bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioural, emotional and family functioning of hospitalized children in China and Hong Kong
Authors: Kennedy C. , Kools S. , Kong S. K. F. , Chen J.‐L. , Franck L. , Wong T. K. S.
Published: February 2004

Purpose: This study examined behavioural and emotional problems, social competence and family functioning of hospitalized Chinese children in Hong Kong and the Chinese Mainland. Method: A sample of 210 hospitalized children (ages 2–11 years) and their families participated in the study. The families were from a cross‐section of geographical areas in Hong Kong (two hospitals) and the Chinese Mainland (five hospitals). Parents completed an age‐appropriate Chinese version of the Child Behaviour Checklist and the Family Assessment Device. Multiple regression models were used to examine predictors of children's behaviour problems. Results:  Behavioural patterns appeared to be specific to the developmental stage. Children had greater problems when their families demonstrated poorer affective involvement. Hospitalized children on the Chinese Mainland experienced more internalizing and externalizing behaviour problems than those in Hong Kong. Sick children, according to their parents, however, demonstrate some resiliency based on social and academic competency factors. Conclusions: Hospitalized Chinese children manifest behavioural, emotional and family problems that vary by region, the child's development and gender. Problems predominantly of an internalizing nature characterized this group. The findings support the need for culturally appropriate behavioural assessments and interventions with hospitalized children.
The Society for Research in Child Development at 70: Progress and Promise
Authors: Parke Ross D.
Published: February 2004

The major conceptual and empirical advances in the field of child development and in the Society for Research for Child Development (SRCD) as a professional organization over the last 70 years are examined. First, despite reasons for some skepticism, it is argued that both the field and organization have achieved significant progress. Second, several issues that need more attention in the future are noted. These include the need for a culturally diverse approach to child development, an interdisciplinary approach to the field, and increased attention to interdomain links. Finally, the value of a multisite, multi‐investigator collaborative model as a complement to an individual‐investigator paradigm for developmental science is emphasized.
Sleepless in Chicago: Tracking the Effects of Adolescent Sleep Loss During the Middle School Years
Authors: Fredriksen Katia , Rhodes Jean , Reddy Ranjini , Way Niobe
Published: February 2004

The influence of the sleep patterns of 2,259 students, aged 11 to 14 years, on trajectories of depressive symptoms, self‐esteem, and grades was longitudinally examined using latent growth cross‐domain models. Consistent with previous research, sleep decreased over time. Students who obtained less sleep in sixth grade exhibited lower initial self‐esteem and grades and higher initial levels of depressive symptoms. Similarly, students who obtained less sleep over time reported heightened levels of depressive symptoms and decreased self‐esteem. Sex of the student played a strong role as a predictor of hours of sleep, self‐esteem, and grades. This study underscores the role of sleep in predicting adolescents' psychosocial outcomes and highlights the importance of using idiographic methodologies in the study of developmental processes.
Salient and Emerging Developmental Tasks in the Transition to Adulthood
Authors: Roisman Glenn I. , Masten Ann S. , Coatsworth J. Douglas , Tellegen Auke
Published: February 2004

Drawing on data from a normative sample of 205 children tracked into adulthood, this study examined the predictive links from 3 salient (friendship, academic, conduct) and 2 emerging (work, romantic) developmental tasks during the transition years around age 20 to adult adaptation 10 years later. Results (a) confirm the utility of salient developmental tasks for predicting adult success, (b) suggest that emerging domains have limited long‐term predictive significance, and (c) more generally support a view that developmental tasks follow a course through life of waxing and waning salience and organization that has implications for future adaptation.
Mothers' Parenting Cognitions in Cultures of Origin, Acculturating Cultures, and Cultures of Destination
Authors: Bornstein Marc H. , Cote Linda R.
Published: February 2004

Japanese and South American immigrant mothers' parenting cognitions (attributions and self‐perceptions) were compared with mothers from their country of origin (Japan and Argentina, respectively) and European American mothers in the United States. Participants were 231 mothers of 20‐month‐old children. Generally, South American immigrant mothers' parenting cognitions more closely resembled those of mothers in the United States, whereas Japanese immigrant mothers' cognitions tended to be similar to those of Japanese mothers or intermediate between Japanese and U.S. mothers. This study provides insight into the nature of parenting cognitions generally and those of immigrant mothers specifically and therefore the parenting climate in which immigrant children are reared.
Holism, Contextual Variability, and the Study of Friendships in Adolescent Development
Authors: Crosnoe Robert , Needham Belinda
Published: February 2004

This study treated a key relationship in the developmental ecology of adolescence, friendships, as multidimensional and context specific. First, it examined 4 characteristics of friends (academic achievement, alcohol use, emotional distress, and extracurricular participation) as independent factors and as components in holistic friendship group profiles. Longitudinal analyses of 9,224 adolescents (ages 12–20) revealed that multiple characteristics of friends predicted adolescent behavioral problems, as did membership in the best adjusted group profile. Second, the study examined whether the associations between friendship factors and adolescent behavior varied as a function of the larger peer network and school context, finding that network centrality, school academic press, and intergenerational bonding in schools conditioned the role of friends' characteristics and group profiles in positive and negative ways.
Why Do Managers Explain Their Earnings Forecasts?
Authors: BAGINSKI STEPHEN P. , HASSELL JOHN M. , KIMBROUGH MICHAEL D.
Published: February 2004

Managers often explain their earnings forecasts by linking forecasted performance to their internal actions and the actions of parties external to the firm. These attributions potentially aid investors in the interpretation of management forecasts by confirming known relationships between attributions and profitability or by identifying additional causes that investors should consider when forecasting earnings. We investigate why managers choose to provide attributions with their forecasts and whether the attributions are related to security price reactions to management earnings forecasts. Using a sample of 951 management earnings forecasts issued from 1993 to 1996, we find that attributions are more likely for larger firms, less likely for firms in regulated industries, less likely for forecasts issued over longer horizons, more likely for bad news forecasts, and more likely for forecasts that are maximum type. Furthermore, attributions are associated with greater absolute price reactions to management forecasts, more negative price reactions to management forecasts (forecast news held constant), and a greater price reaction per dollar of unexpected earnings. Our findings hold after control for the aforementioned determinants of attributions and after control for other firm‐ and forecast‐specific variables that are often associated with security prices.
Reliability‐Relevance Trade‐Offs and the Efficiency of Aggregation
Authors: DYE RONALD A. , SRIDHAR SRI S.
Published: February 2004

This paper studies how an accountant's method of aggregating information in a financial report is affected by differences in the reliability and relevance of components of the report. We study a firm that hires an accountant to produce a report that reveals information to investors regarding the returns to the firm's past investments. In constructing the report, the accountant must combine information elicited from the firm's manager with other information directly observable to the accountant. The manager's information is assumed to be directly observable only by the manager and to be of superior quality to the other information available to the accountant. Reliability‐relevance trade‐offs arise because as the accountant places more weight on the manager's report, potentially more useful information gets included in the report, at the cost of encouraging the manager to distort his or her information to a greater extent. Capital market participants anticipate this behavior and price the firm accordingly. We show how the market's price response to the release of the firm's aggregate report, the efficiency of the firm's investment decisions, and the manager's incentives to manipulate the soft information under his or her control are all affected by—and affect—the aggregation procedure the accountant adopts. In addition, we identify a broad range of circumstances under which aggregated reports are strictly more efficient than disaggregated reports because aggregation tempers the manager's misreporting incentives. We also demonstrate that, as any given component of the aggregated accounting report becomes softer, the equilibrium level of the firm's investment diminishes and the market places greater weight on the remaining components of the report.
Adolescent Self‐Consciousness: Longitudinal Age Changes and Gender Differences in Two Cohorts
Authors: Rankin Jane L. , Lane David J. , Gibbons Frederick X. , Gerrard Meg
Published: February 2004

Adolescence is frequently described as a period of pervasive self‐consciousness, but an age‐related peak in adolescence is not consistently obtained, and higher self‐consciousness in girls is frequently obtained but not predicted by theoretical accounts. Two cohorts of adolescents (N=393), initially assessed at 13 and 15, completed public and private self‐consciousness measures 3 times in 4 years. They also reported social comparisons and social engagement. Public self‐consciousness decreased and private self‐consciousness increased in both cohorts, and girls scored higher on both measures, both in longitudinal and sibling replication samples (n=188). Public self‐consciousness appears to be a normative response to adolescent social challenges, with girls' higher levels largely attributable to their closer social engagement. Private self‐consciousness emerges as an individual difference in adolescence but is more likely to be salient and predictive of social behavior in adulthood.
Maternal Influences on Smoking Initiation Among Urban Adolescent Girls
Authors: Nichols Tracy R. , Graber Julia A. , Brooks‐Gunn Jeanne , Botvin Gilbert J.
Published: February 2004

This study examined associations between maternal social influences to smoke and girls' early smoking behaviors. Data were collected separately from 450 urban minority girls (65.7% Black, 21.5% Latina, and 12.8% other) and their mothers on smoking frequency as well as demographic and social factors hypothesized to promote smoking. Results showed perception of mothers' smoking to be associated with girls' early smoking behaviors, whereas mothers' report of their smoking status was not. Interactions were found between ethnicity and perception of mothers' smoking, with Black girls more influenced by their perceptions of mothers' smoking status and by mothers' expectations of adult smoking than Latinas. Findings are discussed in terms of implications for preventive efforts and recommendations for future studies with urban populations.
OppA, the Substrate-Binding Subunit of the Oligopeptide Permease, Is the Major Ecto-ATPase ofMycoplasma hominis
Authors: Hopfe Miriam , Henrich Birgit
Published: February 2004

Most ATPases, involved in energy-driven processes, act in the cytoplasm. However, external membrane-bound ATPases have also been described in parasites and eukaryotic cells. InMycoplasma hominis, a bacterium lacking a cell wall, the surface-exposed substrate-binding protein OppA of an oligopeptide permease (Opp) contains an ATP binding P-loop structure in the C-terminal region. With ATP affinity chromatography and tryptic digestion in the presence or absence of ATP, the functionality of the Mg2+-dependent ATP binding site is demonstrated. In addition to ATP, ADP also could bind to OppA. The presence of an ATPase activity on the surface ofM. hominisis indicated by the inactivation of ATP hydrolyzing activity of intact mycoplasma cells by the impermeable ATPase inhibitor 4′,4′-diisothiocyanostilbene-2′,2′-disulfonic acid and influenced by the ATP analog 5′-fluorosulfonyl-benzoyladenosine. Comparing equimolar amounts of OppA in intact mycoplasma cells and in the purified form indicated that more than 80% of the surface-localized ATPase activity is derived from OppA, implying that OppA is the main ATPase on the surface of mycoplasma cells. Together, these data present the first evidence that the cytoadhesive substrate binding protein OppA of the oligopeptide permease also functions as an ecto-ATPase inMycoplasma hominis.
Structural and Functional Characterization of Gene Clusters Directing Nonribosomal Synthesis of Bioactive Cyclic Lipopeptides in
Bacillus amyloliquefaciens
Strain FZB42
Authors: Koumoutsi Alexandra , Chen Xiao-Hua , Henne Anke , Liesegang Heiko , Hitzeroth Gabriele , Franke Peter , Vater Joachim , Borriss Rainer
Published: February 2004

The environmental strain
Bacillus amyloliquefaciens
FZB42 promotes plant growth and suppresses plant pathogenic organisms present in the rhizosphere. We sampled sequenced the genome of FZB42 and identified 2,947 genes with >50% identity on the amino acid level to the corresponding genes of
Bacillus subtilis
168. Six large gene clusters encoding nonribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) occupied 7.5% of the whole genome. Two of the PKS and one of the NRPS encoding gene clusters were unique insertions in the FZB42 genome and are not present in
B. subtilis
168. Matrix-assisted laser desorption ionization-time of flight mass spectrometry analysis revealed expression of the antibiotic lipopeptide products surfactin, fengycin, and bacillomycin D. The fengycin (
fen
) and the surfactin (
srf
) operons were organized and located as in
B. subtilis
168. A large 37.2-kb antibiotic DNA island containing the
bmy
gene cluster was attributed to the biosynthesis of bacillomycin D. The
bmy
island was found inserted close to the
fen
operon. The responsibility of the
bmy
,
fen
, and
srf
gene clusters for the production of the corresponding secondary metabolites was demonstrated by cassette mutagenesis, which led to the loss of the ability to produce these peptides. Although these single mutants still largely retained their ability to control fungal spread, a double mutant lacking both bacillomycin D and fengycin was heavily impaired in its ability to inhibit growth of phytopathogenic fungi, suggesting that both lipopeptides act in a synergistic manner.
Differential Expression of Two Paralogous Genes of
Bacillus subtilis
Encoding Single-Stranded DNA Binding Protein
Authors: Lindner Cordula , Nijland Reindert , van Hartskamp Mariska , Bron Sierd , Hamoen Leendert W. , Kuipers Oscar P.
Published: February 2004

The
Bacillus subtilis
genome comprises two paralogous single-stranded DNA binding protein (SSB) genes,
ssb
and
ywpH
, which show distinct expression patterns. The main
ssb
gene is strongly expressed during exponential growth and is coregulated with genes encoding the ribosomal proteins S6 and S18. The gene organization
rpsF-ssb-rpsR
as observed in
B. subtilis
is found in many gram-positive as well as some gram-negative bacteria, but not in
Escherichia coli
. The
ssb
gene is essential for cell viability, and like other SSBs its expression is elevated during SOS response. In contrast, the paralogous
ywpH
gene is transcribed from its own promoter at the onset of stationary phase in minimal medium only. Its expression is ComK dependent and its gene product is required for optimal natural transformation.
Mechanism of Transcription Activation at the
comG
Promoter by the Competence Transcription Factor ComK of
Bacillus subtilis
Authors: Susanna K. A. , van der Werff A. F. , den Hengst C. D. , Calles B. , Salas M. , Venema G. , Hamoen L. W. , Kuipers O. P.
Published: February 2004

The development of genetic competence in
Bacillus subtilis
is regulated by a complex signal transduction cascade, which results in the synthesis of the competence transcription factor, encoded by
comK
. ComK is required for the transcription of the late competence genes that encode the DNA binding and uptake machinery and of genes required for homologous recombination. In vivo and in vitro experiments have shown that ComK is responsible for transcription activation at the
comG
promoter. In this study, we investigated the mechanism of this transcription activation. The intrinsic binding characteristics of RNA polymerase with and without ComK at the
comG
promoter were determined, demonstrating that ComK stabilizes the binding of RNA polymerase to the
comG
promoter. This stabilization probably occurs through interactions with the upstream DNA, since a deletion of the upstream DNA resulted in an almost complete abolishment of stabilization of RNA polymerase binding. Furthermore, a strong requirement for the presence of an extra AT box in addition to the common ComK-binding site was shown. In vitro transcription with
B. subtilis
RNA polymerase reconstituted with wild-type α-subunits and with C-terminal deletion mutants of the α-subunits was performed, demonstrating that these deletions do not abolish transcription activation by ComK. This indicates that ComK is not a type I activator. We also show that ComK is not required for open complex formation. A possible mechanism for transcription activation is proposed, implying that the major stimulatory effect of ComK is on binding of RNA polymerase.
ArgR and AhrC Are Both Required for Regulation of Arginine Metabolism in
Lactococcus lactis
Authors: Larsen Rasmus , Buist Girbe , Kuipers Oscar P. , Kok Jan
Published: February 2004

The DNA binding proteins ArgR and AhrC are essential for regulation of arginine metabolism in
Escherichia coli
and
Bacillus subtilis
, respectively. A unique property of these regulators is that they form hexameric protein complexes, mediating repression of arginine biosynthetic pathways as well as activation of arginine catabolic pathways. The
gltS-argE
operon of
Lactococcus lactis
encodes a putative glutamate or arginine transport protein and acetylornithine deacetylase, which catalyzes an important step in the arginine biosynthesis pathway. By random integration knockout screening we found that derepression mutants had IS
S1
integrations in, among others,
argR
and
ahrC
. Single as well as double regulator deletion mutants were constructed from
Lactococcus lactis
subsp.
cremoris
MG1363. The three arginine biosynthetic operons
argCJDBF
,
argGH
, and
gltS-argE
were shown to be repressed by the products of
argR
and
ahrC
. Furthermore, the arginine catabolic
arcABD1C1C2TD2
operon was activated by the product of
ahrC
but not by that of
argR
. Expression from the promoter of the
argCJDBF
operon reached similar levels in the single mutants and in the double mutant, suggesting that the regulators are interdependent and not able to complement each other. At the same time they also appear to have different functions, as only AhrC is involved in activation of arginine catabolism. This is the first study where two homologous arginine regulators are shown to be involved in arginine regulation in a prokaryote, representing an unusual mechanism of regulation.
Identification of Genes Controlled by the Essential YycG/YycF Two-Component System ofStaphylococcus aureus
Authors: Dubrac Sarah , Msadek Tarek
Published: February 2004

The YycG/YycF essential two-component system (TCS), originally identified inBacillus subtilis, is very highly conserved and appears to be specific to low-G+C gram-positive bacteria, including several pathogens such asStaphylococcus aureus. By studying growth ofS. aureuscells where theyycoperon is controlled by an isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible promoter, we have shown that this system is essential inS. aureusduring growth at 37°C and that starvation for the YycG/YycF regulatory system leads to cell death. During a previous study of the YycG/YycF TCS ofB. subtilis, we defined a potential YycF consensus recognition sequence, consisting of two hexanucleotide direct repeats, separated by five nucleotides [5′-TGT(A/T)A(A/T/C)-N5-TGT(A/T)A(A/T/C)-3′]. A detailed DNA motif analysis of theS. aureusgenome indicates that there are potentially 12 genes preceded by this sequence, 5 of which are involved in virulence. An in vitro approach was undertaken to determine which of these genes are controlled by YycF. The YycG and YycF proteins ofS. aureuswere overproduced inEscherichia coliand purified. Autophosphorylation of the YycG kinase and phosphotransfer to YycF were shown in vitro. Gel mobility shift and DNase I footprinting assays were used to show direct binding in vitro of purified YycF to the promoter region of thessaAgene, encoding a major antigen and previously suggested to be controlled by YycF. YycF was also shown to bind specifically to the promoter regions of two genes, encoding the IsaA antigen and the LytM peptidoglycan hydrolase, in agreement with the proposed role of this system in controlling virulence and cell wall metabolism.
γ-Glutamyltranspeptidase, but Not YwrD, Is Important in Utilization of Extracellular Glutathione as a Sulfur Source in
Bacillus subtilis
Authors: Minami Hiromichi , Suzuki Hideyuki , Kumagai Hidehiko
Published: February 2004

γ-Glutamyltranspeptidase (EC 2.3.2.2) of
Bacillus subtilis
, which is an extracellular enzyme, hydrolyzes the γ-glutamyl linkage of glutathione. YwrD, which is homologous to γ-glutamyltranspeptidase, was speculated to have a similar physiological role. It was shown that γ-glutamyltranspeptidase, but not YwrD, is important in utilizing glutathione as the sole sulfur source in
Bacillus subtilis
.
Architecture of the
Bacteroides cellulosolvens
Cellulosome: Description of a Cell Surface-Anchoring Scaffoldin and a Family 48 Cellulase
Authors: Xu Qi , Bayer Edward A. , Goldman Milana , Kenig Rina , Shoham Yuval , Lamed Raphael
Published: February 2004

A large gene downstream of the primary
Bacteroides cellulosolvens
cellulosomal scaffoldin (
cipBc
, now renamed
scaA
) was sequenced. The gene, termed
scaB
, contained an N-terminal leader peptide followed by 10 type I cohesins, an “X” domain of unknown structure and function, and a C-terminal S-layer homology (SLH) surface-anchoring module. In addition, a previously identified gene in a different part of the genome, encoding for a dockerin-borne family 48 cellulosomal glycoside hydrolase (Cel48), was sequenced completely, and a putative cellulosome-related family 9 glycosyl hydrolase was detected. Recombinant fusion proteins, comprising dockerins derived from either the ScaA scaffoldin or Cel48, were overexpressed. Their interaction with ScaA and ScaB cohesins was examined by immunoassay. The results indicated that the ScaB type I cohesin of the new anchoring protein binds selectively to the ScaA dockerin, whereas the Cel48 dockerin binds specifically to the type II ScaA cohesin 5. Thus, by virtue of the 11 type II ScaA cohesins and the 10 type I ScaB cohesins, the relatively simple two-component cellulosome-integrating complex would potentially incorporate 110 enzyme molecules onto the cell surface via the ScaB SLH module. Compared to previously described cellulosome systems, the apparent roles of the
B. cellulosolvens
cohesins are reversed, in that the type II cohesins are located on the enzyme-binding primary scaffoldin, whereas the type I cohesins are located on the anchoring scaffoldin. The results underscore the extensive diversity in the supramolecular architecture of cellulosome systems in nature.
Vascular endothelial growth factor-induced secretion of fibronectin is ERK dependent
Authors: Kazi Altaf S. , Lotfi Shidan , Goncharova Elena A. , Tliba Omar , Amrani Yassine , Krymskaya Vera P. , Lazaar Aili L.
Published: February 2004

In severe asthma, cytokines and growth factors contribute to the proliferation of smooth muscle cells and blood vessels, and to the increased extracellular matrix deposition that constitutes the process of airway remodeling. Vascular endothelial growth factor (VEGF), which regulates vascular permeability and angiogenesis, also modulates the function of nonendothelial cell types. In this study, we demonstrate that VEGF induces fibronectin secretion by human airway smooth muscle (ASM) cells. In addition, stimulation of ASM with VEGF activates ERK, but not p38MAPK, and fibronectin secretion is ERK dependent. Both ERK activation and fibronectin secretion appear to be mediated through the VEGF receptor flt-1, as evidenced by the effects of the flt-1-specific ligand placenta growth factor. Finally, we demonstrate that ASM cells constitutively secrete VEGF, which is increased in response to PDGF, transforming growth factor-β, IL-1β, and PGE2. We conclude that ASM-derived VEGF, through modulation of the extracellular matrix, may play an important role in airway remodeling seen in asthma.
Initial responses to ventilation of premature lambs exposed to intra-amniotic endotoxin 4 days before delivery
Authors: Ikegami Machiko , Kallapur Suhas G. , Jobe Alan H.
Published: February 2004

Preterm delivery is frequently preceded by chorioamnionitis, resulting in exposure of the fetal lung to inflammation. We hypothesized that ventilation of the antenatally inflamed lung would result in amplification of the lung injury. Therefore, we induced fetal lung inflammation with intra-amniotic endotoxin (10 mg of Escherichia coli 055:B5) 4 days before premature delivery at 130 days of gestation. Lung function and lung inflammation after surfactant treatment and 4 h of mechanical ventilation were evaluated. Inflammatory cell numbers in amniotic fluid were increased >10-fold by antenatal endotoxin exposure. Antenatal endotoxin exposure had minimal effects on blood pressure, heart rate, lung compliance, and blood gas values. The endotoxin-exposed lungs required higher ventilation pressures. Ventilation did not increase the number of inflammatory cells or the protein in bronchoalveolar lavage fluid of the endotoxin-exposed animals above that measured in endotoxin-exposed fetuses that were not ventilated. IL-1β, IL-6, and IL-8 mRNA in cells from bronchoalveolar lavage fluid were increased by antenatal endotoxin exposure but not changed by ventilation. IL-1β and IL-8 protein was increased in lung tissue by 4 h of ventilation. Very little inflammation was induced by ventilation in this premature lamb model of surfactant treatment and gentle ventilation. After lung inflammation was induced by intra-amniotic endotoxin injection, ventilation did not increase lung injury.
TRPV1 receptors mediate particulate matter-induced apoptosis
Authors: Agopyan N. , Head J. , Yu S. , Simon S. A.
Published: February 2004

Exposure to airborne particulate matter (PM) is a world-wide health problem mainly because it produces adverse cardiovascular and respiratory effects that frequently result in morbidity. Despite many years of epidemiological and basic research, the mechanisms underlying PM toxicity remain largely unknown. To understand some of these mechanisms, we measured PM-induced apoptosis and necrosis in normal human airway epithelial cells and sensory neurons from both wild-type mice and mice lacking TRPV1 receptors using Alexa Fluor 488-conjugated annexin V and propidium iodide labeling, respectively. Exposure of environmental PMs containing residual oil fly ash and ash from Mount St. Helens was found to induce apoptosis, but not necrosis, as a consequence of sustained calcium influx through TRPV1 receptors. Apoptosis was completely prevented by inhibiting TRPV1 receptors with capsazepine or by removing extracellular calcium or in sensory neurons from TRPV1(-/-) mice. Binding of either one of the PMs to the cell membrane induced a capsazepine-sensitive increase in cAMP. PM-induced apoptosis was augmented upon the inhibition of PKA. PKA inhibition on its own also induced apoptosis, thereby suggesting that this pathway may be endogenously protective against apoptosis. In summary, it was found that inhibiting TRPV1 receptors prevents PM-induced apoptosis, thereby providing a potential mechanism to reduce their toxicity.
Photoperiod differentially modulates photic and nonphotic phase response curves of hamsters
Authors: Evans J. A. , Elliott J. A. , Gorman M. R.
Published: February 2004

Circadian pacemakers respond to light pulses with phase adjustments that allow for daily synchronization to 24-h light-dark cycles. In Syrian hamsters, Mesocricetus auratus, light-induced phase shifts are larger after entrainment to short daylengths (e.g., 10 h light:14 h dark) vs. long daylengths (e.g., 14 h light:10 h dark). The present study assessed whether photoperiodic modulation of phase resetting magnitude extends to nonphotic perturbations of the circadian rhythm and, if so, whether the relationship parallels that of photic responses. Male Syrian hamsters, entrained for 31 days to either short or long daylengths, were transferred to novel wheel running cages for 2 h at times spanning the entire circadian cycle. Phase shifts induced by this stimulus varied with the circadian time of exposure, but the amplitude of the resulting phase response curve was not markedly influenced by photoperiod. Previously reported photoperiodic effects on photic phase resetting were verified under the current paradigm using 15-min light pulses. Photoperiodic modulation of phase resetting magnitude is input specific and may reflect alterations in the transmission of photic stimuli.
Polyuria and impaired renal blood flow after asphyxia in preterm fetal sheep
Authors: Quaedackers J. S. , Roelfsema V. , Hunter C. J. , Heineman E. , Gunn A. J. , Bennet L.
Published: February 2004

Renal impairment is common in preterm infants, often after exposure to hypoxia/asphyxia or other circulatory disturbances. We examined the hypothesis that this association is mediated by reduced renal blood flow (RBF), using a model of asphyxia induced by complete umbilical cord occlusion for 25 min ( n = 13) or sham occlusion ( n = 6) in chronically instrumented preterm fetal sheep (104 days, term is 147 days). During asphyxia there was a significant fall in RBF and urine output (UO). After asphyxia, RBF transiently recovered, followed within 30 min by a secondary period of hypoperfusion ( P < 0.05). This was mediated by increased renal vascular resistance (RVR, P < 0.05); arterial blood pressure was mildly increased in the first 24 h ( P < 0.05). RBF relatively normalized between 3 and 24 h, but hypoperfusion developed again from 24 to 60 h ( P < 0.05, analysis of covariance). UO significantly increased to a peak of 249% of baseline between 3 and 12 h ( P < 0.05), with increased fractional excretion of sodium, peak 10.5 ± 1.4 vs. 2.6 ± 0.6% ( P < 0.001). Creatinine clearance returned to normal after 2 h; there was a transient reduction at 48 h to 0.32 ± 0.02 ml·min-1·g-1(vs. 0.45 ± 0.04, P < 0.05) corresponding with the time of maximal depression of RBF. No renal injury was seen on histological examination at 72 h. In conclusion, severe asphyxia in the preterm fetus was associated with evolving renal tubular dysfunction, as shown by transient polyuria and natriuresis. Despite a prolonged increase in RVR, there was only a modest effect on glomerular function.
Focused Attention Modulates Visual Responses in the Primate Prefrontal Cortex
Authors: DeSouza Joseph F.X. , Everling Stefan
Published: February 2004

Several current models propose an important role of the prefrontal cortex (PFC) in attention. To test the effects of attention in PFC, we recorded from PFC neurons in monkeys performing a task in which they had to attend to one hemifield and wait for a single stimulus that matched a previously presented cue. Neurons exhibited a slight decrease in their initial response and an enhanced activity late in the response to a stimulus at the cued location. The data demonstrate attentional effects on the activity of PFC neurons but they also show that single visual stimuli are initially represented in the activity of PFC neurons even when they are behaviorally irrelevant.
Dynamics of Population Rate Codes in Ensembles of Neocortical Neurons
Authors: Silberberg G. , Bethge M. , Markram H. , Pawelzik K. , Tsodyks M.
Published: February 2004

Information processing in neocortex can be very fast, indicating that neuronal ensembles faithfully transmit rapidly changing signals to each other. Apart from signal-to-noise issues, population codes are fundamentally constrained by the neuronal dynamics. In particular, the biophysical properties of individual neurons and collective phenomena may substantially limit the speed at which a graded signal can be represented by the activity of an ensemble. These implications of the neuronal dynamics are rarely studied experimentally. Here, we combine theoretical analysis and whole cell recordings to show that encoding signals in the variance of uncorrelated synaptic inputs to a neocortical ensemble enables faithful transmission of graded signals with high temporal resolution. In contrast, the encoding of signals in the mean current is subject to low-pass filtering.
Short-Term Adaptation of Auditory Receptive Fields to Dynamic Stimuli
Authors: Kvale Mark N. , Schreiner Christoph E.
Published: February 2004

Short-term adaptation and recovery from adaptation have a strong impact on the processing of dynamic stimuli. Adaptive effects on neuronal activity have been studied most commonly for changes in first-order statistics of stimuli such as stepwise increments or decrements in stimulus amplitude. However, changes in higher moment statistics, such as the variance of the amplitude distribution in visual stimuli, also can invoke pronounced adaptation behavior. We demonstrate here that neurons in the inferior colliculus (ICC) of the cat show adaptation to dynamic auditory stimuli that differ in the variance of their modulation depth distribution. In addition, it is shown that neurons show adaptation to other higher moment statistics (e.g., kurtosis) of the modulation envelope. The time course of adaptation is specific for the altered stimulus property and the direction of parameter change. The use of dynamic stimuli allows an estimate of the effects of the adaptation on the temporal response properties of the neurons. We demonstrate that temporal receptive fields of neurons undergo change during the course of adaptation. We show that adaptation to variance in the ICC has many similarities to that in the retina and suggest that adaptation to variance is a general property of sensory systems that allows them to effectively deal with a nonstationary environment.
Factors Underlying Bursting Behavior in a Network of Cultured Hippocampal Neurons Exposed to Zero Magnesium
Authors: Mangan Patrick S. , Kapur Jaideep
Published: February 2004

Factors contributing to reduced magnesium-induced neuronal action potential bursting were investigated in primary hippocampal cell culture at high and low culture density. In nominally zero external magnesium medium, pyramidal neurons from high-density cultures produced recurrent spontaneous action potential bursts superimposed on prolonged depolarizations. These bursts were partially attenuated by the NMDA receptor antagonist d-APV. Pharmacological analysis of miniature excitatory postsynaptic currents (EPSCs) revealed 2 components: one sensitive to d-APV and another to the AMPA receptor antagonist DNQX. The components were kinetically distinct. Participation of NMDA receptors in reduced magnesium-induced synaptic events was supported by the localization of the NR1 subunit of the NMDA receptor with the presynaptic vesicular protein synaptophysin. Presynaptically, zero magnesium induced a significant increase in EPSC frequency likely attributable to increased neuronal hyperexcitability induced by reduced membrane surface charge screening. Mean quantal content was significantly increased in zero magnesium. Cells from low-density cultures did not exhibit action potential bursting in zero magnesium but did show increased EPSC frequency. Low-density neurons had less synaptophysin immunofluorescence and fewer active synapses as determined by FM1-43 analysis. These results demonstrate that multiple factors are involved in network bursting. Increased probability of transmitter release presynaptically, enhanced NMDA receptor-mediated excitability postsynaptically, and extent of neuronal interconnectivity contribute to initiation and maintenance of elevated network excitability.
Organization of Action Sequences and the Role of the Pre-SMA
Authors: Kennerley Steve W. , Sakai K. , Rushworth M.F.S.
Published: February 2004

To understand the contribution of the human presupplementary motor area (pre-SMA) in sequential motor behavior, we performed a series of finger key-press experiments. Experiment 1 revealed that each subject had a spontaneous tendency to organize or “chunk” a long sequence into shorter components. We hypothesized that the pre-SMA might have a special role in initiating each chunk but not at other points during the sequence. Experiment 2 therefore examined the effect of 0.5-s, 10-Hz repetitive transcranial magnetic stimulation (rTMS) directed over the pre-SMA. As hypothesized, performance was disrupted when rTMS was delivered over the pre-SMA at the beginning of the second chunk but not when it was delivered in the middle of a chunk. Contrary to the hypothesis, TMS did not disrupt sequence initiation. Experiments 3 and 4 examined whether the very first movement of a sequence could be disrupted under any circumstances. Pre-SMA TMS did disrupt the initiation of sequences but only when subjects had to switch between sequences and when the first movement of each sequence was not covertly instructed by a learned visuomotor association. In conjunction, the results suggest that for overlearned sequences the pre-SMA is primarily concerned with the initiation of a sequence or sequence chunk and the role of the pre-SMA in sequence initiation is only discerned when subjects must retrieve the sequence from memory as a superordinate set of movements without the aid of a visuomotor association. Control experiments revealed such effects were not present when rTMS was applied over the left dorsal premotor cortex.
Reward-Predicting Activity of Dopamine and Caudate Neurons—A Possible Mechanism of Motivational Control of Saccadic Eye Movement
Authors: Kawagoe Reiko , Takikawa Yoriko , Hikosaka Okihide
Published: February 2004

Recent studies have suggested that the basal ganglia are related to motivational control of behavior. To study how motivational signals modulate motor signals in the basal ganglia, we examined activity of midbrain dopamine (DA) neurons and caudate (CD) projection neurons while monkeys were performing a one-direction-rewarded version (1DR) of memory-guided saccade task. The cue stimulus indicated the goal position for an upcoming saccade and the presence or absence of reward after the trial. Among four monkeys we studied, three were sensitive to reward such that saccade velocity was significantly higher in the rewarded trials than in the nonrewarded trials; one monkey was insensitive to reward. In the reward-sensitive monkeys, both DA and CD neurons responded differentially to reward-indicating and no-reward-indicating cues. Thus DA neurons responded with excitation to a reward-indicating cue and with inhibition to a no-reward-indicating cue. A group of CD neurons responded to the cue in their response fields (mostly contralateral) and the cue response was usually enhanced when it indicated reward. In the reward-insensitive monkey, DA neurons showed no response to the cue, while the cue responses of CD neurons were not modulated by reward. Many CD neurons in the reward-sensitive monkeys, but not the reward-insensitive monkey, showed precue activity. These results suggest that DA neurons, with their connection to CD neurons, modulate the spatially selective signals in CD neurons in the reward-predicting manner and CD neurons in turn modulate saccade parameters with their polysynaptic connections to the oculomotor brain stem.
Median and Dorsal Raphe Neurons Are Not Electrophysiologically Identical
Authors: Beck Sheryl G. , Pan Yu-Zhen , Akanwa Adaure C. , Kirby Lynn G.
Published: February 2004

The dorsal (DR) and median raphe (MR) nuclei contain 5-hydroxytryptamine (serotonin, 5-HT) cell bodies that give rise to the majority of the ascending 5-HT projections to the forebrain limbic areas that control emotional behavior. In the past, the electrophysiological identification of neurochemically identified 5-HT neurons has been limited. Recent technical developments have made it possible to re-examine the electrophysiological characteristics of identified 5-HT- and non-5-HT-containing neurons. Visualized whole cell electrophysiological techniques in combination with fluorescence immunohistochemistry for 5-HT were used. In the DR, both 5-HT- and non-5-HT-containing neurons exhibited similar characteristics that have historically been attributed to putative 5-HT neurons. In contrast, in the MR, the 5-HT-and non-5-HT-containing neurons had very different characteristics. Interestingly, the MR 5-HT-containing neurons had a shorter time constant and larger afterhyperpolarization (AHP) amplitude than DR 5-HT-containing neurons. The 5-HT1A receptor-mediated response was also measured. The efficacy of the response elicited by 5-HT1A receptor activation was greater in 5-HT-containing neurons in the DR than the MR, whereas the potency was similar, implicating greater autoinhibition in the DR. Non-5-HT-containing neurons in the DR were responsive to 5-HT1A receptor activation, whereas the non-5-HT-containing neurons in the MR were not. These differences in the cellular characteristics and 5-HT1A receptor-mediated responses between the MR and DR neurons may be extremely important in understanding the role of these two 5-HT circuits in normal physiological processes and in the etiology and treatment of pathophysiological states.
Recasting the Smooth Pursuit Eye Movement System
Authors: Krauzlis Richard J.
Published: February 2004

Primates use a combination of smooth pursuit and saccadic eye movements to stabilize the retinal image of selected objects within the high-acuity region near the fovea. Pursuit has traditionally been viewed as a relatively automatic behavior, driven by visual motion signals and mediated by pathways that connect visual areas in the cerebral cortex to motor regions in the cerebellum. However, recent findings indicate that this view needs to be reconsidered. Rather than being controlled primarily by areas in extrastriate cortex specialized for processing visual motion, pursuit involves an extended network of cortical areas, and, of these, the pursuit-related region in the frontal eye fields appears to exert the most direct influence. The traditional pathways through the cerebellum are important, but there are also newly identified routes involving structures previously associated with the control of saccades, including the basal ganglia, the superior colliculus, and nuclei in the brain stem reticular formation. These recent findings suggest that the pursuit system has a functional architecture very similar to that of the saccadic system. This viewpoint provides a new perspective on the processing steps that occur as descending control signals interact with circuits in the brain stem and cerebellum responsible for gating and executing voluntary eye movements. Although the traditional view describes pursuit and saccades as two distinct neural systems, it may be more accurate to consider the two movements as different outcomes from a shared cascade of sensory–motor functions.
Salicylic acid-induced suppression of Meloidogyne incognita infestation of okra and cowpea
Authors: Nandi Bidyut , Babu Santi Prasad Sinha , Banerjee Nirmalya , Kundu Kabita
Published: February 2004

Salicylic acid (SA) applied as 10 mM foliar spray to okra (Abelmoschus esculentus) cv. Purbani Kranti and cowpea (Vigna unguiculata) cv. Pusa Ruby plants 24 h before inoculation of roots with Meloidogyne incognita juveniles, reduced infestation. Salicylic acid had no direct influence on plant growth and did not kill nematodes in an in vitro test. It induced increased accumulation of a 14 kDa pathogenesis-related protein (PR-1) in roots of both non-inoculated and inoculated salicylic acid-sprayed okra but not in the treated leaves. Salicylic acid sprays enhanced phenylalanine ammonia lyase (PAL) activity in roots of both non-inoculated and inoculated cowpea, estimated at 15 days after inoculation. Infected roots had higher PAL activity than roots of the corresponding non-inoculated treatments. Both PAL activity and SA-induced resistance gradually declined with plant age after treatment.
Effects of sex on sleep-disordered breathing in adolescents
Authors: Fuentes-Pradera M.A. , Sánchez-Armengol Á. , Capote-Gil F. , Quintana-Gallego E. , Carmona-Bernal C. , Polo J. , Delgado-Moreno F. , Castillo-Gómez J.
Published: February 2004

This study was conducted to determine the influence of puberty on features of sleep-disordered breathing (SDB) in adolescents.

The study was performed in a general population sample of 226 adolescents of both sexes (aged 11–19 yrs) recruited from the secondary school population of the city of Seville, Spain. Subjects were divided into two groups: 1) postpubertal,i.e.females who had undergone menarche and males in whom axillary hair development or peak height velocity had occurred >1 yr before the study; and 2) peripubertal,i.e.females who had not undergone menarche and males who had not developed axillary hair nor reached peak height velocity, or subjects in whom these pubertal changes had appeared <1 yr before the study. All subjects answered a questionnaire on SDB and underwent overnight cardiorespiratory polygraphy.

There were 50 males and 40 females (mean±sd age 13.5±1.2 yrs) in the peripubertal group, and 54 males and 82 females (age 16.3±1.7 yrs) in the postpubertal group. Males exhibited significantly higher neck circumference/height index and waist/hip index than females in both the peripubertal and postpubertal groups. In the postpubertal group, snoring and polygraphic alterations (respiratory events and oximetric parameters) were significantly more frequent in males than in females. Postpubertal adolescents showed sex differences in clinical and polygraphic parameters that were not observed at earlier pubertal stages.

These findings support the influence of sex hormones on sex differences in sleep-disordered breathing.