bluuebunny/crossref_metadata_2025 huggingface dataset:
Prefrontal and amygdala volumes are related to adolescents' affective behaviors during parent–adolescent interactions
Authors: Whittle Sarah , Yap Marie B. H. , Yücel Murat , Fornito Alex , Simmons Julian G. , Barrett Anna , Sheeber Lisa , Allen Nicholas B.
Published: February 2008

Adolescence is a key period for the development of brain circuits underlying affective and behavioral regulation. It remains unclear, however, whether and how adolescent brain structure influences day-to-day affective behavior. Because of significant changes in the nature of family relations that also typically occur during adolescence, parent–child interactions provide a meaningful context where affective behavior and its regulation may be assessed. In a sample of 137 early adolescents, we investigated the relationship between aspects of the adolescents' brain structure and their affective behavior as assessed during observation of parent–child interactions. We found a significant positive association between volume of the amygdala and the duration of adolescent aggressive behavior during these interactions. We also found male-specific associations between the volume of prefrontal structures and affective behavior, with decreased leftward anterior paralimbic cortex volume asymmetry associated with increased duration of aggressive behavior, and decreased leftward orbitofrontal cortex volume asymmetry associated with increased reciprocity of dysphoric behavior. These findings suggest that adolescent brain structure is associated with affective behavior and its regulation in the context of family interactions, and that there may be gender differences in the neural mechanisms underlying affective and behavioral regulation during early adolescence. Particularly as adolescence marks a period of rapid brain maturation, our findings have implications for mental health outcomes that may be revealed later along the developmental trajectory.
Both ovarian hormones estrogen and progesterone are necessary for hormonal mammary carcinogenesis in ovariectomized ACI rats
Authors: Blank Edward W. , Wong Po-Yin , Lakshmanaswamy Rajkumar , Guzman Raphael , Nandi Satyabrata
Published: February 2008

August–Copenhagen–Irish (ACI) rats are unique in that the ovary-intact females develop high incidence of mammary cancers induced solely by hormones upon prolonged exposure to high levels of estrogen alone. Studies have also shown that such prolonged exposure to high-dose estrogen results in human-like aneuploid mammary cancers in ovary-intact ACI rats. To determine the role of progesterone in mammary carcinogenesis, six-week-old intact and ovariectomized ACI rats were continuously exposed to low- and high-dose estrogen alone, progesterone alone, low-dose estrogen plus progesterone, and ovariectomized ACI rats with high-dose estrogen plus progesterone. Also, ovariectomized ACI rats were treated with high-dose estrogen plus progesterone plus testosterone to determine the role of the androgen, testosterone, if any, in hormonal mammary carcinogenesis. The results indicate that continuous exposure to high, but not low, concentrations of estrogen alone can induce mammary carcinogenesis in intact but not in ovariectomized rats. Mammary carcinogenesis in ovariectomized ACI rats requires continuous exposure to high concentrations of estrogen and progesterone. The addition of testosterone propionate does not affect tumor incidence in such rats. These results suggest that both ovarian hormones estrogen and progesterone are necessary for mammary carcinogenesis induced solely by hormones in ovariectomized ACI rats. Our results are in agreement with the Women's Health Initiative studies, where treatment of postmenopausal women with estrogen (ERT) alone did not increase the risk of breast cancer, but estrogen and progesterone (HRT) did.
Interaction with factor inhibiting HIF-1 defines an additional mode of cross-coupling between the Notch and hypoxia signaling pathways
Authors: Zheng Xiaofeng , Linke Sarah , Dias José M. , Zheng Xiaowei , Gradin Katarina , Wallis Tristan P. , Hamilton Brett R. , Gustafsson Maria , Ruas Jorge L. , Wilkins Sarah , Bilton Rebecca L. , Brismar Kerstin , Whitelaw Murray L. , Pereira Teresa , Gorman Jeffrey J. , Ericson Johan , Peet Daniel J. , Lendahl Urban , Poellinger Lorenz
Published: February 2008

Cells adapt to hypoxia by a cellular response, where hypoxia-inducible factor 1α (HIF-1α) becomes stabilized and directly activates transcription of downstream genes. In addition to this “canonical” response, certain aspects of the pathway require integration with Notch signaling, i.e., HIF-1α can interact with the Notch intracellular domain (ICD) to augment the Notch downstream response. In this work, we demonstrate an additional level of complexity in this cross-talk: factor-inhibiting HIF-1 (FIH-1) regulates not only HIF activity, but also the Notch signaling output and, in addition, plays a role in how Notch signaling modulates the hypoxic response. We show that FIH-1 hydroxylates Notch ICD at two residues (N
1945
and N
2012
) that are critical for the function of Notch ICD as a transactivator within cells and during neurogenesis and myogenesis
in vivo
. FIH-1 negatively regulates Notch activity and accelerates myogenic differentiation. In its modulation of the hypoxic response, Notch ICD enhances recruitment of HIF-1α to its target promoters and derepresses HIF-1α function. Addition of FIH-1, which has a higher affinity for Notch ICD than for HIF-1α, abrogates the derepression, suggesting that Notch ICD sequesters FIH-1 away from HIF-1α. In conclusion, the data reveal posttranslational modification of the activated form of the Notch receptor and an intricate mode of cross-coupling between the Notch and hypoxia signaling pathways.
A GATA-1-regulated microRNA locus essential for erythropoiesis
Authors: Dore Louis C. , Amigo Julio D. , dos Santos Camila O. , Zhang Zhe , Gai Xiaowu , Tobias John W. , Yu Duonan , Klein Alyssa M. , Dorman Christine , Wu Weisheng , Hardison Ross C. , Paw Barry H. , Weiss Mitchell J.
Published: February 2008

MicroRNAs (miRNAs) control tissue development, but their mechanism of regulation is not well understood. We used a gene complementation strategy combined with microarray screening to identify miRNAs involved in the formation of erythroid (red blood) cells. Two conserved miRNAs,
miR 144
and
miR 451
, emerged as direct targets of the critical hematopoietic transcription factor GATA-1.
In vivo
, GATA-1 binds a distal upstream regulatory element to activate RNA polymerase II-mediated transcription of a single common precursor RNA (pri-miRNA) encoding both mature miRNAs. Zebrafish embryos depleted of
miR 451
by using antisense morpholinos form erythroid precursors, but their development into mature circulating red blood cells is strongly and specifically impaired. These results reveal a miRNA locus that is required for erythropoiesis and uncover a new regulatory axis through which GATA-1 controls this process.
Chromatid cohesion defects may underlie chromosome instability in human colorectal cancers
Authors: Barber Thomas D. , McManus Kirk , Yuen Karen W. Y. , Reis Marcelo , Parmigiani Giovanni , Shen Dong , Barrett Irene , Nouhi Yasaman , Spencer Forrest , Markowitz Sanford , Velculescu Victor E. , Kinzler Kenneth W. , Vogelstein Bert , Lengauer Christoph , Hieter Philip
Published: February 2008

Although the majority of colorectal cancers exhibit chromosome instability (CIN), only a few genes that might cause this phenotype have been identified and no general mechanism underlying their function has emerged. To systematically identify somatic mutations in potential CIN genes in colorectal cancers, we determined the sequence of 102 human homologues of 96 yeast CIN genes known to function in various aspects of chromosome transmission fidelity. We identified 11 somatic mutations distributed among five genes in a panel that included 132 colorectal cancers. Remarkably, all but one of these 11 mutations were in the homologs of yeast genes that regulate sister chromatid cohesion. We then demonstrated that down-regulation of such homologs resulted in chromosomal instability and chromatid cohesion defects in human cells. Finally, we showed that down-regulation or genetic disruption of the two major candidate CIN genes identified in previous studies (
MRE11A
and
CDC4
) also resulted in abnormal sister chromatid cohesion in human cells. These results suggest that defective sister chromatid cohesion as a result of somatic mutations may represent a major cause of chromosome instability in human cancers.
Hypothalamic neurodegeneration and adult-onset obesity in mice lacking the
Ubb
polyubiquitin gene
Authors: Ryu Kwon-Yul , Garza Jacob C. , Lu Xin-Yun , Barsh Gregory S. , Kopito Ron R.
Published: February 2008

Nearly all neurodegenerative diseases are associated with abnormal accumulation of ubiquitin (Ub) conjugates within neuronal inclusion bodies. To directly test the hypothesis that depletion of cellular Ub is sufficient to cause neurodegeneration, we have disrupted
Ubb
, one of four genes that supply Ub in the mouse. Here, we report that loss of
Ubb
led to a progressive degenerative disorder affecting neurons within the arcuate nucleus of the hypothalamus. This neurodegenerative cytopathology was accompanied by impaired hypothalamic control of energy balance and adult-onset obesity.
Ubb
was highly expressed in vulnerable hypothalamic neurons and total Ub levels were selectively reduced in the hypothalamus of
Ubb
-null mice. These findings demonstrate that maintenance of adequate supplies of cellular Ub is essential for neuronal survival and establish that decreased Ub availability is sufficient to cause neuronal dysfunction and death.
Book Reviews
Authors: Smith Hans-jørgen
Published: February 2008

Optical Coherence Tomography in Cardiovascular Research. Edited by E. Regar, A. M. G. J. van Leeuwen, & P. W. Serruys. Abingdon, UK: Informa Healthcare, 2007. ISBN: 1-84184-611-2. 338 pages. Price hardcover: USD 290
Book Reviews
Authors: Skaane Per
Published: February 2008

Breast Cancer: Early Detection with Mammography. Casting Type Calcifications: Sign of a Subtype with Deceptive Features. By L. Tabar, T. Tot, & P. B. Dean. Stuttgart and New York: Thieme Verlag, 2007. ISBN: 978-3-13-135391-7. 280 pages, 900 figures. Price hardcover: EUR 99.95
Book Reviews
Authors: Witwit Alaa Kasid
Published: February 2008

Essential Radiology: Clinical Presentation, Pathophysiology, Imaging. 2nd edition. By R. B. Gunderman. Series edited by T. Hiscock. New York, Thieme Medical Publishers, 2006 ISBN: 1-58890-082-7 (the Americas). ISBN: 3-13-110472-4 (rest of the world). 354 pages. Price paperback: GBP 40.00
Incidence of ventricular fibrillation during left coronary arteriography in pigs: comparison of a solution of the nonionic dimer iodixanol with solutions of five different nonionic monomers
Authors: Chai C. M. , Karlsson J. O. G. , Almén T.
Published: February 2008

Background: Solutions of iodine contrast media (CM) used for selective coronary arteriography (CA) should have minimal propensity to cause ventricular fibrillation (VF). Commonly used CM for CA are nonionic monomers or dimers.

Purpose: To compare VF propensity of ready-to-use solutions of one nonionic dimer, iodixanol, and five nonionic monomers, iobitridol, iopamidol, iomeprol, iopromide, and ioversol.

Material and Methods: Twenty milliliters of each CM was injected into the left coronary artery (LCA) through an inflated balloon catheter (0.5 ml/s) in 14 pigs; the longest period of injection was 40 s. If VF occurred before 40 s, the injection was stopped and the heart was defibrillated. After VF, there was a delay of 40 min before the next injection. Hemodynamic parameters and vector electrocardiography (VECG) were monitored. A CM with a lower frequency of VF and a longer period between start of injection and start of VF was considered to have a lower VF propensity.

Results: Following 14 injections, each of the five nonionic monomers caused 14 VF, whereas iodixanol caused three VF ( P<0.01). When VF occurred after iodixanol, it occurred later than after the other CM ( P<0.001). Iodixanol caused less prolongation in QRS time ( P<0.01) and QTc time ( P<0.05) than the other CM. Prolongations in QRS and QTc times caused by CM parallel the VF propensities of the CM.

Conclusion: Ready-to-use solutions of the dimer iodixanol have lower VF propensity than solutions of the five monomeric CM. This is related to the fact that the solutions of the dimer iodixanol have lower osmolality, higher viscosity, and higher concentrations of NaCl and CaCl2 than solutions of the five monomers.
Anterior dynamic ultrasound and graf's examination in neonatal hip instability
Authors: Finnbogason T. , Jorulf H. , Söderman E. , Rehnberg L.
Published: February 2008

Background: Discrepancy between neonatal hip morphology and stability has been reported in the literature. Comparative ultrasound studies on this issue are limited.

Purpose: To compare neonatal hip instability, as assessed by dynamic ultrasound and clinical examination, with acetabular morphology, as assessed by Graf's method.

Material and Methods: 536 newborn infants with clinical signs of hip instability, ambiguous findings at clinical hip examination, or positive risk factors for DDH were investigated with two ultrasound methods, the Graf method and anterior dynamic ultrasound, at an average age of 12 days. The hips were allocated to three groups according to the Graf result: A, normal (type Ia and b); B, borderline or immature (type IIa); and C, pathologic (type IIc and worse). Graf examination was compared with two diagnostic tests for instability, namely clinical examination by senior pediatric orthopedists and anterior dynamic ultrasound.

Results: According to Graf's method, 77% of the hips were normal, 20% borderline/immature, and 3% pathologic. On clinical hip examination, 82% were stable, 14% unstable, and 4% dislocatable. The dynamic ultrasound outcome was 88% stable hips, 10% unstable, and 2% dislocatable. Of the hips considered unstable or dislocatable on dynamic ultrasound, 21% had normal (type I) and 66% immature acetabular morphology according to the Graf method. Of the hips that were stable on dynamic ultrasound, only one (0.1%) was dysplastic according to the Graf method. Graf's examination showed the smallest number of normal hips, but also the fewest pathologic hips, with many indeterminate results that needed follow-up.

Conclusion: Acetabular morphology correlated better to stability as assessed by dynamic ultrasound than to the clinical examination results, with fair to moderate agreement. Graf's examination resulted in a large number of indeterminate results that needed follow-up, but when used as the sole criterion for deciding treatment did not lead to a higher treatment rate than when the decision was based on clinical hip examination.
Ergosterol promotes pheromone signaling and plasma membrane fusion in mating yeast
Authors: Jin Hui , McCaffery J. Michael , Grote Eric
Published: February 2008

Ergosterol depletion independently inhibits two aspects of yeast mating: pheromone signaling and plasma membrane fusion. In signaling, ergosterol participates in the recruitment of Ste5 to a polarized site on the plasma membrane. Ergosterol is thought to form microdomains within the membrane by interacting with the long acyl chains of sphingolipids. We find that although sphingolipid-free ergosterol is concentrated at sites of cell–cell contact, transmission of the pheromone signal at contact sites depends on a balanced ratio of ergosterol to sphingolipids. If a mating pair forms between ergosterol-depleted cells despite the attenuated pheromone response, the subsequent process of membrane fusion is retarded. Prm1 also participates in membrane fusion. However, ergosterol and Prm1 have independent functions and only prm1 mutant mating pairs are susceptible to contact-dependent lysis. In contrast to signaling, plasma membrane fusion is relatively insensitive to sphingolipid depletion. Thus, the sphingolipid-free pool of ergosterol promotes plasma membrane fusion.
Four key signaling pathways mediating chemotaxis in Dictyostelium discoideum
Authors: Veltman Douwe M. , Keizer-Gunnik Ineke , Van Haastert Peter J.M.
Published: February 2008

Chemotaxis is the ability of cells to move in the direction of an external gradient of signaling molecules. Cells are guided by actin-filled protrusions in the front, whereas myosin filaments retract the rear of the cell. Previous work demonstrated that chemotaxis of unpolarized amoeboid Dictyostelium discoideum cells is mediated by two parallel pathways, phosphoinositide-3-kinase (PI3K) and phospholipase A2 (PLA2). Here, we show that polarized cells exhibit very good chemotaxis with inhibited PI3K and PLA2 activity. Using genetic screens, we demonstrate that this activity is mediated by a soluble guanylyl cyclase, providing two signals. The protein localizes to the leading edge where it interacts with actin filaments, whereas the cyclic guanosine monophosphate product induces myosin filaments in the rear of the cell. We conclude that chemotaxis is mediated by multiple signaling pathways regulating protrusions at the front and rear of the cell. Cells that express only rear activity are polarized but do not exhibit chemotaxis, whereas cells with only front signaling are unpolarized but undergo chemotaxis.
Caspase-8 is activated by cathepsin D initiating neutrophil apoptosis during the resolution of inflammation
Authors: Conus Sébastien , Perozzo Remo , Reinheckel Thomas , Peters Christoph , Scapozza Leonardo , Yousefi Shida , Simon Hans-Uwe
Published: February 2008

In the resolution of inflammatory responses, neutrophils rapidly undergo apoptosis. We describe a new proapoptotic pathway in which cathepsin D directly activates caspase-8. Cathepsin D is released from azurophilic granules in neutrophils in a caspase-independent but reactive oxygen species–dependent manner. Under inflammatory conditions, the translocation of cathepsin D in the cytosol is blocked. Pharmacological or genetic inhibition of cathepsin D resulted in delayed caspase activation and reduced neutrophil apoptosis. Cathepsin D deficiency or lack of its translocation in the cytosol prolongs innate immune responses in experimental bacterial infection and in septic shock. Thus, we identified a new function of azurophilic granules that is in addition to their role in bacterial defense mechanisms: to regulate the life span of neutrophils and, therefore, the duration of innate immune responses through the release of cathepsin D.
Post‐translational modification of host proteins in pathogen‐triggered defence signalling in plants
Authors: STULEMEIJER IRIS J. E. , JOOSTEN MATTHIEU H. A. J.
Published: February 2008

Microbial plant pathogens impose a continuous threat to global food production. Similar to animals, an innate immune system allows plants to recognize pathogens and swiftly activate defence. To activate a rapid response, receptor‐mediated pathogen perception and subsequent downstream signalling depends on post‐translational modification (PTM) of components essential for defence signalling. We discuss different types of PTMs that play a role in mounting plant immunity, which include phosphorylation, glycosylation, ubiquitination, sumoylation, nitrosylation, myristoylation, palmitoylation and glycosylphosphatidylinositol (GPI)‐anchoring. PTMs are rapid, reversible, controlled and highly specific, and provide a tool to regulate protein stability, activity and localization. Here, we give an overview of PTMs that modify components essential for defence signalling at the site of signal perception, during secondary messenger production and during signalling in the cytoplasm. In addition, we discuss effectors from pathogens that suppress plant defence responses by interfering with host PTMs.
Transfer of isoniazid from circulation to breast milk in lactating women on chronic therapy for tuberculosis
Authors: Singh Neera , Golani Anil , Patel Zarine , Maitra Anurupa
Published: February 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Isoniazid is the most widely used first line antituberculosis drug.

• It is considered safe during lactation, but limited data are available on the transfer of isoniazid from circulation to milk in lactating women, which can provide an assessment of extent of exposure to the nursling.

WHAT THIS STUDY ADDS

• The study documents the transfer pattern and milk to plasma (M : P) ratio of isoniazid at a steady state.

• Peak plasma and milk concentrations of isoniazid were reached within 1 h and the projected exposure of the drug to the infant is much lower than the prophylactic dose, supporting its safety during breast feeding.

AIM

To determine milk to plasma (M : P) ratios and infant dose (absolute and relative) for isoniazid in lactating women on antituberculosis therapy.

METHODS

Concentrations of isoniazid in plasma and milk were measured in exclusively breast feeding women taking 300 mg day−1 as treatment for tuberculosis.

RESULTS

Peak plasma and milk concentrations of isoniazid were observed at 1 h. A mean M : PAUC value of 0.89 (95% CI 0.7, 1.1) was calculated for isoniazid from seven women over 24 h. The mean absolute infant dose was estimated to be 89.9 μg kg day−1 (95% CI 65.6, 114) and the relative infant dose was 1.2% of the weight adjusted maternal dose.

CONCLUSIONS

The mean relative dose of isoniazid (1.2%) transmitted to the infant via breast milk is below the 10% notional level of concern. These data suggest that isoniazid therapy is safe during breastfeeding.
Cord blood stem cell transplantation for haemoglobinopathies
Authors: Pinto Fernando O. , Roberts Irene
Published: February 2008

Despite improvements in supportive care, patients with β‐thalassaemia major or sickle cell disease (SCD) may benefit from haematopoietic stem cell transplantation at some point during their lives. Human leucocyte antigen (HLA)‐matched sibling bone marrow donors are not always available and alternative sources of stem cells have been sought, including related and unrelated donor cord blood transplants (CBT). The outcome of CBT from related donors for the treatment of both thalassaemia major and SCD is now approaching that for bone marrow transplantation, with around 90% of patients surviving disease‐free. The main complication is graft rejection, which may be reduced by increasing pretransplant immune suppression. Transplant‐related mortality following HLA‐identical matched related donor CBT is extremely low but is significant in the small series of unrelated and/or mis‐matched donor CBT. The principal limitation to extending the use of CB stem cells for the cure of haemoglobinopathies is the need to better understand the mechanisms of action and optimal conditioning regimens used to secure long‐term engraftment while minimizing morbidity and mortality. Further biological studies and clinical trials are needed to address this aim.
A single weekly dose of imatinib is sufficient to induce and maintain remission of chronic eosinophilic leukaemia in FIP1L1‐PDGFRA‐expressing patients
Authors: Helbig Grzegorz , Stella‐Hołowiecka Beata , Majewski Mirosław , Całbecka Małgorzata , Gajkowska Jolanta , Klimkiewicz Ryszard , Moskwa Andrzej , Grzegorczyk Janina , Lewandowska Monika , Hołowiecki Jerzy
Published: February 2008

Hypereosinophilic syndrome (HES) is defined as chronic, unexplained hypereosinophilia with organ involvement. A subset of HES patients presents an interstitial deletion in chromosome 4q12, which leads to the expression of an imatinib‐responsive fusion gene, FIP1L1‐PDGFRA. These patients are diagnosed as chronic eosinophilic leukaemia (CEL). We treated seven CEL and HES patients, six of which expressed FIP1L1‐PDGFRA, with imatinib using initial daily doses ranging from 100 to 400 mg. In a remission maintenance phase, the patients were treated with imatinib once weekly. All imatinib‐treated patients achieved a complete haematological remission (CHR), and five of the six patients with FIP1L1‐PDGFRA expression exhibited molecular remission. The decreased imatinib doses were as follows: 200 mg/week in three patients, 100 mg/week in two patients and 100 mg/d in the remaining two patients. For remission maintenance, imatinib doses were set at 100 mg/week in five patients and 200 mg/week in two patients. At a median follow‐up of 30 months all patients remained in CHR and FIP1L1‐PDGFRA expression was undetectable in five of the six FIP1L1‐PDGFRA‐expressing patients. These data suggest that a single weekly dose of imatinib is sufficient to maintain remission in FIP1L1‐PDGFRA‐ positive CEL patients.
Epicutaneous sensitization with Dermatophagoides farinae induces generalized allergic dermatitis and elevated mite‐specific immunoglobulin E levels in a canine model of atopic dermatitis
Authors: Pucheu‐Haston C. M. , Jackson H. A. , Olivry T. , Dunston S. M. , Hammerberg B.
Published: February 2008

Background
Atopic dermatitis (AD) is a cutaneous hypersensitivity associated with elevated levels of antigen‐specific IgE, commonly to house dust mites (HDMs). It remains controversial as to whether sensitization and clinical disease are induced by cutaneous exposure to HDM.

Objectives
The objectives of this study were to determine whether repeated applications of Dermatophagoides farinae slurry to intact skin of Maltese–Beagle atopic (MAB) dogs would result in the development of clinical signs or lesions resembling spontaneous canine AD, to determine whether repeated slurry applications would induce elevations in mite‐specific IgE and/or IgG, and to determine whether mite antigens could be demonstrated within the dermis of application sites.

Methods
Dogs received weekly slurry applications to the axilla and groin, and were patch tested at 120 days, or were patch tested at days 1, 60 and 120, but did not receive further slurry applications. Skin biopsies and serum samples were obtained on days 1, 60 and 120.

Results
Pruritic dermatitis was seen in all dogs by day 60. D. farinae‐specific IgE was elevated by day 60. Histologic examination of early application sites revealed mild, mononuclear perivascular dermatitis. Later application sites were characterized by a dense inflammatory infiltrate and oedema in both the dermis and the epidermis. Immunofluorescent staining confirmed the presence of D. farinae antigens in the dermis.

Conclusions
This study demonstrated that epicutaneous application of HDM slurry to MAB dogs results in elevations of HDM‐specific IgE, localized and generalized pruritic dermatitis resembling spontaneous canine AD, and histologic changes typical of IgE‐driven inflammation. We feel that these results suggest that epicutaneous exposure to allergen may play an important role during both the sensitization and the perpetuation of AD, and provide support for the use of a canine model in the investigation of the pathogenesis of AD.
Trigeminal nasal‐specific neurons respond to nerve growth factor with substance‐P biosynthesis
Authors: Mingomataj E. , Dinh Q. T. , Groneberg D. , Feleszko W. , Schmeck B. , Joachim R. , Noga O. , Nagel S. , Klapp B. F. , Fischer A.
Published: February 2008

Background
Nerve growth factor (NGF) has been found to induce substance‐P biosynthesis in large‐diameter A‐fibres vagal airway neurons. However, the effect of NGF on trigeminal neurons innervating the nasal mucosa of the mouse has not been investigated so far.

Objective
NGF has been implicated in allergic diseases by modulating sensory nerves. Therefore, the present study investigated the effect of NGF on neuropeptides expression such as substance‐P and glutamate in nasal trigeminal neurons.

Methods
Using neuronal tracing in combination with double labelling immunohistochemistry the expression of substance‐P, glutamate and neurofilament protein 68‐kDa expression was examined in nasal‐specific trigeminal neurons of BALB/c‐mice.

Results
The numbers of Fast blue‐labelled trigeminal neurons expressing substance‐P were significantly increased after NGF exposure (NGF‐treated ganglia: 16.4 ± 0.6% vs. control: 7.0 ± 0.4%, P0.001). NGF treatment‐induced substance‐P biosynthesis in neurofilament‐positive (NGF‐treated ganglia: 8.6 ± 0.2% vs. control: 1.1 ± 0.2%, P0.001) as well as neurofilament‐negative (NGF‐treated ganglia: 7.8 ± 0.6% vs. control: 5.9 ± 0.4%, P=0.05) and non‐glutamatergic neurons (NGF‐treated ganglia: 11.8 ± 1.9% vs. control 1.1 ± 1.0%, P0.001) 24 h after NGF exposure.

Conclusion
Under normal conditions, substance‐P was expressed in nasal‐specific neurofilament‐negative, glutamatergic and C‐fibre neurons. Nasal‐specific trigeminal neurons respond to NGF treatment with substance‐P biosynthesis in non‐glutamatergic, neurofilament‐positive as well as ‐negative neurons. These findings suggest that nasal‐specific trigeminal neurons are composed of heterogenous subpopulations in relation to their peptide profiles and therefore may have different functions in neurogenic airway inflammation.
Where temperate meets tropical: multi‐factorial effects of elevated CO2, nitrogen enrichment, and competition on a mangrove‐salt marsh community
Authors: McKEE KAREN L. , ROOTH JILL E.
Published: February 2008

Our understanding of how elevated CO2 and interactions with other factors will affect coastal plant communities is limited. Such information is particularly needed for transitional communities where major vegetation types converge. Tropical mangroves (Avicennia germinans) intergrade with temperate salt marshes (Spartina alterniflora) in the northern Gulf of Mexico, and this transitional community represents an important experimental system to test hypotheses about global change impacts on critical ecosystems. We examined the responses of A. germinans (C3) and S. alterniflora (C4), grown in monoculture and mixture in mesocosms for 18 months, to interactive effects of atmospheric CO2 and pore water nitrogen (N) concentrations typical of these marshes. A. germinans, grown without competition from S. alterniflora, increased final biomass (35%) under elevated CO2 treatment and higher N availability. Growth of A. germinans was severely curtailed, however, when grown in mixture with S. alterniflora, and enrichment with CO2 and N could not reverse this growth suppression. A field experiment using mangrove seedlings produced by CO2‐ and N‐enriched trees confirmed that competition from S. alterniflora suppressed growth under natural conditions and further showed that herbivory greatly reduced survival of all seedlings. Thus, mangroves will not supplant marsh vegetation due to elevated CO2 alone, but instead will require changes in climate, environmental stress, or disturbance to alter the competitive balance between these species. However, where competition and herbivory are low, elevated CO2 may accelerate mangrove transition from the seedling to sapling stage and also increase above‐ and belowground production of existing mangrove stands, particularly in combination with higher soil N.
Probing surface plasmon fields by far‐field Raman imaging
Authors: LAURENT G. , FÉLIDJ N. , GRAND J. , AUBARD J. , LÉVI G. , HOHENAU A. , KRENN J. R. , AUSSENEGG F. R.
Published: February 2008

This article reports on the imaging of the surface plasmon fields of lithographically designed micrometre‐sized gold structures. We investigate rings made of disk‐shaped particles and individual crescent‐shaped particles. These structures are imaged with two techniques, dark field imaging of elastically scattered light and imaging the surface‐enhanced Raman scattering signal of methylene blue dye adsorbed onto the structures. Although elastically scattered light images result from the coherently summed contributions from all elementary scattering volumes, surface‐enhanced Raman scattering images reflect the optical near‐field intensity incoherently averaged over a surface area corresponding to the spatial resolution of the microscope objective. The combination of both imaging methods enables us to emphasize the role of plasmon coupling and antenna effect in the surface‐enhanced Raman scattering enhancement.
Broadband optical near‐field microscope for nanoscale absorption spectroscopy of organic materials
Authors: POMRAENKE R. , ROPERS C. , RENARD J. , LIENAU C. , LÜER L. , POLLI D. , CERULLO G.
Published: February 2008

Conjugated organic materials in the solid state are generally amorphous or polycrystalline, with local order only achieved in mesoscopic domains with size ranging from a few tens to a few hundreds of nanometres. Understanding the interplay between mesoscopic order and macroscopic behaviour of these materials calls for a spatially resolved study of their optical properties. Near‐field scanning optical microscopy allows one in principle to beat the diffraction limit in optical imaging. A quantitative measurement of nanoscale absorption spectra is, however, complicated by the difficulty of obtaining broadband near‐field illumination with sufficiently high intensity. Here we demonstrate a near‐field spectrometer with 100‐nm spatial resolution based on an ultrabroadband Ti : sapphire oscillator coupled to an aperture‐based near‐field scanning optical microscopy, enabling structural phase‐selective imaging of organic materials at the nanoscale. In polycrystalline phtalocyanine films we can distinguish between the crystalline and the amorphous phase, thus providing previously unavailable information on their mesoscopic texture.
Stress imagining of semiconductor surface by tip‐enhanced Raman spectroscopy
Authors: SAITO Y , MOTOHASHI M. , HAYAZAWA N. , KAWATA S.
Published: February 2008

Tip‐enhanced Raman imaging of strained silicon reveals the property of nanoscale stress imposed on the lattice. Our approach relies on the highly localized excitation provided by a metallized tip. Surface sensitive detections in nanoscale are realized by a reflection‐mode configuration combined with 442‐nm excitation and a silver‐coated silicon nitride tip. The background signals from an underlying silicon germanium layer and a tip are well suppressed. The quantitative stress analysis is made on the basis of the Raman shift of the Si–Si phonon mode. We succeeded in visualizing the localized stress with a spatial resolution down to 25 nm whereas a conventional micro Raman technique provides only a uniform image because of the averaging effect within a diffraction‐limited focused spot.
Optical near field dressed by localized and coherent phonons
Authors: TANAKA Y. , KOBAYASHI K.
Published: February 2008

We present a quantum‐field theoretical model to explain the experimentally suggested spatial localization of photons associated with the coherent state of phonons in an optical near‐field probe system. Considering the localized phonon modes due to the impurity in a one‐dimensional system, we have obtained the temporal evolution of the localization of photons, which depends on the photon–phonon coupling constant, as well as the hopping constant of photons. Numerical results show that photons move and localize at the impurity sites when the hopping constant is comparable to the photon–phonon coupling.
Individual gold dimers investigated by far‐ and near‐field imaging
Authors: LEREU A. L. , SANCHEZ‐MOSTEIRO G. , GHENUCHE P. , QUIDANT R. , VAN HULST N. F.
Published: February 2008

Plasmon resonances in 3D nanoparticle arrangements can produce strong localized optical fields, which are of importance for any application involving interaction of light with subwavelength volumes of matter down to the molecular level. In particular, remarkable field enhancement and confinement occur in a dimer geometry formed by two identical closely spaced particles. Although, recent advances in nanofabrication have rendered the fabrication of complex plasmon architectures more accessible, addressing their local fields in a nonperturbative fashion remains not straightforward, because metallic nanostructures are rather sensitive to their local environment. Here we study gold dimers fabricated by e‐beam lithography. Individual dimers are imaged both by far‐ and near‐field methods. First, the near‐field electromagnetic interaction in an ensemble of dimers is investigated by scattering spectroscopy, using dark field microscopy. Next, to probe their local field, we explore the luminescence of individual gold dimers utilizing a confocal microscope with single molecule detection sensitivity. We provide a statistical analysis of the dimer luminescence for different incident polarizations, with direct comparison to single particles (monomers). Finally, the near‐field transmission of the resonant dimers is mapped with a subwavelength resolution using polarized controlled near‐field scanning optical microscopy. Surprisingly, no clear evidence of the high mode density in the dimer gap is observed. This result may be attributed to the limited coupling of the field emitted by the aperture probe to the dimer mode.
Near‐field measurement of ZnS:Mn nanocrystal and bulk thin‐film electroluminescent devices
Authors: GRMELA L. , MACKU R. , TOMANEK P.
Published: February 2008

A near‐field study of the electro‐optical phenomena and aging characteristics of nanostructured and bulk ZnS:Mn alternating‐current thin‐film electro‐optical devices is presented. ZnS:Mn nanocrystals embedded in the glass matrices as well as ZnS:Mn thin‐film phosphors contain four different concentrations of Mn (from 0.05 to 1.0 mol%). The activator impurity in the phosphor influences the spectral properties and, to a large extent, the temporal properties of optical emission and an aging process of the devices. Therefore, a local photoluminescence and electroluminescence investigation using a scanning near‐field optical microscope technique is provided and the aging characteristics of ZnS:Mn nanocrystal structure also presented.
A metamaterial based on coupled metallic nanoparticles and its band‐gap property
Authors: ROCKSTUHL C. , SCHARF T.
Published: February 2008

The properties of an ensemble of densely packed metallic nanoparticles and the effective material properties of a metamaterial based on them are studied in detail using rigorous diffraction theory. We show that in the spectral vicinity of the plasmon resonance, the metamaterial shows a well‐defined Lorentzian resonance in its effective permittivity whereas the permeability is unaltered. The metamaterial shows a stop band in the spectral domain where the real part of the effective permittivity is negative. Modifying the effective properties of the metamaterial allows efficient tuning of the band‐gap properties. The implementation of the proposed approach towards a band‐gap metamaterial employing self‐organization in liquid crystals is discussed.
Raman and near‐field spectroscopic study on localized surface plasmon excitation from the 2D nanostructure of gold nanoparticles
Authors: HOSSAIN M. K. , SHIMADA T. , KITAJIMA M. , IMURA K. , OKAMOTO H.
Published: February 2008

We have studied electromagnetic field on the surface of two‐dimensional nanostructure of gold nanoparticles through two‐photon–induced photoluminescence images by using scanning near‐field optical microscope and far‐field surface‐enhanced Raman scattering measurements. The near‐field two‐photon–induced photoluminescence image shows that strong inhomogeneous enhancement in two‐photon–induced photoluminescence occurs over the two‐dimensional nanostructure, representing localized surface plasmon excitations. The results suggest that the local structure of the two‐dimensional nanostructure influences the distribution of localized surface plasmon excitation.
Hamilton–Jacobi approach to photon wave mechanics: near‐field aspects
Authors: KELLER O.
Published: February 2008

After having briefly reviewed the Hamilton–Jacobi theory of classical point‐particle mechanics, its extension to the quantum regime and the formal identity between the Hamilton–Jacobi equation for Hamilton's characteristic function and the eikonal equation of geometrical optics, an eikonal theory for free photons is established. The space‐time dynamics of the photon is described on the basis of the six‐component Riemann–Silberstein energy wave function. Form‐identical eikonal equations are obtained for the positive and negative helicity dynamics. Microscopic response theory is used to describe the linear photon–matter interaction. In the presence of matter the free‐photon concept is replaced by a quasi‐photon concept, and there is a quasi‐photon for each of the two helicity states. After having established integro–differential equations for the wave functions of the two quasi‐photons, the eikonal conditions for the quasi‐photons are determined. It appears that the eikonal condition contains complicated space integrals of the gradient of the eikonal over volumes of near‐field domain size. In these space integrals the dynamics of the electrons (matter particles) appears via transverse transition current densities between pairs of many‐body states. Generalized microscopic polarization and magnetization fields are introduced to establish the connection between the quasi‐photon and macroscopic eikonal theories.
Annular nanoantenna on fibre micro‐axicon
Authors: GROSJEAN T. , FAHYS A. , SUAREZ M. , CHARRAUT D. , SALUT R. , COURJON D.
Published: February 2008

In this paper, we propose to extend the concept of loop antenna to the optical domain. The aim is to develop a new generation of optical nanocollectors that are sensitive to specific electric or magnetic vectorial field components. For validating our approach, a preliminary one‐micron‐diameter gold nanoring is micromachined on the apex of a cone lens obtained from a tapered optical fibre. It is shown that such a nano‐object behaves as a nano‐antenna able to detect the longitudinal electric field from a Bessel beam in radial polarization and the longitudinal magnetic component from a Bessel beam in azimuthal polarization. In the latter case, the annular nano‐antenna exhibits the properties of an optical inductance.
Coupling efficiency of probes in emission‐mode scanning near‐field optical microscopy
Authors: ALVAREZ L. , XIAO M.
Published: February 2008

In scanning near‐field optical microscopy, a tapered fibre tip scans above the sample surface at nanometric distances. The fibre tip can be used either as a detector to receive the near‐field signal or as the light source to illuminate the sample or simultaneously for both purposes. When used as an emitter of light, the scanning near‐field optical microscopy is said to function in emission mode. In such emission mode, the light emitted by the probe interacts with the microscopic features on the sample surface, and the result of this interaction is focussed by means of a conventional microscope. In our present work, we concentrate on how the light is emitted from the fibre tip. The power emitted by the probe is critical because it is directly related to the power that reaches the detector and in turn to the resolution of the instrument. A typical probe is made of a tapered optical fibre coated with metal. For probes fabricated by etching, the taper angle is high and the radii of the core and cladding are constant. Thus, the probe can be crudely approximated by a circular aperture on top of a metal‐coated optical fibre end. It is interesting to study how the dielectric waveguide modes will couple into the metallic waveguide modes. In this work, a single mode excited in the dielectric waveguide is assumed, and calculations of the power transmitted through the aperture are carried out. A comparison between the power transmitted by different optical fibre modes and different optical fibre parameters is conducted, and the implications for the coupling efficiency of emission‐mode fibre tips are discussed.
The transcriptomics of life‐history trade‐offs in whitefish species pairs (Coregonussp.)
Authors: ST‐CYR J. , DEROME N. , BERNATCHEZ L.
Published: February 2008

Despite the progress achieved in elucidating the ecological mechanisms of adaptive radiation, there has been little focus on documenting the extent of adaptive differentiation in physiological functions during this process. Moreover, a thorough understanding of the genomic basis underlying phenotypic adaptive divergence is still in its infancy. One important evolutionary process for which causal genetic mechanisms are largely unknown pertains to life‐history trade‐offs. We analysed patterns of gene transcription in liver tissue of sympatric dwarf and normal whitefish from two natural lakes, as well as from populations reared in controlled environments, using a 16 006‐gene cDNA microarray in order to: (i) document the extent of physiological adaptive divergence between sympatric dwarf and normal species pairs, and (ii) explore the molecular mechanisms of differential life history trade‐offs between growth and survival potentially involved in their adaptive divergence. In the two natural lakes, 6.45% of significantly transcribed genes showed regulation either in parallel fashion (2.39%) or in different directions (4.06%). Among genes showing parallelism in regulation patterns, we observed a higher proportion of over‐expressed genes in dwarf relative to normal whitefish (70.6%). Patterns observed in controlled conditions were also generally congruent with those observed in natural populations. Dwarf whitefish consistently showed significant over‐expression of genes potentially associated with survival through enhanced activity (energy metabolism, iron homeostasis, lipid metabolism, detoxification), whereas more genes associated with growth (protein synthesis, cell cycle, cell growth) were generally down‐regulated in dwarf relative to normal whitefish. Overall, parallelism in patterns of gene transcription, as well as patterns of interindividual variation across controlled and natural environments, provide strong indirect evidence for the role of selection in the evolution of differential regulation of genes involving a vast array of potentially adaptive physiological processes between dwarf and normal whitefish. Our results also provide a first mechanistic, genomic basis for the observed trade‐off in life‐history traits distinguishing dwarf and normal whitefish species pairs, wherein enhanced survival via more active swimming, necessary for increased foraging and predator avoidance, engages energetic costs that translate into slower growth rate and reduced fecundity in dwarf relative to normal whitefish.
YcbX and yiiM, two novel determinants for resistance of Escherichia coli to N‐hydroxylated base analogues
Authors: Kozmin Stanislav G. , Leroy Prune , Pavlov Youri I. , Schaaper Roel M.
Published: February 2008

We have shown previously that lack of molybdenum cofactor (MoCo) in Escherichia coli leads to hypersensitivity to the mutagenic and toxic effects of N‐hydroxylated base analogues, such as 6‐N‐hydroxylaminopurine (HAP). However, the nature of the MoCo‐dependent mechanism is unknown, as inactivation of all known and putative E. coli molybdoenzymes does not produce any sensitivity. Presently, we report on the isolation and characterization of two novel HAP‐hypersensitive mutants carrying defects in the ycbX or yiiM open reading frames. Genetic analysis suggests that the two genes operate within the MoCo‐dependent pathway. In the absence of the ycbX‐ and yiiM‐dependent pathways, biotin sulfoxide reductase plays also a role in the detoxification pathway. YcbX and YiiM are hypothetical members of the MOSC protein superfamily, which contain the C‐terminal domain (MOSC) of the eukaryotic MoCo sulphurases. However, deletion of ycbX or yiiM did not affect the activity of human xanthine dehydrogenase expressed in E. coli, suggesting that the role of YcbX and YiiM proteins is not related to MoCo sulphuration. Instead, YcbX and YiiM may represent novel MoCo‐dependent enzymatic activities. We also demonstrate that the MoCo/YcbX/YiiM‐dependent detoxification of HAP proceeds by reduction to adenine.