bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemokine receptor expression in the human ectocervix: implications for infection by the human immunodeficiency virus‐type I
Authors: Yeaman Grant R. , Asin Susana , Weldon Sally , Demian Douglas J. , Collins Jane E. , Gonzalez Jorge L. , Wira Charles R. , Fanger Michael W. , Howell Alexandra L. 
Published: November 2004

SummaryHuman immunodeficiency virus‐type 1 (HIV‐1) is a sexually transmitted pathogen that can infect cells in the female reproductive tract (FRT). The mechanism of viral transmission within the FRT and the mode of viral spread to the periphery are not well understood. To characterize the frequency of potential targets of HIV infection within the FRT, we performed a systematic study of the expression of HIV receptors (CD4, galactosyl ceramide (GalCer)) and coreceptors (CXCR4 and CCR5) on epithelial cells and leucocytes from the ectocervix. The ectocervix is a likely first site of contact with HIV‐1 following heterosexual transmission, and expression of these receptors is likely to correlate with susceptibility to viral infection. We obtained ectocervical tissue specimens from women undergoing hysterectomy, and compared expression of these receptors among patients who were classified as being in the proliferative or secretory phases of their menstrual cycle at the time of hysterectomy, as well as from postmenopausal tissues. Epithelial cells from tissues at early and mid‐proliferative stages of the menstrual cycle express CD4, although by late proliferative and secretory phases, CD4 expression was absent or weak. In contrast, GalCer expression was uniform in all stages of the menstrual cycle. CXCR4 expression was not detected on ectocervical epithelial cells and positive staining was only evident on individual leucocytes. In contrast, CCR5 expression was detected on ectocervical epithelial cells from tissues at all stages of the menstrual cycle. Overall, our results suggest that HIV infection of cells in the ectocervix could most likely occur through GalCer and CCR5. These findings are important to define potential targets of HIV‐1 infection within the FRT, and for the future design of approaches to reduce the susceptibility of women to infection by HIV‐1.
T cell receptor induced intracellular redistribution of type I protein kinase A
Authors: Zhou Wenhong , Vergara Leoncio , König Rolf 
Published: November 2004

SummaryThe productive activation of CD4+ T lymphocytes, leading to proliferation and cytokine secretion, requires precise temporal regulation of intracellular cyclic AMP concentrations. The major effector molecule activated by cyclic AMP in mammalian cells is the cyclic AMP‐dependent protein kinase A (PKA). The type I PKA isozyme mediates the inhibitory effects of cyclic AMP on T‐cell activation. Using laser scanning confocal microscopy, we demonstrated that the regulation of PKA type I activity involves spatial redistribution of PKA type I molecules following T‐cell receptor (TCR) stimulation. In resting T cells, PKA type I was located in membrane proximal regions and distributed equally across the cell. Shortly after antigen engagement, T cells and antigen‐presenting cells formed an area of intense contact, known as the immunological synapse. TCR concentrated at the synapse, whereas PKA type I molecules redistributed to the opposite cell pole within 10 min after T‐cell stimulation. Type I PKA redistribution was solely dependent on TCR signalling, because we observed the same temporal and spatial distribution after antibody‐mediated cross‐linking of the TCR‐associated CD3 complex. Segregation of TCR and PKA type I molecules was maintained for at least 20 min. Thirty minutes after stimulation, PKA type I partially colocalized with the TCR. After 60 min, PKA type I distribution again approached the resting state. Considering that initial TCR signals lead to increases in intracellular cyclic AMP, PKA type I molecules may be targeted towards localized cyclic AMP accumulations or transported away from these areas, depending on the requirements of the cellular response.
Regulation of T‐cell receptor signalling by membrane microdomains
Authors: Razzaq Tahir M. , Ozegbe Patricia , Jury Elizabeth C. , Sembi Phupinder , Blackwell Nathan M. , Kabouridis Panagiotis S. 
Published: November 2004

SummaryThere is now considerable evidence suggesting that the plasma membrane of mammalian cells is compartmentalized by functional lipid raft microdomains. These structures are assemblies of specialized lipids and proteins and have been implicated in diverse biological functions. Analysis of their protein content using proteomics and other methods revealed enrichment of signalling proteins, suggesting a role for these domains in intracellular signalling. In T lymphocytes, structure/function experiments and complementary pharmacological studies have shown that raft microdomains control the localization and function of proteins which are components of signalling pathways regulated by the T‐cell antigen receptor (TCR). Based on these studies, a model for TCR phosphorylation in lipid rafts is presented. However, despite substantial progress in the field, critical questions remain. For example, it is unclear if membrane rafts represent a homogeneous population and if their structure is modified upon TCR stimulation. In the future, proteomics and the parallel development of complementary analytical methods will undoubtedly contribute in further delineating the role of lipid rafts in signal transduction mechanisms.
Structural modifications in Rhizobium meliloti Nod factors influence their stability against hydrolysis by root chitinases
Authors: Staehelin Christian , Schultze Michael , Kondorosi Éva , Mellor Robert B. , Boiler Thomas , Kondorosi Adam 
Published: November 2004

SummaryAcylated chitooligosaccharide signals (Nod factors) trigger the development of root nodules on leguminous plants and play an important role in determining host specificity in the Rhizobium‐plant symbiosis. Here, the ability of plant chitinases to hydrolyze different Nod factors and the potential significance of the structural modifications of Nod factors in stabilizing them against enzymatic inactivation were investigated. Incubation of the sulfated Nod factors of Rhizobium meliloti, NodRm‐IV(S) and NodRm‐V(S), as well as their desulfated derivatives NodRm‐IV and NodRm‐V, with purified chitinases from the roots of the host plant Medicago and the nonhost plant Vicia resulted in the release of the acylated lipotrisaccharide NodRm‐III from NodRm‐V, NodRm‐IV and NodRm‐V(S), whereas NodRm‐IV(S) was completely resistant to digestion by both chitinases. Kinetic analysis showed that the structural parameters determining host specificity, the length of the oligosaccharide chain, the acylation at the nonreducing end and the sulfatation at the reducing end of the lipooligosaccharide, influence the stability of the molecule against degradation by chitinases. When the Nod factors were incubated in the presence of intact roots of Medicago, as well as of Vicia, the acylated lipotrisaccharide was similarly released in vivo from all Nod factors except NodRm‐IV(S). In addition, a dimer‐forming activity was observed in intact roots which also cleaved NodRm‐IV(S). This activity was much greater in Medicago than in Vicia and increased upon incubation. The initial overall degradation rate of the Nod factors on Medicago was inversely correlated with their biological activities on Medicago roots. These results open the possibility that the activity of Nod factors on Medicago may partly be determined by the action of chitinases.
Gibberellic acid‐induced microtubule reorientation in dwarf peas is accompanied by rapid modification of an α‐tubulin isotype
Authors: Duckett Catherine M. , Lloyd Clive W. 
Published: November 2004

SummaryTo test whether shifts induced in microtubuie orientation by gibberellic acid (GA3) involved changes in tubulin isotypes, pea stem cells were examined when elongation had been enhanced by GA3. The behaviour of a dwarf recessive mutation (le), with very low endogenous levels of gibberellin, was compared with the tall (Le) plant.Two hours after adding GA3, cells were measurably longer than controls and this coincided with a net shift of microtubule orientation from longitudinal and oblique to transverse — an effect that was more pronounced in the dwarf. There were always more cells with net‐transverse microtubules in GA3‐treated tissue than in controls, but as growth ceased, the major orientation of the microtubule arrays became oblique in both samples. Microtubule reorientation was rapid and was closely correlated with the growth of the cells.Although changes in orientation and isotype were monitored over a 40 h period, immunoblotting 2D gels with the well characterized antibodies YL1/2 and YOL1/34 confirmed that alterations to the α‐tubulin constellation could be detected as early as the 2 h time point. Again the effect was especially pronounced in dwarf plants. In the presence of added GA3, one α‐tubulin isotype (designated α1) retained its position in the α‐tubulin constellation (as determined by total protein staining and with YOL1/34 that recognizes detyrosinated as well as tyrosinated tubulin). It was no longer recognized, however, by the anti‐tyrosinated α‐tubulin antibody YL1/2.This indicates that as GA3 begins to cause a reorientation of the cortical microtubules (and to enhance the rate of cell elongation) the α1 isotype is rapidly changed, probably by post‐translational modification.
Regulation of pea cytosolic ascorbate peroxidase and other antioxidant enzymes during the progression of drought stress and following recovery from drought
Authors: Mittler Ron , Zilinskas Barbara A. 
Published: November 2004

SummaryThe molecular mechanism underlying the regulation of the expression of Apxl, the gene encoding cytosolic ascorbate peroxidase, as well as other antioxidant enzymes, was studied during the progression of drought stress and following recovery from drought. Increase in steady‐state transcript levels of the cytosolic isozymes of ascorbate peroxidase and Cu/Zn‐superoxide dismutase paralleled the increase in stomatal resistance during drought stress, but was even more dramatically enhanced following recovery from drought. Cytosolic Cu/Zn‐superoxide dismutase and ascorbate peroxidase and chloroplastic Cu/Zn‐superoxide dismutase protein and activity increased during drought stress and following recovery. In contrast, catalase activity increased during drought stress but returned to normal levels following recovery. During recovery from drought stress, cytosolic ascorbate peroxidase expression was regulated post‐transcriptionally at the level of protein synthesis. The transcription rate of the Apxl gene, as determined by nuclear run‐on assay, increased during drought stress and at 10 h following rewatering.
Recovery of transgenic peanut (Arachis hypogaea L.) plants from elite cultivars utilizing ACCELL® technology
Authors: Brar Gurdip S. , Cohen Barry A. , Vick Carole L. , Johnson Grant W. 
Published: November 2004

SummaryTransgenic plants of Florunner and Florigiant, two of the most widely cultivated peanut cultivars in the USA, have been developed using the ACCELL® gene delivery method. Shoot meristems of mature embryonic axes were bombarded with gold beads coated with DNA encoding β‐glucuronidase (gus), phosphinothricin acetyl transferase (bar), and tomato spotted wilt virus‐nucleocapsid protein (tswv‐np) genes. Transgenic shoots were identified by screening for GUS activity, and independent transformants were recovered from both cultivars. Molecular analysis of two of these transformants in R0 and R1 generations demonstrated the stable integration of the foreign genes into the plant genome. One transgenic plant had one to two copies of the genes integrated into the genome of its progeny, whereas the other had multiple copies. Gus and bar genes exhibited predictable segregation ratios in the R1 and R2 generations and were genetically linked. Integration of the bar gene conferred resistance to BASTATM, a wide‐spectrum herbicide, applied at 500 p.p.m. of active ingredient. Resistance of the transgenic plants to tomato spotted wilt virus is currently being tested under greenhouse conditions. The ACCELL® particle bombardment system is expected to be effective for transformation of a wide variety of commercial peanut cultivars.
Initiation and propagation behaviour of fatigue cracks in hard‐shot peened Type 316L steel in high cycle fatigue
Authors: MASAKI K. , OCHI Y. , MATSUMURA T. 
Published: November 2004

ABSTRACTObservations of fatigue crack growth behaviour were made during rotating‐bend testing of hard‐shot peened Type 316L steel. From the results of these observations, the crack that developed in the axial direction was observed and the mechanism of the fatigue crack properties was clarified as follows: (1) Small circumferential surface fatigue cracks were detected at 60% of the fatigue lifetime. These cracks propagated very slowly in both the circumferential and radial directions. (2) When a radial crack reached a depth of between 150 and 350 μm, axial fatigue cracks were formed. (3) In the next stage, either the radial or the axial fatigue cracks continued propagating, or an inwards growing radial crack formed from the axial crack. (4) In the final stage, the circumferential surface crack began to grow rapidly and resulted in fracture. (5) The fracture type of hard‐shot peened Type 316L is a particular type of surface fracture.
Fatigue life prediction under wide band random loading
Authors: PETRUCCI G. , ZUCCARELLO B. 
Published: November 2004

ABSTRACTIn this paper, a method for the high‐cycle fatigue life prediction of components subjected to gaussian, stationary, wide band random loading is presented. It allows the user to evaluate the fatigue life of components subjected to uniaxial stress states directly from the stress power spectral density (PSD), avoiding onerous simulations in time domain. The proposed method can be applied to random stress processes having PSD of any shape, and the fatigue life predictions obtained are more accurate than that provided by most of the frequency domain techniques proposed in literature.
The effect of a school‐wide inclusion training programme upon teachers’ attitudes about inclusion
Authors: Wilkins Tina , Nietfeld John L. 
Published: November 2004

Abstract This study compared survey responses of teachers from a reform‐based programme focused on promoting inclusion‐based classrooms, namely Project WINS (Winning Ideas Network for Schools) schools, with teachers from non‐Project WINS schools with regard to their attitude about inclusion in the classroom. Surprisingly, the results of this study revealed no differences between the two groups of teachers on most facets of inclusion. The one significant difference found a greater preference for inclusion by non‐Project WINS teachers with regard to classroom climate. The study also revealed a higher preference for inclusion for teachers with higher self‐reported expertise in special education regardless of what group the teacher was surveyed from. Findings from this study indicate the need for further research and improvements in training methods for Project WINS and similar programmes that attempt to change teachers’ attitudes towards inclusion as an important first step in improving practice in inclusion‐based classrooms. As the movement for more inclusion in schools increases, administrators, special educators and teachers are caught in the midst of the tide. Proponents of inclusion believe change is needed now, but those not in favour of such changes recommend not implementing inclusion without further research (Snyder, 1999). In addition, schools need assistance in developing and implementing policies and practices that will lead to an effective inclusion experience for all parties involved (Johnson, 2000). The primary purpose of this study was to further this research by examining attitudes related to inclusion of teachers participating in a programme implemented in middle schools with the explicit goal of fostering effective inclusion‐based classrooms. Second, we tested the relationship between perceived expertise in special education and attitudes towards inclusion. Below we briefly describe some of the factors that research has shown to influence teachers’ level of acceptance of inclusion‐based classrooms.
Half‐lives of docosahexaenoic acid in rat brain phospholipids are prolonged by 15 weeks of nutritional deprivation of n‐3 polyunsaturated fatty acids
Authors: DeMar James C. , Ma Kaizong , Bell Jane M. , Rapoport Stanley I. 
Published: November 2004

AbstractMale rat pups (21 days old) were placed on a diet deficient in n‐3 polyunsaturated fatty acids (PUFAs) or on an n‐3 PUFA adequate diet containing α‐linolenic acid (α‐LNA; 18 : 3n‐3). After 15 weeks on a diet, [4,5‐3H]docosahexaenoic acid (DHA; 22 : 6n‐3) was injected into the right lateral cerebral ventricle, and the rats were killed at fixed times over a period of 60 days. Compared with the adequate diet, 15 weeks of n‐3 PUFA deprivation reduced plasma DHA by 89% and brain DHA by 37%; these DHA concentrations did not change thereafter. In the n‐3 PUFA adequate rats, DHA loss half‐lives, calculated by plotting log10 (DHA radioactivity) against time after tracer injection, equaled 33 days in total brain phospholipid, 23 days in phosphatidylcholine, 32 days in phosphatidylethanolamine, 24 days in phosphatidylinositol and 58 days in phosphatidylserine; all had a decay slope significantly greater than 0 (p < 0.05). In the n‐3 PUFA deprived rats, these half‐lives were prolonged twofold or greater, and calculated rates of DHA loss from brain, Jout, were reduced. Mechanisms must exist in the adult rat brain to minimize DHA metabolic loss, and to do so even more effectively in the face of reduced n‐3 PUFA availability for only 15 weeks.
Biochemical and structural brain alterations in female mice with cerebral pyruvate dehydrogenase deficiency
Authors: Pliss Lioudmila , Pentney Roberta J. , Johnson Mark T. , Patel Mulchand S. 
Published: November 2004

AbstractPyruvate dehydrogenase complex (PDC) deficiency is an inborn metabolic disorder associated with a variety of neurologic abnormalities. This report describes the development and initial characterization of a novel murine model system in which PDC deficiency has been introduced specifically into the developing nervous system. The absence of liveborn male and a roughly 50% reduction in female offspring following induction of the X‐linked mutation indicate that extensive deficiency of PDC in the nervous system leads to pre‐natal lethality. Brain tissue from surviving females at post‐natal days 15 and 35 was shown to have approximately 75% of wild‐type PDC activity, suggesting that a threshold of enzyme activity exists for post‐natal survival. Detailed histological analyses of brain tissue revealed structural defects such as disordered neuronal cytoarchitecture and neuropil fibers in grey matter, and reduced size of bundles and disorganization of fibers in white matter. Many of the histologic abnormalities resemble those found in human female patients who carry mutations in the X‐linked ortholog. These findings demonstrate a requirement for PDC activity within the nervous system for survival in utero and suggest that impaired pyruvate metabolism in the developing brain can affect neuronal migration, axonal growth and cell–cell interactions.
Pramipexole protects against apoptotic cell death by non‐dopaminergic mechanisms
Authors: Gu Mei , Irvani M. , Cooper J Mark , King Diane , Jenner Peter , Schapira Anthony H. V. 
Published: November 2004

AbstractWe have investigated the ability of pramipexole, a dopamine agonist used in the symptomatic treatment of Parkinson's disease (PD), to protect against cell death induced by 1‐methyl‐4‐phenylpyridinium (MPP+) and rotenone in dopaminergic and non‐dopaminergic cells. Pre‐incubation with either the active (–)‐ or inactive (+)‐enantiomer forms of pramipexole (10 μm) decreased cell death in response to MPP+ and rotenone in dopaminergic SHSY‐5Y cells and in non‐dopaminergic JK cells. The protective effect was not prevented by dopamine receptor blockade using sulpiride or clozapine. Protection occurred at concentrations at which pramipexole did not demonstrate antioxidant activity, as shown by the failure to maintain aconitase activity. However, pramipexole reduced caspase‐3 activation, decreased the release of cytochrome c and prevented the fall in the mitochondrial membrane potential induced by MPP+ and rotenone. This suggests that pramipexole has anti‐apoptotic actions. The results extend the evidence for the neuroprotective effects of pramipexole and indicate that this is not dependent on dopamine receptor occupation or antioxidant activity. Further evaluation is required to determine whether the neuroprotective action of pramipexole is translated to a disease‐modifying effect in PD patients.
Patterns of Utilization for the Minnesota Senior Health Options Program
Authors: Kane Robert L. , Homyak Patricia , Bershadsky Boris , Flood Shannon , Zhang Hui 
Published: November 2004

Objectives: To compare the use of medical services provided under the Minnesota Senior Health Options (MSHO) (a special program designed to serve dually eligible older persons) with that provided to controls who received fee‐for‐service Medicare and Medicaid managed care.Design: Quasi‐experimental design using two control groups; separate matched cohort and rolling cross‐sectional analyses; regression models used to adjust for case‐mix differences.Setting: Urban Minnesota community and nursing home long‐term care.Participants: Dually eligible elderly MSHO enrollees in the community and in nursing homes were compared with two sets of controls; one was drawn from nonenrollees living in the same area (control‐in) and another from comparable persons living in another urban area where the program was not available (control‐out). Cohorts living in the community and in nursing homes were included.Measurements: Use of hospitals and emergency rooms, physician visits.Results: In the community cohort, there were no significant differences in hospital admission rates or in hospital days. MSHO enrollees had significantly fewer preventable hospital admissions and significantly fewer preventable emergency services than the control‐in group. MSHO nursing home enrollees had significantly fewer hospital admissions than either control group with or without adjustment at 12 and 18 months. MSHO enrollees had significantly fewer hospital days and preventable hospitalizations than the control‐in group. MSHO enrollees had significantly fewer emergency room visits and preventable emergency room visits than either control group.Conclusion: In general, the results of this evaluation are mixed but favor MSHO. The effect of MSHO was stronger for nursing home enrollees than community enrollees. The lower rate of preventable hospitalizations and emergency room visits of MSHO enrollees suggests that MSHO affected the process of care by providing more of some types of preventive and community‐care services for community residents.