bluuebunny/crossref_metadata_2025 huggingface dataset:
Light Microscopical and Ultrastructural Characterization of Black Howler Monkey (Alouatta caraya) Ovarian Follicles
Authors: Lopes L. H. R. , Lucci C. M. , Garcia M. P. , De Azevedo R. B. , Báo S. N.
Published: February 2006

The present study describes the morphological characteristics of black howler monkey (Alouatta caraya) ovarian follicles. One ovary of an adult healthy black howler monkey was collected and processed for light and electron microscopy. Primordial, primary, secondary, tertiary and pre‐ovulatory follicles were evaluated for their morphometrical aspects. The ovary of black howler monkey presented a distinct conformation with a uniform distribution of the follicles mostly in the peripheric cortex. This black howler monkey ovary presented a total of 59 921 ovarian follicles. From this amount, 71.1% were classified as primordial, 18.9% as primary, 8.1% as secondary, 1.4% as tertiary and 0.5% as pre‐ovulatory follicles. From all these developmental stages, the mean diameters of follicles, oocytes, oocytes nuclei and the mean number of granulosa cells are described. Moreover, primordial, primary and secondary follicles have been observed by electron microscopy.
Immunolocalization of Gastrin‐Releasing Peptide (GRP) in the Uteroplacenta of the Mouse Deer
Authors: Kimura J. , Budipitojo T. , Sasaki M. , Kitamura N. , Yamada J. , Endo H. , Fukuta K.
Published: February 2006

The considerable phylogenetical differences between mouse deer and other ruminants have been established by means of DNA sequence analysis and anatomical observations. To clarify the physiological role of the uteroplacenta of the mouse deer, immunohistochemical observation was attempted by using GRP, which has been suggested as a novel regulatory peptide in the female reproductive tract, as an indicator to compare with other ruminants. Strong positive reactions for the GRP were detected in the uterine glands of the pregnant animals, but not in the non‐pregnant ones. Although the placenta of the mouse deer is categorized as a diffuse placenta that is different from other ruminants’ polycotyledonary placenta, in terms of GRP immunoreactivity, the mouse deer placenta can be classified as a synepithecholial placenta like the other ruminants’. The secretion of GRP from the uterine glands is of some importance to the fetus in the mouse deer.
Mesenchymal epimorphin is important for pancreatic duct morphogenesis
Authors: Tulachan Sidhartha S. , Doi Ryuichiro , Hirai Yohei , Kawaguchi Yoshiya , Koizumi Masayuki , Hembree Mark , Tei Eri , Crowley Amanda , Yew Hooi , McFall Chris , Prasadan Krishna , Preuett Barry , Imamura Masayuki , Gittes George K.
Published: March 2006

Epithelial–mesenchymal interactions are crucial for the proper development of many organs, including the pancreas. Within the pancreas, the ducts are thought to harbor stem/progenitor cells, and possibly to give rise to pancreatic ductal carcinoma. Little is known about the mechanism of formation of pancreatic ducts in the embryo. Pancreatic mesenchyme contains numerous soluble factors which help to sustain the growth and differentiation of exocrine and endocrine structures. Here, we report that one such morphoregulatory mesenchymal protein, epimorphin, plays an important role during pancreatic ductal proliferation and differentiation. We found that epimorphin is expressed in pancreatic mesenchyme during early stages of development, and at mesenchymal–epithelial interfaces surrounding the ducts at later stages. Strong upregulation of epimorphin expression was seen during in vitro pancreatic duct differentiation. Similarly, in vitro pancreatic duct formation was inhibited by a neutralizing antibody against epimorphin, whereas addition of recombinant epimorphin partially rescued duct formation. Together, our study demonstrates the role of epimorphin in pancreatic ductal morphogenesis.
Immunoadjuvant chaperone, GRP170, induces ‘danger signals’ upon interaction with dendritic cells
Authors: Manjili Masoud H , Park Jun‐Eui , Facciponte John G , Wang Xiang‐Yang , Subjeck John R
Published: February 2006

When chaperoning tumour antigens, glucose‐regulated protein 170 (GRP170) is capable of inducing effective antitumour immune responses. In the present study, we determined whether such immunoadjuvant properties of GRP170 also involve the ability to induce ‘danger signals’ through interaction with APC. We prepared recombinant GRP170 in the baculovirus expression system with low endotoxin concentration at which LPS did not have any effect on dendritic cells (DC). We showed that GRP170 binds DC in a receptor‐mediated fashion and induces DC to upregulate the expression of MHC class II, CD86 and CD40 molecules, and to secrete pro‐inflammatory cytokines. GRP170 also induced expression of CD40 molecules in a B16F10 cell line, whereas LPS failed to do so. These findings show that GRP170 acts as a danger signal through its interaction with DC, regardless of its endotoxin component.
Genetic susceptibility to mycobacterial disease in humans
Authors: Fernando Suran L , Britton Warwick J
Published: February 2006

Mycobacterial disease remains a serious global health problem. Tuberculosis causes more than 2 million deaths a year, and leprosy is still a cause of severe disability in many parts of the world. As a result of the study of individuals with marked susceptibility to usually nonpathogenic mycobacteria, as well as case–control studies with candidate genes and genome‐wide screens of affected populations, there is substantial evidence for the role of genetic factors in the susceptibility to mycobacterial disease. These studies have defined immunological processes essential for the control of mycobacteria infections in humans.
A novel approach to examining compositional heterogeneity of detergent‐resistant lipid rafts
Authors: George Saira , Nelson Matthew D , Dollahon Norman , Bamezai Anil
Published: February 2006

Lipid rafts play an important role in cell signalling, cell adhesion and other cellular functions. Compositional heterogeneity of lipid rafts provides one mechanism of how lipid rafts provide the spatial and temporal regulation of cell signalling and cell adhesion. The constitutive presence of some signalling receptors/molecules and accumulation of others in the lipid raft allows them to interact with each other and thereby facilitate relay of signals from the plasma membrane to the cell interior. Devising a method that can analyze these lipid microdomains for the presence of signalling receptors/molecules on an individual raft basis is required to address the issue of lipid raft heterogeneity. SDS–PAGE analysis, currently used for analyses of detergent‐resistant lipid rafts, does not address this question. We have designed a cell‐free assay that captures detergent‐resistant lipid rafts with an antibody against a raft‐resident molecule and detects the presence of another lipid raft molecule. Our results suggest that detergent‐resistant lipid rafts, also known as detergent‐resistant membranes, are heterogeneous populations on an immortalized mouse T‐cell plasma membrane with respect to antigen receptor/signalling complex and other signalling/adhesion proteins. This cell‐free assay provides a simple and quick way to examine the simultaneous presence of two proteins in the lipid rafts and has the potential to estimate trafficking of molecules in and out of the lipid microdomains during cell signalling on a single detergent‐resistant lipid raft basis.
Lack of detrimental or therapeutic effects of cyclooxygenase inhibition in bile duct‐ligated rats with hepatic encephalopathy
Authors: Chan Cho‐Yu , Lee Fa‐Yauh , Wang Teh‐Fang , Huang Seng‐Wong , Chang Full‐Young , Lu Rei‐Hwa , Chen Yi‐Chou , Wang Sun‐Sang , Huang Hui‐Chun , Lee Shou‐Dong
Published: March 2006

Background:  The pathogenetic mechanisms of hepatic encephalopathy (HE) are not fully understood. Cerebral blood flow regulated by cyclooxygenase (COX) may be involved in the development of HE. There are no comprehensive data concerning the effects of COX inhibition on HE in chronic liver disease.

Methods:  Male Sprague–Dawley rats weighing 240–270 g at the time of surgery were selected for experiments. Secondary biliary cirrhosis was induced by bile duct ligation (BDL). Those rats were then divided into two groups to receive i.p. injection of indomethacin (5 mg/kg per day) or distilled water for 7 days from day 36 to day 42 after BDL. The control group consisted of rats receiving a sham operation. Severity of encephalopathy was assessed by counts of motor activity. Plasma levels of tumor necrosis factor (TNF)‐α and 6‐keto‐prostaglandin F1α (6‐keto‐PGF1α), and liver biochemistry tests were determined after treatment.

Results:  The motor activity in both groups of BDL rats were significantly lower than that of the control group (P < 0.001). As compared with the BDL rats treated with distilled water, BDL rats treated with indomethacin had significant lower levels of 6‐keto‐PGF1α, but the motor activity, TNF‐α levels and serum biochemistry tests were not significantly different between both BDL groups.

Conclusions:  Chronic indomethacin administration did not have significantly detrimental or therapeutic effects on the severity of encephalopathy in BDL rats.
Restoration in vitro of impaired T‐cell responses in patients with chronic hepatitis B by autologous dendritic cells loaded with hepatitis B virus proteins (R2)
Authors: Duan Xue‐Zhang , He Hong‐Xia , Zhuang Hui
Published: March 2006

Background:  The purpose of the present paper was to investigate dendritic cell (DC) and T‐cell functions in patients with chronic hepatitis B (CHB) and determine whether therapeutic DC vaccines could restore T‐cell function in those patients in vitro.

Methods:  Twelve patients with CHB and 10 normal control subjects with positivity for antibodies to hepatitis B surface and core antigens (anti‐HBs and anti‐HBc positivity) were enrolled in the present study. Phenotype analysis and allogeneic mixed lymphocyte reaction assay of DC from CHB patients and normal controls were made in the absence or presence of a cocktail of cytokines: interleukin‐1β (IL‐1β), prostaglandin E2 (PGE2), IL‐6 and tumor necrosis factor‐α (TNF‐α). Autologous T‐cell proliferation assays and the enzyme‐linked immunospot (ELISPOT) method for detecting interferon‐γ (IFN‐γ)‐producing CD8+ T cells were used to evaluate the efficacy of DC loaded in vitro with HBsAg or HBcAg.

Results:  The DC from CHB patients had a lower expression of costimulatory molecules CD80, CD86 and impaired allogeneic mixed lymphocyte reaction capacity compared to those from normal controls. However, the impaired DC function could be restored partially by cytokine cocktail supplemented in vitro. Mature DC loaded with HBsAg or HBcAg showed a greater capacity for autologous T‐cell proliferation and antigen‐specific IFN‐γ production than immature DC. Moreover, as a DC ‐loading antigen, HBcAg was more immunogenic than HBsAg.

Conclusions:  The impaired function of DC in patients with CHB may be restored by supplementation in vitro with a cocktail of cytokines, and therapeutic DC vaccines might be effective to treat CHB infection in humans.
Clinical usefulness of subgrouping of patients with non‐cardiac chest pain according to characteristic symptoms in Korea
Authors: Kim Jeong Hwan , Rhee Poong‐Lyul , Park Eun‐Ha , Son Hee Jung , Kim Jae J , Rhee Jong Chul
Published: March 2006

Background:  Non‐cardiac chest pain (NCCP) is a heterogeneous disorder. There is controversy about the associations between symptoms and causes in NCCP patients. The purpose of the present study was to evaluate the clinical usefulness of subgrouping according to characteristic symptoms in NCCP patients.

Patients and Methods:  Fifty‐eight patients were classified into two groups, as patients with typical reflux symptoms (group I, n = 24) and those without typical reflux symptoms (group II, n = 34). They underwent upper endoscopy, manometry, and 24‐h esophageal pH monitoring.

Results:  Twenty‐four (41%) of the patients were diagnosed with gastroesophageal reflux disease (GERD) at upper endoscopy or 24‐h esophageal pH monitoring. Eleven (19%) were diagnosed with GERD‐associated esophageal motility disorder and 13 (22%) were diagnosed with non‐GERD‐associated esophageal motility disorder. The two groups did not differ significantly in age, sex, weight, smoking history, history of chronic alcoholism, or the severity, duration and frequency of symptoms. The sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio of group I for GERD‐related NCCP were significantly higher than those of group II. Group I had a higher proportion of patients with GERD‐associated esophageal motility disorder (55%) than non‐GERD‐associated esophageal motility disorder (23%).

Conclusion:  Typical reflux symptoms can be used to distinguish patients with GERD‐related NCCP from patients with NCCP, and subgrouping according to characteristic symptoms may assist the diagnosis of these patients in Korea.
Crack initiation in the brittle fracture of ferritic steels
Authors: COATES M. , KUMAR A. , ROBERTS S. G.
Published: March 2006

Fracture in many steels is thought to initiate from fractured carbides. It is often supposed that in pre‐cracked specimens, many carbides fracture in the plastic zone of the pre‐crack, and that eventually fracture propagates from one of these to cause fracture of the whole specimen. Sources of fracture initiation in steels were investigated using a modified A533B steel as a model material. Specimens were annealed to produce a distribution of micron‐sized carbides in a ferrite matrix. Four‐point bend tests were carried out in the temperature range 77–373K to determine the material's ductile brittle transition. Pre‐cracked samples were loaded up to 90% of the fracture strength at temperatures on the lower shelf (163K) and at the mid point of the transition region (243K). The samples were then sectioned and polished to produce SEM and TEM samples containing the crack tip. Other samples were made of areas some distance from the crack tip and out of the plastic zone. An extensive search for fracture initiation sites found no evidence for fracture initiation originating from fractured carbides.
A weight function‐critical plane approach for low‐cycle fatigue under variable amplitude multiaxial loading
Authors: CHEN X. , JIN D. , KIM K. S.
Published: March 2006

Low‐cycle fatigue data of type 304 stainless steel obtained under axial‐torsional loading of variable amplitudes are analyzed using four multiaxial fatigue parameters: SWT, KBM, FS and LKN. Rainflow cycle counting and Morrow's plastic work interaction rule are used to calculate fatigue damage. The performance of a fatigue model is dependent on the fatigue parameter, the critical plane and the damage accumulation rule employed in the model. The conservatism and non‐conservatism of predicted lives are examined for some combinations of these variables. A new critical plane called the weight function‐critical plane is introduced for variable amplitude loading. This approach is found to improve the KBM‐based life predictions.
Aspects of cleavage fracture initiation – relative influence of stress and strain
Authors: WALLIN K. , LAUKKANEN A.
Published: March 2006

Cleavage fracture initiation has generally been assumed to be controlled mainly by matrix stress. Recently, several different cleavage fracture models have been proposed, where also strain is included in the failure criterion. However, the proposals have been rather crude and unable to provide clearly improved fracture estimates. Here, the first two steps of cleavage fracture (particle failure and grain fracture) are examined in more detail. It is shown that both stress and strain are important for cleavage fracture initiation, but that strain mainly affects particle failure, whereas grain fracture is controlled by a pure Griffith criterion. The findings are important for the development of new cleavage fracture models and to the proper way of accounting for constraint.
Glutamate receptor changes associated with transient anoxia/hypoglycaemia in hippocampal slice cultures
Authors: Quintana Patrice , Alberi Stefano , Hakkoum David , Muller Dominique
Published: March 2006

Transient anoxia/hypoglycaemia in organotypic hippocampal slice cultures, a model of transient brain ischaemia, ultimately results in delayed cell death. Although the mechanisms underlying this delayed death remain unknown, an increase in excitatory drive has been postulated. We report here that transient anoxia/hypoglycaemia in rat hippocampal slice cultures resulted in a 70–80% enhancement of evoked, α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolpropionic acid (AMPA) receptor‐mediated, excitatory responses lasting over 60 min. This effect was prevented by blockade of N‐methyl‐d‐aspartate (NMDA) receptors, did not involve changes of paired‐pulse facilitation ratio, but was associated with a 50% increase in amplitude, but not frequency, of spontaneous miniature excitatory postsynaptic currents (mEPSCs). Consistent with this, paired recordings revealed the appearance of AMPA receptor‐mediated EPSCs at previously silent synapses and occlusion by prior induction of long‐term potentiation (LTP). Transient anoxia/hypoglycaemia further resulted in a 63% potentiation of evoked NMDA receptor‐dependent synaptic responses, accounting for the 20% increase in ratio of AMPA to NMDA responses. No change in rectification properties of AMPA receptor‐mediated currents could be detected within the first hour following anoxia/hypoglycaemia‐induced potentiation. Western blot analyses of slice cultures exposed to either control conditions or a short anoxia/hypoglycaemia revealed a marked, 50–70% increase of GluR1, GluR2/3 and NR1 subunits 1 h, but not 15 min, after the anoxic/hypoglycaemic episode. This increase was blocked by an inhibitor of protein synthesis. Together these results indicate that a transient anoxia/hypoglycaemia is associated with a marked enhancement of excitatory transmission sharing similarities with the mechanisms underlying LTP, and is correlated with an increased synthesis of excitatory receptor subunits.
Role of L‐type Ca2+ channels in neural stem/progenitor cell differentiation
Authors: D'Ascenzo Marcello , Piacentini Roberto , Casalbore Patrizia , Budoni Manuela , Pallini Roberto , Azzena Gian Battista , Grassi Claudio
Published: March 2006

Ca2+ influx through voltage‐gated Ca2+ channels, especially the L‐type (Cav1), activates downstream signaling to the nucleus that affects gene expression and, consequently, cell fate. We hypothesized that these Ca2+ signals may also influence the neuronal differentiation of neural stem/progenitor cells (NSCs) derived from the brain cortex of postnatal mice. We first studied Ca2+ transients induced by membrane depolarization in Fluo 4‐AM‐loaded NSCs using confocal microscopy. Undifferentiated cells (nestin+) exhibited no detectable Ca2+ signals whereas, during 12 days of fetal bovine serum‐induced differentiation, neurons (β‐III‐tubulin+/MAP2+) displayed time‐dependent increases in intracellular Ca2+ transients, with ΔF/F ratios ranging from 0.4 on day 3 to 3.3 on day 12. Patch‐clamp experiments revealed similar correlation between NSC differentiation and macroscopic Ba2+ current density. These currents were markedly reduced (−77%) by Cav1 channel blockade with 5 µm nifedipine. To determine the influence of Cav1‐mediated Ca2+ influx on NSC differentiation, cells were cultured in differentiative medium with either nifedipine (5 µm) or the L‐channel activator Bay K 8644 (10 µm). The latter treatment significantly increased the percentage of β‐III‐tubulin+/MAP2+ cells whereas nifedipine produced opposite effects. Pretreatment with nifedipine also inhibited the functional maturation of neurons, which responded to membrane depolarization with weak Ca2+ signals. Conversely, Bay K 8644 pretreatment significantly enhanced the percentage of responsive cells and the amplitudes of Ca2+ transients. These data suggest that NSC differentiation is strongly correlated with the expression of voltage‐gated Ca2+ channels, especially the Cav1, and that Ca2+ influx through these channels plays a key role in promoting neuronal differentiation.
The role of ARX in cortical development
Authors: Friocourt Gaëlle , Poirier Karine , Rakić Sonja , Parnavelas John G. , Chelly Jamel
Published: March 2006

The ARX protein (encoded by the aristaless‐related homeobox gene) is a member of the paired class of homeoproteins. More precisely, it is a member of the Aristaless subclass of proteins with a glutamine residue (Q) at the critical position 50 of the homeodomain (Q50). Through identification of diverse inherited or de novo mutations, genetic investigations of X‐linked mental retardation conditions have demonstrated the implication of ARXin a wide spectrum of disorders extending from phenotypes with severe neuronal migration defects, such as lissencephaly, to mild forms of X‐linked mental retardation without apparent brain abnormalities. These investigations have recently directed attention to the role of this gene in brain development. Analysis of its spatiotemporal localization profile have revealed expression mainly in telencephalic structures at all stages of development. Interestingly, in adult, ARX expression becomes restricted to a population of GABAergic neurons. Although the identification of the target genes regulated by ARX remains a crucial step to better understanding its role during brain development, studies of the role of ARX orthologs in different models have indicated that it is essential for important developmental processes such as proliferation, cell differentiation and neuronal migration.
Gene networks controlling early cerebral cortex arealization
Authors: Mallamaci Antonello , Stoykova Anastassia
Published: March 2006

Early thalamus‐independent steps in the process of cortical arealization take place on the basis of information intrinsic to the cortical primordium, as proposed by Rakic in his classical protomap hypothesis [Rakic, P. (1988)Science, 241, 170–176]. These steps depend on a dense network of molecular interactions, involving genes encoding for diffusible ligands which are released around the borders of the cortical field, and transcription factor genes which are expressed in graded ways throughout this field. In recent years, several labs worldwide have put considerable effort into identifying members of this network and disentangling its topology. In this respect, a considerable amount of knowledge has accumulated and a first, provisional description of the network can be delineated. The aim of this review is to provide an organic synthesis of our current knowledge of molecular genetics of early cortical arealization, i.e. to summarise the mechanisms by which secreted ligands and graded transcription factor genes elaborate positional information and trigger the activation of distinctive area‐specific morphogenetic programs.
Human disorders of cortical development: from past to present
Authors: Francis Fiona , Meyer Gundela , Fallet‐Bianco Catherine , Moreno Sarah , Kappeler Caroline , Socorro Alfredo Cabrera , Tuy Françoise Phan Dinh , Beldjord Cherif , Chelly Jamel
Published: March 2006

Epilepsy and mental retardation, originally of unknown cause, are now known to result from many defects including cortical malformations, neuronal circuitry disorders and perturbations of neuronal communication and synapse function. Genetic approaches in combination with MRI and related imaging techniques continually allow a re‐evaluation and better classification of these disorders. Here we review our current understanding of some of the primary defects involved, with insight from recent molecular biology advances, the study of mouse models and the results of neuropathology analyses. Through these studies the molecular determinants involved in the control of neuron number, neuronal migration, generation of cortical laminations and convolutions, integrity of the basement membrane at the pial surface, and the establishment of neuronal circuitry are being elucidated. We have attempted to integrate these results with the available data concerning, in particular, human brain development, and to emphasize the limitations in some cases of extrapolating from rodent models. Taking such species differences into account is clearly critical for understanding the pathophysiological mechanisms associated with these disorders.
Some Personality Correlates of Business White‐Collar Crime
Authors: Blickle Gerhard , Schlegel Alexander , Fassbender Pantaleon , Klein Uwe
Published: February 2006

On présente dans cet article les résultats de la première étude transversale européenne portant sur les dimensions de la personnalité en relation avec les délits financiers commis par les cols blancs. Ce travail est un prolongement de la recherche de Collin & Schmidt (1992) sur les délits des cols blancs aux Etats‐Unis. Les données ont été récoltées auprès de 150 cadres en poste dans des sociétés commerciales allemandes et de 76 délinquants en col blanc anciennement cadres. Les répondants ont rempli des échelles papier crayon mesurant l’hédonisme (l’Echelle de Valeurs de Schwartz), le sens des responsabilités (NEO‐FFI), le narcissisme (DSM‐III‐R), la désirabilité sociale (Crowne & Marlowe), et le self‐control comportemental. L’analyse de régression logistique montra que 69% de la variance était commune aux deux groupes. Le délit financier commis par un col blanc dépend du sexe (les hommes sont surreprésentés), d’un faible self‐control comportemental, d’un hédonisme élevé, d’un fort narcissisme et d’un sens des responsabilités affirmé quand la désirabilité sociale est statistiquement contrôlée. Ce résultat concernant le sens des responsabilités est toutefois en contradiction avec l’interprétation que Collins et Schmidt donnent de leurs travaux (1993). On peut supposer que les délinquants en col blanc haut placés combinent malhonnêteté et sens des responsabilités élevé.

In this paper the results of the first cross‐sectional study in Europe examining personality correlates of white‐collar crime in business are presented. This study is an extension of Collins and Schmidt's (1993) research on white‐collar crime in the United States. The data were obtained from 150 managers currently active in German corporations and 76 white‐collar criminals who formerly held such positions. Participants filled out paper and pencil scales measuring hedonism (Schwartz Value Scale), conscientiousness (NEO‐FFI), narcissism (DSM‐III‐R), social desirability (Crowne & Marlowe, 1960), and behavioral self‐control. The logistic regression analysis accounted for 69 per cent of the variance between the two groups. Business white‐collar crime is predicted by gender (males higher rates than females), low behavioral self‐control, high hedonism, high narcissism, and high conscientiousness after statistically controlling for social desirability. The results concerning conscientiousness, however, contradict the interpretation of findings reported by Collins and Schmidt (1993). It is argued here that high‐ranking white‐collar criminals in business combine low integrity with high conscientiousness.
Personal Goal Facilitation through Work: Implications for Employee Satisfaction and Well‐Being
Authors: Doest Laura ter , Maes Stan , Gebhardt Winifred A. , Koelewijn Hennie
Published: February 2006

Que le travail facilite la réalisation des objectifs personnels dépend de la perception de l’impact du travail sur l’atteinte de ces objectifs personnels. En accord avec la littérature sur l’autorégulation et le modèle cybernétique du stress organisationnel proposé par Edwards (1992), la facilitation de l’accès à ses objectifs personnels par le travail fut supposée en relation positive avec les attitudes relatives à l’emploi et le bien‐être de l’employé. En outre, on a prédit un rapport plus étroit entre la facilitation de l’accès à ses objectifs personnels par le travail et les performances du salarié quand les buts personnels étaient fortement valorisés. Ces hypothèses ont été mises à l’épreuve à travers un questionnaire rempli par 1036 employés du secteur de la santé. D’après l’analyse de régression, la facilitation de l’accès à ses objectifs personnels par le travail expliquait une part importante de la variance du bien‐être et des attitudes relatives à l’emploi, même après avoir contrôlé les caractéristiques des postes en référence au modèle de Karasek concernant les relations agents stressants—tension au travail (1979; Karasek & Theorell, 1990). L’importance des objectifs n’avait qu’une influence des plus limitées. On en conclut que la facilitation de l’accès à ses objectifs personnels par le travail offre une voie prometteuse pour explorer les attitudes liées à l’emploi et le bien‐être, en complément des modèles plus traditionnels des caractéristiques de l’emploi.

Personal goal facilitation through work refers to perceptions of the extent to which one's job facilitates the attainment of one's personal goals. In line with the self‐regulation literature and Edwards’ (1992) cybernetic model of organisational stress, personal goal facilitation through work was predicted to show positive associations with job attitudes and employee well‐being. Moreover, stronger relationships between personal goal facilitation through work and employee outcomes were predicted for highly valued personal goals. These predictions were investigated in a questionnaire study of 1,036 health care employees. In regression analyses, personal goal facilitation through work accounted for substantial variance in job attitudes and well‐being, even after controlling for job characteristics from Karasek's (1979; Karasek & Theorell, 1990) model of occupational stressor–strain relations. There was only very limited evidence of moderating effects of goal importance. It is concluded that personal goal facilitation through work offers a promising source of insight into job attitudes and well‐being, complementing more traditional job characteristics models.
Cultural Values as Moderators of Employee Reactions to Job Insecurity: The Role of Individualism and Collectivism
Authors: Probst Tahira M. , Lawler John
Published: February 2006

Cette recherche part de l’hypothèse que les valeurs culturelles sont l’un des déterminants des réactions des salariés face à l’insécurité professionnelle. Dans la première investigation, les valeurs culturelles ont été appréhendées au niveau de l’individu à partir des réponses de 141 salariés de diverses origines ethniques appartenant à une grande entreprise agro‐alimentaire américaine qui réduisait ses effectifs. Les répondants ont rempli des questionnaires évaluant leurs valeurs culturelles, leur perception de la sécurité au travail, leurs attitudes professionnelles, leurs réactions affectives vis‐à‐vis de la réduction des effectifs et leur niveau de stress lié au travail. Les résultats ont montré que le sentiment d’insécurité professionnelle avait un impact généralement négatif sur les employés. Toutefois, les salariés présentant des valeurs culturelles communautaires ressentaient plus négativement que leurs homologues individualistes le sentiment d’insécurité professionnelle. Dans le second volet de la recherche, la culture a été définie au niveau national. On a proposé aux salariés de sept organisations, quatre chinoises et trois américaines, de remplir des questionnaires appréciant leurs réactions à leur perception de l’insécurité professionnelle. Il apparut que les Chinois (mentalité communautaire) réagissaient plus négativement que les Américains individualistes face à la menace constituée par l’insécurité professionnelle. Les résultats sont analysés à la lumière du développement de pratiques organisationnelles qui comprennent la réduction des effectifs et autres procédures qui impliquent une moindre stabilité des emplois.

This research explored the hypothesis that cultural values moderate employee reactions to job insecurity. In the first study, cultural values were measured at an individual level of analysis based on responses from one hundred and forty‐one ethnically diverse employees of a large US‐based food‐processing company undergoing a downsizing. Participants completed surveys assessing their cultural values, perceptions of job security, job attitudes, affective reactions to the downsizing, and job‐related stress levels. Results indicated that the perception of job insecurity had a generally negative impact on employees. However, employees with collectivist cultural values were more negatively affected by the perception of job insecurity than their individualist counterparts. In the second study, culture was operationalised at the national level of analysis. Employees from seven organisations (four based in China; three based in the US) completed surveys assessing their reactions to perceived job insecurity. Results suggest that Chinese (i.e. collectivist) employees reacted more negatively to the threat of job insecurity than their US counterparts (i.e. individualist employees). These results are discussed in light of growing organisational trends that include the use of downsizing and other techniques that herald a decrease in job stability.
Local vs. regional control on species richness: a new approach to test for competitive exclusion at the community level
Authors: Herzog Sebastian K. , Kessler Michael
Published: February 2006

Aim The degree to which ecosystem properties (niche availability) and interspecific competition limit local species richness continues to be debated. We present a new method that takes advantage of special biogeographical conditions where habitat islands are embedded in a moderately dissimilar matrix. Small, isolated islands lack habitat specialists to varying degrees, allowing matrix species to occupy island habitat. We examined the relative influence of local vs. biogeographical factors on bird richness of habitat islands by evaluating three predictions each for three hypotheses (competitive exclusion, mass effect, species‐area effects).

Location Five naturally isolated dry forest islands and eight extensive dry forest sites in Bolivia.

Methods Linear and multiple regressions were calculated between standardized species richness, the number of typical dry forest, humid forest and habitat generalist species vs. canopy height, elevation, precipitation, habitat area and distance from evergreen forest. The same analyses were performed at the guild level.

Results Our data are consistent with one prediction under each hypothesis, thus partly supporting and partly rejecting all three hypotheses. Bird richness of dry forest islands was primarily determined by local ecosystem properties (vegetation complexity, productivity), with a minor effect of habitat area (inverse) and distance to evergreen forest. The number of dry forest specialists was influenced by habitat area and isolation from source habitats, with elevation and precipitation adding moderate explanatory power. The number of humid forest specialists was determined by precipitation, habitat area (inversely) and canopy height. These patterns were also evident at the guild level, demonstrating that the loss of dry forest species in a given guild was correlated with a gain of humid forest species in the same guild, rather than random species turnover.

Main conclusions

Total local species richness of semi‐isolated habitat islands is determined primarily by local (niche availability) but also by regional (biogeographical) factors, exemplifying MacArthur's paradox. Small dry forest islands historically lost part of their habitat specialists. Vacant niches were filled by species from adjacent humid forest that are competitively excluded by habitat specialists from large dry forest areas, ideally until the community is saturated, although this pattern is to some degree modified by biogeographical factors. This ‘semipermeable island’ approach can be applied to other taxa and regions and is a promising, widely applicable tool for gaining new insights into the regulation of diversity.
On defining and quantifying biotic homogenization
Authors: Olden Julian D. , Rooney Thomas P.
Published: February 2006

Ongoing species invasions and extinctions are changing biological diversity in different ways at different spatial scales. Biotic homogenization (or BH) refers to the process by which the genetic, taxonomic or functional similarities of regional biotas increase over time. It is a multifaceted process that encompasses species invasions, extinctions and environmental alterations, focusing on how the identities of species (or their genetic or functional attributes) change over space and time. Despite the increasing use of the term BH in conservation biology, it is often used erroneously as a synonym for patterns of species invasions, loss of native species or changes in species richness through time. This reflects the absence of an agreed‐upon, cogent definition of BH. Here, we offer an operational definition for BH and review the various methodologies used to study this process. We identify the strengths and weaknesses of these approaches, and make explicit recommendations for future studies. We conclude by citing the need for researchers to: (1) consider carefully the definition of BH by recognizing the genetic, taxonomic and functional realms of this process; (2) recognize that documenting taxonomic homogenization requires tracking the identity of species (not species richness) comprising biotas through space and time; and (3) employ more rigorous methods for quantifying BH.
Incursion and excursion of Antarctic biota: past, present and future
Authors: Barnes D. K. A. , Hodgson D. A. , Convey P. , Allen C. S. , Clarke A.
Published: February 2006

Aim To investigate the major paradigms of intense isolation and little anthropogenic influence around Antarctica and to examine the timings and scales of the modification of the southern polar biota.

Location Antarctica and surrounding regions.

Methods First, mechanisms of and evidence for long‐term isolation are reviewed. These include continental drift, the development of a surrounding deep‐water channel and the Antarctic Circumpolar Current (ACC). They also include levels of endemism, richness and distinctiveness of assemblages. Secondly, evidence for past and modern opportunities for species transport are investigated. Comparative levels of alien establishments are also examined around the Southern Ocean.

Discussion On a Cenozoic time‐scale, it is clear that Gondwana's fragmentation led to increasing geographical isolation of Antarctica and the initiation of the ACC, which restricted biota exchange to low levels while still permitting some movement of biota. On a shorter Quaternary time‐scale, the continental ice‐sheet, influenced by solar (Milankovitch) cycles, has expanded and contracted periodically, covering and exposing terrestrial and continental shelf habitats. There were probably refugia for organisms during each glacial maxima. It is also likely that new taxa were introduced into Antarctica during cycles of ice sheet and oceanic front movement. The current situation (a glacial minimum) is not ‘normal’; full interglacials represent only 10% of the last 430 ka. On short (ecological) time‐scales, many natural dispersal processes (airborne, oceanic eddy, rafting and hitch‐hiking on migrants) enable the passage of biota to and from Antarctica. In recent years, humans have become influential both directly by transporting organisms and indirectly by increasing survival and establishment prospects via climate change.

Main conclusions Patterns of endemism and alien establishment are very different across taxa, land and sea, and north vs. south of the Polar Frontal Zone. Establishment conditions, as much as transport, are important in limiting alien establishment. Three time‐scales emerge as important in the modification of Antarctica's biota. The natural ‘interglacial’ process of reinvasion of Antarctica is being influenced strongly by humans.
Continental fire density patterns in South America
Authors: Di Bella C. M. , Jobbágy E. G. , Paruelo J. M. , Pinnock S.
Published: February 2006

Aims  Quantification of the effects and interactions of natural and anthropogenic factors, including climate, canopy structure, land use and management conditions, on vegetation burning. The study of these relationships is fundamental to predict regional fire patterns and develop sound management and regulation policies for biomass burning at national and global levels.

Location  Southern South America, including Argentina, Brazil, Paraguay, Uruguay, Bolivia and Chile.

Methods  Based on National Oceanic and Atmosphere Administration–Advance Very High Resolution Radiometer (NOAA–AVHRR) satellite images, we identified fires in southern South America with a daily frequency for two periods (1999/2000 and 2000/01) using a contextual fire detection algorithm and integrating the density of these fires at a monthly scale into a 0.5 × 0.5° grid. We combined vegetation and climate global databases and land use information from national census data to explore the relationship of these factors with fires across the region.

Results  The whole study region had a mean fire density of 0.10 and 0.05 fires km−2 year−1 in 1999/2000 and 2000/01, respectively, with extreme values as high as 1.37 in fires km−2 year−1 in Para State, Brazil. Water deficit estimates, derived from a climatic water balance, showed the better correlation with fire density (r = 0.28; P < 0.001; n = 4467), interacting strongly with land use. In areas with low agricultural use fire density increased with water deficit, whereas in highly agricultural areas this relationship was not observed. Agriculture significantly reduced fire density in prairies and savannas but increased its frequency in rain forests.

Main conclusions  These results suggest that agriculture prevents biomass burning in semiarid areas but enhances it in humid environments, where biomass accumulates at faster rates.
Are Friendly Acquisitions Too Bad for Shareholders and Managers? Long‐Term Value Creation and Top Management Turnover in Hostile and Friendly Acquirers
Authors: Sudarsanam Sudi , Mahate Ashraf A.
Published: February 2006

The well‐documented failure of the majority of acquisitions to create value is often identified in popular discussion with hostile acquisitions, whereas friendly acquirers seem to get a friendly press. The relative performance of friendly and hostile acquirers therefore warrants a rigorous empirical investigation. Clear evidence of superior value creation in hostile over friendly acquisitions allows us to judge the efficacy of the market for corporate control. In this article we examine the long‐term shareholder wealth performance of four types of acquirers – friendly bidder, hostile bidder, white knight and hostile bidder facing a white knight or another hostile bidder. For a sample of 519 acquisitions of UK target firms during 1983–1995, we estimated the three‐year post‐acquisition gains to acquirer shareholders and found that hostile acquirers deliver significantly higher shareholder value than friendly acquirers. We found that friendly acquirers with high stock‐market ratings destroyed more value than hostile acquirers with a similar rating. Friendly acquirer top managers suffered greater job losses than those of hostile acquirers, perhaps paying the price for their inferior value‐creation performance. Our study provides evidence of the superior value‐creation performance of hostile acquirers and makes the case against takeover regulatory rules that may impede hostile takeovers.
Organizational Identification During a Merger: Determinants of Employees' Expected Identification With the New Organization*
Authors: Bartels Jos , Douwes Rynke , de Jong Menno , Pruyn Ad
Published: February 2006

In order to investigate the development of organizational identification during a merger, a quasi‐experimental case study was conducted on a pending merger of police organizations. The research was conducted among employees who would be directly involved in the merger and among indirectly involved employees. In contrast to earlier studies, organizational identification was measured as the expected identification prior to the merger. Five determinants were used to explain the employees' expected identification: (a) identification with the pre‐merger organization, (b) sense of continuity, (c) expected utility of the merger, (d) communication climate before the merger and (e) communication about the merger. The five determinants appeared to explain a considerable proportion of the variance of expected organizational identification. Results suggest that in order to obtain a strong identification with the soon‐to‐be‐merged organization, managers should pay extra attention to current departments with weaker social bonds as these are expected to identify the least with the new organization. The role of the communication variables differed between the two employee groups: communication about the merger only contributed to the organizational identification of directly involved employees; and communication climate only affected the identification of indirectly involved employees.
Working Under a Black Cloud: How to Sustain Organizational Identification after a Merger*
Authors: van Dick Rolf , Ullrich Johannes , Tissington Patrick A.
Published: February 2006

This article argues against the merger folklore that maintains that a merger negatively affects well‐being and work attitudes primarily through the threat of job insecurity. We hold that the workplace is not only a resource for fulfilling a person's financial needs, but that it is an important component of the self‐concept in terms of identification with the organization, as explained by social identity theory. We unravel the key concepts of the social identity approach relevant to the analysis of mergers and review evidence from previous studies. Then, we present a study conducted during a merger to substantiate our ideas about the effects of post‐merger organizational identification above and beyond the effects of perceived job insecurity. We recommend that managers should account for these psychological effects through the provision of continuity and specific types of communication.
The Impact of Leadership and Change Management Strategy on Organizational Culture and Individual Acceptance of Change during a Merger
Authors: Kavanagh Marie H. , Ashkanasy Neal M.
Published: February 2006

This article reports a longitudinal study that examined mergers between three large multi‐site public‐sector organizations. Both qualitative and quantitative methods of analysis are used to examine the effect of leadership and change management strategies on acceptance of cultural change by individuals. Findings indicate that in many cases the change that occurs as a result of a merger is imposed on the leaders themselves, and it is often the pace of change that inhibits the successful re‐engineering of the culture. In this respect, the success or otherwise of any merger hinges on individual perceptions about the manner in which the process is handled and the direction in which the culture is moved. Communication and a transparent change process are important, as this will often determine not only how a leader will be regarded, but who will be regarded as a leader. Leaders need to be competent and trained in the process of transforming organizations to ensure that individuals within the organization accept the changes prompted by a merger.