bluuebunny/crossref_metadata_2025 huggingface dataset:
A loop–loop interaction and a K-turn motif located in the lysine aptamer domain are important for the riboswitch gene regulation control
Authors: Blouin Simon , Lafontaine Daniel A.
Published: June 2007

The lysine riboswitch is associated to the lysC gene in Bacillus subtilis, and the binding of lysine modulates the RNA structure to allow the formation of an intrinsic terminator presumably involved in transcription attenuation. The complex secondary structure of the lysine riboswitch aptamer is organized around a five-way junction that undergoes structural changes upon ligand binding. Using single-round transcription assays, we show that a loop–loop interaction is important for lysine-induced termination of transcription. Moreover, upon close inspection of the secondary structure, we find that an unconventional kink-turn motif is present in one of the stems participating in the loop–loop interaction. We show that the K-turn adopts a pronounced kink and that it binds the K-turn-binding protein L7Ae of Archaeoglobus fulgidus in the low nanomolar range. The functional importance of this K-turn motif is revealed from single-round transcription assays, which show its importance for efficient transcription termination. This motif is essential for the loop–loop interaction, and consequently, for lysine binding. Taken together, our results depict for the first time the importance of a K-turn-dependent loop–loop interaction for the transcription regulation of a lysine riboswitch.
Widespread use of poly(A) tail length control to accentuate expression of the yeast transcriptome
Authors: Beilharz Traude H. , Preiss Thomas
Published: June 2007

Control of poly(A) tail length can affect translation and stability of eukaryotic mRNAs. Although well established for individual cases, it was not known to what extent this type of adjustable gene control is used to shape expression of eukaryotic transcriptomes. Here we report on microarray-based measurements of mRNA poly(A) tail lengths and association with the poly(A)-binding protein Pab1 in S. cerevisiae, revealing extensive correlation between tail length and other physical and functional mRNA characteristics. Gene ontology analyses and further directed experiments indicate coregulation of tail length on functionally and cytotopically related mRNAs to coordinate cell-cycle progression, ribosome biogenesis, and retrotransposon expression. We show that the 3′-untranslated region drives transcript-specific adenylation control and translational efficiency of multiple mRNAs. Our findings suggest a wide-spread interdependence between 3′-untranslated region-mediated poly(A) tail length control, Pab1 binding, and mRNA translation in budding yeast. They further provide a molecular explanation for deadenylase function in the cell cycle and suggest additional cellular processes that depend on control of mRNA polyadenylation.
The Role of Adipocytokines in Insulin Resistance in Normal Pregnancy: Visfatin Concentrations in Early Pregnancy Predict Insulin Sensitivity
Authors: Mastorakos George , Valsamakis Georgios , Papatheodorou Dimitrios C , Barlas Ioannis , Margeli Alexandra , Boutsiadis Anastasios , Kouskouni Evangelia , Vitoratos Nikolaos , Papadimitriou Apostolos , Papassotiriou Ioannis , Creatsas George
Published: June 2007

Background: Throughout pregnancy maternal adipose tissue is metabolically active, producing adipocytokines involved in the process of insulin resistance. We explored the role of serum adipocytokines, including the newly identified adipocytokine visfatin, in the process of insulin resistance in normal pregnancy.

Methods: We examined 80 pregnant nonobese, nondiabetic white women during the 3 trimesters of pregnancy. All study participants underwent anthropometric measurements, adipocytokine evaluation, and a 75-g oral glucose tolerance test. Homeostasis mathematical model assessment (HOMA-R), insulin sensitivity index (ISI), and indices of β-cell secretion were calculated.

Results: Maternal weight, percentage total body fat, hip circumference, and indices of β-cell secretion increased significantly during the 3 trimesters, and HOMA-R and ISI increased and decreased, respectively, in the 3rd trimester. During early pregnancy, insulin resistance, β-cell secretion, and weight correlated positively with leptin. During the 1st trimester, visfatin correlated negatively with percentage body fat and was the best positive predictor of 2nd trimester ISI. In the 2nd trimester, serum visfatin was the best negative predictor of percentage body fat.

Conclusions: During normal pregnancy of nonobese, nondiabetic women, adipose tissue increases, accompanied by a significant progressive increase of insulin resistance. Visfatin concentrations in the 1st trimester positively predict insulin sensitivity during the 2nd trimester. Body fat mass during 1st trimester of pregnancy is negatively associated with insulin sensitivity during the 2nd trimester and perhaps should be kept under control.
Analytical and Diagnostic Characteristics of 11 2nd- and 3rd-Generation Immunoenzymatic Methods for the Detection of Antibodies to Citrullinated Proteins
Authors: Bizzaro Nicola , Tonutti Elio , Tozzoli Renato , Villalta Danilo
Published: June 2007

Background: Measurement of antibodies to citrullinated peptides or proteins (CP) is a new test for the diagnosis of rheumatoid arthritis (RA). We analyzed the analytical characteristics and diagnostic accuracy of commercially available methods.

Methods: We studied 11 commercially available 2nd- and 3rd-generation methods that used various citrullinated antigen substrates: synthetic cyclic peptides, recombinant rat filaggrin, mutated human vimentin, and Epstein–Barr virus- or IgG-derived peptides. We assessed imprecision by measuring samples with low, intermediate, and high concentrations 5 times on each of 5 days. We measured CPs by each of the assays in 100 serum samples from patients with RA and in 202 samples from healthy persons or patients with other autoimmune, viral, or neoplastic diseases.

Results: The between-run imprecision (CV) of the methods was between 0.4% and 22%, and the repeatability (within-run imprecision) was 0.5%–19%. The areas under the ROC curves varied between 0.79 (95% CI, 0.72–0.85) and 0.92 (0.88–0.95). At a fixed specificity of 98.5%, the sensitivities ranged from 41% (95% CI, 31%–51%) to 74% (64%–82%). Sensitivities and specificities varied markedly at the manufacturer’s suggested cutoffs. Most false-positive results were recorded in patients with viral infections. The methods that use the original synthetic cyclic CP gave the best and very similar performances, although these methods use different components in their reagent sets (conjugate, type of substrate, dilution, and washing buffers). This finding shows that the antigenic source is the most important variable in determining the diagnostic accuracy of the methods.

Conclusions: The analytical imprecision and diagnostic accuracies of commercially available methods for the detection of anti-CP antibodies differ. Careful selection of methods is needed.
Is the organised screening of prostate cancer reasonable?
Authors: Döbrőssy Lajos , Kovács Attila , Budai András , Cornides Ágnes
Published: June 2007

A prosztatarák Magyarországon is jelentős népegészségügyi probléma, ezért a halálozás mérséklése céljából szűrővizsgálata indokolt lenne. Szűrővizsgálati módszerek, úgymint a prosztataspecifikus antigén (PSA) kimutatása és a rectalis digitális vizsgálat rendelkezésre állnak, ám érzékenységük, fajlagosságuk, pozitív jósló értékük kívánnivalókat hagy maguk után. Nem randomizált vizsgálatokból származó bizonyítékok a szűrés lehetséges haszna mellett szólnak, azonban randomizált, ellenőrzött vizsgálatok még nem szolgáltattak meggyőző bizonyítékot. A szűrővizsgálat – a fajlagosság korlátozott volta miatt – túldiagnosztizálás és túlkezelés révén jelentős kárt is okozhat. A szerzők népegészségügyi szempontból megalapozott álláspontja szerint a szűrővizsgálati módszerek alkalomszerű felhasználása a szakorvosi diagnosztika keretében nem ütközik akadályba, azonban népegészségügyi lakosságszűrés nem kezdhető el mindaddig, amíg a folyamatban lévő randomizált, ellenőrzött vizsgálatok meg nem hozzák a várt bizonyítékokat.
Preserving the Socket Dimensions With Bone Grafting in Single Sites: An Esthetic Surgical Approach When Planning Delayed Implant Placement
Authors: Irinakis Tassos , Tabesh Moe
Published: June 2007

Recent advancements in barrier membranes, bone grafting substitutes, and surgical techniques have led to a predictable arsenal of treatment methods for clinicians who practice implant dentistry. The contemporary clinician is supplied with proven knowledge, substantiated materials, and instrument inventory that allows implant placement in cases that used to be reserved for the specialist in the past because of their complexity. Nowadays, postextraction alveolar ridge maintenance can be a predictable procedure and can certainly aid the clinician in preventing ridge collapse, thereby allowing for implant placement in a position that satisfies esthetics and function. Extraction socket maintenance for future implant therapy does not rule out immediate implant placement but rather provides an additional option when treatment planning implant patients. This article will focus on the concept of extraction socket preservation using regenerative materials. It will describe a technique suggested by the authors to resist bone resorption and soft tissue shrinkage following tooth extraction.
Identification and Characterization of Vitamin A-Storing Cells in Fetal Liver: Implications for Functional Importance of Hepatic Stellate Cells in Liver Development and Hematopoiesis
Authors: Kubota Hiroshi , Yao Hsin-lei , Reid Lola M.
Published: June 2007

Hepatic stellate cells (HpSTCs) are major regulators of hepatic fibrogenesis in adults. However, their early development in fetal liver is largely unknown. To characterize fetal HpSTCs in the liver, in which hepatic development and hematopoiesis occur in parallel, we determined the phenotypic characteristics of HpSTCs from rat fetal livers, using a strategy focused on vitamin A. Storage of vitamin A in the cytoplasm is a unique characteristic of HpSTCs, permitting identification of them by vitamin A-specific autofluorescence (vA+) when excited with UV light using flow cytometry. A characteristic vA+ cell population was identified in liver as early as 13 days post coitum; it had a surface phenotype of RT1A− intercellular adhesion molecule (ICAM)-1+ vascular cell adhesion molecule (VCAM)-1+ β3-integrin+. Although nonspecific autofluorescent cells were found with the antigenic profile of RT1A− ICAM-1+ VCAM-1+, they were β3-integrin− and proved to be hepatoblasts, bipotent hepatic parenchymal progenitors. In addition to expression of classic HpSTC markers, the vA+ cells were able to proliferate continuously in a serum-free hormonally defined medium containing leukemia inhibitory factor, which was found to be a key factor for their replication. These results demonstrated that the vA+ cells are fetal HpSTCs with extensive proliferative activity. Furthermore, the vA+ cells strongly express hepatocyte growth factor, stromal-derived factor-1α, and Hlx (homeobox transcription factor), indicating that they play important roles for hepatic development and hematopoiesis. The abilities to isolate and expand fetal HpSTCs enable further investigation into their roles in early liver development and facilitate identification of possibly novel signals of potential relevance for liver diseases.

Disclosure of potential conflicts of interest is found at the end of this article.
Characterization, Cryopreservation, and Ablation of Spermatogonial Stem Cells in Adult Rhesus Macaques
Authors: Hermann Brian P. , Sukhwani Meena , Lin Chih-Cheng , Sheng Yi , Tomko Jamie , Rodriguez Mario , Shuttleworth Jennifer J. , McFarland David , Hobbs Robin M. , Pandolfi Pier Paolo , Schatten Gerald P. , Orwig Kyle E.
Published: June 2007

Spermatogonial stem cells (SSCs) are at the foundation of mammalian spermatogenesis. Whereas rare Asingle spermatogonia comprise the rodent SSC pool, primate spermatogenesis arises from more abundant Adark and Apale spermatogonia, and the identity of the stem cell is subject to debate. The fundamental differences between these models highlight the need to investigate the biology of primate SSCs, which have greater relevance to human physiology. The alkylating chemotherapeutic agent, busulfan, ablates spermatogenesis in rodents and causes infertility in humans. We treated adult rhesus macaques with busulfan to gain insights about its effects on SSCs and spermatogenesis. Busulfan treatment caused acute declines in testis volume and sperm counts, indicating a disruption of spermatogenesis. One year following high-dose busulfan treatment, sperm counts remained undetectable, and testes were depleted of germ cells. Similar to rodents, rhesus spermatogonia expressed markers of germ cells (VASA, DAZL) and stem/progenitor spermatogonia (PLZF and GFRα1), and cells expressing these markers were depleted following high-dose busulfan treatment. Furthermore, fresh or cryopreserved germ cells from normal rhesus testes produced colonies of spermatogonia, which persisted as chains on the basement membrane of mouse seminiferous tubules in the primate to nude mouse xenotransplant assay. In contrast, testis cells from animals that received high-dose busulfan produced no colonies. These studies provide basic information about rhesus SSC activity and the impact of busulfan on the stem cell pool. In addition, the germ cell-depleted testis model will enable autologous/homologous transplantation to study stem cell/niche interactions in nonhuman primate testes.

Disclosure of potential conflicts of interest is found at the end of this article.
Post-elastic behaviour of ground-floor slabs. Part 1: Plain-concrete slabs
Authors: Abbas A. A. , Pavlović M. N. , Kotsovos M. D.
Published: June 2007

There is a growing trend to utilise ground-floor slabs (GFS) beyond their elastic limit, notably using plastic analysis. The current paper focuses on the inelastic behaviour of such slabs by means of non-linear finite-element analysis (NLFEA) and represents the first paper of a two-part study. This first paper considers the analysis of plain-concrete slabs. The second paper will concentrate on the study of fabric-reinforced concrete slabs. The NLFEA utilises a concrete constitutive model that is based on valid experimental data on concrete behaviour under triaxial states of stress. The present study proposes a new performance-based (PB) definition for the failure criterion that takes into account the all-important slope condition that often governs practical design. NLFEA-based design charts are produced and their predictions are validated by comparison with existing experimental results. The proposed design charts are also compared with existing elastic and plastic guidelines, and thus recommendations are made on the safety and economy of these guidelines.
Evaluating the short- and long-term moisture transport phenomena in lightweight aggregate concretes
Authors: Neithalath N.
Published: June 2007

The primary descriptor of moisture transport in concretes is sorptivity, which represents the moisture intake through the capillary pores at early times. Although the effectiveness of this parameter in quantifying the near surface characteristics is well established, it is also necessary to consider the effect of long-term moisture transport through the smaller pores at later periods of time (diffusion) in order meaningfully to compare the durability of different mixtures and to arrive at more accurate indicators of service life. The present paper uses a combination of the exponential equation for sorption and a solution of Fick's second law for diffusion to estimate the moisture transport parameters in lightweight aggregate concretes. Lightweight aggregate concrete specimens are subjected to different pre-conditioning regimes before being subjected to moisture transport tests in order to understand the influence of moisture conditions on the transport parameters. A ‘saturation index’ is used to quantify the influence of saturation levels in moisture transport. The transport parameters at any saturation level could be linked to the saturation indices and the corresponding parameters at near-perfect saturation. It is shown in this paper that the total mass of water absorbed by a specimen cannot be viewed as a direct indicator of its moisture transport parameters. The relative contributions of sorption and diffusion to the total moisture intake are also explored. While the contribution of diffusion to the total moisture intake never exceeds that of sorption in normal-weight aggregate concretes, it is seen that in lightweight concretes, as the saturation levels are lowered, the contribution of diffusion does exceed that of sorption.
Effect of corrosion on the bond between steel and concrete: an overview
Authors: Lundgren K.
Published: June 2007

The volume increase that takes place when reinforcement in concrete corrodes causes splitting stresses in the concrete. Thereby, the bond between the reinforcement and the concrete is influenced. This effect has been studied both experimentally and theoretically by many researchers. In the current paper, the effect of corrosion on the bond between reinforcement and concrete is investigated and described in a systematic way. Literature studies of experimental work are combined with finite element analyses of different cases. In this way, modelling is used as a tool to give the basic understanding, and the results are compared with experiments. An overview of the effect depending on the reinforcement type, existence of transverse reinforcement and confinement owing to concrete and boundaries is given. This overview is intended to be of help in understanding the phenomena as well as in assessment of existing structures.
Damage to Chromosomes and DNA of Rhesus Monkey Sperm Following Cryopreservation
Authors: Li Ming‐Wen , Meyers Stuart , Tollner Theodore L. , Overstreet James W.
Published: June 2007

ABSTRACT: Fresh and frozen‐thawed rhesus monkey sperm were analyzed for DNA damage using the comet assay and for chromosome damage by cytogenetic analysis after intracytoplasmic sperm injection (ICSI) into mouse oocytes. The percentage of fresh sperm with damaged DNA in ejaculated semen was 0 to 2.7% (n = 5). Conventional cryopreservation and storage in liquid nitrogen caused DNA damage in 25.3% to 43.7% of sperm; when sperm were frozen without cryoprotectants, 52.7% to 92.0% of thawed sperm had DNA damage. However, no significant difference in chromosome damage was found between fresh sperm and frozen‐thawed sperm when motile sperm were selected for ICSI. The percentage of sperm with abnormal karyotypes ranged from 0 to 8.3%. The most common structural chromosomal abnormalities in fresh motile sperm and frozen‐thawed motile sperm were chromosome breaks or fragments. Our findings suggest that genetically competent frozen‐thawed macaque sperm can be selected for fertilization by using only motile sperm for ICSI.
Expression and Possible Functions of a Novel Gene SPATA12 in Human Testis
Authors: Dan Li , Lifang Yang , Guangxiu Lu
Published: June 2007

ABSTRACT: In our previous study, a novel human testis‐specific gene, SPATA12, was identified using the digital differential display program. In the current study, both SPATA12 mRNA and protein levels in the developmental stage of the testis were detected by SYBR real‐time reverse transcriptase polymerase chain reaction and Western blot. A high level of SPATA12 gene expression was observed in normal adult testis but was completely absent in fetal testis. Both in situ hybridization and immunohistochemical analysis showed that SPATA12 was expressed in seminiferous tubules of adult testis—more precisely in spermatocytes, spermatids, and spermatozoa—but there was no expression in Sertoli and Leydig cells. These results showed that SPATA12 is a stage‐specific and germ cell—specific gene, which suggests that it must be involved in the development of testicular maturation. It was also found that the expression level of SPATA12 mRNA in the testes of infertile men was associated with the amount and density of germ cells. With a decrease in the number of germ cells, the expression of SPATA12 mRNA was lower. In addition, the signal in the testes of patients with cryptorchidism or Sertoli cell only syndrome was not detected. Flow cytometry analysis of SPATA12 in human HeLa cells and mouse GC‐1 spg germ cells indicated that the expression of the SPATA12 gene may delay the progression of G1 to S in the cell cycle. SPATA12 was also shown to be lost in testicular germ cell tumors both at the level of transcription and translation. We hypothesized that the putative function of SPATA12 is to maintain the cell in a differentiated state and/or to suppress cell proliferation.
Metformin Restores the Penile Expression of Nitric Oxide Synthase in High‐ Fat—Fed Obese Rats
Authors: Kim Yong‐Woon , Park So‐Young , Kim Jong‐Yeon , Huh Jung‐Yoon , Jeon Woo‐Sung , Yoon Chang‐Jun , Yun Sung‐Su , Moon Ki‐Hak
Published: June 2007

ABSTRACT: Obesity is a well‐known risk factor for erectile dysfunction, which is associated with reduced penile nitric oxide synthase (NOS) expression. Recently it was reported that metformin activates AMP‐activated protein kinase (AMPK), which increases the expression of neuronal (n) NOS and endothelial (e) NOS. Thus, to evaluate whether metformin restores NOS expression in penile tissue, we measured penile expression of nNOS and eNOS after 4 weeks of metformin treatment (300 mg/kg/d) in 5‐month‐old high‐ fat—fed obese (HFO) rats. HFO rats have increased fat accumulation in visceral areas and marked suppression of nNOS and eNOS expression in penile tissue. However, metformin treatment decreased visceral fat deposition and restored nNOS and eNOS expression in penile tissue. The levels of AMPK and phosphorylated AMPK were also decreased in HFO rats but were subsequently elevated by metformin treatment. These results suggest that expression of NOS was suppressed by the high‐fat diet but restored by metformin treatment. The effect of metformin on the expression of NOS may be associated with its activation of AMPK.
Biphasic Effects of Postnatal Exposure to Diethylhexylphthalate on the Timing of Puberty in Male Rats
Authors: Ge Ren‐Shan , Chen Guo‐Rong , Dong Qiang , Akingbemi Benson , Sottas Chantal M. , Santos Michelle , Sealfon Stuart C. , Bernard Daniel J. , Hardy Matthew P.
Published: June 2007

ABSTRACT: Phthalate esters such as di(2‐ethylhexyl)phthalate (DEHP), which are commonly found in cosmetics and in flexible plastics distributed by the food, construction, and medical products industries, have been classified as anti‐androgens. High‐dose DEHP exposure in utero is associated with decreased androgen levels. However, when administered after birth, low doses of DEHP (eg, 10 mg/kg body weight) may stimulate androgen production. In the present study, the potential of phthalate exposure to advance or delay the timing of puberty was assessed. Male Long‐Evans rat pups were chronically subjected to low or high doses of DEHP, with the androgen‐driven process of preputial separation serving as an index of pubertal timing. Rats were treated with 0, 10, 500, or 750 mg/kg body weight DEHP for 28 days starting at day 21 postpartum. The average age at which the animals completed preputial separation was measured in each group. The age of preputial separation was 41.5 ± 0.1 days postpartum in controls (vehicle). The 10 mg/kg DEHP dose advanced pubertal onset significantly to 39.7 ± 0.1 days postpartum, whereas the 750 mg/kg DEHP dose delayed pubertal onset to 46.3 ± 0.1 days postpartum. The 10 mg/kg DEHP dose also significantly increased serum testosterone (T) levels (3.13 ± 0.37 ng/mL) and seminal vesicle weights (0.33 ± 0.02 g) compared with control serum T (1.98 ± 0.20 ng/mL) and seminal vesicle weight (0.26 ± 0.02 g), while the 750 mg/kg dose decreased serum T (1.18 ± 0.18 ng/mL) as well as testes and body weights. Direct action of the DEHP metabolite, monoethylhexylphthalate (MEHP), on Leydig cell steroidogenic capacity was investigated in vitro. MEHP treatment at a low concentration (100 μM) increased luteinizing hormone—stimulated T production, whereas 10 mM concentrations were inhibitory. In conclusion, data from the present study indicate that DEHP has a biphasic effect on Leydig cell function, with low‐dose exposure advancing the onset of puberty. High doses of DEHP, which are anti‐androgenic, may also be outside the range of real environmental exposure levels.
Simultaneous Observation of DNA Fragmentation and Protein Loss in the Boar Spermatozoon Following Application of the Sperm Chromatin Dispersion (SCD) Test
Authors: de, la Torre Joaquina , López‐Fernández Carmen , Pita Miguel , Fernández Jose Luis , Johnston Steve D. , Gosálvez Jaime
Published: June 2007

ABSTRACT:DNA fragmentation and the nuclear protein matrix in boar spermatozoa were simultaneously assessed using a specific variant of the sperm chromatin dispersion (SCD) test that allows direct visualization of DNA and nuclear proteins under standard conditions of chemical lysis. Nuclear proteins remaining after lysis were stained with the fluorochrome 2,7‐dibrom‐4‐hydroxy‐mercury‐fluorescein for specific protein staining. DNA and nuclear protein were stained in control‐untreated (no lysis) and treated sperm cells (lysis), resulting in the identification of 3 cell types: type 1: nonlysed (control‐untreated) cells; type 2: lysed cells showing nonfragmented DNA; and type 3: lysed cells showing fragmented DNA. DNA damage was also purposely induced by incubating the sperm in 0.015% H2O2for 48 hours at 37°C; the cells were correspondingly stained for DNA fragmentation and protein. Nonlysed control sperm (type 1) nuclei showed no halos and stained strongly for protein in the postacrosomal region. Lysed spermatozoa with nonfragmented DNA (type 2) showed evidence of restricted DNA loop dispersions at the caudal extremity of the sperm head and a more homogenous but similar distribution of protein matrix in comparison with untreated spermatozoa. Lysed spermatozoa with fragmented DNA (type 3) exhibited large halos of DNA loops and a loss of the nuclear protein matrix component. Sperm cells exposed to 48 hours' incubation at 37°C and then treated with the lysing agent showed a concurrent and progressive loss of nuclear protein in association with correspondingly increased levels of DNA fragmentation. Discriminant analysis of quantitative fluorescence using digital image analysis and conducted after SCD processing revealed that DNA fragmentation and protein could be evaluated in an automated system. Ninety‐seven percent of the total analyzed cells were accurately classified according to previously defined cell types (1, 2, and 3). The results of the current study demonstrated a synergistic relationship between that of nuclear protein alteration and DNA damage in the boar sperm cell. The importance of abnormal nuclear protein alteration to DNA fragmentation and any related effect on fertility remains to be investigated.
GM1 Dynamics as a Marker for Membrane Changes Associated With the Process of Capacitation in Murine and Bovine Spermatozoa
Authors: Selvaraj Vimal , Buttke Danielle E. , Asano Atsushi , McElwee John L. , Wolff Collin A. , Nelson Jacquelyn L. , Klaus Angela V. , Hunnicutt Gary R. , Travis Alexander J.
Published: June 2007

ABSTRACT: We previously showed that in live murine and bovine sperm heads, the ganglioside GM1 localizes to the sterol‐rich plasma membrane overlying the acrosome (APM). Labeling GM1 using the pentameric cholera toxin subunit B (CTB) induced a dramatic redistribution of signal from the APM to the sterol‐poor postacrosomal plasma membrane (PAPM) upon sperm death. We now show a similar phenomenon in the flagellum where CTB induces GM1 redistribution to sterol‐poor membrane subdomains of the annulus and flagellar zipper. Because sterol efflux from the plasma membrane is required for capacitation, we examined whether GM1 localization might be useful to detect membrane changes associated with capacitation and/or acrosomal exocytosis. First, incubation of murine and bovine sperm with their respective stimuli for capacitation did not change GM1 distribution in live cells. However, incubation of sperm of both species with specific stimuli for capacitation, followed by the use of specific fixation conditions, induced reproducible, stimulus‐specific patterns of GM1 distribution. By assessing changes in GM1 distribution in response to progesterone‐induced AE, we show that these patterns reflect the response of murine sperm populations to capacitating stimuli. These data suggest that GM1 localization can be used as a diagnostic tool for evaluating sperm response to stimuli for capacitation and/or AE. Such information could be useful when deciding between technologies of assisted reproduction or when screening for male fertility. Furthermore, stimulus‐specific changes in GM1 distribution showed that sperm could respond to NaHCO3 or mediators of sterol efflux independently, thereby refining existing models of capacitation.
Molecular Study of (TG)m(T)n Polymorphisms in Iranian Males With Congenital Bilateral Absence of the Vas Deferens
Authors: Radpour Ramin , Gourabi Hamid , Gilani Mohamad Ali Sadighi , Dizaj Ahmad Vosough
Published: June 2007

ABSTRACT: Congenital bilateral absence of the vas deferens (CBAVD) is a frequent cause of obstructive azoospermia. Nearly 75% of men with CBAVD have at least 1 detectable common mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The different alleles at the (TG)m(T)n polymorphic locus at the 3′ end of human CFTR intron 8 determine the efficiency of exon 9 splicing. To study the CFTR gene mutations and (TG)m(T)n polymorphisms in Iranian CBAVD patients with presumed low CF frequency and to better understand the complex regulation of exon 9 splicing among our study population, we analyzed CFTR mutations and (TG)m(T)n polymorphisms in 112 Iranian CBAVD, 7 congenital unilateral absence of the vas deferens males from Iran, and 84 fertile males as controls. Moreover, we compared the rate of CFTR transcripts with exon 9 (9+) with reduction of the (T)n repeat in our study population. Our study showed that the 5T mutation was present with high frequency in our patients. Longer (TG)m polymorphic tracts increase the proportion of exon 9 deletion transcripts but only when activated by the 5T allele. The combination of the 5T allele in 1 copy of the CFTR gene with a CF mutation in the other copy is the most common cause of CBAVD in the Iranian population. We also observed the highest level of exon 9+ splicing efficiency among the tested samples with the (TG)12(T)7 allele, which represents the most common intron 8 splice variant allele in the general population. Our results support the idea that a putative role of the (T)n repeat is to distance the (TG)m repeat from the 3′ splice site and that the different alleles at the (T)n locus affect the efficiency by which the splice acceptor consensus sequence is recognized.
Unowned Places and Times: Maps and Interviews About Violence in High Schools
Authors: Astor Ron Avi , Meyer Heather Ann , Behre William J.
Published: June 2007

Students and teachers in five high schools were given maps of their schools and asked to identify the locations and times of the most violent events and most dangerous areas in and around the school. Participants were also asked to identify the ages and genders of the perpetrators/victims of the violent events. Participants were then interviewed about why they believed violence occurred in the locations and times which were indicated on the maps. Results suggested that violent events occurred primarily in spaces such as hallways, dining areas, and parking lots at times when adults were not typically present. Interviews with children and school staff suggest that these territories within schools tend to be "unowned" by school personnel and students. The study participants suggested ways to address violence in these contexts and increase ownership of these spaces. Teachers,' students,' and administrators' views on variables such as teacher/child relationships, gender, race, and the organizational response to school violence are contrasted. In addition, their thoughts about existing interventions such as security guards, suspension, and video/electronic monitoring are presented. Based on the findings of this inquiry, the authors recommend that interventions be designed to increase the role of students, teachers, and other school community members in reclaiming unowned school territories.
Educating World Citizens: Toward Multinational Curriculum Development
Authors: Parker Walter C. , Ninomiya Akira , Cogan John
Published: June 2007

School curricula are virtually everywhere developed nationally and intranationally—by national or local curriculum committees. Ironically, even the portion of the curriculum that involves world study (e.g., courses in world history, world geography, world problems) is developed within nations. Has the time not come to create some portions of the school curriculum multinationally? A multinational research team from nine nations used Cultural Futures Delphi procedures to interview then survey iteratively a multinational panel drawn from an array of fields in the same nine nations. The panelists reached consensus on (a) complex global crises that humans will face in the next 25years, (b) human characteristics needed for dealing with these crises, and (c) education strategies needed for developing these characteristics. Interpreting these findings, the research team developed a curriculum geared to the development of world citizens capable of dealing with the crises.
Beyond Language: Ebonics, Proper English, and Identity in a Black-American Speech Community
Authors: Ogbu John U.
Published: June 2007

The discourse on the ebonics resolution passed in December 1996 by the Board of Education in Oakland, CA, has increased national awareness of the language problems faced by African-American children in the public school. The discourse focused almost exclusively on dialect differences per se between the standard English of the public school and the children's home dialect or ebonics. This article has three objectives: (a) to contribute to sociolinguistic studies of speech communities; (b) to describe and explain sociolinguistic factors (beyond language/dialect) that affect Black children's performance on standard English; and (c) to show a connection between the children's dialect beliefs, attitudes, and behaviors in school with those of their parents and community. This article is based on a 2-year ethnographic study of a Black speech community in Oakland, CA, characterized by bidialectalism and diglossia. However, the community and its children face a dilemma in learning and using proper English because of their incompatible beliefs about standard English.
School Adaptation: A Triangular Process
Authors: Brizuela Bárbara M. , García-Sellers Martha J.
Published: June 2007

In this article, we present the results of a year-long, follow-up study through vignettes from four of the case studies carried out with a group of 16 first-grade, Spanish-speaking children whose families recently immigrated to the United States. During the 1995–1996 school year, we followed the unfolding of the school adaptation of the children, families, and teachers in the process. Through the findings, we seek to challenge traditional views of school adaptation that focus on the child, on the child and family, and, in the case of linguistic minorities or immigrant children, on their English proficiency. We present a comprehensive perspective of school adaptation that considers the child, family, and school and centers on various factors such as cognitive development, socialization, the cultural and political milieu, and family and teacher expectations. We argue for the role of a home-school mediator as a facilitator of children's adaptation to school.
The Institutional Context of Departmental Prestige in American Higher Education
Authors: Keith Bruce
Published: June 2007

Departmental ratings for research doctorate programs in the United States are frequently placed within a theoretical framework that represents an egalitarian science enterprise based on the meritorious performance of their faculty and students. From this viewpoint, there is no need to examine the institutional context of academic departments because distinction is viewed as a matter of merit rather than affiliation. Juxtaposed to this perspective, the present inquiry, based on data from three comparable national studies of research doctorate programs, presents evidence that the ratings reflect a contextual property representative of the university and not various performance-based departmental attributes. In effect, academic departments within universities are found to be quite similar to one another with respect to external raters'perceptions of their "quality." The importance of this finding rests not with the relative ranking of departments or universities to one another but in the discovery that departmental status operates primarily within a stable institutional context. Administrative policy implications of these findings, which are relevant to both faculty leaders and institutional decision makers, are discussed in light of current perspectives on the use of departmental ratings.
Institutional Constraints on Business Involvement in K–12 Education Policy
Authors: Sipple John W.
Published: June 2007

With each passing decade, the U.S. public educational system has been under increasing scrutiny and pressure to change. This pressure has come from many fronts–including, the media, parents, government, and business. In this study, I examine the actions of a group of business leaders representing several multinational corporations as they try to affect education policy in the state of Michigan. I focus special attention on the environments in which the corporations and K–12 public schools operate and uncover the relationships between the many agents calling for school improvement. The fact that this group took a thoughtful approach and had a significant impact on education reform is by no means an indication that other business groups will do the same. Given enough good information and time to reflect on the complex issues surrounding schools, it is possible that business leaders and educators can reach consensus on a direction for educational reform.
A Test of Some Common Contentions About Educational Research
Authors: Kennedy Mary M.
Published: June 2007

In recent years, educational researchers have become consumed by arguments about the relative merits of different genres of research. Some researchers advocate experiments, others advocate ethnographies, and still others advocate narratives. Many genre advocates refer to teachers to justify their arguments, claiming that teachers need more authoritative knowledge (so we should conduct experiments), more dynamic portraits that reveal multiple truths (so we should write narratives), or more richly detailed accounts (so we should do ethnographies). This study examined a variety of contentions about research genres by asking teachers to read and discuss five examples of research, with each example representing a different research genre. Teachers' responses to these articles did not support any of the common contentions about research genres. I conclude from the study that genre is not the most important determinant of an article's value to teachers and that the genre argument is distracting educational researchers from other, more important research tasks.
Multifocal Educational Policy Research: Toward a Method for Enhancing Traditional Educational Policy Studies
Authors: Young Michelle D.
Published: June 2007

This article emerges from a perception of educational policy studies as restrained in its theoretical and methodological tools. It is argued that because most educational policy studies take place within a traditional rationalist frame, the findings of these studies do not provide a comprehensive understanding of the policy problems being researched and, thus, should not be used as the sole basis for making educational policy. In response to this problem, the author argues in favor of, describes a procedure for, and demonstrates the utility of using more than one theoretical frame in educational policy research. As a means of illustrating this process, traditional and critical theories and methods are used to examine and analyze the same issue: the relationship between parental involvement policy and the participation of Mexican-American mothers from a low-income community in their children's education. This bitheoretical process, it is argued, reveals not only a fuller portrait but also the narrowness and constrictedness of each perspective when used alone.
Power, Learning, and Legitimation: Assessment Implementation Across Levels in the United States and the United Kingdom
Authors: Firestone William A. , Fitz John , Broadfoot Patricia
Published: June 2007

Fieldwork conducted in two American states and in England and Wales helps to clarify the implementation of assessment policy at the central, local administrative (school and district), and classroom levels. This article examines implementation from three perspectives. The power perspective suggests that formal sanctions can result in educators attending to assessments but that such sanctions are not likely to change practice alone. A second perspective highlights what educators need to learn in order to change practice and the shortage of opportunities to do so. The legitimacy perspective attends to the ways in which policymakers generate confidence in their institutions at different levels and the conflicting criteria for supporting institutions. We conclude that assessment policy is useful for promoting easily observable changes but not deep modifications of teaching practice.
Tracking the Mathematics of Automobile Production: Are Schools Failing to Prepare Students for Work?
Authors: Smith John P.
Published: June 2007

Global competition and technological innovation, it is often argued, have fundamentally changed the nature of work, making it more technically demanding, while schools have not kept pace. But the mathematics used in workplaces, much less whole industries, is rarely examined carefully. Observations at 16 sites involved in automobile manufacturing indicate that the level and content of mathematics required by work practices vary substantially. High-volume assembly made minimal to modest demands on workers, primarily for measurement and numerical/quantitative reasoning. Machine tool operation and work in quality labs, however, required substantial spatial and geometric knowledge in two and three dimensions. Technology affected the mathematical demands of work, but the effect was shaped by management orientation and patterns of work organization. These results raise questions about how badly schools are failing to prepare students for “the global competitive workplace.”
The Construction of Teachers' Paradoxical Interests by Teacher Union Leaders
Authors: Poole Wendy L.
Published: June 2007

In this case study, the author examines (1) bow leaders construct the relationship between teachers' self-interests and teachers' broader educational interests and (2) the internal and external factors that influence how teacher union leaders pursue union interests. Union leaders, construct variable paradoxical relationships between teachers' self-interests and broader educational interests. The various perspectives are examined using Ford and Backoff's framework of paradox construction (Ford, J., & Backoff, R. (1998). Paradox and transformation: Toward a theory of change in organization and management ) Findings indicate that most union leaders.focus on a dialectic relationship between economic welfare and professional development, which they believe leads to education quality. Long-term, moral purposes related to quality education and social justice encourage the union to transcend a dialectic construction of the paradox. The realities of internal and external pressures lead to dynamic shifts in emphasis between basic, short-term interests and long-term, higher order interests, and make it difficult for the union to permanently transcend current constructions of the paradox. Threats from the provincial government during the. 1990s caused the union to focus" on basic, short-term self-interests.
Against the Odds: Self-Efficacy Beliefs of Women in Mathematical, Scientific, and Technological Careers
Authors: Zeldin Amy L. , Pajares Frank
Published: June 2007

The purpose of this study was to explore the personal stories of women who selected and continue to excel at careers in areas of mathematics, science, and technology to better understand the ways in which their self-efficacy beliefs influenced their academic and career choices. Analysis of 15 narratives revealed that verbal persuasions and vicarious experiences were critical sources of the women's self-efficacy beliefs. These findings suggest that the perceived importance of these sources of self-efficacy believes may be stronger for women in male-oriented domains than for individuals operating in traditional settings. Academic and relational self efficacy perceptions resulted in the perseverance and resiliency required to overcome academic and career obstacles. Findings support and refine the theoretical tenets of A. Bandura's (1986) social cognitive theory, and they also suggest that critical tenets in this theory are consistent with the work of C. Gilligan (1982) and N. Noddings (1992) .
Collective Teacher Efficacy: Its Meaning, Measure, and Impact on Student Achievement
Authors: Goddard Roger D. , Hoy Wayne K. , Hoy Anita Woolfolk
Published: June 2007

This article is a theoretical and empirical analysis of the construct of collective teacher efficacy. First, a model of collective efficacy was elaborated for use in schools. Then, an operational measure of collective teacher efficacy was developed, tested, and found to have strong reliability and reasonable validity. Finally, using the instrument to examine urban elementary schools in one large midwestern district, collective teacher efficacy was positively associated with differences between schools in student-level achievement in both reading and mathematics.
Longitudinal Analysis of the Antecedents of Emergent Spanish Literacy and Middle-School English Reading Achievement of Spanish-Speaking Students
Authors: Reese Leslie , Garnier Helen , Gallimore Ronald , Goldenberg Claude
Published: June 2007

Among students entering kindergarten speaking Spanish, those with greater emergent Spanish literacy development and oral English proficiency were better able to maintain grade level performance in Spanish reading, transition more quickly to English reading, and attain a higher level of English reading proficiency in middle school. Non-English speaking student success in learning to read in English does not rest exclusively on primary language input and development, nor is it solely the result of rapid acquisition of English. Both apparently contribute to students' subsequent English reading achievement. Family factors predicting both early Spanish literacy and later English reading were parents' socioeconomic status and family literacy practices, as well as grandparents' educational level. Results suggest that early literacy experiences support subsequent literacy development, regardless of language; and time spent on literacy activity in the native language—whether it takes place at home or at school—is not time lost with respect to English reading acquisition, at least through middle school. The results also indicate the value of encouraging families to provide home literacy activities (in whatever languages they control) as well as formal preschool experiences.