Search Results - (Author, Cooperation:C. Aguilera)

2011-01-05

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Acetylation ; Animals ; Cell Line, Tumor ; Cell Proliferation ; Colonic Neoplasms/metabolism/pathology ; DNA-Binding Proteins/*antagonists & inhibitors/deficiency/*metabolism ; Gene Expression Regulation, Neoplastic ; Histones/metabolism ; Intestines/cytology ; JNK Mitogen-Activated Protein Kinases/metabolism ; Mi-2 Nucleosome Remodeling and Deacetylase Complex/*antagonists & ; inhibitors/chemistry/*metabolism ; Mice ; Phosphorylation ; Promoter Regions, Genetic/genetics ; Protein Binding ; Proto-Oncogene Proteins c-jun/*chemistry/*metabolism ; Receptors, G-Protein-Coupled/genetics ; Stem Cells/cytology ; Transcription Factors/*antagonists & inhibitors/deficiency/*metabolism

1365-4632

Blackwell Publishing Journal Backfiles 1879-2005

Medicine

Electronic Resource

1432-1920

Chiari malformation ; Dysraphism ; Lipoma ; Lipomyelomeningocele ; Magnetic resonance imaging ; Syringomyelia

Springer Online Journal Archives 1860-2000

Medicine

Abstract Co-existence of Chiari I malformation and myelomeningocele is uncommon. Syringomyelia, when associated with a Chiari I malformation, classically involves the cervical spinal cord. Intramedullary extension of lipoma is unusual in lipomyeloschisis. A patient with lumbar lipomyelomeningocele with tethered cord, lower thoracic syringomyelia and Chiari I malformation, shown by MRI is reported.

Electronic Resource

1365-3040

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Abstract. The effect of growth temperatures on quantum yield (φ) was examined for leaves at different stages of development within the immature canopies of two crops of field grown maize (Zea mays cv. LG11) sown on 3 May and 20 June 1990. During the period of 23 to 49d after sowing, the crop sown on the 3 May experienced temperatures below 10°C on 19 occasions compared with only two for the crop sown on 20 June. A period of severe chilling at the end of May and the beginning of June was associated with a marked reduction in φ for all leaves in the early-sown crop. This chill-induced depression in φ was greater in recently emerged than more mature leaves in the canopy and was found to be accompanied by modifications in the polypeptide profiles of thylakoids isolated from the leaves. During the chilling period, decreases in some polypeptides, notably in the range of 41–42 and 20kDa apparent molecular size, and increases of polypeptides of c. 15–16kDa were observed compared with leaves developing at warmer temperatures in July. The efficiency of converting intercepted radiation into dry matter (conversion efficiency) was 42% lower in the early- than late-sown crop, but no significant relationship between conversion efficiency and quantum yield was found in either treatment.

Electronic Resource

1399-3054

Blackwell Publishing Journal Backfiles 1879-2005

Biology

Six genotypes of Zea mays L. were grown in pots inside a glasshouse at a mean temperature of 22±2°C and a minimum photosynthetic photon flux density (Q) during the daylight period of 400 μmol m−2 s−1. Chilling-dependent photoinhibition was induced by exposing plants to a temperature of 7°C and a Q of 1 000 μmol m−2 s−1 for 6 h. Recovery from photoinhibition was then followed at a temperature of 25°C and a Q of 200 μmol m−2 s−1. Leaf gas exchange and chlorophyll fluorescence were measured on attached leaves at room temperature prior to the photoinhibitory treatments and at 6 sampling intervals from 0 to 24 h during the recovery period. The relative water content (RWC) was also measured during the recovery period. The results showed a significant genotypic variation in the susceptibility to and rate of recovery from chilling-dependent photoinhibition of photosynthesis in Zea mays seedlings. The Highland Pool 1a from highland sites in Mexico was the least susceptible to chill-induced photoinhibition, but had the slowest rate of recovery. The hybrid variety LG11 showed the highest rate of recovery, whilst the inbred line ZPF307 was the most susceptible to chill-induced photoinhibition. Susceptibility to photoinhibition and subsequent recovery were at least partially independent, suggesting that selection for improved genotypes will require independent selection for both tolerance and capacity for recovery. Although chlorophyll fluorescence provided a more rapid method of assessing the occurrence of photoinhibition, it was not as effective as direct gas-exchange measurements of the maximum quantum yield of photosynthesis (φ) in separating genotypes with respect to their susceptibility to photoinhibition, especially in the most vulnerable genotypes such as ZPF307. Water stress induced by chilling and high Q treatments appeared to impair the recovery processes. Decreases in stomatal conductance (gs) produce a significant decrease in intercellular CO2 concentration (Ci), although this decrease was never so extreme that it limited photosynthetic rates at the light intensities used to determine φ. Nevertheless, closure of stomata in patches, producing local restriction of CO2 supply, would explain the poor correlation between chlorophyll fluorescence and quantum yield measurements in some genotypes immediately after photoinhibitory treatments.

Electronic Resource

1436-2449

Springer Online Journal Archives 1860-2000

Chemistry and Pharmacology

Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Physics

Summary New thermotropic Polyesters having mesogenic groups based on substituted hydroquinone units and highly flexible oligosiloxan spacer in the main chain, are synthesized and characterized. The mesophase formed at low temperature are studied by differential scanning calorimetry (DSC) and polarized light microscopy. The liquid crystalline behaviour of these polyesters, particulary their transition temperatures and the mesophase width could be explained on the basis of their structural features.

Electronic Resource

1432-1920

Skull amyloidoma ; Computed tomography ; Magnetic resonance imaging

Springer Online Journal Archives 1860-2000

Medicine

Abstract Amyloidomas involving bone are rare. The 67-year-old man reported here had a large amyloidoma of the left frontal, parietal, sphenoid (greater wing) and temporal bones causing neural compression. Plain radiographs CT and MRI are shown.

Electronic Resource

1432-1920

Key words Skull amyloidoma ; Computed tomography ; Magnetic resonance imaging

Springer Online Journal Archives 1860-2000

Medicine

Abstract Amyloidomas involving bone are rare. The 67-year-old man reported here had a large amyloidoma of the left frontal, parietal, sphenoid (greater wing) and temporal bones causing neural compression. Plain radiographs CT and MRI are shown.

Electronic Resource

1432-1920

Key words Behçet's disease ; Magnetic resonance imaging ; Meninges

Springer Online Journal Archives 1860-2000

Medicine

Abstract Behçet's disease is a multisystem disease that involves the central nervous system up to half of cases. Presentation with neurologic symptoms occurs in 5 % of cases and cerebral venous thrombosis is one of its major manifestations. A feature not previously reported is progressive meningeal thickening with involvement of both optic nerves. We report a patient with cerebral venous thrombosis, meningeal thickening and contrast enhancement on MRI. This patient had two other unusual features: positive antineutrophil cytoplasmic antibodies and later development of central diabetes insipidus.

Electronic Resource

1432-1920

Key words Ganglioglioma ; Neuronal tumours ; Brain ventricles ; Magnetic resonance imaging

Springer Online Journal Archives 1860-2000

Medicine

Abstract We report a case of ganglioglioma located in the body and frontal horn of the right lateral ventricle. The lesion was found in a 71-year-old man who suffered from recurrent episodes of right hemicranial headache. CT and MRI showed a heterogeneous intraventricular tumour with multiple microcysts that suggested a diagnosis of subependymoma or central neurocytoma, but the pathological findings were consistent with ganglioglioma. Although the most frequent intracranial location of ganglioglioma is the temporal lobe, any location in the central nervous system may be seen. Nevertheless an exclusively intraventricular location is exceptional. To our knowledge this is the first complete radiological report of a purely intraventricular ganglioglioma.

Electronic Resource

1432-1920

Key words Pituitary adenoma ; Suprasellar tumour ; Magnetic resonance imaging ; Computed tomography

Springer Online Journal Archives 1860-2000

Medicine

Abstract We present five proven giant pituitary adenomas studied by CT and MRI, and review the clinical and imaging findings. Our aim was to examine the radiologic appearances and to search for criteria useful in distinguishing these tumors from other sellar and suprasellar tumours, mainly craniopharyngioma. The main differences from small adenomas were high prevalence of macrocysts, a more invasive behaviour and a clinical picture dominated by mass effect rather than endocrine disturbance. Factors supporting the diagnosis of pituitary adenoma in a giant intra- and suprasellar mass include: infrasellar extension, absence of calcification and presence of low-signal cysts on T1-weighted images.

Electronic Resource

1432-1084

Key words: Brain neoplasms – Brain ventricles – MR imaging – CT

Springer Online Journal Archives 1860-2000

Medicine

Abstract. Intraventricular tumours represent a diverse group of lesions, some of them infrequent, with a wide variety of radiological features. Determination of their precise aetiology or origin can be difficult. Nevertheless, considering patient's age, location within the ventricles, and some specific radiological features, the radiologist should be able to narrow down the differential diagnosis. This paper reviews the characteristic radiological appearances of the diverse intraventricular lesions emphasising its differential diagnosis.

Electronic Resource

1573-5079

photosynthesis ; leaf age ; maize

Springer Online Journal Archives 1860-2000

Biology

Abstract Changes in the photosynthetic light-response curve during leaf development were determined for the fourth leaf of maize crops sown on 23 April and 10 June. Temperatures were unusually mild during late spring/early summer and neither crop experienced chilling damage. The concept of thermal time was used to take into account the effects of different temperature regimes on developmental stage, thereby enabling photosynthetic light-response data to be combined for both crops to describe the general response. Large variations in the upper asymptote (Asat) and convexity (Θ) of the light-response curve occurred during leaf development, but the maximum quantum yield of CO2 assimilation remained relatively constant throughout. Dark respiration rates showed a small but significant decrease with leaf age and generally ranged between 5 and 10% of Asat. A simple mathematical model was developed to assess the sensitivity of daily leaf photosynthesis (AL) to reductions in the Asat, Θ and the initial slope (Φ) of the light-response curve at different stages of leaf development. On bright sunny days, and at all developmental stages, AL was ca. twice as sensitive to reductions in Asat than to reductions in Φ and Θ. In overcast conditions, however, all three parameters contributed significantly to reductions in leaf photosynthesis, although the contribution of Φ was greatest during early leaf growth, while older leaves were most sensitive to depressions in Asat. The implications of these results for modelling the sensitivity of canopy photosynthesis to chill-induced photoinhibition of the light-response curve are discussed.

Electronic Resource