bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of ecological interactions on the physiological flexibility of lizards
Authors: NAYA D. E. , BOŽINOVIĆ F.
Published: June 2006

An organism's ability to adjust its physiological traits to changes in environmental conditions is central for its ecological success. However, the effect of ecological interactions on physiological flexibility has rarely been investigated. Here we carry out a factorial experiment to analyse how food limitation (a potential result of competition) and tail loss (a potential result of sub‐lethal predation) affect anatomical and physiological traits of the South American lizard Liolaemus nitidus.

The size of several internal organs was affected by food availability. Small intestine mass increased with food consumption, allowing animals to keep constant digestibility at greater levels of digesta, which in turn permitted higher rates of food assimilation. Organs related to energy storage reached larger sizes in autotomized animals with high food availability, but tail regeneration rate after 3 weeks did not change with food availability.

Metabolic rate was affected by tail loss, and animals regenerating their tail showed higher metabolic rates than tailed ones. Because this increase in metabolic rate was independent of internal organ mass, a local effect of tail regeneration process (e.g. cell proliferation) on metabolic rate is suggested.

When anatomical and metabolic data are jointly considered it follows that lizards adopt different physiological strategies, changing both energetic inputs and expenditures. This fact illustrates the complex interplay between ecological factors and physiological flexibility, which ultimately determine an organism's fitness.
Swimming with…Devonian fish
Authors: Morrissey Lance B. , Janvier Philippe , Braddy Simon J. , Bennett John P. , Marriott Susan B. , Tarrant Peter R.
Published: June 2006

Armoured jawless fish, or ‘ostracoderms’, lived 450–360 million years ago, and display unusual morphologies, unlike any modern fish group. Since they left no living descendants, their mode of swimming has, until recently, remained speculative, although this is a crucial question as the first true pectoral fins evolved within the ‘ostracoderms’. The discovery of the oldest‐known fish trails, from the Early Devonian (400 million year old) ‘Lower Old Red Sandstone’ of south‐east Wales offers new insights into the swimming behaviour of these early fish, notably the osteostracan ‘ostracoderms’ (or cephalaspids), whose horseshoe‐shaped head and paddle‐shaped pectoral fins have remained a functional riddle.
William Buckland (1784–1856)
Authors: Duffin Christopher J.
Published: June 2006

This year marks the 150th anniversary of William Buckland's death. One of the liveliest characters in the early history of our science, Buckland was a keen observer, indefatigable scholar, enthusiastic field geologist, inspirational communicator and possessed of an innovative mind which could quickly embrace, process and apply new ideas. His influence on an emerging discipline during its arguably most formative years in the early nineteenth century, and upon subsequent generations of Earth science scholars, should not be underestimated.
A Wealden guide I: the Weald Sub‐basin
Authors: Radley Jonathan D.
Published: June 2006

The Wealden strata of southern England provide a range of evidence for Early Cretaceous non‐marine environments and their inhabitants, and a climate of warm to hot, ‘Mediterranean’ aspect. Because of its exposure, and its range of facies, distinguishing a variety of sedimentary environments, the Wealden has long fascinated geologists intent on providing an environmental model. This article is one of two intended to give an overview of Wealden environments, providing the geological framework of these strata. In this article, the type‐succession in the Weald Sub‐basin of south‐east England is summarized and briefly interpreted.
Influence of attachment wear on retention of mandibular overdenture
Authors: RUTKUNAS V. , MIZUTANI H. , TAKAHASHI H.
Published: June 2006

summary  The aims of this study were: (i) to evaluate and compare retention of two‐teeth (implant) supported mandibular overdenture with either stud or magnetic attachments during linear (axial) and rotational (paraxial) dislodgements; (ii) to compare retentive properties before and after wear simulation. The test group consisted of five magnetic and four stud overdenture attachments (n = 12 specimens for each attachment type). Retention in axial direction was evaluated on one‐tooth (implant) model by measuring maximum retentive force (N) and range of retention (mm) during the linear dislodgement. Retention in the paraxial direction was evaluated on mandibular‐overdenture model by measuring the maximum retentive force (N) during three types of rotational dislodgements – anterior, lateral and posterior. The minimum number of cycles required to simulate wear was determined by special wear test. Afterwards, the wear was simulated in the test group, and retention in axial and paraxial directions was measured again. Statistical analysis: one‐way anova, Scheffe post hoc and paired‐samples t‐tests (P < 0·05). Initially, studs had higher retention (4–11 N) than magnets (4·5–6 N) in axial direction. After the wear simulation, it had decreased from 76% to 48% for some of the studs and had become similar to the retention of magnetic attachments. Magnets had lower retention range (0·2–0·3 mm) than studs (0·5–1·1 mm). Studs provided similar or higher retention in paraxial directions than magnetic attachments both before and after wear simulation. Retentive properties of magnets decreased mostly with posterior rotational dislodgement. Retentive properties of stud overdenture attachments were less constant.
Unravelling first‐generation pedigrees in wild endangered salmon populations using molecular genetic markers
Authors: HERBINGER C. M. , O’REILLY P. T. , VERSPOOR E.
Published: June 2006

There is increasing interest in the use of molecular genetic data to infer genealogical relationships among individuals in the absence of parental information. Such analyses can provide insight into mating systems and estimations of heritability in the wild. In addition, accurate pedigree reconstruction among the founders of endangered populations being reared in captivity would be invaluable. Many breeding programs for endangered species attempt to minimize loss of genetic variation and inbreeding through strategies designed to minimize global co‐ancestry, but they assume a lack of relatedness among the founders. Yet populations that are the target of such programs are generally in serious demographic decline, and many of the available founders may be closely related. Here we demonstrate determination of full and half‐sib relationships among the wild founders of a captive breeding program involving two endangered Atlantic salmon populations using two different approaches and associated software, pedigree and colony. A large portion of the juveniles collected in these two rivers appear to be derived from surprisingly few females mating with a large number of males, probably small precocious parr. Another group of potential founders, obtained from a local hatchery, clearly originated from a small number of full‐sib crosses. These results allowed us to prioritize individuals on the basis of conservation value, and are expected to help minimize loss of genetic variation through time. In addition, insight is provided into the number of contributing parents and the mating systems that produced this last generation of endangered wild Atlantic salmon.
How female reed buntings benefit from extra‐pair mating behaviour: testing hypotheses through patterns of paternity in sequential broods
Authors: BOUWMAN KAREN M. , BURKE TERRY , KOMDEUR JAN
Published: June 2006

Extra‐pair paternity is an important aspect of reproductive strategies in many species of birds. Given that in most species females control whether fertilization occurs, they are expected to benefit in some way from the extra‐pair matings. In this study we use patterns of extra‐pair paternity (EPP) in broods of individual reed buntings (Emberiza schoeniclus), both within and between seasons, to test four hypothesized female benefits: (1) assessing potential future partners and seeking (2) genetic diversity (3) good genes, or (4) compatible genes. Reed buntings are socially monogamous, multibrooded passerines with extremely high levels of extra‐pair paternity. We studied a population of reed buntings in the Netherlands in 2002 and 2003; 51% of offspring in 74% of nests were extra‐pair. We showed that patterns of EPP did not support the first and second hypotheses, since females did not form a pair with previous extra‐pair partners, EPP was not evenly distributed among broods and more broods than expected were sired by a single male. Furthermore, there was no relation between a male's within‐ and extra‐pair fertilization success, no consistency in EPP between breeding attempts, no effect of parental relatedness on EPP and several cases of reciprocal paternity. These patterns do not support the good genes hypothesis and are most consistent with the genetic compatibility hypothesis. However, our previous finding that older males are more successful in gaining EPP, suggests some effect of good genes. These hypotheses need not be mutually exclusive, as females may select compatible males above a certain quality threshold (e.g. old males).
MMP‐1 promoter gene polymorphism and susceptibility to chronic periodontitis in a Chinese population
Authors: Cao Z. , Li C. , Zhu G.
Published: June 2006

A single nucleotide polymorphism in the promoter region of −1607 bp of the human MMP‐1 gene has been found to be associated with an increased risk of various inflammatory diseases and cancer metastasis. This study aimed to evaluate the association between the MMP‐1 promoter gene polymorphism and chronic periodontitis susceptibility and/or severity in a Chinese population. Genomic DNA was obtained from whole blood samples in 60 Chinese subjects with chronic periodontitis and 50 periodontally healthy subjects as controls. MMP‐1 promoter fragment was amplified by polymerase chain reaction, and the polymorphism was analyzed by restriction endonuclease cleavage. In the control subjects, the 2G allele was observed a frequency of 49%, while in severely diseased patients, the 2G allele was seen in 73.4%. The individuals with the 2G allele seem to be approximately three times at greater risk for developing the severe chronic periodontitis (χ2 = 12.148, P = 0.000). The genotype of 2G/2G was found in 58.5% of the severe periodontitis and 24% of the control group (χ2 = 11.779, P = 0.003). This study suggests that a single nucleotide polymorphism in the MMP‐1 promoter region of −1607 bp may be associated with severe chronic periodontitis in a Chinese population.
Low‐cost, simultaneous, single‐sequence genotyping of the HLA‐A, HLA‐B and HLA‐C loci
Authors: Abbott W. G. H. , Tukuitonga C. F. , Ofanoa M. , Munn S. R. , Gane E. J.
Published: June 2006

New automated DNA sequencing technology has enabled the development of an assay for genotyping the three major HLA class 1 loci from a single sequence of each gene containing exon 3, intron 2 and exon 2. The assay allows 31 subjects (with 3 negative controls) to be genotyped at all three loci simultaneously, using a 96‐well plate format. Genotypes were assigned by comparing each sequence to a database of 307 HLA‐A, 563 HLA‐B and 166 HLA‐C alleles. Unequivocal, 4‐digit allele assignments were made for 40 of 130 HLA‐A genes, 82 of 130 HLA‐B genes and 97 of 130 HLA‐C genes from 21 European, 20 Tongan and 24 Niuean subjects. Ambiguity in interpretation of the sequence contributed to 66 of the 170 equivocal allele assignments, and 105 equivocal assignments were due to polymorphisms outside exons 2 and 3. All known alternative interpretations of ambiguous genotypes were identified, and seven HLA‐B and two HLA‐C ambiguities were resolved by reading the out‐of‐phase exon 2 sequence that followed an indel in intron 2. The genotypes of a subgroup of 27 heterozygous subjects, whose genotypes contained all of the alleles identified in this study, were confirmed with commercial, generic PCR‐SSP typing. In European subjects, the repertoire of HLA‐B/HLA‐C haplotypes was almost identical to previously published data. We identified five new HLA‐B/HLA‐C haplotypes in the Polynesian subjects, and the remaining haplotypes were of Asian origin. In summary, we are describing a low‐cost, sequencing assay for the three major HLA class I loci that provides a level of resolution that is comparable with a commercial PCR‐SSP assay.
Long‐term cultured neonatal porcine islet cell monolayers: a potential tissue source for transplant in diabetes
Authors: Mancuso Francesca , Basta Giuseppe , Calvitti Mario , Luca Giovanni , Guido Lucia , Racanicchi Leda , Montanucci Pia , Becchetti Ennio , Calafiore Riccardo
Published: June 2006

Abstract:  Background:  The restricted availability of cadaveric human donor pancreases mandates validation of possibly inexhaustible, alternative sources of insulin secretory cells in order to expand islet transplant for the therapy of insulin dependent diabetes mellitus (T1DM).

Methods:  Neonatal pig pancreatic islets (NPI), isolated and purified by our method, were specially cultured until confluent cell monolayers were obtained. Expression of several β‐cell phenotype transcriptional factors, under glucose and other stimuli, were examined throughout 90 days of culture.

Results:  High glucose concentration and glucagon‐like peptide 1 (GLP‐1) were associated with maintenance either of insulin secretory patterns from the incubated cell monolayers, or expression of transcriptional markers associated with β‐cell like phenotypes.

Conclusion:  Morphological and molecular expression of β‐cell markers and products from NPI cell monolayers seem to identify a novel and potentially powerful source of insulin producing cells that might fulfill transplant needs for insulin substitution therapy
Molecular interactions between porcine and human gammaherpesviruses: implications for xenografts?
Authors: Santoni Fabio , Lindner Iris , Caselli Elisabetta , Goltz Michael , Luca Dario Di , Ehlers Bernhard
Published: June 2006

Abstract:  Background:  Reactivation of latent herpesviruses is an important cause of morbidity and mortality in human transplantation. This issue might be further complicated in the case of xenotransplantation. Zoonotic viruses could reactivate and replicate in the transplanted tissue, and interactions with homologous human viruses could take place. Since the pig is a favoured animal as donor of organs for human transplants, we analysed the possibility of interactions between porcine and human herpesviruses. Porcine lymphotropic herpesvirus 1 (PLHV‐1) is a gammaherpesvirus homologous to Epstein–Barr virus (EBV) and to human herpesvirus 8 (HHV‐8), is highly prevalent in pigs and is associated to lymphoproliferative disease in immunosuppressed and transplanted miniature swine.

Methods:  The main viral transactivators of PLHV‐1, ORF50, ORF57, ORFA6/BZLF1h, were cloned and tested for their transactivating ability on several EBV and HHV‐8 promoters using reporter assays. Also the effects of HHV‐8 ORF50, ORF57 and ORFK8 and EBV BRLF1/ R‐transactivator (Rta) and BZLF1/ Z‐transactivator (Zta) on PLHV‐1 lytic promoters were analysed.

Results:  Porcine lymphotropic herpesvirus 1 ORF50 upregulated all HHV‐8 promoters and PLHV‐1 ORFA6/BZLF1h transactivated EBV promoters. Furthermore, transfection of PLHV‐1 ORF50 into BC‐3 cells, latently infected with HHV‐8, resulted in HHV‐8 reactivation. Likewise, HHV‐8 ORF50 and EBV BRLF1/Rta had a strong transactivating effect on PLHV‐1 promoters. Also EBV BZLF1/Zta and HHV‐8 ORF57 induced PLHV‐1 transactivation, but at lower levels.

Conclusion:  The results suggest that reciprocal molecular interactions between human and porcine herpesviruses might occur in vivo, and support the hypothesis that PLHV‐1 might have pathogenic relevance in the course of xenotransplantation.
Health status of transgenic pigs expressing the human complement regulatory protein CD59
Authors: Deppenmeier Stefanie , Bock Oliver , Mengel Michael , Niemann Heiner , Kues Wilfried , Lemme Erika , Wirth Dagmar , Wonigeit Kurt , Kreipe Hans
Published: June 2006

Abstract:  Background:  Microinjection of foreign DNA into pronuclei of zygotes has been the method of choice for the production of transgenic domestic animals. Following microinjection the transgene is randomly integrated into the host genome which can be associated with insertional mutagenesis and unwanted pathological side effects.

Methods:  Here, we evaluated the health status of pigs transgenic for the human regulator of complement activation (RCA) CD59 and conducted a complete pathomorphological examination on 19 RCA transgenic pigs at 1 to 32 months of age from nine transgenic lines. Nine wild‐type animals served as controls. Expression levels of human complement regulator CD59 (hCD59) mRNA were measured by RT‐PCR and distribution of hCD59 protein was determined by immunohistochemistry.

Results:  Albeit variable transgene expression levels, no specific pathomorphologic phenotype associated with the presence of the transgene in all analyzed pig lines could be detected.

Conclusions:  Transgenic expression of this human RCA gene construct is not correlated with a specific pathological phenotype in pigs. This is crucial for the application of the technology and the use of transgenic pigs for biomedical and agricultural applications.
Colour forms of Amazonian cichlid fish represent reproductively isolated species
Authors: Ready J. S. , Sampaio I. , Schneider H. , Vinson C. , Dos Santos T. , Turner G. F.
Published: June 2006

Laboratory mate choice experiments have confirmed species status for cichlid fish in the African Great Lakes that differ in colour and little else. Colour differences between allopatric populations of the South American cichlid genus Apistogramma are known for many species, yet the status of such populations has not been previously tested. Analysis of the genetic relationships and mate choice characteristics of populations previously described as Apistogramma caetei from eastern Amazonia indicates genetic differentiation into at least three allopatric lineages, which also show strong prezygotic isolation through female mate choice, confirming them as Biological species. If future studies confirm that this result is indicative of a general trend, the species richness of the South American cichlid fishes may presently be seriously underestimated.
Alveolata histone-like proteins have different evolutionary origins
Authors: Chan Y. H. , Kwok Alvin C. M. , Tsang Jimmy S. H. , Wong Joseph T. Y.
Published: June 2006

Prokaryotic histone-like proteins (Hlps) are abundant proteins found in bacterial and plastid nucleoids. Hlps are also found in the eukaryotic dinoflagellates and the apicomplexans, two major lineages of the Alveolata. It may be expected that Hlps of both groups were derived from the same ancestral Alveolates. However, our phylogenetic analyses suggest different origins for the dinoflagellate and the apicomplexan Hlps. The apicomplexan Hlps are affiliated with the cyanobacteria and probably originated from Hlps of the plastid genome. The dinoflagellate Hlps and the proteobacterial long Hlps form a clade that branch off from the node with the proteobacterial short Hlps.
Premating Avoidance of Inbreeding Absent in Female Guppies (Poecilia reticulata)
Authors: Viken Åslaug , Fleming Ian A. , Rosenqvist Gunilla
Published: June 2006

The recognition and avoidance of kin during mating can be an important means of reducing the potential for inbreeding depression in offspring. We report here that premating mechanisms to avoid inbreeding, either innate or learnt through juvenile experience, are at best weak in female guppies (Poecilia reticulata). Guppies are small, ovoviviparous, neo‐tropical freshwater fish, with a polygamous mating system where males actively court females and females are selective of their mates. In a series of mate‐choice experiments, naïve, virgin females of the Quare River population in Trinidad were given a choice between a brother and a non‐sib male from the same population. Initially, females were only provided olfactory cues upon which to base their choice and then subsequently both olfactory and visual cues. Despite the females displaying mate choice, we found no evidence of them discriminating between the male types in either experiment. There was thus no indication of inbreeding avoidance, suggesting that experiences after maturation or with mature males (e.g. rare male preference), dispersal and/or post‐mating mechanisms may be evolutionarily more important avoidance mechanisms.
Emx2 in the developing hippocampal fissure region
Authors: Zhao Tianyu , Kraemer Nadine , Oldekamp Judit , Çankaya Murat , Szabó Nora , Conrad Sabine , Skutella Thomas , Alvarez‐Bolado Gonzalo
Published: June 2006

Mice deficient in transcription factor gene Emx2 show developmental alterations in the hippocampal dentate gyrus. Emx2, however, is also expressed in the region around the developing hippocampal fissure. The developing fissure contains a radial glial scaffolding, and is surrounded by the outer marginal zone and the dentate marginal zone, which become specifically colonized by neurons and differentiate into stratum lacunosum‐moleculare and molecular layer of the dentate, respectively. In this study we show that the Emx2 mutant lacks the glial scaffolding of the fissure and has an outer marginal zone (precursor of the stratum lacunosum‐moleculare), as well as a dentate marginal zone severely reduced in size while most of the reelin (Reln)‐expressing cells that should occupy it fail to be generated. We have also identified a subpopulation of hippocampal Reln‐expressing cells of the marginal zone, probably born in the hem, expressing a specific combination of markers, and for which Emx2 is not essentially required. Additionally, we show differential mutant phenotypes of both Emx2 and Pax6 in neocortical vs. hippocampal Reln‐expressing cells, indicating differential development of both subpopulations.
P2Y1 and P2X7 receptors induce calcium/calmodulin‐dependent protein kinase II phosphorylation in cerebellar granule neurons
Authors: León David , Hervás Cristina , Miras‐Portugal M. Teresa
Published: June 2006

The activation of nucleotide receptors − both ionotropic, P2X, and most of metabotropic, P2Y − increases intracellular calcium concentration, resulting in calcium/calmodulin‐dependent protein kinase II (CaMKII) activation. Stimulation of cerebellar granule neurons in culture − with different P2X and P2Y agonists and their effect on CaMKII phosphorylation − was studied using immunocytochemical and microfluorimetrical techniques. P2X agonist: 2′‐3′‐o‐(4‐benzoylbenzoyl)‐adenosine 5′‐triphosphate (BzATP), α,β‐methylene adenosine 5′‐triphosphate (α,β‐meATP) and diadenosine pentaphosphate (Ap5A); and P2Y agonists: 2‐(methylthyo)‐adenosine diphosphate (2MeSADP) and uridine 5′‐bisphosphate (UDP); tested induced a CaMKII phosphorylation but with a different immunostaining pattern in each group. Stimulation with 2MeSADP induced a Ca2+ release from intracellular stores and a significant CaMKII phosphorylation in cell somas and neurites. This agrees with the subcellular distribution of P2Y1. MRS 2179, a specific P2Y1 inhibitor, antagonized the 2MeSADP effect. On the other hand, cerebellar granule neuron stimulation with BzATP, in Mg2+‐free conditions, produced extracellular calcium entrance and, as a result, a significant increase in CaMKII phosphorylation mostly in fibres, which correspond with P2X7 subdistribution. Immunocytochemical and microfluorimetrical experiments, using Zn2+ and Brilliant Blue G (BBG), as a specific P2X7 antagonist, confirmed that BzATP was acting through the P2X7 receptor. These results indicate that P2Y1 and P2X7 produce a significant increase in CaMKII phosphorylation, but show important differences in subcellular distribution and in effect duration. P2X7 activation in granule neurons is not associated with pore formation, according to the absence of YO‐PRO‐1 fluorescence. The abundant presence of P2X7 at the synaptic structures suggests a relevant role played by this receptor in synaptic plasticity.
Distinct localization of prokineticin 2 and prokineticin receptor 2 mRNAs in the rat suprachiasmatic nucleus
Authors: Masumoto Koh‐hei , Nagano Mamoru , Takashima Naoyuki , Hayasaka Naoto , Hiyama Hideki , Matsumoto Shun‐ichiro , Inouye Shin‐Ichi T. , Shigeyoshi Yasufumi
Published: June 2006

The suprachiasmatic nucleus (SCN) is the master circadian clock that regulates physiological and behavioral circadian rhythms in mammals. Prokineticin 2 (PK2) is highly expressed in the SCN, and its involvement in the generation of circadian locomotor activity has been reported previously. In the present study, using in situ hybridization methods, we investigated the localization of PK2 and prokineticin receptor 2 (PKR2), a specific receptor for PK2, in the rat SCN. In steady light : dark (L : D = 12 : 12 h) and constant dark conditions, rPK2 mRNA displayed a robust circadian oscillation with a peak occurring during the day. Moreover, during peak expression, the rPK2 mRNA‐positive neurons were scattered in both the dorsomedial and ventrolateral SCN, which are two functionally and morphologically distinct subregions. Furthermore, double‐labeling in situ hybridization experiments revealed that greater than 50% of the rPK2 mRNA‐containing neurons co‐expressed either vasoactive intestinal peptide (VIP), gastrin‐releasing peptide (GRP) or arginine vasopressin (AVP) in the SCN. In contrast, the rPKR2 mRNA levels did not show significant diurnal alterations. rPKR2 mRNA‐containing neurons were also clustered in the dorsolateral part of the SCN, which shows negligible labeling of either rAVP, rVIP, rGRP or rPK2 transcripts. In addition, this region exhibited a delayed cycling of the rPer1 gene. These results suggest an intrinsic PK2 neurotransmission and functionally distinct roles for PKR2‐expressing neurons in the SCN.
Defects in tangential neuronal migration of pontine nuclei neurons in the Largemyd mouse are associated with stalled migration in the ventrolateral hindbrain
Authors: Qu Qiang , Crandall James E. , Luo Tuanlian , McCaffery Peter J. , Smith Frances I.
Published: June 2006

The LARGE gene encodes a putative glycosyltransferase that is required for normal glycosylation of dystroglycan, and defects in LARGE can cause abnormal neuronal migration in congenital muscular dystrophy (CMD). Previous studies have focused on radial migration, which is disrupted at least in part due to breaks in the basal lamina. Through analysis of precerebellar nuclei development in the Largemyd mouse hindbrain, we show that tangential migration of a subgroup of hindbrain neurons may also be disrupted. Within the precerebellar nuclei, the pontine nuclei (PN) are severely disrupted, whereas the inferior olive (IO), external cuneate nuclei (ECN) and lateral reticular nuclei (LRN) appear unaffected. Large and dystroglycan are widely expressed in the hindbrain, including in the pontine neurons migrating in the anterior extramural migratory stream (AES). BrdU labeling and immunohistochemical studies suggest normal numbers of neurons begin their journey towards the ventral midline in the AES in the Largemyd mouse. However, migration stalls and PN neurons fail to reach the midline, surviving as ectopic clusters of cells located under the pial surface dorsally and laterally to where they normally would finish their migration near the ventral midline. Stalling of PN neurons at this location is also observed in other migration disorders in mice. These observations suggest that glycan‐dependent dystroglycan interactions are required for PN neurons to correctly respond to signals at this important migrational checkpoint.
Blockade of glucocorticoid receptors rapidly restores hippocampal CA1 synaptic plasticity after exposure to chronic stress
Authors: Krugers H. J. , Goltstein P. M. , Van Der Linden S. , Joëls M.
Published: June 2006

Prolonged exposure to stressful events has been reported to inhibit the ability of hippocampal synapses to increase their synaptic efficacy. Here we tested if these effects could be prevented by blocking activation of glucocorticoid receptors during the last 4 days of the stress paradigm. In order to address this question, animals were exposed to 21 days of variable and inescapable stressors. Handled animals served as controls. During the last 4 days of the stress regime, animals were treated with the glucocorticoid receptor antagonist RU486. We found that 1 day after the last stressor, synaptic plasticity in the CA1 area of hippocampal slices is impaired in chronically stressed animals. Importantly, treating chronically stressed animals with RU486 for 4 days completely prevented this decrease in synaptic potentiation; RU486 treatment of handled controls did not affect potentiation. Treating hippocampal slices from control animals with high levels of corticosterone also impaired synaptic plasticity; this effect was similar for untreated and RU486‐treated animals. Treating slices from chronically stressed animals with corticosterone did not further decrease synaptic plasticity. These data indicate that 4 days blockade of the glucocorticoid receptor, during a stress regime, is sufficient to fully restore synaptic plasticity.
Infralimbic cortex projects to all parts of the pontine and medullary lateral tegmental field in cat
Authors: Kuipers Rutger , Mensinga Gabe M. , Boers José , Klop Esther Marije , Holstege Gert
Published: June 2006

The infralimbic cortex (ILc) in cat is the ventralmost part of the anterior cingulate gyrus. The ILc, together with the amygdala, bed nucleus of the stria terminalis and lateral hypothalamus, is involved in the regulation of fear behavior. The latter three structures are thought to take part in triggering the fear response by means of their projections to the pontine and medullary lateral tegmental field (LTF). The LTF is a large region extending from the parabrachial nuclei rostrally to the spinal cord caudally. It contains almost all the premotor interneurons for the brainstem and for some upper spinal cord motoneurons innervating the muscles of face, head and throat. The question is whether ILc also projects to the LTF. Such a pathway would allow the ILc to influence the fear response by acting directly on these premotor interneurons. Anterograde tracer injections were made in the medial surface of the cortex in four cats. Only when the injection sites involved ILc were anterogradely labeled fibers observed throughout the rostrocaudal extent of the LTF. To verify whether these projections indeed originated from ILc, in two other cases retrograde tracer injections were made in the pontomedullary LTF. The results showed many retrogradely labeled neurons in ILc, but none in adjacent cortical regions. These results show that the ILc projects to the LTF in cat and can possibly modulate the fear response not only via indirect but also via direct routes to the premotor interneurons in the brainstem.
Calcium‐induced calcium release in rod photoreceptor terminals boosts synaptic transmission during maintained depolarization
Authors: Cadetti Lucia , Bryson Eric J. , Ciccone Cory A. , Rabl Katalin , Thoreson Wallace B.
Published: June 2006

We examined the contribution of calcium‐induced calcium release (CICR) to synaptic transmission from rod photoreceptor terminals. Whole‐cell recording and confocal calcium imaging experiments were conducted on rods with intact synaptic terminals in a retinal slice preparation from salamander. Low concentrations of ryanodine stimulated calcium increases in rod terminals, consistent with the presence of ryanodine receptors. Application of strong depolarizing steps (−70 to −10 mV) exceeding 200 ms or longer in duration evoked a wave of calcium that spread across the synaptic terminals of voltage‐clamped rods. This secondary calcium increase was blocked by high concentrations of ryanodine, indicating it was due to CICR. Ryanodine (50 µm) had no significant effect on rod calcium current (Ica) although it slightly diminished rod light‐evoked voltage responses. Bath application of 50 µm ryanodine strongly inhibited light‐evoked currents in horizontal cells. Whether applied extracellularly or delivered into the rod cell through the patch pipette, ryanodine (50 µm) also inhibited excitatory post‐synaptic currents (EPSCs) evoked in horizontal cells by depolarizing steps applied to rods. Ryanodine caused a preferential reduction in the later portions of EPSCs evoked by depolarizing steps of 200 ms or longer. These results indicate that CICR enhances calcium increases in rod terminals evoked by sustained depolarization, which in turn acts to boost synaptic exocytosis from rods.
Selective excitotoxic lesions of the hippocampus and basolateral amygdala have dissociable effects on appetitive cue and place conditioning based on path integration in a novel Y‐maze procedure
Authors: Ito Rutsuko , Robbins Trevor W. , McNaughton Bruce L. , Everitt Barry J.
Published: June 2006

The hippocampus and amygdala are thought to be functionally distinct components of different learning and memory systems. This functional dissociation has been particularly apparent in pavlovian fear conditioning, where the integrity of the hippocampus is necessary for contextual conditioning, and of the amygdala for discrete cue conditioning. Their respective roles in appetitive conditioning, however, remain equivocal mainly due to the lack of agreement concerning the operational definition of a ‘context’. The present study used a novel procedure to measure appetitive conditioning to spatial context or to a discrete cue. Following selective excitotoxic lesions of the hippocampus (HPC) or basolateral amygdala (BLA), rats were initially trained to acquire discrete CS‐sucrose conditioning in a Y‐maze apparatus with three topographically identical chambers, the chambers discriminated only on the basis of path integration. The same group of animals then underwent ‘place/contextual conditioning’ where the CS presented in a chamber assigned as the positive chamber was paired with sucrose, but the same CS presented in either of the other two chambers was not. Thus, spatial context was the only cue that the animal could use to retrieve the value of the CS. HPC lesions impaired the acquisition of conditioned place preference but facilitated the acquisition of cue conditioning, while BLA lesions had the opposite effect, retarding the acquisition of cue conditioning but leaving the acquisition of conditioned place preference intact. Here we provide strong support for the notion that the HPC and BLA subserve complementary and competing roles in appetitive cue and contextual conditioning.
Analysis of population genetic structure of two closely related tortricid species of economic importance on macadamias and litchis in South Africa
Authors: Timm A. E. , Geertsema H. , Warnich L.
Published: June 2006

Abstract 

The macadamia nut borer Thaumatotibia (Cryptophlebia) batrachopa and the litchi moth Cryptophlebia peltastica are Afrotropical species causing extensive damage to cultivated macadamias and litchis in the northernmost provinces in South Africa. Cryptophlebia peltastica also occurs as natural populations throughout the country.

To analyse the population genetic structure of the two species, amplified fragment length polymorphism analysis was conducted. Patterns of genetic diversity in C. peltastica populations in the Mpumalanga province, where the species is controlled, were compared with those in the Western Cape, where populations occur under natural conditions.

Gene diversity was high within T. batrachopa populations (H = 0.2219) with significant genetic differentiation among populations (Gst = 0.358). Cluster analysis showed that geographical populations were closely related and extensive divergence was found over local scales.

Similar to that of T. batrachopa, genetic diversity and population differentiation was high within both C. peltastica Mpumalanga and Western Cape populations (H = 0.1906 and 0.1687 and Gst = 0.4124 and 0.3799, respectively).

It is suggested that the population genetic structure of both species is influenced by their limited ability to disperse. In addition, chemical control of C. peltastica in the Mpumalanga province has not succeeded in reducing the population size, but the C. peltastica population subdivision in the Western Cape may be influenced by the limited distribution of host plants in this region.
Output of the Spanish Cortes (1979–2000): A case of adaptation to party government
Authors: DE DIOS MANUEL SANCHEZ
Published: June 2006

Abstract.  This article considers the activity of the Spanish Cortes in law production and the control of the executive during the six parliaments of the democratic government. It mainly examines the output of the lower chamber due to the asymmetrical bicameralism and weak status of the Senate. In Spain, the legislative output has been dependent on different situations of party government. In general terms, the Cortes have been always very active in controlling the executive and its participation in law‐making was highly relevant when there was a minority government. Because parties are central actors in parliament and due to the strong party discipline in the Spanish case, the author mainly studied parliament output from the viewpoint of strategies of opposition parties. Sometimes parties behaved in parliament procedures in a competitive way, while in others they behave cooperatively. There was a great variety of patterns of strategic behaviour on account of the different situations of party government and the diverse opposition parties. Half of the parliaments had minority governments in which minority parties played a very important role by supporting the government in parliament; however, the main opposition party was never the same since there were two changes of government.
Organizational Silence and Hidden Threats to Patient Safety
Authors: Henriksen Kerm , Dayton Elizabeth
Published: June 2006

Organizational silence refers to a collective‐level phenomenon of saying or doing very little in response to significant problems that face an organization. The paper focuses on some of the less obvious factors contributing to organizational silence that can serve as threats to patient safety. Converging areas of research from the cognitive, social, and organizational sciences and the study of sociotechnical systems help to identify some of the underlying factors that serve to shape and sustain organizational silence. These factors have been organized under three levels of analysis: (1) individual factors, including the availability heuristic, self‐serving bias, and the status quo trap; (2) social factors, including conformity, diffusion of responsibility, and microclimates of distrust; and (3) organizational factors, including unchallenged beliefs, the good provider fallacy, and neglect of the interdependencies. Finally, a new role for health care leaders and managers is envisioned. It is one that places high value on understanding system complexity and does not take comfort in organizational silence.
Struggling to Invent High‐Reliability Organizations in Health Care Settings: Insights from the Field
Authors: Dixon Nancy M. , Shofer Marjorie
Published: June 2006

The Mission of the Agency for Healthcare Research and Quality (AHRQ) has been to support and conduct health services research and to disseminate those research findings. Recently the Agency has changed its mission to: “Improving the quality, safety, efficiency and effectiveness of health care for all Americans.” For agency personnel working with the topic of patient safety, that change has created a need to develop greater awareness of the current patient safety initiatives underway at leading health care systems in order to determine where AHRQ might best play a role in helping these systems more rapidly adopt new practices to improve patient safety.

In order to make that determination, AHRQ conducted a customer needs assessment of leaders in selected health care systems, asking them questions about their current implementation initiatives and their perceived needs for continued implementation of patient safety initiatives. Although not designed or conducted as a research study, the hour‐long interviews produced rich insights into the implementation efforts of patient safety initiatives.

The senior leaders interviewed in each of the health care systems, described implementing patient safety initiatives on multiple fronts—in some systems as many as 15 initiatives were underway. As the number of initiatives attests, there was no lack of knowledge about what patient safety practices should be implemented (CPOE, rapid response teams, reduction in surgical site infections) rather the major struggle these health care systems faced was the “how to” of implementation. Most initiatives were only newly begun, so these leaders were not yet confident about what they had learned from these efforts or whether they could be sustained over time. These health care systems drew many of the ideas for initiatives from outside of health care, for example, the nuclear power industry or aviation. The executives expressed concern about a number of issues including: how patient safety initiatives should be sequenced, the lack of benchmarking data to measure their systems against and the pressing need for IT standardization.

The insights from this customer needs assessment revealed a wealth of implementation knowledge in the field and has led AHRQ to create an opportunity for leading edge health care systems to learn from each other via learning networks.
How Much Risk Pooling Is There in the Individual Insurance Market?
Authors: Marquis M. Susan , Buntin Melinda Beeuwkes
Published: June 2006

Objective. To examine how much pooling of risks occurs among potential purchasers in the individual market, how much pooling occurs among those who purchase coverage, and whether there is greater pooling among longer‐term enrollees.

Data Sources. The data are administrative records for enrollees in individual insurance plans in California in 2001, and from a survey of Californians enrolled in the individual insurance market and the uninsured.

Study Design. Logit models were estimated for 5 health outcome measures to compare the insured and uninsured after adjusting for other factors that affect insurance status and health. Multivariate models were also estimated to explore the relationship between health and three measures of pooling in the market: plan type, pricing tier, and the actuarially adjusted premium paid by the enrollee.

Principal Findings. Those who purchase individual health insurance are in better health than those who remain uninsured. On the other hand, a large share of people with health problems does obtain individual insurance. The distribution of subscribers across plan type and pricing tier varies with their health status. Those in poor health are less likely to purchase low benefit plans. There is less separation of risks for those who become sick after enrollment based on the measure of pricing tier. The distribution of subscribers across plan type for those who have health problems at enrollment and those who become sick differs, but so does the distribution of those who become sick and those who remain healthy.

Conclusions. Despite small differences among the healthy and sick, our results support the conclusion that there is considerable risk pooling in the individual market. To some extent, this pooling occurs because underwriting happens at the time people enroll and there is greater pooling among those who become sick than those who enroll sick. Our results however suggest that health savings accounts may further fragment the market.
Provider Attitudes toward Pay‐for‐Performance Programs: Development and Validation of a Measurement Instrument
Authors: Meterko Mark , Young Gary J. , White Bert , Bokhour Barbara G. , Burgess James F. , Berlowitz Dan , Guldin Matthew R. , Nealon Seibert Marjorie
Published: June 2006

Objective. To develop an instrument for assessing physician attitudes toward quality incentive programs, and to assess its reliability and validity.

Data Sources. Study involved primary data collection. A 40‐item paper and pencil survey of primary care physicians in Rochester, New York, and Massachusetts was conducted between May 2004 and December 2004. Seven‐hundred and ninety‐eight completed questionnaires were received, representing a response rate of 32 percent (798/2,497).

Study Design. Based on an extensive review of the literature and discussions with experts in the field, we developed a conceptual framework representing the features of pay‐for‐performance (P4P) programs hypothesized to affect physician behavior in that context. A draft questionnaire was developed based on that conceptual model and pilot tested in three groups of physicians. The questionnaire was modified based on the physician feedback, and the revised version was distributed to 2,497 primary care physicians affiliated with two of the seven sites participating in Rewarding Results, a national evaluation of quality target and financial incentive programs.

Data Collection. Respondents were randomly divided into a derivation and a validation sample. Exploratory factor analysis was applied to the responses of the derivation sample. Those results were used to create scales in the validation sample, and these were then subjected to multitrait analysis (MTA). One scale representing physicians' perception of the impact of P4P on their clinical practice was regressed on the other scales as a test of construct validity.

Principal Findings. Seven constructs were identified and demonstrated substantial convergent and discriminant validity in the MTA: awareness and understanding, clinical relevance, cooperation, unintended consequences, control, financial salience, and impact. Internal consistency reliabilities (Cronbach's α coefficients) ranged from 0.50 to 0.80. A statistically significant 25 percent of the variation in perceived impact was accounted for by physician perceptions of the other six characteristics of P4P programs.

Conclusions. It is possible to identify and measure the key salient features of P4P programs using a valid and reliable 26‐item survey. This instrument may now be used in further studies to better understand the impact of P4P programs on physician behavior.