Numerous Changes (numerous + change)

Distribution by Scientific Domains

Selected Abstracts

Proteomic and functional alterations in brain mitochondria from Tg2576 mice occur before amyloid plaque deposition

Frank Gillardon Dr.
Abstract Synaptic dysfunction is an early event in Alzheimer's disease patients and has also been detected in transgenic mouse models. In the present study, we analyzed proteomic changes in synaptosomal fractions from Tg2576 mice that overexpress mutant human amyloid precursor protein (K670N, M671L) and from their nontransgenic littermates. Cortical and hippocampal tissue was microdissected at the onset of cognitive impairment, but before deposition of amyloid plaques. Crude synaptosomal fractions were prepared by differential centrifugation, proteins were separated by 2-D DIGE and identified by MS/MS. Significant alterations were detected in mitochondrial heat shock protein 70 pointing to a mitochondrial stress response. Subsequently, synaptosomal versus nonsynaptic mitochondria were purified from Tg2576 mice brains by density gradient centrifugation. Mitochondrial proteins were separated by IEF or Blue-native gel electrophoresis in the first dimension and SDS-PAGE in the second dimension. Numerous changes in the protein subunit composition of the respiratory chain complexes I and III were identified. Levels of corresponding mRNAs remain unchanged as shown by Affymetrix oligonucleotide array analysis. Functional examination revealed impaired state 3 respiration and uncoupled respiration in brain mitochondria from young Tg2576 mice. By immunoblotting, amyloid-beta oligomers were detected in synaptosomal fractions from Tg2576 mice and reduced glucose metabolism was observed in Tg2576 mice brains by [14C]-2-deoxyglucose infusion. Taken together, we demonstrate alterations in the mitochondrial proteome and function that occur in Tg2576 mice brains before amyloid plaque deposition suggesting that mitochondria are early targets of amyloid-beta aggregates. [source]

Early Adolescence Talking Points: Questions that Middle School Students Want To Ask Their Parents,

Rhonda A. Richardson
In early adolescence, young people need caring parents to guide them through numerous changes and decisions. Little is known about what particular issues middle school students want to discuss with their parents. This study provides a basis for promoting parent,child communication by identifying topics that young adolescents would like to talk about with parents, using responses from 1,124 students age 10 to 15. Findings were that the largest percentage of questions pertained to family issues, whereas only 1 in 4 dealt with sensitive subjects such as drugs and sex. Implications for practice are included. [source]

Deconstructing helicoplacoids: reinterpreting the most enigmatic Cambrian echinoderms

James Sprinkle
Abstract Helicoplacoids, the most enigmatic group of Early Cambrian echinoderms, have a spirally plated, inverted pear- to spindle-shaped theca with numerous interambulacral pleats and a long triradiate ambulacrum. They occur in western Laurentia along with the earliest edrioasteroids and epispire-bearing eocrinoids(?), but unlike these other groups, helicoplacoids do not show pentameral symmetry around a centrally located, upward-facing mouth. It is uncertain where the major body openings were located in helicoplacoids, where new plates were added during thecal growth, and whether helicoplacoids were primitive, pre-pentameral, stem-group echinoderms or derived, relatively specialized forms that had lost several ambulacra. We made highly modified, side-layout, plating diagrams of different helicoplacoid species by cutting the theca apart half-way between the spiraling ambulacra, leaving four to six interambulacral pleats on each side. This deconstructed thecal strip resulted in an elongate sigmoid-shaped plating diagram with a long central single or paired ambulacrum that is interpreted as three ambulacral branches (A down, C and D up) around a central mouth on the side of the theca. The unrolled plating diagram resembles an elongate French curve drawing template with nearly parallel sides, a large or small sigmoidal top (where the theca is rounded and the interambulacral pleats converge), and an open deviated bottom, where the interambulacral pleats turn down to a truncated conical base. The two upward-extending ambulacra are only one to two interambulacral pleats apart, which only slightly increases the plating strip width. New interambulacral plates are added at the summit and base, and interambulacral pleats rarely branch elsewhere. New floor and cover plates are added at the top and bottom distal ambulacral tips. If this plating model is correct, the anus (which has still not been identified) should be located near the thecal summit where the C and D ambulacra end, and all imperforate extraxial plating has apparently been lost from the theca. If upright, spirally pleated helicoplacoids with three ambulacra were derived from attached, domal or pyrgate, pentameral edrioasteroids, numerous changes must have occurred in the thecal shape, number of ambulacra, and interambulacral areas. These changes either occurred gradually in a sequence, or a single major change (spiralled body form?) caused all the others to rapidly follow. Copyright © 2005 John Wiley & Sons, Ltd. [source]

The Lag from Monetary Policy Actions to Inflation: Friedman Revisited

Nicoletta Batini
This paper updates and extends Friedman's (1972) evidence on the lag between monetary policy actions and the response of inflation. Our evidence is based on UK and US data for the period 1953,2001 on money growth rates, inflation and interest rates, as well as annual data on money growth and inflation. We reaffirm Friedman's result that it takes over a year before monetary policy actions have their peak effect on inflation. This result has persisted despite numerous changes in monetary policy arrangements in both countries. Similarly, advances in information processing and in financial market sophistication do not appear to have substantially shortened the lag. The empirical evaluation of dynamic general equilibrium models needs to be extended to include an assessment of these models' ability to account for the monetary transmission lags found in the data. [source]

The Life and Death of the Canadian Contingent Gains and Losses Accounting Standards Project,

ABSTRACT In April 1994, the Canadian Accounting Standards Board formally approved a new accounting standard for contingent gains and losses. The new standard would have increased the frequency of recording contingent losses, enabled the accrual of some contingent gains, and enhanced disclosures for all contingencies. The changes would primarily have been achieved by requiring management, and their legal advisers, to make predictions, estimates, and disclosures that the existing accounting standard enabled them to avoid. Over two years later, and following numerous changes to the implementation date, the board ultimately decided not to release the new standard, and in July 1999, formally abandoned the contingencies project. This study provides a telling of the standard's genesis, development, and ultimate demise, which should prove instructive to those parties with an interest and a stake in accounting standard setting. [source]

Infancy is not a quiescent period of testicular development

Héctor E. Chemes
Postnatal evolution of the testis in most laboratory animals is characterized by the close continuity between neonatal activation and pubertal development. In higher primates, infancy, a long period of variable duration, separates birth from the beginning of puberty. This period has been classically considered as a quiescent phase of testicular development, but is actually characterized by intense, yet inapparent activity. Testicular volume increases vigorously shortly after birth and in early infancy due to the growth in length of seminiferous cords. This longitudinal growth results from active proliferation of infantile Sertoli cells which otherwise display a unique array of functional capabilities (oestrogen and anti-müllerian hormone secretion, increase of FSH receptors and maximal response to FSH). Leydig cells also show recrudescence after birth, possibly determined by an active gonadotrophic-testicular axis which results in increased testosterone secretion of uncertain functional role. This postnatal activation slowly subsides during late infancy when periodic phases of activation of the hypothalamo-pituitary-testicular axis are paralleled by incomplete spermatogenic spurts. The beginning of puberty is marked by the simultaneous reawakening of Leydig cell function and succeeding phases of germ cell differentiation/degeneration which ultimately lead to final spermatogenic maturation. The marked testicular growth in this stage is due to progressive increase at seminiferous tubule diameter. Sertoli cells, which have reached mitotic arrest, develop and differentiate, establishing the seminiferous tubule barrier, fluid secretion and lumen formation, and acquiring cyclic morphological and metabolic variations characteristic of the mature stage. All of these modifications indicate that, far from being quiescent, the testis in primates experiences numerous changes during infancy, and that the potential for pubertal development and normal adult fertility depends on the successful completion of these changes. [source]

Community health practitioner's practice guideline for a changing health care: Korean contribution

Il Sun Ko
Aims and objectives., The specific aims of the study were (1) to identify community residents' health problems and community health practitioners' activities, (2) to explore community health practitioners' perception of the practice guidelines and (3) to provide recommendations for the development of a new practice guideline in the future. Background., Community health practitioners in Korea are recognised as a critical component of the public health workforce in rural areas. Community health practitioners are registered nurses with six months special training, who have the chief responsibility of delivering primary health care to remote or isolated communities. Although there has been numerous changes in focus of community health practitioners practice over the two decades, community health practitioners guidelines have never been updated since being first developed in 1981. Design., This investigation employed a cross-sectional survey and focus group interview. Methods., The samples included two different groups: 1003 community health practitioners participated in a survey and a group of 12 community health practitioners participated in a focus group interview. A measure of perception of the guideline was developed from Mansfield's work. Goolsby's criteria were revised and used to guide the focus group interview. Results., The participants recognised that the role of community health practitioners is in a process of transition and expect to use well developed guidelines that will allow an appropriate response to the needs of the community. Community health practitioners are generally supportive of practice guidelines although they report various contextual, social and resource barriers to the use of practice guidelines. Finally, the researchers have provided recommendations for the development of new community health practitioners practice guidelines. Conclusion., A newly developed community health practitioners guideline should assist in articulating new roles and responsibilities in the practice of community health practitioners and establish a foundation for knowledge, skills and training necessary for them to work independently. Relevance to clinical practice., New services made available for under-recognised health problems may be a direct outcome of newly developed guidelines. [source]

How microspores transform into haploid embryos: changes associated with embryogenesis induction and microspore-derived embryogenesis

José M. Seguí-Simarro
Microspore embryogenesis is the most powerful androgenic pathway to produce haploid and doubled haploid plants. To deviate a microspore toward embryogenesis, a number of factors, different for each species, must concur at the same time and place. Once induced, the microspore undergoes numerous changes at different levels, from overall morphology to gene expression. Induction of microspore embryogenesis not only implies the expression of an embryogenic program, but also a stress-related cellular response and a repression of the gametophytic program to revert the microspore to a totipotent status. In this review, we compile the most recent advances in the understanding of the changes undergone by the induced microspore to readapt to the new developmental scenario. We devote special attention to the efforts made to uncover changes in the transcriptome of the induced microspore and microspore-derived embryo (MDE). Finally, we discuss the influence that an in vitro environment exerts over the MDE, as compared with its zygotic counterpart. [source]

Toxic effects of dexamethasone on mouse testicular germ cells

ANDROLOGIA, Issue 4 2010
M. Orazizadeh
Summary Exposure to glucocorticoids (GCs) leads to numerous changes in various biological systems including the reproductive system. This work evaluated effects of dexamethasone (Dex), a widely used GC, on mouse testicular germ cells. Experimental groups (E1,E3) received one of the following treatments daily for 7 days: 4, 7 and 10 mg kg,1 Dex respectively. Control groups were treated with equivalent volumes of saline. Testicular histopathology, morphometric analysis and deoxy-UTP-digoxigenin nick end labeling (TUNEL) assessment were performed for evaluation of the toxic effects of Dex and detection of the apoptotic cells. The results showed that Dex induces histopathological alterations such as epithelial vacuolisation, atrophy and reduction in testicular spermatozoid. Morphometrical data showed that Dex significantly reduced tubular diameter and epithelial height (P < 0.05). Johnsen's scoring also showed poor spermatogenesis in E2 and E3 groups (P < 0.05). Apoptotic index of germ cells was significantly increased in E2 (18.9% versus 1.76%, P < 0.01) and E3 (24.6 versus 1.76%, P < 0.001) groups. It is concluded that Dex acts as testicular toxicant and that further studies are needed to establish its mechanism of action upon spermatogenesis. [source]

Development of the WHO Classification of Tumors of the Central Nervous System: A Historical Perspective

Bernd W. Scheithauer MD
Abstract The classification of brain tumors has undergone numerous changes over the past half century. The World Health Organization has played a key role in the effort. Four versions of its Classification of Tumours of the Central Nervous System have been published. The present work chronicles their progress, placing emphasis on the historical context of the earliest effort. [source]

Lipooligosaccharide-independent alteration of cellular homeostasis in Neisseria meningitidis -infected epithelial cells

Robert A. Bonnah
Summary Neisseria meningitidis (MC) is an important cause of meningitis and septic shock. Primary loose attachment of MC to host epithelial cells is mediated by type IV pili. Lipooligosaccharide (LOS), opacity (Opa) proteins and glycolipid adhesins facilitate subsequent tight attachment. MC infection causes numerous changes in host epithelial cell homeostasis. These include cortical plaque formation, increased expression of proinflammatory cytokines and alterations in host iron homeostasis. Using both biochemical and genetic approaches, we examined the role of LOS in mediating these events. We first examined specific cellular iron homeostasis changes that occur following addition of purified MC LOS to epithelial cells. Using an MC mutant that completely lacks LOS (MC lps tbp), we examined pili-mediated attachment and cortical plaque formation in human endocervical epithelial cells (A431). We also tested whether the lack of LOS alters cellular homeostasis, including changes in the levels of host stress response factors and proinflammatory cytokines. MC lps tbp elicited the formation of cortical plaques in A431 cells. However, the plaques were less pronounced than those formed by the MC parent. Surprisingly, the proinflammatory cytokine TNF, was upregulated during infection in MC lps tbp -infected cells. Furthermore, alterations in iron homeostasis, including lower transferrin receptor 1 (TfR-1) levels, altered TfR-1 trafficking, an ,iron-starvation' gene expression profile and low iron regulatory protein (IRP) binding activity are independent of LOS. Our results demonstrate that LOS is partially involved in both the attachment to host cells and formation of cortical plaques. However, TNF, induction and changes in iron homeostasis observed in MC-infected epithelial cells are independent of LOS. [source]