likely functions as an efficient sperm transfer mechanism if two conditions are met: 1) eggs are retained as broods within benthic females, 2) egg masses are at intermediate distances from spawning males.
Ultrastuctural and cytochemical study of spermatogenesis in Scrobicularia plana (Mollusca, Bivalvia)
Authors: Sousa Mário , Corral Laura , Azevedo Carlos
Published: February 2005

The ultrastructure of the mature spermatozoa and spermatogenesis of the bivalve Scrobicularia plana are described. Support cells extend from the basal lamina to the lumen of the testis and are laterally connected to the germinal epithelium. Germ cells present intercellular bridges and flagella since the spermatogonial stage. While spermatogonia and spermatocytes appear connected to support cells by desmosome‐like junctions, elongated spermatids are held at the acrosomal region by support cell finger‐like processes. During spermiogenesis, the acrosomal vesicle differentiates from a golgian saccule and then migrates to the nuclear apex. A microtubular manchette arising from centrioles surrounds the acrosomal vesicle, the nucleus, and the mitochondria at the time these three organelles start their elongation, disappearing after that. The mature spermatozoon of S. plana lacks a distinct midpiece because the mitochondria extend from the region of the pericentriolar complex along the nucleus anteriorly for approximately 1.4 μm. The features of this bivalve type of modified spermatozoon are compared with those of other animal groups having similar modifications.
Effect of sulfated glycoconjugates on capacitation and the acrosome reaction of bovine and hamster spermatozoa
Authors: Parrish J. J. , Susko‐Parrish J. L. , Handrow R. R. , Ax R. L. , First N. L.
Published: February 2005

The effects of sulfated glycoconjugates on the preparation of mammalian sperm for fertilization were investigated. The three sulfated glycoconjugates tested were heparin, dextran sulfate, and the fucose sulfate glycoconjugate (FSG) from the sea urchin egg jelly coat. In vivo, FSG induces the acrosome reaction in sea urchin sperm. Bovine sperm were found to be capacitated by heparin and FSG as judged both by ability of lysophosphatidylcholine (LC) to induce an acrosome reaction and by ability to fertilize bovine oocytes in vitro. The mechanism by which heparin or FSG capacitated bovine sperm appeared similar, since glucose inhibited capacitation by both glycoconjugates. In contrast to effects on bovine sperm, heparin and FSG induced the acrosome reaction in capacitated hamster sperm. When hamster sperm were incubated under noncapacitating conditions, heparin had no effect on capacitation or the acrosome reaction. Three molecular weights (MW) of dextran sulfate (5,000, 8,000, 500,000) were found to capacitate bovine sperm as judged by the ability of LC to induce an acrosome reaction. Whereas bovine sperm incubated with 5,000 or 8,000 M W dextran sulfate fertilized more bovine oocytes than control sperm (P <0.05), sperm treated with 500,000 M W dextran sulfate failed to penetrate oocytes. The high‐MW dextran sulfate appeared to interact with the zona pellucida and/or sperm to prevent sperm binding. Results suggest that sulfated glycoconjugates may prepare sperm for fertilization across a wide range of species.
Transformation of sperm nuclei into male pronuclei in nucleate and anucleate fragments of parthenogenetic mouse eggs
Authors: Borsuk Ewa , Tarkowski Andrzej K.
Published: February 2005

Our objective was to examine the ability of nucleate and anucleate fragments of artificially activated mouse eggs to transform sperm nucleus into male pronucleus. To this end, zona‐free oocytes in metaphase II were activated by ethanol and bisected into halves (one with the spindle, the other anucleate) either within 10 to 20 min (series A) or 3 or 5 hr later (series B). In series A, the fragments were inseminated 3,5, and 8 h after activation, and in series B. 3 and 5 h after activation. Both nucleate and anucleate fragments lose the capability of transforming sperm nucleus into fully formed pronucleus sometime between 3 and 5 h after activation. In 8 h old parthenogenetic fragments, the majority of sperm nuclei remain unchanged or begin decondensation but never reach the stage of an early pronucleus. In over 1/3 of anucleate fragments of this age group, sperm nuclei develop defectively: chromatin decondenses inside the persisting nuclear envelope. In other experimental groups, the incidence of these abnormal sperm nuclei varies between 0 and 10%. In general, the anuclcate fragments retain the capability to transform sperm nuclei (fully or partially) longer than their nuclear counterparts. This difference may be accounted for by a different level of substances required for pronuclcar growth (extrachromosomal constituents of the germinal vesicle and nuclear lamins): high and constant in the cytoplasm of anucleate egg halves and low and progressively decreasing in the nucleate halves because of their putative uptake by the female pronucleus. However, the cytoplasmic factors responsible for the initial stages of transformation (nuclear envelope breakdown, chromatin decondensation) become eventually inactivated both in the presence and in the absence of a female pronucleus.
Catchlike property of skeletal muscle: Recent findings and clinical implications
Authors: Binder‐Macleod Stuart , Kesar Trisha
Published: February 2005

The catchlike property of skeletal muscle is the force augmentation produced by the inclusion of an initial, brief, high‐frequency burst of two to four pulses at the start of a subtetanic low‐frequency stimulation train. Catchlike‐inducing trains take advantage of the catchlike property of skeletal muscle and augment muscle performance compared with constant‐frequency trains, especially in the fatigued state. Literature spanning more than 30 years has provided comprehensive information about the catchlike property of skeletal muscle. The pattern of the catchlike‐inducing train that maximizes muscle performance is fairly similar across different muscles of different species and under various stimulation conditions. This review summarizes the mechanisms of the catchlike property, factors affecting force augmentation, techniques used to identify patterns of catchlike‐inducing trains that maximize muscle performance, and potential clinical applications to provide a historical and current perspective of our understanding of the catchlike property. Muscle Nerve, 2005
Skinned single fibers from normal and dystrophin‐deficient dogs incur comparable stretch‐induced force deficits
Authors: Childers Martin K. , Staley Jerry T. , Kornegay Joe N. , McDonald Kerry S.
Published: February 2005

Intact dystrophin‐deficient canine muscles were previously shown to incur greater‐than‐normal stretch‐induced force deficits. Here we tested the hypothesis that maximally activated detergent‐treated (skinned) single fibers from normal and dystrophin‐deficient dogs would incur comparable force deficits after stretch. Skinned cranial sartorius (CS) fibers from dystrophin‐deficient and normal dogs were calcium‐activated (pCa 4.5) and rapidly stretched. A single 30% stretch induced force deficits of 27.07 ± 3.9% and 29.7 ± 4.8% in dystrophin‐deficient (n = 22) and normal (n = 18) fibers, respectively. Our data support the hypothesis that maximally activated skinned single fibers from normal and dystrophin‐deficient dogs incur comparable force deficits after stretch. Our findings suggest that knowledge of the extent of stretch‐induced force deficits following repeated stretch‐activations in the GRMD dog may be useful to assess future therapeutic interventions aimed at replacing dystrophin in the sarcolemmal membrane. Muscle Nerve, 2005
Temperature‐Dependent Growth of Germanium Oxide and Silicon Oxide Based Nanostructures, Aligned Silicon Oxide Nanowire Assemblies, and Silicon Oxide Microtubes
Authors: Hu Junqing , Jiang Yang , Meng Xiangmin , Lee Chun‐Sing , Lee Shuit‐Tong
Published: February 2005

We demonstrate the temperature‐dependent growth of germanium oxide and silicon oxide based composite nanostructures (multiple nanojunctions of Ge nanowires and SiOx nanowires, Ge‐filled SiO2 nanotubes, Ge/SiO2 coaxial nanocables, and a variety of interesting micrometer‐sized structures), aligned SiOx nanowire assemblies, and SiOx microtubes. The structures were characterized by SEM, TEM, energy‐dispersive X‐ray spectroscopy, and electron diffraction. The combination of laser ablation of a germanium target and thermal evaoporation of silicon monoxide powders resulted in the formation of Ge and SiOx species in a carrier gas; the nano/micro‐sized structures grow by either a Ge‐catalyzed vapor–liquid–solid or a Ge‐nanowire‐templated vapor–solid process.
Cover Picture: Fabrication of Nanoscale Rings, Dots, and Rods by Combining Shadow Nanosphere Lithography and Annealed Polystyrene Nanosphere Masks (Small 4/2005)
Authors: Kosiorek Adam , Kandulski Witold , Glaczynska Hanna , Giersig Michael
Published: February 2005

The cover picture shows an ordered array of iron nanorings, which were prepared by means of shadow nanosphere lithography. By altering the nature of the mask used in the procedure, rods, dots, as well as rings can be prepared (the insets show computer simulations of the types of shapes that might be achieved). For more information, please read “Fabrication of Nanoscale Rings, Dots, and Rods by Combining Shadow Nanosphere Lithography and Annealed Polystyrene Nanosphere Masks” by M. Giersig and co‐workers on page 439ff.
Non‐invasive tests to predict fetal anemia in Kell‐alloimmunized pregnancies
Authors: van Dongen H. , Klumper F. J. C. M. , Sikkel E. , Vandenbussche F. P. H. A. , Oepkes D.
Published: February 2005

Objectives

To compare test characteristics of ultrasound and Doppler parameters in the prediction of fetal anemia in Kell‐alloimmunized pregnancies.

Methods

In this prospective study, 27 fetuses at risk for anemia due to Kell alloimmunization were evaluated with ultrasound and Doppler imaging. Spleen perimeter, liver length, middle cerebral artery (MCA) peak systolic velocity and intrahepatic umbilical venous (IHUV) maximum velocity were measured. Results were compared with fetal hemoglobin values at first intrauterine blood sampling or delivery. Severe fetal anemia was defined as a hemoglobin deficit of at least 5 SD below the mean for gestational age.

Results

Eighteen fetuses were anemic and required intrauterine transfusions. In the other nine pregnancies no transfusions were performed; one of these fetuses was severely anemic at birth. MCA and IHUV flow velocities were the best predictors of fetal anemia in Kell alloimmunized fetuses (sensitivity 89% for each test). Sensitivities for spleen perimeter (15%) and liver length (14%) were disappointing.

Conclusions

Doppler evaluation of MCA peak systolic velocity and IHUV maximum velocity can be used to reliably predict severe fetal anemia in Kell alloimmunization. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Improved first‐trimester Down syndrome screening performance by lowering the false‐positive rate: a prospective study of 9941 low‐risk women
Authors: Wøjdemann K. R. , Shalmi A. C. , Christiansen M. , Larsen S. O. , Sundberg K. , Brocks V. , Bang J. , Nørgaard‐Pedersen B. , Tabor A.
Published: February 2005

Objective

To determine the performance of screening for Down syndrome (DS) and other major chromosomal abnormalities using nuchal translucency (NT), free β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) in a prospective study of a non‐selected population.

Methods

Of 9941 women with an early ultrasound examination, NT was measured in 8622 singleton pregnancies with a gestational age between 10 + 3 and 13 + 6 weeks. β‐hCG and PAPP‐A were analyzed in 6441 cases. Detection rates (DR) and false‐positive rates (FPR) for the NT screening, the double test (β‐hCG and PAPP‐A) and the combined test (NT and the double test) were calculated using a 1 : 250 cut‐off.

Results

NT could be measured in 97.5% of cases. The DR for DS with NT screening alone was 75% with a FPR of only 1.8%. The double test detected 73% and the combined test 91%, for FPRs of 8.8% and 2.1%, respectively. We detected 80% of fetuses with other major chromosomal abnormalities with a combination of NT screening and other ultrasound findings. Low β‐hCG and PAPP‐A values (below 0.4 MoM) were observed in 0.5% of the women including all cases of triploidy and trisomy 18 and 13.

Conclusions

The performance of a screening strategy for DS using a combination of NT and the double test was superior to that using either NT or the double test alone due to a very low FPR and a higher DR. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Dynamic morphological changes in the anterior vaginal wall before and after laparoscopic Burch colposuspension in primary urodynamic stress incontinence
Authors: Yang J.‐M. , Yang S.‐H. , Huang W.‐C.
Published: February 2005

Objective

To evaluate dynamic morphological changes in the anterior vaginal wall in primary urodynamic stress incontinence before and after laparoscopic Burch colposuspension and to explore the related effects on urethral and voiding functions.

Methods

Ultrasound cystourethrography and urodynamic study were performed in 112 patients with primary urodynamic stress incontinence before and 3 months after laparoscopic Burch colposuspension. Ultrasound assessment included measurement of the bladder neck positions at rest and during straining, the bladder wall thickness at the dome and trigone, and observation of the motion of the bladder neck in addition to the development of cystocele on Valsalva maneuver. On ultrasonography, a cystocele was defined as prolapse or descent of the bladder base below the bladder neck at rest, on Valsalva, or both.

Results

After laparoscopic Burch colposuspension, ultrasound cystourethrography revealed significant differences in the bladder neck position at rest and during stress (preoperative median 93° vs. postoperative 70° at rest and preoperative 160° vs. postoperative 81° during stress, P < 0.001, respectively) and rotational angle (preoperative median 58° vs. postoperative 10°, P < 0.001). A laparoscopic Burch operation corrected 50% (5/10) of the preoperative cystoceles. However, a residual cystocele developed postoperatively in 29% (30/102) of the women who did not have one previously. Postoperative ultrasonographic and urodynamic studies did not reveal any differences between those women with or without postoperative cystocele except for the residual urine volume, detrusor opening pressure, and straining and rotational angles of the bladder neck (P < 0.001, 0.032, 0.010 and < 0.001, respectively).

Conclusions

Laparoscopic Burch colposuspension may correct a pre‐existing cystocele, but in other patients a cystocele may persist or be disclosed. After laparoscopic Burch operation a persistent cystocele is not associated with urethral compression or voiding impairment. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Nuchal translucency in pregnancies conceived after assisted reproduction technology
Authors: Hui P. W. , Tang M. H. Y. , Lam Y. H. , Yeung W. S. B. , Ng E. H. Y. , Ho P. C.
Published: February 2005

Objectives

Levels of maternal serum markers of fetal Down syndrome in pregnancies conceived after assisted reproduction are different from those of normal spontaneous pregnancies. The present study examined the effects of conventional in‐vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI) and embryo cryopreservation on nuchal translucency (NT) thickness.

Methods

A retrospective analysis on 16 673 spontaneous pregnancies, 119 pregnancies with fresh embryos from IVF, 62 pregnancies with frozen‐thawed embryos from IVF, 81 pregnancies with fresh embryos from ICSI and 39 frozen‐thawed embryos from ICSI was performed. All were singletons with known normal outcomes. Multiples of the median (MoM) of NT were compared.

Results

The median NT MoM of spontaneous pregnancies was 1.01. In the assisted reproduction pregnancies, the median NT MoM were significantly increased to 1.07 (P = 0.003), 1.09 (P = 0.009) and 1.09 (P = 0.001) in pregnancies conceived with fresh embryos from IVF, frozen‐thawed embryos from IVF and fresh embryos from ICSI, respectively. A non‐significant increase in median NT MoM (1.04; P = 0.489) was also observed in pregnancies with frozen‐thawed embryos from ICSI.

Conclusions

Increased NT in assisted reproduction pregnancies is postulated to be due to some delay in fetal development. Another possible reason might be related to adverse antenatal course in these pregnancies. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Binding of [125I]iodocyanopindolol by rat Harderian gland crude membranes: Kinetic characteristics and day—night variations
Authors: Harmouch A. , Osuna C. , Rafii-El-Idrissi M. , Calvo J. R. , Guerrero J. M.
Published: February 2005

The Harderian glands are innervated by sympathetic fibers originating in the superior cervical ganglia. The aim of this study is to characterize the β-adrenergic receptors in the rat Harderian gland. The characteristics of β-adrenergic receptors were determined in crude membrane preparations from rat Harderian gland, using [125I]iodocyanopindolol ([125I]CYP) as radioligand. The binding of the ligand to the receptor is rapid, reversible, saturable, specific and dependent on time, temperature and membrane concentration. At 30 °C, stoichiometric data suggest the presence of one binding site with a Kd value of 0.29 nM and Bmax of 32 pmol/L. The interaction shows a high degree of specificity for β-adrenergic agonists and blockers, as suggested by competitive displacement experiments with isoproterenol (IC50=19.1 nM), propranolol (IC50=28.1 nM), and norepinephrine (IC50=96.3 nM). Clonidine, yohimbine, methoxamine, and prazosin are ineffective at concentrations up to 1 μM. In the other hand, binding of [125I]CYP by Harderian gland membranes exhibits day—night variations. Binding values are low during the daytime and increase progressively late in the evening to reach a maximum at 2200 h (2 h after the onset of dark period), but decreased to the end of the dark period (0600 h). In conclusion, the results presented in this paper show the functional and pharmacological characterization of β-adrenergic receptors in the rat Harderian gland. This neurotransmitter may play a physiological role at this level regulating, at least, processes such as a thyroid hormone metabolism.
Quantal Ca2+ release and inactivation in a model of the inositol 1,4,5-trisphosphate receptor involving transformation of the ligand by the receptor
Authors: Kaimachnikov Nikolai P. , Nazarenko Vladimir G.
Published: February 2005

A model explaining quantal Ca2+ release as an intrinsic property of the inositol 1,4,5-trisphosphate (IP3) receptor has been put forward. The model is based on the hypothesis that the IP3 receptor can catalyze a transformation of the IP, molecule differing from its conventional metabolism. A simple kinetic mechanism is considered, in which IP3-induced Ca2+ channel opening is followed by the step of IP3 conversion and channel closure. Examination of the resulting mathematical model shows that it can reproduce well both partial release of stored Ca2+ and the same responsiveness to subsequent IP3 additions. On incorporation of an additional closed state of the channel, the model describes also a time-dependent channel inactivation at a high IP3 dose. Temperature sensitivity of the catalytic step accounts for the reported elimination of quantal responses and inactivation at low temperature. The transformation product is surmised to be a positional or stereo isomer of IP3.
Successful theory development in biology: A consideration of the theories of oxidative phosphorylation proposed by Davies and Krebs, Williams and Mitchell
Authors: Prebble John N.
Published: February 2005

The chemiosmotic theory is normally attributed to Peter Mitchell's formulation published in Nature in 1961. However, the essential elements of the theory were published 9 years earlier by Davies and Krebs. Why, then, was this earlier formulation overlooked? The success of Mitchell's theory is examined in comparison with those of Davies and Krebs and of Williams.
Studies with wortmannin and cytochalasins suggest a pivotal role of phosphatidylinositols in the regulation of tight junction integrity
Authors: Nybom Pia , Magnusson Karl-Eric
Published: February 2005

Wortmannin, a selective inhibitor of phosphatidylinositol 3-kinase (P13K), was found to give a dose and time-dependent, bimodal effect-initial increase, followed by decrease on the tight junction integrity of MDCK-1 monolayers, as assessed by electrical resistance measurement of the epithelia. Moreover, dihydrocytochalasin B inhibited the wortmannin-induced alteration, whereas cytochalasin B had a negligible influence on the wortmannin effect. Wortmannin was also found to cause changes in the cytoskeleton structure. These alterations were also seen when wortmannin was combined with cytochalasin B. However, in accordance with the electrical resistance measurements, dihydrocytochalasin B was able to abolish wortmannin-induced filamentous (F-) actin changes. These findings suggest that the P13K, phosphatidylinositols, and filamentous actin rearrangements, in combination, play an important role in the modulation of the junctional integrity.
Direct effects of vitamin D3 analogues on G-protein mediated signalling systems in rat osteosarcoma cells and rat pituitary adenoma cells
Authors: Mortensen Berit M. , Lund Hanne W. , Jablonski Greg , Paulssen Ruth H. , Gordeladze Jan O.
Published: February 2005

In normal rats treated with 1,25(OH)2D3 or 24,25(OH)2D3, serum Ca2+, ALP, PRL and GH are significantly altered. In order to study the primary effect of vitamin D3 analogues on target organ function, rat UMR 106 osteosarcoma and GH3 pituitary adenoma cells in monolayer culture were exposed accordingly.

Surprisingly, prolonged exposure of these cell lines to physiological levels of either 1,25(OH)2D3 or 24,25(OH)2D3 did not significantly affect the secretory parameters (ALP, PRL or GH) tested. However, 1,25(OH)2D3 exposure significantly reduced PTH- and Gpp(NH)p-elicited AC as well as Gpp(NH)p-stimulated PLC activities in the UMR 106 cells. These changes were accompanied by an increase and decrease in the membrane contents of the G-protein subunits G36β and Gq/11α, respectively. In contrast, 24,25(OH)2D3 remained without significant biological effect on these signalling systems despite concomitantly augmented levels of G36β. TRH- and Gpp(NH)p-elicited PLC activities in the GH3 cells were significantly reduced by 1,25(OH)2D3 with a concurrent reduction in cellular amounts of Gq/11α, however, 24,25(OH)2D3 did not significantly alter any signalling systems nor G-proteins analyzed.

It is concluded that the osteoblastic and pituitary cell secretion of ALP, PRL and GH remain unaffected by the presence of 1,25(OH)2D3 and 24,25(OH)2D3, despite distinct alterations in components of G-protein mediated signalling pathways. Hence, other factors like ambient Ca2+ may be responsible for the perturbed secretory patterns of ALP and PRL seen in vitamin D3 treated rats.
Mechanism of liposome destabilization by polycationic amino acids
Authors: Epand Richard M. , Lim Wendy
Published: February 2005

Polycationic amino acids induce the leakage and fusion of liposomes containing anionic lipids. We have investigated the nature and extent of the changes in membrane physical properties caused by these polypeptides which could result in the observed membrane destabilization. We found that in the range of pH 5 to pH 7 both poly-l-histidine and poly-l-lysine were ineffective in shifting the bilayer to hexagonal phase transition temperature of dielaidoylphosphatidylethanolamine, either in the presence of absence of 1-palmitoyl-2-oleoylphosphatidylserine. We also studied the gel to liquid crystalline phase transition properties of 1:1 mixtures of phosphatidylserine and phosphatidylethanolamine, both in dimyristoyl forms as well as the 1-palmitoyl-2-oleoyl forms, as a function of pH and in the presence and absence of polycationic amino acids. We observed that these two lipids were largely miscible at all pH values and in the presence and absence of the polypeptides. However, there was some increased tendency for phase separation at higher pH and in the absence of polypeptide. Thus neither changes in curvature strain nor lateral phase separation induced by the polycationic amino acids could account for their marked ability to induce leakage and fusion.

Phosphatidylethanolamine labelled with pyrene on one of the acyl chains gives rise to fluorescent emission from both monomer and excimer forms. The ratio of emission intensity from these two forms is indicative of lateral phase separation and the degree of lateral mobility of this probe. In equimolar mixtures of the 1-palmitoyl-2-oleoyl forms of phosphatidylserine and phosphatidylethanolamine in the liquid crystalline phase at 30 °C we find little effect of pH on the ratio of excimer to monomer emission intensity. However poly-l-lysine markedly lowers the fraction of excimer emission from these liposomes through the pH range from 5 to 7. Poly-l-histidine lowers the excimer to monomer emission ratio at pH 5 but not at pH 7. This is opposite to what one would expect for lateral phase separation and is interpreted at being the consequence of the polypeptide lowering the rate of lateral diffusion of the lipids. This effect of poly-l-histidine is observed over a range of temperatures from 0 to 40°C in both gel and liquid crystalline phases. There is no evidence from the behaviour of the pyrene fluorescent probe for lipid interdigitation. We conclude that the promotion of leakage and fusion in anionic liposomes by polycationic amino acids is not a result of large changes in the physical properties or arrangements of the lipids but rather to a surface binding of the polyamino acids.
Characterisation of protein structure/function relationship by sequence analysis without previous alignment: Distinction between sub-groups of protein kinases
Authors: Guerrucci Marie-Anne , Bellé Robert
Published: February 2005

Using an approach for protein comparison by computer analysis based on signal treatment methods without previous alignment of the sequence, we have analysed the structure/function relationship of related proteins. The aim was to demonstrate that from a few members of related proteins, specific parameters can be obtained and used for the characterisation of newly sequenced proteins obtained by molecular biology techniques. The analysis was performed on protein kinases, which comprise the largest known family of proteins, and therefore allows valid estimations to be made. We show that using only a dozen defined proteins, the specific parameters extracted from their sequences classified the protein kinase family into two sub-groups: the protein serine/threonine kinases (PSKs) and the protein tyrosine kinases (PTKs). The analysis, largely involving computation, appears applicable to large scale data-bank analysis and prediction of protein functions.
Treatment of cultured pancreatic B-cells with streptozotocin induces cell death by apoptosis
Authors: Morgan Noel G. , Cable Hazel C. , Newcombe Nicole R. , Williams Gwyn T.
Published: February 2005

Treatment of cultured pancreatic B-cells (HIT-T15 and RINm5F) with the diabetogenic drug Streptozotocin resulted in a significant increase in the number of cells that became detached from the substrate during a subsequent culture period. Examination of the detached cells by fluorescence microscopy after staining with acridine orange or by electron microscopy revealed evidence of chromatin condensation and margination. Isolation and fractionation of DNA from these cells revealed a pattern of oligonucleosomal fragmentation that was not evident in untreated cells. All of these features are characteristic of entry of the cells into apoptosis and the results suggest that the diabetogenic action of Streptozotocin involves induction of apoptosis in pancreatic B-cells.
A transformation-based synthesis of temporal specifications
Authors: Noël Philippe
Published: February 2005

This paper is concerned with specifications expressed in propositional temporal logic with finite past extension. The variables of the specifications are partitioned into input variables, the value of which is determined by the environment, output variables, the value of which may be required by the environment, and internal variables. We present a method to synthesise temporal specifications, i.e. to rewrite them into a form from which a valuation for the output variables may be generated from the input values without backtracking. The transformed specification characterises the same set of input/output functions as the original specification, but in a more explicit way. A simple interpreter chooses the actual function to be used.
On simulation, subtyping and substitutability in sequential object systems
Authors: Maung Ian
Published: February 2005

The aim of this article is to clarify the concepts of behavioural subtype and substitutability that are used to establish the safety of dynamic binding and run-time polymorphism in object-oriented programming. A new model of object behaviour is introduced and used to define the states of an object and the notion of object type. A notion of simulation between object behaviours is defined and a subtype relation between object types is derived from it. The syntax and structural operational semantics of an elementary OOPL is given, and the concepts of object and type substitutability are defined. It is shown formally that simulation is equivalent to object substitutability and that subtyping is equivalent to type substitutability.
The formalization and analysis of a communications protocol
Authors: Bruns Glenn , Anderson Stuart
Published: February 2005

The MSMIE protocol [SBC89] allows processors in a distributed system to communicate via shared memory. It was designed to meet the reliability and efficiency needs of applications such as nuclear safety systems. We present a formal model of the MSMIE protocol expressed in the notation CCS. Desirable properties of the protocol are expressed in the modal mu-calculus, an expressive modal logic. We show that the protocol lacks an important liveness property. In actual operation, additional operating constraints are checked to avoid potential problems. We present a modified protocol and show that it possesses the liveness property even without checking operating constraints. We also show how parts of the analysis were automated with the Concurrency Workbench.
Essential concepts of algebraic specification and program development
Authors: Sannella Donald , Tarlecki Andrzej
Published: February 2005

The main ideas underlying work on the model-theoretic foundations of algebraic specification and formal program development are presented in an informal way. An attempt is made to offer an overall view, rather than new results, and to focus on the basic motivation behind the technicalities presented elsewhere.
DUALITY: A simple formalism for the analysis of UNITY
Authors: Dijkstra Rutger M.
Published: February 2005

The ‘programming’ language DUALITY is presented and its utility for the description and analysis of UNITY is demonstrated. DUALITY is a simple language supporting demonic and angelic choice and two forms of tail-recursion. Starting from the predicate transformer semantics that was developed by C.S. Jutla, E. Knapp, and J.R. Rao for UNITY, we show that, given a UNITY program, we can write a program in DUALITY that has the same formal characteristics. This we use to reformulate and reprove some important theorems from the UNITY theory, viz. the ‘PSP-rule’ and the ‘completion rule’. Finally we show that the predicate transformers proposed by K.M. Chandy and B.A. Sanders for reasoning about concurrent computation also fit nicely within this framework.
Specification by interface separation
Authors: Hayes I. J. , Sanders J. W.
Published: February 2005

In specifying an operation it is often advantageous to describe it with abstract inputs and outputs whose concrete representation is described separately. For example, it is often convenient to describe as a set, input which in practice occurs as a sequence. The primary advantage of this approach is that one can initially concentrate on specifying an operation without the representations of its interface (that is, its inputs and outputs) obscuring the more important concerns of its abstract functional properties. Interface representations can be tackled independently, after the abstract functionality has been decided. Such separation of an operation into an abstract core and its interface with its environment makes the task of specification simpler, aids clarity of the result, and encourages reuse of both the abstract operation and its interface descriptions.
Compositional failure-based semantic models for Basic LOTOS
Authors: Valmari Antti , Tienari Martti
Published: February 2005

A systematic analysis of trace- and failure-based compositional semantic models for Basic LOTOS is presented. The analysis is motivated by the fact that the weakest known equivalences preserving sufficient information for several typical verification tasks are failure-based, and the weakness of an equivalence can be advantageous for verification. Both the equivalences and the preorders corresponding to the semantic models are covered. The analysis yields in a natural way two compositional semantic models, which are particularly suited for the verification of a general class of liveness properties, a task which cannot be performed with most established models.
Using a formal specification contractually
Authors: O'Halloran C. , Arthan R. , King D.
Published: February 2005

A commonly made criticism of formal methods is that they increase costs. Selective use of formal methods to define critical requirements can, however, lead to a significant decrease in lifecycle costs. In particular the economic and technical benefits of outsourcing the development of software can be fully realized and the cost of outsourcing slightly reduced by use of a formal specification. In this paper we describe a development in which a formal specification prepared by the customer formed part of the contract with the supplier. We conclude that this use of a formal specification can reduce risks and costs for all concerned and can help foster fruitful and co-operative relations in situations which are often fraught with confrontation.
The connection between initial and unique solutions of domain equations in the partial order and metric approach
Authors: Baier Christel , Majster-Cederbaum Mila
Published: February 2005

The purpose of this paper is twofold: First, we show in which way the initial solution of a domain equation for cpo's and the unique solution of a corresponding domain equation for metric spaces are related. Second, we present a technique to lift a given domain equation for cpo's to a corresponding domain equation for metric spaces.
Object-extending class transformations
Authors: Lieberherr Karl J. , Hürsch Walter L. , Xiao Cun
Published: February 2005

Reorganisation and evolution of class hierarchies is important for object-oriented system development and has received considerable attention in the literature. The contributions of this paper are: (1) a formal study of a set of extension relations and transformations on class hierarchies; (2) a presentation of a small set of primitive transformations which form a minimal and complete basis for the extension relations; and (3) an analysis of the impact of these transformations at the object level.

The study leads to a better understanding of evolution and reuse of object-oriented software and class hierarchies. It also provides a terminology and a means of classification for design reuse. The theory presented in this paper is based on the Demeter data model, which gives a concise mathematical foundation for classes and their inheritance and part-of relationships. Parts of the theory have been implemented in the Demeter System

TM

C++, a CASE tool for object-oriented design and programming.
List partitions
Authors: Bird R. S. , de Moor O.
Published: February 2005

By definition, a
partition
of a list is a division of that list into nonempty contiguous segments. Many programming and operations research problems can be specified in terms of list partitions, and we present a hierarchy of theorems for deriving programs from such specifications. Throughout, reasoning is conducted in an equational style using the calculus for program synthesis developed by Bird and Meertens.
Types with intersection: An introduction
Authors: Hindley J. Roger
Published: February 2005

This paper is an informal introduction to the theory of types which use a connective “∧” for the intersection of two types and a constant “
ω
” for a universal type, besides the usual connective “→” for function-types. This theory was first devised in about 1977 by Coppo, Dezani and Sallé in the context of
λ
-calculus and its main development has been by Coppo and Dezani and their collaborators in Turin. With suitable axioms and rules to assign types to
λ
-calculus terms, they obtained a system in which (i) the set of types given to a term does not change under
λ
-conversion, (ii) some interesting sets of terms, for example the solvable terms and the terms with normal form, can be characterised exactly by the types of their members, and (iii) the type-apparatus is not so complex as polymorphic systems with quantifier-containing types and therefore probably not so expensive to implement mechanically as these systems.

There are in fact several variant systems with different detailed properties. This paper defines and motivates the simplest one from which the others are derived, and describes its most basic properties. No proofs are given but the motivation is shown by examples. A comprehensive bibliography is included.
Towards a formal foundation of the specification and description language SDL
Authors: Broy Manfred
Published: February 2005

A formal model is described for the CCITT specification and description language SDL which provides a graphical concept for representing designs of systems interacting by signals. The model is based on functional descriptions of interactive systems using the concept of streams and stream processing functions. The foundations for this functional modelling of interactive systems are introduced. The graphical constructs of SDL are related to this model. In particular it is shown how the meaning of SDL graphical forms can be represented by specifications in the form of conditional equations or by functional programs. Based on the functional formal model the application of specification and verification methods for SDL is demonstrated. Small examples are treated. A number of tools are discussed that can be based on that model.

This study does not define a semantic model for the specification and design language SDL, but it gives

An introduction to the functional modelling of distributed systems

An explanation of how to translate SDL designs into functional descriptions An extended example for the translation of an SDL design

A discussion of the possibilities of supporting SDL designs by such a semantic foundation
Structured calculational proof
Authors: Back Ralph , Grundy Jim , von Wright Joakim
Published: February 2005

We propose a new format for writing proofs, called
structured calculational proof
. The format resembles the calculational style already familiar to many computer scientists, but extends it to allow the hierarchical decomposition of larger proofs into smaller ones. Structured calculation is actually an alternative presentation of natural deduction, a style of reasoning which uses hierarchical decomposition to great effect, but which is traditionally expressed in a notation that is inconvenient for writing calculational proofs. The hierarchical nature of structured calculational proofs can be used for browsing proofs in electronic publications.
An algebraic verification of a mobile network
Authors: Orava Fredrik , Parrow Joachim
Published: February 2005

In a mobile communication network some nodes change locations, and are therefore connected to different other nodes at different points in time. We show how some important aspects of such a network can be formally defined and verified using the
π
-calculus, which is a development of CCS (Calculus of Communicating Systems) allowing port names to be sent as parameters in communication events. As an example of a mobile network we consider the Public Land Mobile Network currently being developed by the European Telecommunication Standards Institute and concentrate on the handover procedure which controls the dynamic topology of the network.
On equivalence-completions of fairness assumptions
Authors: Francez Nissim , Back Ralph -J. J. , Kurki-Suonio Reino
Published: February 2005

The paper considers the treatment of fairness assumptions which are
not equivalence-robust
, a central issue in relating
interleaving semantics
to
partial order semantics
. A notion of
completion
is introduced and studied, and two specific completions are considered:
maximal completion
, which is easier to implement (shown by a broadcast bus implementation) but guarantees only weak liveness properties of programs using it; and
minimal completion
, which may be harder to implement but induces stronger liveness properties on programs using it. Some properties of completions are formulated. Finally, the impact of non-equivalence-robustness on compositionality with respect to separate fairness assumptions is considered.