bluuebunny/crossref_metadata_2025 huggingface dataset:
Differentiation-Dependent Expression of 17β-Hydroxysteroid Dehydrogenase, Type 10, in the Rodent Testis: Effect of Aging in Leydig Cells
Authors: Ivell Richard , Balvers Marga , Anand Ravinder J. K. , Paust Hans-Joachim , McKinnell Chris , Sharpe Richard
Published: March 2003

Expression of the new 17β-hydroxysteroid dehydrogenase (HSD), type 10 (17β-HSD-10), formerly known as endoplasmic reticulum-associated amyloid-binding protein, has been investigated in the testes of various mammals under normal and perturbed conditions. Results show that 17β-HSD-10 is a major product of both fetal and adult-type Leydig cells. In the former, protein persists until late in postnatal development; and in the short-day hamster model, it does not disappear when Leydig cells involute. During puberty in the rat, immunohistochemical staining for 17β-HSD-10 in adult-type Leydig cells first becomes evident on d 20, increasing to maximal staining intensity by d 35. In the rat, but not in the mouse or any other species examined, there is also staining in late spermatids. Examination of testes from rats subjected to perinatal treatment with either a GnRH antagonist or low and high doses of diethylstilbestrol revealed that expression of 17β-HSD-10 follows closely Leydig cell differentiation status, correlating with 3β-HSD expression in a previous study. In aging (23 months) rat testes, Leydig cell (but not germ cell) immunostaining for 17β-HSD-10 is markedly reduced. 17β-HSD-10 seems to preferentially convert 3α-androstanediol into dihydrotestosterone, and estradiol to estrone. Thus, perinatal expression of this enzyme in fetal Leydig cells may contribute to protecting these cells from estrogens and encourage androgen formation.
Loss ofEmx2function leads to ectopic expression ofWnt1in the developing telencephalon and cortical dysplasia
Authors: Ligon Keith L. , Echelard Yann , Assimacopoulos Stavroula , Danielian Paul S. , Kaing Sovann , Grove Elizabeth A. , McMahon Andrew P. , Rowitch David H.
Published: March 2003

Leptomeningeal glioneuronal heterotopias are a focal type of cortical dysplasia in which neural cells migrate aberrantly into superficial layers of the cerebral cortex and meninges. These heterotopias are frequently observed as microscopic abnormalities in the brains of individuals with central nervous system (CNS) malformations and epilepsy. Previous work has demonstrated that the function of Emx2, which encodes a homeodomain transcription factor, is essential for development of the cortical preplate, which gives rise to the marginal zone and subplate. However, transcriptional targets of EMX2 during CNS development are unknown. We report that leptomeningeal glioneuronal heterotopias form in Emx2–/– mice that are equivalent to human lesions. Additionally, we observed ectopic expression of Wnt1 in the embryonic roofplate organizer region and dorsal telencephalon. To determine the phenotypic consequences of such Wnt1 misexpression, we deleted a putative EMX2 DNA-binding site from the Wnt1 enhancer and used this to misexpress Wnt1 in the developing murine CNS. Heterotopias were detected in transgenic mice as early as 13.5 days postcoitum, consistent with a defect of preplate development during early phases of radial neuronal migration. Furthermore, we observed diffuse abnormalities of reelin- and calretinin-positive cell populations in the marginal zone and subplate similar to those observed in Emx2-null animals. Taken together, these findings indicate that EMX2 is a direct repressor of Wnt1 expression in the developing mammalian telencephalon. They further suggest that EMX2-Wnt1 interactions are essential for normal development of preplate derivatives in the mammalian cerebral cortex.
Mechanisms of pattern formation in development and evolution
Authors: Salazar-Ciudad Isaac , Jernvall Jukka , Newman Stuart A.
Published: March 2003

We present a classification of developmental mechanisms that have been shown experimentally to generate pattern and form in metazoan organisms. We propose that all such mechanisms can be organized into three basic categories and that two of these may act as composite mechanisms in two different ways. The simple categories are cell autonomous mechanisms in which cells enter into specific arrangements (`patterns') without interacting, inductive mechanisms in which cell communication leads to changes in pattern by reciprocal or hierarchical alteration of cell phenotypes (`states')and morphogenetic mechanisms in which pattern changes by means of cell interactions that do not change cell states. The latter two types of mechanism can be combined either morphostatically, in which case inductive mechanisms act first, followed by the morphogenetic mechanism, or morphodynamically, in which case both types of mechanisms interact continuously to modify each other's dynamics. We propose that this previously unexplored distinction in the operation of composite developmental mechanisms provides insight into the dynamics of many developmental processes. In particular, morphostatic and morphodynamic mechanisms respond to small changes in their genetic and microenvironmental components in dramatically different ways. We suggest that these differences in `variational properties' lead to morphostatic and morphodynamic mechanisms being represented to different extents in early and late stages of development and to their contributing in distinct ways to morphological transitions in evolution.
Parallel early development of zebrafish interrenal glands and pronephros:differential control bywt1andff1b
Authors: Hsu Hwei-Jan , Lin Guang , Chung Bon-chu
Published: March 2003

Steroids are synthesized mainly from the adrenal cortex. Adrenal deficiencies are often associated with problems related to its development,which is not fully understood. To better understand adrenocortical development, we studied zebrafish because of the ease of embryo manipulation. The adrenocortical equivalent in zebrafish is called the interrenal, because it is embedded in the kidney. We find that interrenal development parallels that of the embryonic kidney (pronephros). Primordial interrenal cells first appear as bilateral intermediate mesoderm expressing ff1b in a region ventral to the third somite. These cells then migrate toward the axial midline and fuse together. The pronephric primordia are wt1-expressing cells located next to the interrenal. They also migrate to the axial midline and fuse to become glomeruli at later developmental stages. Our gene knockdown experiments indicate that wt1 is required for its initial restricted expression in pronephric primordia, pronephric cell migration and fusion. wt1 also appears to be involved in interrenal development and ff1b expression. Similarly, ff1b is required for interrenal differentiation and activation of the differentiated gene, cyp11a1. Our results show that the zebrafish interrenal and pronephros are situated close together and go through parallel developmental processes but are governed by different signaling events.
Retinoic acid-induced developmental defects are mediated by RARβ/RXR heterodimers in the pharyngeal endoderm
Authors: Matt Nicolas , Ghyselinck Norbert B. , Wendling Olivia , Chambon Pierre , Mark Manuel
Published: March 2003

Fusion and hypoplasia of the first two branchial arches, a defect typically observed in retinoic acid (RA) embryopathy, is generated in cultured mouse embryos upon treatment with BMS453, a synthetic compound that exhibits retinoic acid receptor β (RARβ) agonistic properties in transfected cells. By contrast, no branchial arch defects are observed following treatment with synthetic retinoids that exhibit RARα or RARγ agonistic properties. The BMS453-induced branchial arch defects are mediated through RAR activation, as they are similar to those generated by a selective pan-RAR agonist, are prevented by a selective pan-RAR antagonist and cannot be mimicked by exposure to a pan-RXR agonist alone. They are enhanced in the presence of a pan-RXR agonist, and cannot be generated in Rarb-null embryos. Furthermore, they are accompanied, in the morphologically altered region, by ectopic expression of Rarb and of several other direct RA target genes. Therefore, craniofacial abnormalities characteristic of the RA embryopathy are mediated through ectopic activation of RARβ/RXR heterodimers, in which the ligand-dependent activity of RXR is subordinated to that of RARβ. Endodermal cells lining the first two branchial arches respond to treatment with the RARβ agonist, in contrast to neural crest cells and ectoderm, which suggests that a faulty endodermal regionalization is directly responsible for RA-induced branchial arch dysmorphologies. Additionally, we provide the first in vivo evidence that the synthetic RARβ agonist BMS453 exhibits an antagonistic activity on the two other RAR isotypes.
FRL-1, a member of the EGF-CFC family, is essential for neural differentiation inXenopusearly development
Authors: Yabe Shin-Ichiro , Tanegashima Kousuke , Haramoto Yoshikazu , Takahashi Shuji , Fujii Tomoyuki , Kozuma Siro , Taketani Yuji , Asashima Makoto
Published: March 2003

Recent studies indicate an essential role for the EGF-CFC family in vertebrate development, particularly in the regulation of nodal signaling. Biochemical evidence suggests that EGF-CFC genes can also activate certain cellular responses independently of nodal signaling. Here, we show that FRL-1, a Xenopus EGF-CFC gene, suppresses BMP signaling to regulate an early step in neural induction. Overexpression of FRL-1in animal caps induced the early neural markers zic3, soxD and Xngnr-1, but not the pan-mesodermal marker Xbra or the dorsal mesodermal marker chordin. Furthermore, overexpression of FRL-1 suppressed the expression of the BMP-responsive genes, Xvent-1 and Xmsx-1, which are expressed in animal caps and induced by overexpressed BMP-4. Conversely, loss of function analysis using morpholino-antisense oligonucleotides against FRL-1 (FRL-1MO)showed that FRL-1 is required for neural development. FRL-1MO-injected embryos lacked neural structures but contained mesodermal tissue. It was suggested previously that expression of early neural genes that mark the start of neuralization is activated in the presumptive neuroectoderm of gastrulae. FRL-1MO also inhibited the expression of these genes in dorsal ectoderm, but did not affect the expression of chordin, which acts as a neural inducer from dorsal mesoderm. FRL-1MO also inhibited the expression of neural markers that were induced by chordin in animal caps,suggesting that FRL-1 enables the response to neural inducing signals in ectoderm. Furthermore, we showed that the activation of mitogen-activated protein kinase by FRL-1 is required for neural induction and BMP inhibition. Together, these results suggest that FRL-1 is essential in the establishment of the neural induction response.
Mammary gland, limb and yolk sac defects in mice lackingTbx3,the gene mutated in human ulnar mammary syndrome
Authors: Davenport Todd G. , Jerome-Majewska Loydie A. , Papaioannou Virginia E.
Published: March 2003

Spontanteous mutations in the T-box gene TBX3, result in the human ulnar-mammary syndrome, a dominant developmental disorder characterized by abnormal forelimb and apocrine gland development. In order to develop a mouse model to study the role of this gene during development and disease, we produced a mutation in the mouse ortholog, Tbx3. The phenotype of the mutant mice verifies the role of this gene in limb and mammary gland development, and, in addition, reveals a previously unknown role for the gene in the yolk sac, a fetal membrane that is the site of hematopoiesis and is essential for survival during gestation. In homozygous mutant embryos, the yolk sac undergoes cell death and degeneration at midgestation and the fetuses die over a range of several days; none survive to birth. Tbx3 is the first T-box gene implicated in yolk sac development. Homozygous embryos show a deficiency of mammary gland induction, and exhibit both forelimb and hindlimb abnormalities. Although heterozygous mice, unlike their heterozygous human counterparts, have no apparent phenotype in limb or mammary gland, the homozygous defects in the development of these organs represent more severe manifestations of the defects characteristic of the ulnar-mammary syndrome.
A novel role for a nodal-related protein; Xnr3 regulates convergent extension movements via the FGF receptor
Authors: Yokota Chika , Kofron Matt , Zuck Mike , Houston Douglas W. , Isaacs Harry , Asashima Makoto , Wylie Chris C. , Heasman Janet
Published: March 2003

Convergent extension behaviour is critical for the formation of the vertebrate body axis. In Xenopus, components of the Wnt signaling pathway have been shown to be required for convergent extension movements but the relationship between cell fate and morphogenesis is little understood. We show by loss of function analysis that Xnr3 activates Xbra expression through FGFR1. We show that eFGF activity is not essential in the pathway, and that dishevelled acts downstream of Xnr3 and not in a parallel pathway. We provide evidence for the involvement of the EGF-CFC protein FRL1, and suggest that the pro-domain of Xnr3 may be required for its activity. Since Xnr3 is a direct target of the maternal βcatenin/XTcf3 signaling pathway, it provides the link between the initial, maternally controlled, allocation of cell fate, and the morphogenetic movements of cells derived from the organizer.
Provitamin A conversion to retinal via theβ,β-carotene-15,15′-oxygenase (bcox) is essential for pattern formation and differentiation during zebrafish embryogenesis
Authors: Lampert Johanna M. , Holzschuh Jochen , Hessel Susanne , Driever Wolfgang , Vogt Klaus , von Lintig Johannes
Published: March 2003

The egg yolk of vertebrates contains carotenoids, which account for its characteristic yellow color in some species. Such plant-derived compounds,e.g. β-carotene, serve as the natural precursors (provitamins) of vitamin A, which is indispensable for chordate development. As egg yolk also contains stored vitamin A, carotenoids have so far been solely discussed as pigments for the coloration of the offspring. Based on our recent molecular identification of the enzyme catalyzing provitamin A conversion to vitamin A,we address a possible role of provitamin A during zebrafish (Danio rerio) development. We cloned the zebrafish gene encoding the vitamin A-forming enzyme, a β,β-carotene-15,15′-oxygenase. Analysis of its mRNA expression revealed that it is under complex spatial and temporal control during development. Targeted gene knockdown using the morpholino antisense oligonucleotide technique indicated a vital role of the provitamin A-converting enzyme. Morpholino-injected embryos developed a morphological phenotype that included severe malformation of the eyes, the craniofacial skeleton and pectoral fins, as well as reduced pigmentation. Analyses of gene expression changes in the morphants revealed that distinct retinoic acid-dependent developmental processes are impaired, such as patterning of the hindbrain and differentiation of hindbrain neurons, differentiation of neural crest derivatives (including the craniofacial skeleton), and the establishment of the ventral retina. Our data provide strong evidence that, for several developmental processes, retinoic acid generation depends on local de novo formation of retinal from provitamin A via the carotene oxygenase, revealing an unexpected, essential role for carotenoids in embryonic development.
Altered myogenesis inSix1-deficient mice
Authors: Laclef Christine , Hamard Ghislaine , Demignon Josiane , Souil Evelyne , Houbron Christophe , Maire Pascal
Published: March 2003

Six homeoproteins are expressed in several tissues, including muscle,during vertebrate embryogenesis, suggesting that they may be involved in diverse differentiation processes. To determine the functions of the Six1 gene during myogenesis, we constructed Six1-deficient mice by replacing its first exon with the lacZ gene. Mice lacking Six1 die at birth because of severe rib malformations and show extensive muscle hypoplasia affecting most of the body muscles in particular certain hypaxial muscles. Six1–/– embryos have impaired primary myogenesis, characterized, at E13.5, by a severe reduction and disorganisation of primary myofibers in most body muscles. While Myf5,MyoD and myogenin are correctly expressed in the somitic compartment in early Six1–/– embryos, by E11.5 MyoD and myogenin gene activation is reduced and delayed in limb buds. However, this is not the consequence of a reduced ability of myogenic precursor cells to migrate into the limb buds or of an abnormal apoptosis of myoblasts lacking Six1. It appears therefore that Six1 plays a specific role in hypaxial muscle differentiation,distinct from those of other hypaxial determinants such as Pax3, cMet,Lbx1 or Mox2.
Comparative analysis of neurogenesis in the myriapodGlomeris marginata(Diplopoda) suggests more similarities to chelicerates than to insects
Authors: Dove Hilary , Stollewerk Angelika
Published: March 2003

Molecular data suggest that myriapods are a basal arthropod group and may even be the sister group of chelicerates. To find morphological indications for this relationship we have analysed neurogenesis in the myriapod Glomeris marginata (Diplopoda). We show here that groups of neural precursors, rather than single cells as in insects, invaginate from the ventral neuroectoderm in a manner similar to that in the spider: invaginating cell groups arise sequentially and at stereotyped positions in the ventral neuroectoderm of Glomeris, and all cells of the neurogenic region seem to enter the neural pathway. Furthermore, we have identified an achaete-scute, a Delta and a Notch homologue in Glomeris. The genes are expressed in a pattern similar to the spider homologues and show more sequence similarity to the chelicerates than to the insects. We conclude that the myriapod pattern of neural precursor formation is compatible with the possibility of a chelicerate-myriapod sister group relationship.
Fgf3 and Fgf8 dependent and independent transcription factors are required for otic placode specification
Authors: Liu Dong , Chu Hsin , Maves Lisa , Yan Yi-Lin , Morcos Paul A. , Postlethwait John H. , Westerfield Monte
Published: March 2003

The vertebrate inner ear develops from the otic placode, an ectodermal thickening that forms adjacent to the presumptive hindbrain. Previous studies have suggested that competent ectodermal cells respond to signals from adjacent tissues to form the placode. Members of the Fgf family of growth factors and the Dlx family of transcription factors have been implicated in this signal-response pathway. We show that compromising Fgf3 and Fgf8 signaling blocks ear development; only a few scattered otic cells form. Removal of dlx3b, dlx4b and sox9a genes together also blocks ear development, although a few residual cells form an otic epithelium. These cells fail to form if sox9b function is also blocked. Combined loss of Fgf signaling and the three transcription factor genes, dlx3b,dlx4b and sox9a, also completely eliminates all indications of otic cells. Expression of sox9a but not dlx3b, dlx4b or sox9b requires Fgf3 and Fgf8. Our results provide evidence for Fgf3-and Fgf8-dependent and -independent genetic pathways for otic specification and support the notion that Fgf3 and Fgf8 function to induce both the otic placode and the epithelial organization of the otic vesicle.
TheArabidopsismutantferoniadisrupts the female gametophytic control of pollen tube reception
Authors: Huck Norbert , Moore James M. , Federer Michael , Grossniklaus Ueli
Published: March 2003

Reproduction in angiosperms depends on communication processes of the male gametophyte (pollen) with the female floral organs (pistil, transmitting tissue) and the female gametophyte (embryo sac). Pollen-pistil interactions control pollen hydration, germination and growth through the stylar tissue. The female gametophyte is involved in guiding the growing pollen tube towards the micropyle and embryo sac. One of the two synergids flanking the egg cell starts to degenerate and becomes receptive for pollen tube entry. Pollen tube growth arrests and the tip of the pollen tube ruptures to release the sperm cells. Failures in the mutual interaction between the synergid and the pollen tube necessarily impair fertility. But the control of pollen tube reception is not understood. We isolated a semisterile, female gametophytic mutant from Arabidopsis thaliana, named feronia after the Etruscan goddess of fertility, which impairs this process. In the feroniamutant, embryo sac development and pollen tube guidance were unaffected in all ovules, although one half of the ovules bore mutant female gametophytes. However, when the pollen tube entered the receptive synergid of a feronia mutant female gametophyte, it continued to grow, failed to rupture and release the sperm cells, and invaded the embryo sac. Thus, the feronia mutation disrupts the interaction between the male and female gametophyte required to elicit these processes. Frequently, mutant embryo sacs received supernumerary pollen tubes. We analysed feronia with synergid-specific GUS marker lines, which demonstrated that the specification and differentiation of the synergids was normal. However, GUS expression in mutant gametophytes persisted after pollen tube entry, in contrast to wild-type embryo sacs where it rapidly decreased. Apparently, the failure in pollen tube reception results in the continued expression of synergid-specific genes, probably leading to an extended expression of a potential pollen tube attractant.
Synthesis, Crystal Structure, and Nonlinear Optical Property of Two New Chromophores Containing Furan Ring as a Conjugation Bridge
Authors: Zhang Wei , Hua Jianli , Shao Pin , Ren Peng , Qin Jingui , Zhang Yu , Lu Zuhong , Hu Huaimin , Zhang Deqing
Published: March 2003

Two new organic chromophores containing furan ring as a conjugation bridge located near the donor have been synthesized and characterized by X-ray single crystal structure determination. Their first molecular hyperpolarizability (β) are measured by Hyper-Rayleigh Scattering (HRS) technique.
Efficient Electron Injection Characteristics of Tetra-2-pyridinylpyrazine (TPP) in Organic Light Emitting Diodes
Authors: Oyamada Takahito , Maeda Chiharu , Sasabe Hiroyuki , Adachi Chihaya
Published: March 2003

We showed that tetra-2-pyridinylpyrazine (TPP) and TPP: cesium (1:1 molar ratio) composite layers had excellent electron injection and transport characteristics in organic light emitting diodes. High luminescence efficiency with low driving voltage was observed in various cathode configurations, suggesting that the TPP layer can efficiently accept electrons from metal and metal oxide cathode layers, and transport and inject electrons into an adjacent organic layer.
A Convenient Method for the Synthesis of 2-Arylaziridines from Styrene Derivatives via 2-Arylethenyl(diphenyl)sulfonium Salts
Authors: Matsuo Jun-ichi , Yamanaka Hiroyuki , Kawana Asahi , Mukaiyama Teruaki
Published: March 2003

Styrene derivatives reacted with diphenyl(trifluoromethanesulfonyloxy)sulfonium trifluoromethanesulfonate (1) at low temperature to afford 2-arylethenyl(diphenyl)sulfonium triflates (2). Treatment of 2 with primary amines gave the corresponding 2-arylaziridines in high yields. One-pot synthesis of various aziridines was also successfully carried out without isolation of the intermediate 2.
Detection of Hydroxyl Radicals Formed on an Anodically Polarized Diamond Electrode Surface in Aqueous Media
Authors: Komatsu Masaharu , Rao Tata Narasinga , Fujishima Akira
Published: March 2003

Electrochemically generated hydroxyl radicals at anodically polarized boron-doped diamond electrodes in aqueous media have been suggested to be responsible for their ability to electrochemically incinerate organic waste. In this letter, for the first time, we provide experimental evidence for the generation of hydroxyl radicals by using coumarin followed by the fluorescence detection of its hydroxylated product.
Synthesis of an Environmentally Friendly and Nontoxic New Pigment Based on Rare Earth Phosphate
Authors: Imanaka Nobuhito , Masui Toshiyuki , Itaya Masaharu
Published: March 2003

A new inorganic pigment based on rare earth phosphate has been synthesized with the goal of preparing ecologically and environmentally friendly specific pigments. A yellow–green pigment that consists of nontoxic elements was obtained by doping calcium ions into the cerium orthophosphate lattice. Characterizations using XRD, UV–vis spectroscopy, and colorimetric assessment revealed that the formation of a Ca-doped CePO4 solid solution was responsible for the appearance of the color.
Oligothiophene/fullerene Dyads as Active Photovoltaic Materials
Authors: Negishi Nobukazu , Yamada Kohei , Takimiya Kazuo , Aso Yoshio , Otsubo Tetsuo , Harima Yutaka
Published: March 2003

Oligothiophene/fullerene dyads (nT-C60) are incorporated in photovoltaic cells, which demonstrate relatively high incident photon-to-current efficiency. The monochromatic power conversion efficiency of the Al/16T-C60/Au device measured at 456 nm is 0.4%.
Chiral Recognition with Crown Ethers Having Planar Chiral (η4-Diene)tricarbonyliron Moieties
Authors: Yamaguchi Hiroshi , Nakanishi Saburo , Kihara Nobuhiro , Takata Toshikazu
Published: March 2003

Crown ethers with a planar chiral (1,3-η4-diene)tricarbonyliron unit were prepared. They revealed a good chiral recognition ability for α-substituted benzylammonium salts (Krel = 1.3–2.0). Ligand substitution of the iron tricarbonyl moiety with triphenylphosphane inverted the chiral selectivity.
Airflow within major Alpine river valleys under heavy rainfall
Authors: Steiner Matthias , Bousquet Olivier , Houze Robert A. , Smull Bradley F. , Mancini Marco
Published: March 2003

This study documents the airflow within major Alpine river valleys in the presence of precipitation. The analysis seeks a conceptual understanding of the effect of rain on the valley flow. Ground‐based and airborne Doppler radar and surface data from the Mesoscale Alpine Programme show that during persistent rainy periods the subsidence caused by melting and evaporation of precipitation particles contributes to the formation of a down‐valley flow. This down‐valley flow opposes moist southerly flow aloft, which is lifted over the topographic barrier and in which precipitation particles are formed. Copyright © 2003 Royal Meteorological Society.
Orographic effects on rainfall in MAP cases IOP 2b and IOP 8
Authors: Rotunno Richard , Ferretti Rossella
Published: March 2003

Although the large‐scale flow was similar, important differences in mesoscale atmospheric structure made the difference between moderately intense rain in Intensive Observing Period (IOP) 2b and relatively light rain in IOP 8 in the Lago Maggiore Target Area (LMTA). This conclusion is supported here through analysis of data from, and numerical simulations of, these two cases. Analysis of the large‐scale data shows that there was in both cases a moist tongue of southerly flow moving from the west to the east of the Alpine south side. Mesoscale data analysis and numerical simulations suggest that the most important difference between the two cases was the presence of a cold stable air mass in the Po Valley in IOP 8 which persisted through the period in which the large‐scale moist tongue was progressing eastward and prevented the most humid air from reaching the LMTA. Another difference contributing to the greater rainfall in the LMTA in IOP 2b was the development of conditional instability (with associated convective rain) due to the effect of the Alps on the eastward passage of the moist tongue; in IOP 8 the atmosphere remained locally stable throughout the period. Copyright © 2003 Royal Meteorological Society
Analysis of a potential‐vorticity streamer crossing the Alps during MAP IOP 15 on 6 November 1999
Authors: Hoinka Klaus P. , Richard Evelyne , Poberaj Gorazd , Busen Reinhold , Caccia Jean‐luc , Fix Andreas , Mannstein Hermann
Published: March 2003

In this study a potential‐vorticity (PV) streamer which crossed the Alps during the Special Observing Period of the Mesoscale Alpine Programme (MAP) on 6 November 1999 is analysed. In situ aircraft data, wind‐profiler data, model output data from the French non‐hydrostatic mesoscale model (Meso‐NH), and European Centre for Medium‐Range Weather Forecasts (ECMWF) analyses are used to describe the structure and evolution of the streamer. In addition lower‐stratospheric humidity which was remotely sensed by a Differential Absorption Lidar (DIAL) installed on board the aircraft is analysed. The comparison of measured and simulated lower‐stratospheric humidity data show good agreement in structure and magnitude. The data analysis also reveals that waves are generated by the orography and transmitted into the lower stratosphere where they modify the streamer's PV structure. The impact of orography and diabatic processes on the streamer's evolution is simulated with MesoNH in a series of simulations. These simulations demonstrate that the separate effects of orography and diabatic processes are significant and comparable in magnitude, and that their combined influence leads to the formation of a PV cut‐off. As a synergetic effect it is found that PV filaments are generated north of the Alpine barrier. The influence of orography and diabatic processes reduces the lower‐stratospheric and upper‐tropospheric PV by about 25% above the Alps, compared with the situation where neither effect is present. Copyright © 2003 Royal Meteorological Society.
Relations between radar reflectivity, liquid‐water content, and rainfall rate during the MAP SOP
Authors: Hagen Martin , Yuter Sandra E.
Published: March 2003

Raindrop size distribution data obtained from two Joss–Waldvogel disdrometers located at Locarno‐Monti, Switzerland during the Mesoscale Alpine Programme (MAP) Special Observation Period are analysed to obtain appropriate relationships of radar reflectivity, Z, with both water content, W, and surface rainfall, R, for use in MAP applications. The disdrometer data are accumulated into 10‐minute samples to reduce sampling error associated with the ∼ 1 m3 sample volume of the instruments. Based on previous studies, relations of the form W=qZ(4/7) and Z=aR1.5 are assumed and the coefficients q and a are estimated from the data. The combined dataset of 10‐minute samples from the two disdrometers and the 10‐minute data divided into two independent subsets yielded similar mean values of the coefficients. The recommended relationships are W=3.4Z(4/7) and Z=216R1.5. The uncertainties in these mean relationships as expressed in terms of ±1 standard deviation are approximately equivalent to a ±4.4 dBZ error for the Z–W relationship, and to a ±2.4 dBZ error for the Z–R relationship. Copyright © 2003 Royal Meteorological Society
Substructure of a MAP streamer
Authors: Liniger Mark A. , Davies Huw C.
Published: March 2003

A study is undertaken of the substructure of an upper‐level potential‐vorticity streamer that approached the European Alps during the field phase of the Mesoscale Alpine Programme (MAP). The diagnosis is based upon a Lagrangian Forward Projection (LFP) technique which can provide a spatial refinement of the operational European Centre for Medium‐Range Weather Forecasts analysis fields. The reconstructed fields capture several notable fine‐scale features of the streamer's structure that include spiral arms of a vortex‐like feature and a richly structured western flank to the streamer comprising a deep primary fold surmounted by a significant secondary fold with an intermediate distinctive striation that extends back into the stratosphere.

These features are not at variance with independent high‐resolution satellite water‐vapour images and measurements gathered during a flight mission using an airborne water‐vapour DIfferential Absorption Lidar (DIAL) instrument, and hence lend a measure of credence to both the LFP approach and the DIAL measurements. Moreover, the analysis sheds light on the evolution and dynamics of the streamer's vortices, the origin of the folds, the mismatch between the satellite observations and fields from other sources, and also has implications for stratosphere–troposphere exchange and the accompanying chemical mixing. Copyright © 2003 Royal Meteorological Society.
Scale interaction processes during the MAP IOP 12 south föhn event in the Rhine Valley
Authors: Drobinski P. , Haeberli C. , Richard E. , Lothon M. , Dabas A. M. , Flamant P. H. , Furger M. , Steinacker R.
Published: March 2003

This paper examines the three‐dimensional structure and dynamics of a south föhn flow in the Rhine Valley during its entire life cycle from 29 October 1999 until 31 October 1999. The south föhn event was documented in the framework of the Mesoscale Alpine Programme (MAP). This study investigates the synoptic‐scale forcing sources, the dynamical processes driving the circulation of the föhn flow in the complex network of tributaries of the Rhine Valley, and the degree of inhomogeneity on the scale of the FORM (‘FOehn in the Rhine Valley during the MAP’ programme) target area at the bifurcation between the Rhine and Seez Valleys. Several important data sources were used (ground‐based Doppler lidar, scintillometers, constant‐volume balloons, radiosoundings and surface stations) as well as non‐hydrostatic mesoscale simulations.

The föhn penetrating the FORM target area on 30 October 1999 is preceded by a nocturnal shallow föhn phase which does not penetrate down to the ground due to katabatic drainage flow from the main transverse (east–west oriented) tributaries in which föhn cannot penetrate. This paper shows the contribution of the main tributaries of the Rhine Valley in directing the föhn flow towards the FORM target area during (i) the shallow föhn phase where the westerly upper‐level flow is deflected in the main longitudinal (i.e. north–south oriented) tributaries; (ii) the penetrating föhn phase, where the south/south‐westerly upper‐level flow is nearly aligned with the longitudinal tributaries. The channelling efficiency of the main longitudinal tributaries of the Rhine Valley (particularly the Domleschg) is higher during the föhn phase when the south‐westerly upper‐level flow, experiencing mountain‐wave‐induced downward motion, penetrates these tributaries, than during the shallow föhn.

In the FORM target area, the structure of the föhn flow varies on a 1‐kilometre horizontal length‐scale and the time evolution of the respective location of the cold air pool and the warm föhn air is investigated in detail. Also, flow splitting between the Rhine and Seez Valleys occurs during the entire föhn life cycle, but its vertical extension is maximum during shallow föhn, when lower‐ and upper‐level flows are fully decoupled. Copyright © 2003 Royal Meteorological Society.
Multiscale and unsteady aspects of a deep föhn event during MAP
Authors: Jaubert Genevieve , Stein Joel
Published: March 2003

A strong föhn event occurring during the Mesoscale Alpine Programme Intensive Observing Period 2b (19–20 September) is simulated with the non‐hydrostatic model Meso‐NH. The grid‐nesting techniques and a suitable turbulence scheme allow a coherent downscaling from the analysed scales to the movements inside the Rhine Valley. The flow regime around the Alps changes from a flow‐around regime to a flow‐partly‐over regime, when the wind increases ahead of the cold front. Simplified simulations allow us to estimate a non‐dimensional height for the Alps which controls the flow regime. The föhn characteristics and its temporal evolution are discussed using both measurements and simulation. Backward trajectories show that the föhn air comes from an altitude around 2 km above the Po Valley. Nonlinear phenomena, such as wave breaking near 5 km above sea level just behind some secondary crests, and hydraulic jumps in the foothills, are found in the highest‐resolution simulation, using a mesh of 625 m. This mesh clearly improves the comparison of the numerical simulation with the observations collected in the Rhine Valley. Mass budgets detail the progressive building of the föhn jet in the Rhine Valley. Copyright © 2003 Royal Meteorological Society.
Verification of high‐resolution real‐time forecasts over the Alpine region during the MAP SOP
Authors: Ferretti R. , Paolucci T. , Giuliani G. , Cherubini T. , Bernardini L. , Visconti G.
Published: March 2003

An analysis is presented of the MM5 high‐resolution operational weather forecasts performed during the Special Observing Period (SOP) of the Mesoscale Alpine Programme (MAP). The domain‐averaged model biases of both surface pressure and 2 m temperature suggest MM5 shortcomings related to the surface temperature cycle. The root mean square errors (r.m.s.e.s) for temperature, wind and relative humidity at two different levels and for several forecast times support this finding. The model results show difficulties in forecasting the 2 m temperature during periods of fair weather; furthermore, a few difficulties are found in forecasting the minimum of the temperature for regions under strong marine influence, such as Baleari station. The equitable threat score (ETS), for a few selected IOPs (Intensive Observing Periods) having precipitation over the Po Valley, is used together with the areal distribution of the r.m.s.e.s to evaluate the MM5 at high resolution over the Alpine region. The results show reasonable skill in this region when the model is used in the high‐resolution mode. The ETS using only the stations over the mountains or the plains, suggests a better model skill in the mountain areas than in the valley; whereas the r.m.s.e.s show an MM5 tendency to produce larger errors on the eastern side of the Po Valley than on the western side.

Finally, the analysis of the precipitation time series for IOP 2b, at a few selected stations, confirms the model tendency to underestimate the rainfall at stations located along the Po Valley and to shorten the period of the precipitation. Copyright © 2003 Royal Meteorological Society.
Observations and impacts of upstream blocking during a widespread orographic precipitation event
Authors: Bousquet Olivier , Smull Bradley F.
Published: March 2003

A unique combination of airborne and ground‐based Doppler radar observations, stretching continuously from the Alps south to the Mediterranean Sea, is assembled to document profoundly blocked airflow and associated modification of precipitation processes upstream of the Alps during Intensive Observing Period 8 of the Mesoscale Alpine Programme. This diversion of incident southerly low‐level winds in advance of a deep baroclinic trough served to reduce markedly the transport of warm, moist Mediterranean air toward the steep Alpine slopes. Heavy rains forecast in this flood‐prone region thus failed to materialize, with lighter (though protracted) stratiform precipitation extending over the comparatively flat reaches of the adjacent Po Valley. Release of convective instability did occur, but was displaced well south of the Alps over the coastal Apennine mountain chain and adjacent waters of the Mediterranean Sea. Influences on a variety of scales that evidently led to development of this blocked flow are examined, and multiple expressions of upstream blocking are identified. These range from pervasive down‐valley flows observed within multiple deep Alpine river drainages to a larger‐scale cool easterly low‐level flow channelled alongside the curving south face of the Alps, which was ultimately extruded southward over the Mediterranean. Observed thermodynamic profiles in these contrasting regimes are presented and related to the observed precipitation structure. Copyright © 2003 Royal Meteorological Society.
High‐resolution numerical simulations of the convective system observed in the Lago Maggiore area on 17 September 1999 (MAP IOP 2a)
Authors: Richard Evelyne , Cosma Stephanie , Tabary Pierre , Pinty Jean‐pierre , Hagen Martin
Published: March 2003

During Intensive Observing Period (IOP) 2a of the Mesoscale Alpine Programme (MAP) a significant convective system developed in the Lago Maggiore area. Its evolution is simulated using the Meso‐NH model run over three nested domains with a 2 km horizontal resolution for the finest grid. Model results are assessed by comparing computed precipitation and model radar reflectivities with observed parameters. A control simulation initialized with European Centre for Medium‐Range Weather Forecasts analyses and run with the standard microphysical scheme of the model yields fairly realistic results. Neglecting the ice processes in the microphysical scheme degrades the numerical results, whereas, significant improvement is obtained when heavy rimed particles are considered to be hail instead of graupel. Copyright © 2003 Royal Meteorological Society.
Intraoperative Cholangiography and Risk of Common Bile Duct Injury During Cholecystectomy
Authors: Flum David R. , Dellinger E. Patchen , Cheadle Allen , Chan Leighton , Koepsell Thomas
Published: April 2003

Context

Intraoperative cholangiography (IOC) may decrease the risk of common bile duct (CBD) injury during cholecystectomy by helping to avoid misidentification of the CBD.

Objective

To characterize the relationship of IOC use and CBD injury while controlling for patient and surgeon characteristics.

Design, Setting, and Patients

Retrospective nationwide cohort analysis of Medicare patients undergoing cholecystectomy from January 1, 1992, to December 31, 1999. Patients were identified using Current Procedural Terminology codes from the Medicare Part B depository. Common bile duct injury was defined by a second surgical procedure to repair the CBD injury within 1 year of cholecystectomy. Surgeon demographic features were obtained from matching the Medicare Part B data to the American Medical Association Physician Masterfile database.

Main Outcome Measure

Frequency of CBD injury in patients who did and did not have IOC performed during cholecystectomy, controlling for patient-level (age, sex, race, and case complexity) and surgeon-level (surgeon's age, sex, race, year of surgical procedure, case order, percentage of IOC use in prior surgical procedures, years in medical practice, board certification, and specialization) factors.

Results

The database search identified 1 570 361 cholecystectomies and 7911 CBD injuries (0.5%). Common bile duct injury was found in 2380 (0.39%) of 613 706 patients undergoing cholecystectomy with IOC and in 5531 (0.58%) of 956 655 patients undergoing cholecystectomy without IOC (unadjusted relative risk, 1.49; 95% confidence interval, 1.42-1.57). After controlling for patient-level factors and surgeon-level factors, the risk of injury was increased when IOC was not used (adjusted relative risk, 1.71; 95% confidence interval, 1.38-2.28). While surgeons performing IOCs routinely had a lower rate of CBD injuries than those who did not, this difference disappeared when IOC was not used.

Conclusions

In this study of Medicare patients undergoing cholecystectomy in the 1990s, the risk of CBD injury was significantly higher when IOC was not used. Although IOCs may not prevent all CBD injuries, this study suggests that the routine use of IOC may decrease the rate of CBD injury.
Effect of Hydroxyurea on Mortality and Morbidity in Adult Sickle Cell Anemia
Authors: Steinberg Martin H. , Barton Franca , Castro Oswaldo , Pegelow Charles H. , Ballas Samir K. , Kutlar Abdullah , Orringer Eugene , Bellevue Rita , Olivieri Nancy , Eckman James , Varma Mala , Ramirez Gloria , Adler Brian , Smith Wally , Carlos Timothy , Ataga Kenneth , DeCastro Laura , Bigelow Carolyn , Saunthararajah Yogen , Telfer Margaret , Vichinsky Elliott , Claster Susan , Shurin Susan , Bridges Kenneth , Waclawiw Myron , Bonds Duane , Terrin Michael
Published: April 2003

Context

Hydroxyurea increases levels of fetal hemoglobin (HbF) and decreases morbidity from vaso-occlusive complications in patients with sickle cell anemia (SCA). High HbF levels reduce morbidity and mortality.

Objective

To determine whether hydroxyurea attenuates mortality in patients with SCA.

Design

Long-term observational follow-up study of mortality in patients with SCA who originally participated in the randomized, double-blind, placebo-controlled Multicenter Study of Hydroxyurea in Sickle Cell Anemia (MSH), conducted in 1992-1995, to determine if hydroxyurea reduces vaso-occlusive events. In the MSH Patients' Follow-up, conducted in 1996-2001, patients could continue, stop, or start hydroxyurea. Data were collected during the trial and in the follow-up period.

Setting

Inpatients and outpatients in 21 sickle cell referral centers in the United States and Canada.

Patients

Two-hundred ninety-nine adult patients with frequent painful episodes enrolled in the follow-up. Follow-up data through May 2001 were complete for 233 patients.

Intervention

In the MSH, patients were randomly assigned to receive hydroxyurea (n = 152) or placebo (n = 147).

Main Outcome Measure

Mortality, HbF levels, painful episodes, acute chest syndrome, and blood cell counts. The randomized trial was not designed to detect specified differences in mortality.

Results

Seventy-five of the original 299 patients died, 28% from pulmonary disease. Patients with reticulocyte counts less than 250 000/mm3 and hemoglobin levels lower than 9 g/dL had increased mortality (P = .002). Cumulative mortality at 9 years was 28% when HbF levels were lower than 0.5 g/dL after the trial was completed compared with 15% when HbF levels were 0.5 g/dL or higher (P = .03 ). Individuals who had acute chest syndrome during the trial had 32% mortality compared with 18% of individuals without acute chest syndrome (P = .02). Patients with 3 or more painful episodes per year during the trial had 27% mortality compared with 17% of patients with less frequent episodes (P = .06). Taking hydroxyurea was associated with a 40% reduction in mortality (P = .04) in this observational follow-up with self-selected treatment. There were 3 cases of cancer, 1 fatal.

Conclusions

Adult patients taking hydroxyurea for frequent painful sickle cell episodes appear to have reduced mortality after 9 of years follow-up. Survival was related to HbF levels and frequency of vaso-occlusive events. Whether indications for hydroxyurea treatment should be expanded is unknown.